7,311 results
Search Results
2. Density and salinity effects on the water retention capacity of unsaturated clayey dispersive soil.
- Author
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Han, Yan, Wang, Qing, Liu, Jing, and Lu, Wenxi
- Subjects
CLAY soils ,SOIL moisture ,SALINITY ,ARID regions ,FILTER paper - Abstract
Purpose: Water retention capacity (WRC) is crucial for assessing the hydro-physical behavior of unsaturated soils. Dispersive soil, erodible and found mainly in arid regions, lacks sufficient WRC knowledge, hindering its stability evaluation in unsaturated state. This study aimed to explore the WRC of dispersive soil by measuring its matric suction (ψ) under coupling effects of dry density (ρ
d ) and soluble salt content (η). Materials and method: Compacted specimens with different ρd and η were prepared. For each ρd -η case, six levels of soil mass water content were considered and the ψ was measured via filter paper method. Soil water characteristic curves (SWCCs) were fitted by van Genuchten model. Results and discussion: The WRC of dispersive soil enhances as ρd increases. Increasing η first weakens then strengthens the WRC, showing suction dependence. The air-entry value and residual state suction range within 0.95–17.8 kPa and 15.7–98.4 MPa, respectively. As for the air-entry value, increasing η from 0.3% to 2.0% decreases it from 36.0% to 58.7% when ρd increases, and its average growth rate changes from 174.5% to 265.3% when ρd exceeds 1.53 g/cm3 . Increasing ρd reduces the average water loss rate of SWCC transition stage, while the impact of η is nonmonotonic, with an inflection point at 1.0%. Conclusions: The ρd and η influenced the WRC of dispersive soil individually and interactively. The effect of ρd links to the water release sequence from pores of different sizes, whereas that of η, rather complex and non-monotonic, relates to clay electrochemistry and salt phase. [ABSTRACT FROM AUTHOR]- Published
- 2023
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3. VARIATION IN ANATOMICAL PROPERTIES OF FARM GROWN PTERYGOTA ALATA IN THE SEMI-ARID REGION OF SOUTHERN INDIA.
- Author
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RAJPUT, N. B., SEKAR, I., DIVYA, M. P., BALASUBRAMANIAN, A., RAMAH, K., and PACKIALAKSHMI, M.
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ANATOMICAL variation ,ARID regions ,INSECTS ,PAPER pulp ,FARMS - Abstract
The study was conducted at the Forest College and Research Institute, Mettupalayam, during 2019-2022, to explore new alternative pulpwood species with good paper-making potential. The samples were collected from seeds origin Pterygota alata which were farm grown in Pollachi, India. A total of 12 trees were removed with a specification of four different girth classes (30-45, 45-90, 120-150, 150-180 cm), from that 6 samples were collected from three different radial positions (pith, middle, and periphery) with the dimension of 2x2x2 cm³. Then samples were subjected to microtomy, maceration, and optical analysis. Fibre, vessel, and ray anatomy were studied in the current investigation. Results revealed that the maximum value of fibre length (1458.96 ±3.47 μm), fibre diameter (25.50±1.29 μm), vessel diameter (74.94±0.13 μm), vessels area (47723.47±359.67 μm²), ray height (1731.89±46.89 μm) ray width (165.07±1.41 μm) and ray frequency (5.51±0.02 ray/mm²) were identified at the peripheral region at the girth of 150-180 and 120-150 cm. The study suggested that Pterygota alata could be the prominent alternate species for pulp and paper production. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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4. 2021 APCG Student Paper Awards.
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STUDENT awards , *ENVIRONMENTAL justice , *POOR communities , *COMMUNITIES , *ARID regions , *FOOD security - Published
- 2022
5. Spatiotemporal variation of groundwater quality in an arid area experiencing long-term paper wastewater irrigation, northwest China.
- Author
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Wu, Jianhua, Wang, Lei, Wang, Siting, Tian, Rui, Xue, Chenyang, Feng, Wei, and Li, Yinghao
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GROUNDWATER quality ,SEWAGE ,PAPER industry ,ARID regions ,IRRIGATION ,CHEMICAL oxygen demand ,AMMONIA ,COMPOSITION of water - Abstract
Groundwater is crucial for multiple uses over the world, especially in arid and semiarid regions. However, human activities significantly decreased groundwater quality. In this study, the spatiotemporal variation of groundwater quality was evaluated in an arid area where long-term paper wastewater irrigation has been implemented. For this study, seven wells were regularly monitored for physicochemical parameters over a period of 1 year. Statistical and graphical approaches were applied to interpret the spatiotemporal variation of groundwater quality parameters in the wastewater irrigation zone. Correlation analysis was also carried out to reveal the sources of some major ions. The results indicate that the groundwater type in the study area is dominated by the Cl-Na, followed by the HCO-Na, the HCO-Ca·Mg, and the SO·Cl-Ca·Mg types. Groundwater in the area is significantly contaminated locally with fluoride, nitrite and ammonia, and the chemical oxygen demand levels were increased in some groundwater monitoring wells. Most contaminants showed an increasing trend from the Yellow River water irrigation zone toward the wastewater irrigation zone. Rock weathering, mineral dissolution, and cation exchange are important processes controlling groundwater quality, but human activities, such as wastewater irrigation, play an undeniable role in affecting groundwater quality in this area. The results of this study contribute to the understanding of the formation and circulation of groundwater under human activities and provide a scientific basis for regional water quality evaluation, water quality improvement, and protection. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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6. Revisiting the paper “Using radiometric surface temperature for surface energy flux estimation in Mediterranean drylands from a two-source perspective”.
- Author
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Kustas, William P., Nieto, Hector, Morillas, Laura, Anderson, Martha C., Alfieri, Joseph G., Hipps, Lawrence E., Villagarcía, Luis, Domingo, Francisco, and Garcia, Monica
- Subjects
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RADIOMETRY , *RADIATION measurement instruments , *SURFACE temperature , *SURFACE energy , *FLUX (Energy) , *ARID regions - Abstract
The recent paper by Morillas et al. [Morillas, L. et al. Using radiometric surface temperature for surface energy flux estimation in Mediterranean drylands from a two-source perspective, Remote Sens. Environ. 136, 234–246, 2013] evaluates the two-source model (TSM) of Norman et al. (1995) with revisions by Kustas and Norman (1999) over a semiarid tussock grassland site in southeastern Spain. The TSM - in its current incarnation, the two-source energy balance model (TSEB) - was applied to this landscape using ground-based infrared radiometer sensors to estimate both the composite surface radiometric temperature and component soil and canopy temperatures. Morillas et al. (2013) found the TSEB model substantially underestimated the sensible H (and overestimated the latent heat LE ) fluxes. Using the same data set from Morillas et al. (2013), we were able to confirm their results. We also found energy transport and exchange behavior derived from primarily the observations themselves to differ significantly from a number of prior studies using land surface temperature for estimating heat fluxes with one-source modeling approaches in semi-arid landscapes. However, revisions to key vegetation inputs to TSEB and the soil resistance formulation resulted in a significant reduction in the bias and root mean square error (RMSE) between model output of H and LE and the measurements compared to the prior results from Morillas et al. (2013). These included more representative ground-based vegetation greenness and local leaf area index values as well as modifications to the coefficients of the soil resistance formulation to account for the very rough (rocky) soil surface conditions with a clumped canopy. This indicates that both limitations in remote estimates of biophysical indicators of the canopy at the site and the lack of adjustment in soil resistance formulation to account for site specific characteristics, contributed to the earlier findings of Morillas et al. (2013). This suggests further studies need to be conducted to reduce the uncertainties in the vegetation and land surface temperature input data in order to more accurately assess the effects of the transport exchange processes of this Mediterranean landscape on TSEB formulations. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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7. Molecular mapping of dry root rot resistance genes in chickpea (Cicer arietinum L.).
- Author
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Karadi, Ashwini, Samineni, Srinivasan, Sajja, Sobhan, Sharma, Mamta, Thudi, Mahendar, Mallikarjuna, Bingi P., Viswanatha, Kannalli P., Varshney, Rajeev K., and Gaur, Pooran M.
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ROOT rots ,GENE mapping ,CHICKPEA ,PAPER towels ,ARID regions ,CICER - Abstract
Dry root rot (DRR) caused by Rhizoctonia bataticola [(Taub.) Butler] is an emerging disease of chickpea (Cicer arietinum L.) and a serious constraint to chickpea production in warm and arid regions. To identify the genomic regions conferring resistance to DRR, a total of 182 F
9 derived Recombinant Inbred Lines (RILs) were developed from the cross between a susceptible line BG 212 and moderately resistant breeding line ICCV 08305. The parental lines and RILs were screened against Rb 6 isolate of R. bataticola using paper towel method under controlled environment at ICRISAT during 2016 and 2017. The RILs were genotyped with cost-effective SNP genotyping platform, Affymetrix® Axiom®CicerSNP array. As a result, a high-density genetic map with 13,110 SNP markers spanning 1224.11 cM with an average inter marker distance of 0.09 cM was developed. A single minor QTL ('qDRR-8') explaining 6.70% PVE with LOD scores 3.34 was identified on CaLG08 for DRR resistance which could be further explored for mining candidate genes and the linked SNP markers could be further validated for application in marker-assisted selection of DRR resistance in chickpea breeding programs. [ABSTRACT FROM AUTHOR]- Published
- 2021
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8. Wetlands in a Dry Land: More-Than-Human Histories of Australia's Murray-Darling Basin: By Emily O'Gorman. Seattle: University of Washington Press, 2021. Pp. 261. A$59.40 paper.
- Author
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Hore, Jarrod
- Subjects
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ARID regions , *WETLANDS , *ENVIRONMENTAL history , *WETLAND conservation , *WETLAND restoration ,AUSTRALIAN history - Abstract
O'Gorman grounds this argument in a range of sites, stitching them together over seven chapters that explore the dynamic more-than-human histories of certain water landscapes. We are now perhaps overly familiar with accounts of the Murray-Darling Basin as a "biocultural terrain" (96) over which the effects of colonial (mis)management are writ large, not least because of O'Gorman's 2012 book I Flood Country i . Wetlands in a Dry Land: More-Than-Human Histories of Australia's Murray-Darling Basin: By Emily O'Gorman. [Extracted from the article]
- Published
- 2022
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9. Achieving sustainable development goals through agritourism in Algeria
- Author
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Ait-Yahia Ghidouche, Kamila, Nechoud, Lamia, and Ghidouche, Faouzi
- Published
- 2021
- Full Text
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10. Climate Change and Water Resources Planning, Development, and Management in Zimbabwe : An Issues Paper
- Author
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World Bank
- Subjects
ASSESSMENT OF GROUNDWATER ,RIVERS ,WATER CONSUMPTION ,CATCHMENT LEVEL ,CATCHMENT COUNCILS ,CLIMATE CHANGES ,RIVER BASINS ,FLOOD RISK ,LEAKAGE REDUCTION ,SAFE WATER SUPPLY ,POLLUTION CONTROL ,WATER GOVERNANCE ,GROUNDWATER RESOURCES ,OWNERSHIP OF WATER ,WASTE WATER ,USE OF WATER ,ENVIRONMENTAL HEALTH ,LARGE DAMS ,WATER MANAGEMENT AUTHORITIES ,WATER ,FLOOD PROTECTION ,RURAL WATER SUPPLY ,CHOLERA OUTBREAK ,AGRICULTURAL PRODUCTION ,CIVIL SOCIETY ,ARID AREAS ,AQUATIC ECOSYSTEMS ,ANNUAL RAINFALL ,CLIMATIC CONDITIONS ,WATER AVAILABILITY ,WATER AUTHORITIES ,WATER RESOURCE ,WATER QUALITY PROBLEMS ,FLOOD MANAGEMENT ,ARID REGIONS ,SERVICE PROVIDERS ,HAND PUMPS ,WATER DEMAND ,WATER POLICY ,SURFACE RUNOFF ,ORGANIC MATTER ,WATER INFRASTRUCTURE ,WATER TREATMENT ,RIPARIAN STATES ,AVAILABLE WATER ,SEWERAGE SYSTEMS ,WATER REUSE ,WATER CONTAMINATION ,WATER QUALITY PROTECTION ,METEOROLOGICAL STATIONS ,FRESH WATER ,DOMESTIC WATER SUPPLY ,SERVICE DELIVERY ,HYDROPOWER POTENTIAL ,WATER USES ,SOLID WASTE ,WELLS ,WATER MANAGEMENT ,SURFACE WATER RESOURCES ,HYDROLOGICAL CYCLE ,IRRIGATION SYSTEMS ,HYDROPOWER PRODUCTION ,NATIONAL WATER RESOURCES MANAGEMENT ,QUALITY OF WATER ,NUTRIENT LOADS ,SURFACE WATER ,AVAILABLE WATER RESOURCES ,WATER RIGHTS ,DECISION MAKING ,GROUNDWATER MANAGEMENT ,DRINKING WATER ,MANAGEMENT OF WATER ,WATER ALLOCATION ,WATER MANAGEMENT AGENCIES ,LOCAL COMMUNITIES ,WATER SAVINGS ,CLEAN WATER ,IRRIGATION DEVELOPMENT ,WATER SCARCITY ,ENVIRONMENTAL MANAGEMENT ,MERCURY ,CLIMATE DATA ,WATER SECTOR ,WATER USERS ,RIVER CATCHMENT ,SECTORAL WATER ,DOMESTIC WATER ,DAM CONSTRUCTION ,COLLECTION OF WATER ,DEMAND FOR WATER ,WASTEWATER TREATMENT ,COMMUNITY PARTICIPATION ,CLIMATE CHANGE ,WATER CONSERVATION ,SANITATION FACILITIES ,NATIONAL WATER POLICY ,SUPPLY OF WATER ,WASTEWATER TREATMENT FACILITIES ,NUTRIENTS ,RIVER BASIN ,WATER DEPARTMENT ,SOLID WASTE DISPOSAL ,WASTEWATER SUPPLY ,WATER MANAGERS ,LOCAL COMMUNITY ,SECTORAL POLICIES ,CLIMATE VARIABILITY ,GROUNDWATER USE ,ALGAL BLOOMS ,CONTAMINANTS ,SANITATION SERVICES ,GROUNDWATER DEVELOPMENT ,WATER QUANTITY ,CONTAMINANTS IN WATER ,DROUGHT ,URBAN WATER MANAGEMENT ,SAFE WATER ,EFFICIENT USE OF WATER ,CITY COUNCIL ,SEWAGE TREATMENT ,RENEWABLE WATER RESOURCES ,EFFICIENT WATER USE ,SUSTAINABLE WATER SUPPLY ,FLOOD CONTROL ,CONSERVATION OF NATURE ,WATER SYSTEMS ,SAFE DRINKING WATER ,GROUNDWATER QUALITY ,IRRIGATORS ,INDUSTRIAL DISCHARGES ,LAND USE CHANGE ,DOWNSTREAM USERS ,METEOROLOGICAL SERVICE ,GOOD GOVERNANCE ,URBAN WATER ,RURAL WATER ,DOMESTIC USES ,CATCHMENT AREA ,WEIRS ,NATIONAL WATER RESOURCES ,RIPARIAN COUNTRIES ,WATER ABSTRACTION ,ENVIRONMENTAL IMPACTS ,DEMAND MANAGEMENT ,MANAGEMENT OF GROUNDWATER ,WATER DISTRIBUTION ,WASTEWATER INFRASTRUCTURE ,WATER RATES ,WATER PRICING ,LOCAL AUTHORITIES ,SURFACE WATERS ,URBAN WATER SUPPLY ,WATER ALLOCATIONS ,CONSUMPTIVE USES ,MANAGING WATER RESOURCES ,AGRICULTURAL ACTIVITIES ,WATER QUALITY ,WATER SUPPLY SYSTEMS ,WATER SUPPLY ,WATER USE ,DECISION MAKERS ,FLOOD FORECASTING ,WATER RESOURCES ,WASTE DISPOSAL ,WATER QUALITY MONITORING ,ALLOCATION OF WATER ,DEGRADATION OF GROUNDWATER - Abstract
This Issues Paper, requested by the former Ministry of Water Resources Development and Management as a recommendation of the National Water Policy (NWP), will contribute to the National Climate Change Response Strategy (NCCRS) by examining opportunities for adaptation to climate change in the water resources sector, using both structural and non-structural measures. It uses models to provide preliminary estimates of the possible impacts of climate change in 2050 and 2080 on these water resources. A number of opportunities to adapt to these impacts are discussed. Many of these adaptation opportunities constitute no-regrets actions, in that they are actions that are worth undertaking in their own right, irrespective of the severity of impacts from climate change.
- Published
- 2014
11. Impact of dust accumulation on photovoltaic panels: a review paper.
- Author
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Abuzaid, Haneen, Awad, Mahmoud, and Shamayleh, Abdulrahim
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RENEWABLE energy sources ,PHOTOVOLTAIC power systems ,SOLAR cells ,DUST ,ARID regions ,DEEP learning ,DUST control - Abstract
Photovoltaic systems (PV) have been extensively used worldwide as a reliable and effective renewable energy resource due to their environmental and economic merits. However, PV systems are prone to several environmental and weather conditions that impact their performance. Amongst these conditions is dust accumulation, which has a significant adversative impact on the solar cells' performance, especially in hot and arid regions. This study provides a comprehensive review of 278 articles focused on the impact of dust on PV panels' performance along with other associated environmental factors, such as temperature, humidity, and wind speed. The review highlights the importance of modelling dust accumulation along with other ecological factors due to their interactive nature, and the differences between cleaning techniques and schedules effectiveness. Moreover, the study provides a review of statistical and artificial intelligence models used to predict PV performance and its prediction accuracies in terms of data size and complexity. Finally, the study draws attention to several research gaps that warrant further investigation. Among these gaps is the need for proper dynamic optimisation models for cleaning schedules and a more advanced machine and deep learning models to predict dust accumulation while considering environmental and ageing factors. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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12. 基于遥感影像的新疆渭干河—库车河三角洲 土壤水盐与植被覆盖度的关系.
- Author
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郑柳娜, 江红南, and 孙梦婷
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SOIL moisture ,SOIL salinity ,SOIL depth ,SOIL sampling ,ARID regions - Abstract
Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
- Full Text
- View/download PDF
13. COMPREHENSIVE RISK ASSESSMENT OF FLOODS IN CYPRUS: EVALUATING THE IMPACTS OF CLIMATE CHANGE.
- Author
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Xekalakis, Georgios, Anastasiou, Christos, Riga, Evi, Zuccaro, Giulio, and Christou, Petros
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FLOOD risk ,RAINFALL ,CLIMATE change ,RAIN gardens ,ARID regions ,SEVERE storms - Abstract
Arid and semi-arid regions, including Cyprus, are increasingly experiencing severe weather events due to climate change. These events, characterized by prolonged droughts and flash floods, pose significant challenges to the environment, economy, and societal well-being. This paper aims to analyze the challenges of Flood Risk Management (FRM) in dry areas, focusing on Cyprus as a case study. It reviews historical data on temperature and rainfall patterns, flood types, and severity to propose effective, nature-based mitigation measures. The study examines temperature and rainfall trends over the last 30 years in Cyprus, categorizes floods since 1859 based on severity, and identifies prevalent flood types. The investigation reveals a decrease in annual rainfall and an increase in average temperatures in Cyprus, leading to heightened flood risks. The study categorizes floods into fluvial, pluvial, flash, and coastal types, with pluvial floods being the most common due to urbanization. The paper underscores the role of community and individual participation in adopting nature-based solutions such as permeable materials, rain gardens, tree planting, and roof gardens. Addressing flood risks in Cyprus requires a combined effort of government initiatives and community engagement. The adoption of sustainable, eco-friendly practices can significantly mitigate the adverse effects of climate change on flood hazards. This holistic approach is imperative for enhancing resilience against future climate-related challenges in Cyprus and similar arid regions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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14. Efficacy of labile carbon addition to reduce fast‐growing, invasive non‐native plants: A review and meta‐analysis.
- Author
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Ossanna, Lia Q. R. and Gornish, Elise S.
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INVASIVE plants ,CHEATGRASS brome ,NATIVE plants ,WEED control ,WEEDS ,SOIL amendments ,GRASSLAND soils ,ARID regions ,COST analysis - Abstract
Elevated soil nitrogen (N) resulting from pollution, fertilizer and woody encroachment in grasslands enhances invasion pressures from weedy plant species. Sawdust, sucrose and other labile carbon (C) sources can be used as a soil amendment to combat the growth of fast‐growing, invasive non‐native plants by immobilizing soil N.Here, we present a systematic review of 83 publications, and a meta‐analysis from 48 publications. Using hierarchical mixed‐effects meta‐analytic models, we synthesized 655 responses from native plants and 486 responses from non‐native weeds to quantify the overall effect of C addition. We explored the possible explanations for variation in effect, such as differences in study conditions and how C was applied.Carbon addition studies were almost exclusively reported from the United States, Australia and Canada (93%). The majority of papers (63%) did not include any cost information.Overall, C addition significantly decreased non‐native weed abundance, but did not significantly affect native plant abundance. A C application rate of at least 210 g C m−2 year−1 (5 Mg sucrose ha−1 year−1 or 4.6 Mg sawdust ha−1 year−1) decreased non‐native weed abundance, but a rate of 2110–3000 g C m−2 year−1 (50–71 Mg sucrose ha−1 year−1 or 46–65 Mg sawdust ha−1 year−1) was required to significantly increase native plant abundance. Carbon addition was most effective in the western USA and southeastern Australia, and when used to suppress non‐native grasses (annual or perennial) and annual forbs. Simultaneous seeding of native species prevented an overall decrease in native plant abundance.Synthesis and application. When there is a nearby and inexpensive source of C available, we recommend C addition with simultaneous seeding of native species to control invasive non‐native grasses and annual forbs in semi‐arid and arid regions of the western USA and southeast Australia. In contrast to other weed control measures, especially herbicide, C addition does not significantly harm native perennial plants. Future studies should implement longer‐term monitoring, establish larger plots and include cost analysis to improve guidance for land managers. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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15. Bibliometric Analysis of Land Degradation Studies in Drylands Using Remote Sensing Data: A 40-Year Review.
- Author
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Costa, Diêgo P., Herrmann, Stefanie M., Vasconcelos, Rodrigo N., Duverger, Soltan Galano, Franca Rocha, Washinton J. S., Cambuí, Elaine C. B., Lobão, Jocimara S. B., Santos, Ellen M. R., Ferreira-Ferreira, Jefferson, Oliveira, Mariana, Barbosa, Leonardo da Silva, Cunha Lima, André T., and Lentini, Carlos A. D.
- Subjects
LAND degradation ,REMOTE sensing ,ARID regions ,BIBLIOMETRICS ,TECHNOLOGICAL innovations ,VEGETATION dynamics ,BIBLIOTHERAPY - Abstract
Drylands are vast and face threats from climate change and human activities. Traditional reviews cannot capture interdisciplinary knowledge, but bibliometric analysis provides valuable insights. Our study conducted bibliometric research of scientific production on climate change and land degradation in drylands using remote sensing. We examined 1527 Scopus-indexed publications to identify geographic and thematic hotspots, extracting leading authors, journals, and institutions. China leads in publications, followed by the US, Germany, and Australia. The US has the highest citation count. Collaboration networks involve the US, China, and European countries. There has been an exponential increase in remote sensing of land degradation in drylands (RSLDD) publications since 2011. Key journals include "International Journal of Remote Sensing" and "Remote Sensing of Environment". The analysis highlights the growing interest in the field, driven by Australia, the US, and China. Key areas of study are vegetation dynamics and land use change. Future perspectives for this scientific field involve promoting collaboration and exploring emerging technologies for comprehensive land degradation and desertification research. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
16. New insights on the occurrence of peperites and sedimentary deposits within the silicic volcanic sequences of the Paraná Magmatic Province, Brazil.
- Author
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Luchetti, A. C. F., Nardy, A. J. R., Machado, F. B., Madeira, J., and Arnosio, J. M.
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SILICICLASTIC rocks ,STRATIGRAPHIC geology ,SANDSTONE ,BASALT ,ARID regions ,VOLCANIC ash, tuff, etc. - Abstract
In the Paraná Basin (southern and southeastern Brazil), the stratigraphy of the Paraná Magmatic Province (PMP) is composed of a thick (up to 1600 m) volcanic sequence formed by a succession of petrographically and geochemically distinct units of basic and acidic composition. The whole package may have been emplaced in approximately 3 million yr of almost uninterrupted activity. A few aeolian sandstone layers, indicating arid environmental conditions (Botucatu Formation), are interlayered in the lower basalts. Above the basalts, the Palmas and Chapecó Members of the Early Cretaceous Serra Geral Formation, are composed of silicic volcanic rocks (trachydacites, dacites, rhyolites, and rhyodacites) and basalts. This paper presents new evidence of episodes of sedimentation separating silicic volcanic events, expressed by occurrences of sedimentary deposits. Interaction between the volcanic bodies and the coeval unconsolidated sediments formed peperites. The sediments were observed between basaltic lava flows and silicic rocks or interlayered in the Palmas type rocks, between Chapecó type rocks and underlying basaltic flows, between silicic bodies of Palmas and Chapecó types, and interlayered with Palmas type units. The observed structures indicate that the sediments were still wet and unconsolidated, or weakly consolidated, at the time of volcanism, which coupled with the sediment features reflect environmental conditions that are different from those characterizing the Botucatu arid conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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17. Temperatures and substrates on the germination and vigor of seeds of Pilosocereus catingicola subsp. salvadorensis in the Caatinga biome of Paraíba.
- Author
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Silva de Medeiros, Robson Luis, Camelo de Souza, Vênia, de Araújo, Leandro, Barbosa Neto, Miguel Avelino, Alves de Azerêdo, Gilvaneide, and da Silva Barbosa, Alex
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GERMINATION ,ARID regions ,BIOMES ,TEMPERATURE effect ,TEMPERATURE - Abstract
Copyright of Revista de Ciencias Agroveterinarias is the property of Revista de Ciencias Agroveterinarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
18. Plant Adaptation to Extreme Environments in Drylands—Series II: Studies from Northwest China.
- Author
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Yang, Xiao-Dong, Li, Sai-Qiang, Lv, Guang-Hui, Wu, Nai-Cheng, and Gong, Xue-Wei
- Subjects
EXTREME environments ,PLANT adaptation ,ARID regions ,PHYSIOLOGY ,BIOLOGICAL systems ,DROUGHTS ,RHIZOSPHERE microbiology ,EFFECT of salt on plants - Abstract
This document discusses the challenges faced by plants in arid and semi-arid regions due to harsh environmental conditions such as limited rainfall, high temperatures, and poor soil nutrition. The document highlights the importance of understanding plant adaptation strategies to extreme environments in order to protect and manage local vegetation and ecosystems. The document presents research papers that cover various aspects of plant adaptation in arid regions, including water uptake mechanisms, physiological and biochemical adaptations, plant-soil microbial interactions, and ecosystem services. The research findings provide insights into how plants in arid regions adapt to environmental changes and maintain ecological balance. However, further research is needed to fully understand the processes and mechanisms of plant adaptation in extreme environments. [Extracted from the article]
- Published
- 2024
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- View/download PDF
19. The rectangular tile classification model based on Sentinel integrated images enhances grassland mapping accuracy: A case study in Ordos, China.
- Author
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Guo, Fuchen, Fan, Liangxin, Chen, Weinan, Xiao, Dongyang, and Niu, Haipeng
- Subjects
SYNTHETIC aperture radar ,SOIL conservation ,RANDOM forest algorithms ,ARID regions ,CLASSIFICATION ,SOIL protection ,GRASSLANDS - Abstract
Arid zone grassland is a crucial component of terrestrial ecosystems and plays a significant role in ecosystem protection and soil erosion prevention. However, accurately mapping grassland spatial information in arid zones presents a great challenge. The accuracy of remote sensing grassland mapping in arid zones is affected by spectral variability caused by the highly diverse landscapes. In this study, we explored the potential of a rectangular tile classification model, constructed using the random forest algorithm and integrated images from Sentinel-1A (synthetic aperture radar imagery) and Sentinel-2 (optical imagery), to enhance the accuracy of grassland mapping in the semiarid to arid regions of Ordos, China. Monthly Sentinel-1A median value images were synthesised, and four MODIS vegetation index mean value curves (NDVI, MSAVI, NDWI and NDBI) were used to determine the optimal synthesis time window for Sentinel-2 images. Seven experimental groups, including 14 experimental schemes based on the rectangular tile classification model and the traditional global classification model, were designed. By applying the rectangular tile classification model and Sentinel-integrated images, we successfully identified and extracted grasslands. The results showed the integration of vegetation index features and texture features improved the accuracy of grassland mapping. The overall accuracy of the Sentinel-integrated images from EXP7-2 was 88.23%, which was higher than the accuracy of the single sensor Sentinel-1A (53.52%) in EXP2-2 and Sentinel-2 (86.53%) in EXP5-2. In all seven experimental groups, the rectangular tile classification model was found to improve overall accuracy (OA) by 1.20% to 13.99% compared to the traditional global classification model. This paper presents novel perspectives and guidance for improving the accuracy of remote sensing mapping for land cover classification in arid zones with highly diverse landscapes. The study presents a flexible and scalable model within the Google Earth Engine framework, which can be readily customized and implemented in various geographical locations and time periods. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Effects of cash transfers on household resilience to climate shocks in the arid and semi arid counties of northern Kenya.
- Author
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Matata, Michael Joseph, Ngigi, Margaret W., and Bett, Hillary Kiplangat
- Subjects
CLIMATE change ,HOUSEHOLDS ,ARID regions ,POOR people ,TECHNOLOGY transfer ,COUNTIES - Abstract
Climatic events and other natural-related disasters experienced in the arid and semi-arid lands of northern Kenya negatively affect the pastoral livelihoods of the communities. Addressing vulnerability to climate shocks among pastoral communities of Kenya's Arid and Semi-lands presents a persistent challenge. Cash transfer programmes have increasingly grown as one mode of building household resilience. Understanding the role of cash transfer interventions on household resilience to climate shocks is key to policy programming. This paper aimed at determining the effects of cash transfers on household resilience to climate shocks. The paper evaluated the Hunger Safety Net Program, which is one of the largest unconditional cash transfer programs in Kenya. The Hunger Safety Net Program targeted poor people in northern Kenya including the counties of Turkana, Wajir, Marsabit, and Mandera. To establish the impact the paper compares households which received cash transfers with those that did not receive transfers. The panel fixed effects model was used to determine the effects of cash transfers on household resilience. The results indicate that cash transfers have positive significant effects on household resilience to climate shocks. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. Adapting nomadic pastoralism to climate change.
- Author
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Tugjamba, Navchaa, Walkerden, Greg, and Miller, Fiona
- Subjects
TRADITIONAL knowledge ,PASTORAL societies ,CLIMATE change ,ARID regions - Abstract
This paper presents the results of a detailed review of the research literature on how nomadic pastoralists are being affected by climate change, how they are adapting, and challenges with using traditional knowledge in adaptation. It focuses on research that investigates local, and particularly traditional, knowledge of water, pasture, their variability, and livestock. This knowledge underpins nomadic livelihoods, so is a foundation for effective adaptation. Changes in the total amount of precipitation, and particularly shifts in its timing, and increases in the frequency and intensity of extreme events, are having the greatest impacts on herding livelihoods. Herders in drylands worldwide face common adaptation challenges: declining traditional water sources and pasture degradation. Herders' adaptation strategies fall into five major categories: movement to areas with better water and pasture, improving seasonal access to water, improving seasonal access to feed, shifts in herd composition, and livelihood diversification. Movement is central to nomads' adaptation, yet, as climate change takes hold, restrictions on movement are increasing for both socio-economic reasons and climate reasons. Many papers emphasised the importance of combining traditional knowledge and current science to guide adaptation decision-making at household, locality, and national levels. There is widespread concern about the decline in traditional knowledge. All the papers reviewed emphasised the need to support passing on traditional know-how. Herder women's know-how, in particular, is marginalised in the research literature, so their traditional knowledge should be a focus in further research. Herders' adaptations are mostly localised, incremental, and have a relatively short-term focus. As nomadic pastoralism moves further outside the range of historical experience, the possibility of more profound transformations looms. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. A dynamic harmonic regression approach to estimating groundwater evapotranspiration based on diurnal groundwater-level fluctuations
- Author
-
Huang, Jinting, Wang, Jiawei, Zhou, Yangxiao, Fang, Tuo, Ning, Bohan, Song, Ge, Huang, Tian, Li, Linghua, Yang, Zhan, lv, Qiu, Pu, Fang, Li, Zongze, and Wang, Wenke
- Published
- 2024
- Full Text
- View/download PDF
23. Deriving seasonal dynamics in ecosystem properties of semi-arid savannas using in situ based hyperspectral reflectance.
- Author
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Tagesson, T., Fensholt, R., Huber, S., Horion, S., Guiro, I., Ehammer, A., and Ardö, J.
- Subjects
ECOSYSTEM dynamics ,SAVANNAS ,SPECTRAL reflectance ,HYPERSPECTRAL imaging systems ,PHOTOSYNTHETICALLY active radiation (PAR) ,PRIMARY productivity (Biology) ,ARID regions - Abstract
This paper investigates how seasonal hyperspectral reflectance data (between 350 and 1800 nm) can be used to infer ecosystem properties for a semi-arid savanna ecosystem in West Africa using a unique in situ based dataset. Relationships between seasonal dynamics in hyperspectral reflectance, and ecosystem properties (biomass, gross primary productivity (GPP), light use efficiency (LUE), and fraction of photosynthetically active radiation absorbed by vegetation (FAPAR)) were analysed. Reflectance data (ρ) were used to study the relationship between normalised difference spectral indices (NDSI) and the measured ecosystem properties. Finally, also the effects of variable sun sensor viewing geometry on different NDSI wavelength combinations were analysed. The wavelengths with the strongest correlation to seasonal dynamics in ecosystem properties were shortwave infrared (biomass), the peak absorption band for chlorophyll a and b (at 682 nm) (GPP), the oxygen A-band at 761nm used for estimating chlorophyll fluorescence (GPP, and LUE), and blue wavelengths (FAPAR). The NDSI with the strongest correlation to: (i) biomass combined red edge reflectance (ρ
705 ) with green reflectance (ρ587 ), (ii) GPP combined wavelengths at the peak of green reflection (ρ518 , ρ556 ), (iii) the LUE combined red (ρ688 ) with blue reflectance (ρ436 ), and (iv) FAPAR combined blue (ρ399 ) and near infrared (ρ1295 ) wavelengths. NDSI combining near infrared and shortwave infrared were strongly affected by solar zenith angles and sensor viewing geometry, as were many combinations of visible wavelengths. This study provides analyses based upon novel multi-angular hyperspectral data for validation of Earth Observation based properties of semi-arid ecosystems, as well as insights for designing spectral characteristics of future sensors for ecosystem monitoring. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
24. Trend and climatic sensitivity of vegetation phenology in semiarid and arid ecosystems in the US Great Basin during 1982-2011.
- Author
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Tang, G., Arnone III, J. A., Verburg, P., and Jasoni, R. L.
- Subjects
PLANT phenology ,ARID regions ,VEGETATION greenness ,GROWING season - Abstract
We quantified the temporal trend and climatic sensitivity of vegetation phenology in dryland ecosystems in the US Great Basin during 1982-2011. Our results indicated that vegetation greenness in the Great Basin increased significantly during the study period, and this positive trend occurred in autumn but not spring and summer. Spatially, increases in vegetation greenness were more apparent in the northwestern, southeastern, and eastern Great Basin but less apparent in the central and southwestern Great Basin. In addition, the start of growing season (SOS) was not advanced while the end of growing season (EOS) was delayed significantly at a rate of 3.0 days per decade during the study period. The significant delay in EOS and lack of earlier leaf onset caused growing season length (GSL) to increase at a rate of 3.0 days per decade during 1982-2011. Interestingly, we found that the variation of mean vegetation greenness in the period of March to November (SSA) was not significantly correlated with its mean surface air temperature but was strongly correlated with its total precipitation. Seasonally, the variation of mean vegetation greenness in spring, summer, and autumn was mainly attributable to changes in pre-season precipitation in winter and spring. Nevertheless, climate warming played a strong role in extending GSL that in turn resulted in the upward trend in mean vegetation greenness during 1982-2011. Overall, our results suggested that changes in wintertime and springtime precipitation played a stronger role than temperature in affecting the interannual variability of vegetation greenness while climate warming was mainly responsible for the 30-year upward trend in the magnitudes of mean vegetation greenness in the dryland ecosystems during 1982-2011. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
25. Wind-Powered Desalination on Islands: A Review of Energy–Water Pathways.
- Author
-
Matos, Carlos, Cabrera, Pedro, Carta, José A., and Melián-Martel, Noemi
- Subjects
SALINE water conversion ,WIND power ,BIBLIOMETRICS ,ISLANDS ,WATER shortages ,ARID regions ,ENERGY industries - Abstract
Water scarcity is a global problem that particularly affects islands located in arid regions or regions with limited water resources. This issue has prompted the development of non-conventional water sources such as fossil fuel-powered desalination systems. Concern about the high energy and environmental costs associated with this type of facility has created the ideal framework for the proliferation of desalination projects powered by renewable energies, especially wind energy due to the multiple advantages it offers. This article provides a bibliometric analysis to identify the advances made in wind-powered desalination on islands. While many studies explore wind-powered desalination, none compile references specific to islands. This paper analyses islands' desalination needs and showcases wind-powered systems, exploring their types and uses. Firstly, the most relevant international scientific journals are identified to allow the subsequent selection and quantitative and qualitative analysis of articles directly dealing with wind-powered desalination systems. A total of 2344 articles obtained from the Scopus database were analyzed, of which 144 including 181 case studies were selected. Among the results of this study, an increasing year-on-year trend is observed in the number of published studies tackling wind-powered desalination. Finally, this paper presents a series of maps showing the most relevant facilities, projects, and data in this field, and provides an overview of the lessons learned in the decarbonization of desalination. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Prehispanic Arid Zone Farming: Hybrid Flood and Irrigation Systems along the North Coast of Peru.
- Author
-
Caramanica, Ari
- Subjects
DRY farming ,ARID regions ,SUSTAINABLE agriculture ,EL Nino ,HYBRID zones ,EXTREME environments ,POTASSIUM ,RAINFALL - Abstract
As arid lands expand across the globe, scholars increasingly turn to the archaeological record for examples of sustainable farming in extreme environments. The arid north coast of Peru was the setting of early and intensive irrigation-based farming; it is also periodically impacted by sudden, heavy rainfall related to the El Niño Southern Oscillation (ENSO) phenomenon. While the sociopolitical effects, technologies, and engineering expertise of these irrigation systems have been thoroughly examined and theorized, little is known about how farmers managed periods of water stress. The aim of this study is to test whether arid zone farming was supported by hybrid, intermittent flood and perennial water source systems in the prehispanic past. An arroyo in the Chicama Valley was selected for preliminary data collection, and these data are presented here: (1) drone photography of the arroyo capturing the aftermath of a recent (2023) rain event; and (2) potassium (K) soil test kit results from samples collected near suspected prehispanic check dam features in the same area. The paper combines these data with comparative examples from the literature to suggest that the prehispanic features functioned as water-harvesting infrastructure. The paper concludes that sustainable, arid zone farming can be supported by hybrid, intermittent flood and perennial water source systems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Research on the sustainability of "greening" process in the Mu Us Sandy Land based on the spatiotemporal stability of ecological land.
- Author
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Zhang, Qiumeng, Jia, Baoquan, Li, Tong, and Li, Wenrui
- Subjects
SOIL moisture ,ARID regions ,LAND cover ,VEGETATION dynamics ,REMOTE sensing ,SAND dunes ,SUSTAINABILITY - Abstract
In environmentally sensitive areas, especially the arid and semi-arid regions, the greening stability process and its influencing factors can directly affect the sustainable development of the ecological environment. In this study, multi-source remote sensing data such as land use/cover data, MODIS NDVI, and soil moisture, methods such as stability index, vegetation quantitative remote sensing, and Geodetector were employed to analyze the sustainability of the greening process in the Mu Us Sandy in 2000–2020, which were viewed from three aspects: changes in stability of land use types and function, soil moisture change and influencing factors on greening stability. The results showed that, (1) From the stability of land use types, continuous stable ecological land accounted for more than 50%, showing that decreased from northwest toward southeast. (2) From the functional stability, NDVI showed a fluctuated growth (0.035/a), with an increasing distribution pattern from northwest to southeast. Additionally, Vegetation changes were unstable and concentrated in the western part of the study area (OtogBanner and Otog Front Banner), while the eastern part was stable, in which vegetation improvement took the main position. Moreover, mobile dunes almost disappeared, and semi-fixed dunes decreased and gradually shrank to the west of the sandy area, while fixed dunes soared and were concentrated in the middle of the sandy land. (3) From the soil moisture change, soil moisture at different underground depths showed an overall increasing trend, but the deep soil moisture was higher than the shallow, and spatial distribution varied greatly. (4) From the influencing factors, natural factors significantly influence greening stability, among which precipitation had a particularly profound impact, and interactions with other natural and social factors were higher explanatory. The paper aims to explore whether the ecological environment is developing in a good and orderly direction in the Mu Us Sandy Land, and the potential factors that cause its changes, to provide a theoretical basis for scientific governance in the Mu Us Sandy Land and other arid and semi-arid areas in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Review: Recent progress on groundwater recharge research in arid and semiarid areas of China.
- Author
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Li, Mingyue, Xie, Yueqing, Dong, Yanhui, Wang, Liheng, and Zhang, Zaiyong
- Subjects
GROUNDWATER recharge ,STABLE isotope analysis ,REGIONAL development ,ARID regions ,WATER supply ,WATERSHEDS - Abstract
Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
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- View/download PDF
29. Evaluation of soil salinity amelioration technologies in Timpaki, Crete: a participatory approach.
- Author
-
Panagea, I. S., Daliakopoulos, I. N., Tsanis, I. K., and Schwilch, G.
- Subjects
SOIL salinity ,LAND use ,ARID regions - Abstract
Soil salinity management can be complex, expensive and time demanding, especially in arid and semi-arid regions. Besides taking no action, possible management strategies include amelioration and adaptation measures. Here we use the World Overview of Conservation Approaches and Technologies (WOCAT) framework for the systematic analysis and evaluation of soil salinisation amelioration technologies in close collaboration with stakeholders. The participatory approach is applied in the RECARE Project Case Study of Timpaki, a semi-arid region in south-central Crete (Greece) where the main land use is horticulture in greenhouses irrigated by groundwater. Excessive groundwater abstractions have resulted in a drop of the groundwater level in the coastal part of the aquifer, thus leading to seawater intrusion and in turn to soil salinisation. The documented technologies are evaluated for their impacts on ecosystem services, cost and input requirements using a participatory approach and field evaluations. Results show that technologies which promote maintaining existing crop types while enhancing productivity and decreasing soil salinity are preferred by the stakeholders. The evaluation concludes that rain water harvesting is the optimal solution for direct soil salinity mitigation, whereas green manuring and the use of biological agents can support increasing production/efficiency and improving soil properties. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
30. Spatio-temporal dynamics of tree cover change in semi-arid Ghana: evidence from Sentinel-2 time series data.
- Author
-
Korah, Prosper Issahaku, Korah, Andrews, and Ahmed, Abubakari
- Subjects
ARID regions ,CLIMATE change ,ECOSYSTEM services ,TIME series analysis ,FUELWOOD - Abstract
Trees provide vital ecosystem services, yet anthropogenic activities have continued to reduce tree cover (TC) globally, leading to disparities in the distribution of ecosystem services at various scales. Similarly, empirical analysis of indicators that measure variations in TC at various temporal and spatial scales is limited in the semi-arid regions where global environmental challenges such as climate change are already affecting TC distribution. This paper quantified recent (2017 - 2019) TC changes in the semi-arid region of Ghana using Sentinel-2 times series data and the application of landscape metrics. The results showed that TC declined by 30% within two years. Urbanizing areas showed more rapid TC depletion rates, while some rural areas experienced a slight increase in TC. The findings suggest the need for local environmental governance by consolidating actions towards conserving semi-arid TC. Sustainable charcoal and fuelwood production are imperative for a long-term sustainable supply of ecosystem services. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Research on Improving the Accuracy of SIF Data in Estimating Gross Primary Productivity in Arid Regions.
- Author
-
Liu, Wei, Wang, Yu, Mamtimin, Ali, Liu, Yongqiang, Gao, Jiacheng, Song, Meiqi, Aihaiti, Ailiyaer, Wen, Cong, Yang, Fan, Huo, Wen, Zhou, Chenglong, Peng, Jian, and Sayit, Hajigul
- Subjects
ARID regions ,CARBON offsetting ,CHLOROPHYLL spectra ,DESERT plants ,LEAF area - Abstract
Coupling solar-induced chlorophyll fluorescence (SIF) with gross primary productivity (GPP) for ecological function integration research presents numerous uncertainties, especially in ecologically fragile and climate-sensitive arid regions. Therefore, evaluating the suitability of SIF data for estimating GPP and the feasibility of improving its accuracy in the northern region of Xinjiang is of profound significance for revealing the spatial distribution patterns of GPP and the strong coupling relationship between GPP and SIF in arid regions, achieving the goal of "carbon neutrality" in arid regions. This study is based on multisource SIF satellite data and GPP observation data from sites in three typical ecosystems (cultivated and farmlands, pasture grasslands, and desert vegetation). Two precision improvement methods (canopy and linear) are used to couple multiple indicators to determine the suitability of multisource SIF data for GPP estimation and the operability of accuracy improvement methods in arid regions reveal the spatial characteristics of SIF (GPP). The results indicate the following. (1) The interannual variation of GPP shows an inverted "U" shape, with peaks values in June and July. The cultivated and farmland areas have the highest peak value among the sites (0.35 gC/m
2 /month). (2) The overall suitability ranking of multisource SIF satellite products for GPP estimation in arid regions is RTSIF > CSIF > SIF_OCO2_005 > GOSIF. RTSIF shows better suitability in the pasture grassland and cultivated and farmland areas (R2 values of 0.85 and 0.84, respectively). (3) The canopy method is suitable for areas with a high leaf area proportion (R2 improvement range: 0.05–0.06), while the linear method is applicable across different surface types (R2 improvement range: 0.01–0.13). However, the improvement effect of the linear method is relatively weaker in areas with high vegetation cover. (4) Combining land use data, the overall improvement of SIF (GPP) is approximately 0.11%, and the peak values of its are mainly distributed in the northern and southern slopes of the Tianshan Mountains, while the low values are primarily found in the Gurbantunggut Desert. The annual mean value of SIF (GPP) is about 0.13 mW/m2 /nm/sr. This paper elucidates the applicability of SIF for GPP estimation and the feasibility of improving its accuracy, laying the theoretical foundation for the spatiotemporal coupling study of GPP and SIF in an arid region, and providing practical evidence for achieving carbon neutrality goals. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
32. Seasonal characterization of CDOM for lakes in semi-arid regions of Northeast China using excitation-emission matrices fluorescence and parallel factor analysis (EEM-PARAFAC).
- Author
-
Zhao, Y., Song, K., Wen, Z., Li, L., Zang, S., Shao, T., Li, S., and Du, J.
- Subjects
ARID regions ,EMISSION control ,FLUORESCENCE ,FACTOR analysis ,ABSORPTION - Abstract
The seasonal characteristics of fluorescence components in CDOM for lakes in the semi-arid region of Northeast China were examined by excitation-emission matrices fluorescence and parallel factor analysis (EEM-PARAFAC). Two humic-like peaks C1 (Ex/Em = 230, 300/425 nm) and C2 (Ex/Em = 255, 350/460 nm) and two protein-like B (Ex/Em = 220, 275/320 nm) and T (Ex/Em = 225, 290/360 nm) peaks were identified using PARAFAC. The average fluorescence intensity of the four components differed with seasonal variation from June and August 2013 to February and April 2014. The total fluorescence intensity significantly varied from 2.54 ± 0.68 nm
-1 in June to the mean value 1.93 ± 0.70 nm-1 in August 2013, and then increased to 2.34 ± 0.92 nm-1 in February and reduced to the lowest 1.57 ± 0.55 nm-1 in April 2014. In general, the fluorescence intensity was dominated by peak C1, indicating that most part of CDOM for inland waters being investigated in this study was originated from phytoplankton degradation. The lowest C2 represents only a small portion of CDOM from terrestrial imported organic matter to water bodies through rainwash and soil leaching. The two protein-like intensities (B and T) formed in situ through microbial activity have almost the same intensity. Especially, in August 2013 and February 2014, the two protein-like peaks showed obviously difference from other seasons and the highest C1 (1.02 nm-1 ) was present in February 2014. Components 1 and 2 exhibited strong linear correlation (R² = 0.633). There were significantly positive linear relationships between CDOM absorption coefficients a(254) (R² = 0.72, 0.46, p < 0.01), a(280) (R² = 0.77, 0.47, p < 0.01), a(350) (R² = 0.76, 0.78, p < 0.01) and Fmax for two humic-like components (C1 and C2), respectively. A close relationship (R² = 0.931) was found between salinity and DOC. However, almost no obvious correlation was found between salinity and EEM-PARAFAC extracted components except for C3 (R² = 0.469). Results from this investigation demonstrate that the EEM-PARAFAC technique can be used to evaluate the seasonal dynamics of CDOM fluorescence components for inland waters in semiarid regions of Northeast China. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
33. A Systematic Review of Hepatitis E Virus Detection in Camels.
- Author
-
Santos-Silva, Sérgio, Hemnani, Mahima, Lopez-Lopez, Pedro, Gonçalves, Helena M. R., Rivero-Juarez, António, Van der Poel, Wim H. M., Nascimento, Maria São José, and Mesquita, João R.
- Subjects
HEPATITIS E virus ,CAMELS ,DESERTS ,CAMEL milk ,ARID regions - Abstract
Simple Summary: Acute hepatitis, which is a rising public health issue globally, is mostly caused by the hepatitis E virus (HEV). There is a potential risk of camel-borne zoonotic HEV infection in the desert regions of the Middle East and Africa, where camels frequently interact with human populations and camel-derived food products constitute a component of the food chain. To better understand the current state of this subject, the current work's objective is to provide a scientific review of the detection of HEV genotypes seven and eight in camels around the world. Until today, no review paper has been published compiling and discussing the reports available on HEV in camels. More studies are required to ascertain the prevalence of HEV infection in camels worldwide. Additionally, because camels are utilized as a form of transportation in many countries and because HEV in these animals may pose a threat to public health, there is a possibility of foodborne transmission through contaminated camel products. Hepatitis E virus (HEV) represents a major cause of acute hepatitis and is considered an emerging public health problem around the world. In the Middle East's and Africa's arid regions, where camels frequently interact with human populations and camel-derived food products are a component of the food chain, camel-borne zoonotic HEV infection is a potential threat. To date, no review paper has been published on HEV in camels. As such, the purpose of the current work is to provide a scientific review of the identification of HEV genotypes seven and eight in camels worldwide to have a better understanding of the current status of this topic and to identify gaps in the current knowledge. Searches were carried out in the electronic databases PubMed, Mendeley, Web of Science, and Scopus, including studies published until 31 December 2022 (n = 435). Once the databases were checked for duplicate papers (n = 307), the exclusion criteria were applied to remove any research that was not relevant (n = 118). As a result, only 10 papers were found to be eligible for the study. Additionally, in eight of the ten studies, the rates of HEV infection were found to be between 0.6% and 2.2% in both stool and serum samples. Furthermore, four studies detected HEV genotype seven in dromedary camels, and two studies have shown HEV genotype eight in Bactrian camels. Interestingly, these genotypes were recently reported in camels from the Middle East and China, where one human infection with HEV genotype seven has been associated with the consumption of contaminated camel meat and milk. In conclusion, more research will be needed to determine the prevalence of HEV infection in camels around the world as well as the risk of foodborne transmission of contaminated camel products. As camels are utility animals in several countries, HEV in these animals may pose a potential risk to public health. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. A new approach for a drought composite index.
- Author
-
Bravo, Raissa Zurli Bittencourt, Cunha, Ana Paula Martins do Amaral, Leiras, Adriana, and Cyrino Oliveira, Fernando Luiz
- Subjects
DROUGHT management ,DROUGHTS ,ANALYTIC hierarchy process ,ARID regions ,WIND speed ,WEIGHING instruments ,HUMIDITY - Abstract
Drought is one of the most critical meteorological hazards that has a devastating effect on natural habitats, ecosystems, and many economic and social sectors. Due to these severe impacts of drought events, many studies have focused on drought monitoring, prediction, and risk analysis to aid drought preparedness plans and mitigation measures. This paper presents a new drought composite index (DCI) to measure the intensity and frequency of the hazard component of meteorological drought. The DCI considers multiple indicators, such as precipitation, temperature, evapotranspiration, wind speed, relative humidity, and sunshine duration. The DCI is validated through an application to the Brazilian semiarid context. Based on the expert's opinion, we define the weight of each indicator using the analytical hierarchy process. The results were compared with two other drought indices to provide an initial validation because the other indices are not exclusively meteorological indices. The DCI estimates for January 2019 show that the semiarid central region is the most critical. The findings also indicate that the drought intensity is growing in this region. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
35. Grassland fire effect on soil organic carbon reservoirs in semiarid environment.
- Author
-
Novara, A., Gristina, L., Rühl, J., Pasta, S., D'Angelo, G., La Mantia, T., and Pereira, P.
- Subjects
GRASSLAND fires ,SOIL biology ,RESERVOIRS ,SURFACE temperature ,ARID regions - Abstract
The aim of this work was to investigate the effect of a experimental fire, used for grassland management, on soil organic carbon (SOC) reservoirs. The study was carried out on Hyparrhenia hirta (L.) Stapf (Hh) grassland and Ampelodesmos mauritanicus (Desf.) T. Durand and Schinz (Am) grasslands, located in the north of Sicily. Soil samples were collected at 0-5 cm before and after experimental fire and SOC was measured. During grassland fire soil surface temperature was monitored. Biomass of both grasses was analyzed in order to determine dry weight and its chemical composition. The results showed that SOC varied significantly with vegetation cover, while it is not affected in the short period by grassland fire. Am grassland stored more SOC compared with Hh grassland thanks to lower content in biomass of labile carbon pool. No significant difference was observed in SOC before and after fire which could be caused by several factors: first, in both grassland types the measured soil temperature during fire was low due to thin litter layers; second, in semiarid environment higher mineralization rate results in lower soil carbon labile pool; and third, the C stored in the finest soil fractions, physical protected, is not affected by fire. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
36. Deep CO2 soil inhalation/exhalation induced by synoptic pressure changes and atmospheric tides in a carbonated semiarid steppe.
- Author
-
Sánchez-Cañete, E. P., Kowalski, A. S., Serrano-Ortiz, P., Pérez-Priego, O., and Domingo, F.
- Subjects
SOIL aeration ,ATMOSPHERIC tides ,CARBONATES ,ARID regions ,STEPPES ,CARBON dioxide ,SOIL composition ,CARBON cycle - Abstract
Knowledge of all the mechanisms and processes involved in soil CO
2 emissions is essential to close the global carbon cycle. Apart from molecular diffusion, the main physical component of such CO2 exchange is soil ventilation. Advective CO2 transport, through soil or snow, has been correlated with the wind speed, friction velocity or pressure (p). Here we examine variations in subterranean CO2 molar fractions (Χc ) over two years within a vertical profile (1.5 m) in a semiarid ecosystem, as influenced by short-timescale p changes. Analyses to determine the factors involved in the variations in subterranean Χc were differentiated between the growing period and the dry period. In both periods it was found that variations in deep Χc (0.5-1.5 m) were due predominantly to static p variations and not to wind or biological influences. Within a few hours, the deep Χc can vary by fourfold showing a pattern with two cycles per day, due to p oscillations caused by atmospheric tides. By contrast, shallow Χc (0.15 m) generally has one cycle per day as influenced by biological factors like soil water content and temperature in both periods, while the wind was an important factor in shallow Χc variations only during the dry period. Evidence of emissions was registered in the atmospheric boundary layer by eddy covariance during synoptic pressure changes when subterranean CO2 was released; days with rising barometric pressure -- when air accumulated belowground, including soil-respired CO2 -- showed greater ecosystem uptake than days with falling pressure. Future assessments of the net ecosystem carbon balance should not rely exclusively on Fick's law to calculate soil CO2 effluxes from profile data. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF
37. On the optimal method for evaluating cloud products from passive satellite imagery using CALIPSO-CALIOP data: example investigating the CM SAF CLARA-A1 dataset.
- Author
-
Karlsson, K.-G. and Johansson, E.
- Subjects
REMOTE-sensing images ,CLOUDS ,RADIATION ,CLIMATOLOGY ,PROJECT POSSUM ,METEOROLOGICAL satellites ,ARID regions - Abstract
A method for detailed evaluation of a new satellite-derived global 28-yr cloud and radiation climatology (Climate Monitoring SAF Cloud, Albedo and Radiation dataset from AVHRR data, named CLARA-A1) from polar orbiting NOAA and Metop satellites is presented. The method combines 1 km and 5 km resolution cloud datasets from the CALIPSO-CALIOP cloud lidar for estimating cloud detection limitations and the accuracy of cloud top height estimations. Cloud detection is shown to work efficiently for clouds with optical thicknesses above 0.30 except for at twilight conditions when this value increases to 0.45. Some misclassifications generating erroneous clouds over land surfaces in semi-arid regions in the sub-tropical and tropical regions are revealed. In addition, a substantial fraction of all clouds remains undetected in the Polar regions during the polar winter season due to the lack of or an inverted temperature contrast between Earth surfaces and clouds. Subsequent cloud top height evaluation took into account the derived information about the cloud detection limits. It was shown that this has fundamental importance for the achieved results. An overall bias of -274m was achieved compared to a bias of -2762m if no measures were taken to compensate for cloud detection limitations. Despite this improvement it was concluded that high-level clouds still suffer from substantial height underestimations while the opposite is true for low-level (boundary layer) clouds. The validation method and the specifically collected satellite dataset with optimal matching in time and space are suggested for a wider use in the future for evaluation of other cloud retrieval methods based on passive satellite imagery. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
38. Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland.
- Author
-
Shim, J. H., Powers, H. H., Meyer, C. W., Knohl, A., Dawson, T. E., Riley, W. J., Pockman, W. T., and McDowell, N.
- Subjects
OXYGEN isotopes ,BIOTIC communities ,ARID regions ,FORESTS & forestry ,HYDROLOGIC cycle ,ATMOSPHERIC carbon dioxide - Abstract
We conducted high frequency measurements of the δ
18 O value of atmospheric CO2 from a juniper (Juniperus monosperma) woodland in New Mexico, USA, over a four- year period to investigate climatic and physiological regulation of the δ18 O value of ecosystem respiration (δR ). Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR . Transpiration (ET ) was significantly related to post-pulse δR enrichment because leaf water δ18 O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET /ES ). In contrast, soil water δ18 O value was relatively stable and δR enrichment was not correlated with ES . Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18 O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR , and low soil moisture availability, which attenuates δR enrichment through reduced ET . The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF
39. Microstructure and hydraulic properties of biological soil crusts on sand dunes: a comparison between arid and temperate climates.
- Author
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Fischer, T., Yair, A., and Veste, M.
- Subjects
MICROSTRUCTURE ,HYDRAULICS ,SOIL crusting ,SAND dunes ,ARID regions ,TEMPERATE climate - Abstract
We studied the relationships between crust microstructure, infiltration and water holding capacity under arid and temperate conditions (Factor A: Climate) on biological soil crusts (BSCs) sampled along a catena on mobile sand dunes (Factor B: Catena). The arid study site was located near Nizzana, Israel (precipitation: 86mma
-1 , PET: ~2500mma-1 ) and the temperate site near Lieberose, Germany (precipitation: 569mma-1 , PET: ~780mma-1 ). BSCs were sampled near the dune crest, at the centre of the dune slope and at the dune base at each site. Scanning electron microscopy (SEM) was used to characterize BSC morphology and microstructure. Infiltration was determined using microinfiltrometry under controlled moisture conditions in the lab. Water holding capacities were determined after water saturation of the dry BSCs. Wettability of the crusts was characterized using a "repellency index", which was calculated from water and ethanol sorptivities. Irrespective of the climate, an accumulation of fine particles in the BSCs was found, increasing along the catena from dune crest to dune base. Texture was finer and water holding capacities of the underlying substrate were higher at the arid site, whereas surface wettability was reduced at the temperate site. At both sites, BSCs caused extra water holding capacity compared to the substrate. Infiltration rates decreased along the catena and were generally lower at the dune slope and base of the arid site. A mechanism of crust stabilization is proposed where BSCs benefit from increased texture and biomass mediated water supply, and where the water supply to higher plants was limited due to alteration of physico-chemical surface properties under temperate conditions. [ABSTRACT FROM AUTHOR]- Published
- 2012
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40. Challenges in arid region reclamation with special reference to Indian Thar Desert—its conservation and remediation techniques.
- Author
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Rani, J. and Paul, B.
- Subjects
DEW ,ARID regions ,SALTWATER encroachment ,INTEGRATED agricultural systems ,WATERSHED management ,SPRINKLER irrigation ,WATER harvesting ,PLATEAUS ,WATERSHEDS - Abstract
Arid and semi-arid lands throughout the world suffer from problems like low and erratic rainfall, high temperature, low amount of nutrients and salinity/alkalinity of soil and water. In addition to that, some other factors like composition of bedrock and sea water intrusion exaggerate the problem. The paper gives information about various remediation processes like green remediation, phytoremediation, biochar application, herbal treatment for improvement in soil and water quality. In addition to these methods, some management techniques are also highlighted like water harvesting by tankas, khadin system, watershed management, check dams, the implication of Bhungroo and Zai technology, dew and rain ridge collection system, drip and sprinkler method of irrigation and soil moisture conservation practices. Due to intense heat in the region, the agriculture and farming also get affected. The plant growth-promoting bacteria (PGPR) in the rhizosphere get affected due to insufficient moisture. These PGPR help in root growth, prevention of plant disease and increase availability of nutrients. It has been found that some of the PGPR strains in the arid lands involve in the metabolism and growth of plants by withstanding the unfavorable condition. Integrated farming system and new land use technologies like agroforestry approach are used for better benefits. These techniques will result in the overall uses of resources and restoration of ecological diversity. This paper enumerates various arid regions in India, their adverse soil conditions, water management practices and possible solutions for ecorestoration of the region. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Assessing the Spatiotemporal Evolution and Drivers of Ecological Environment Quality Using an Enhanced Remote Sensing Ecological Index in Lanzhou City, China.
- Author
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Duo, Linghua, Wang, Junqi, Zhang, Fuqing, Xia, Yuanping, Xiao, Sheng, and He, Bao-Jie
- Subjects
ENVIRONMENTAL quality ,REMOTE sensing ,SUSTAINABLE development ,SUSTAINABLE urban development ,DESERTIFICATION ,ARID regions ,DAYLIGHT - Abstract
Lanzhou City is located in the semi-arid region of northwest China, which experiences serious desertification. Moreover, the high intensity of land development, with the accelerated industrialization and urbanization, causes increasingly aggravated conflict between humans and the environment. Exploring the response of the ecological environment quality to the natural environment and anthropogenic activities is important to protect the sustainable development of urban economic construction and the environment. Based on the Google Earth Engine (GEE) platform, this paper constructed a modified Remote Sensing Ecological Index (MRSEI) model which could reflect the ecological environment quality by integrating the desertification index (DI) into the Remote Sensing Ecological index (RSEI) model. This paper explores the spatiotemporal variation in the environmental quality from 2000 to 2020 in Lanzhou, China, and analyzes the natural and anthropogenic factors affecting the environment quality in terms of temperature, precipitation, gross domestic product (GDP), land use, night lighting, and population. The results showed that the mean value of MRSEI ranged from 0.254 to 0.400. The area undergoing fast growth in ecological quality was in the northwestern part of Lanzhou, and the area of decrease was in the central part. Various factors have different degrees of influence on the ecosystem, with temperature, precipitation, and land use having a greater impact, and GDP and population having a limited impact. Precipitation and temperature showed a strong impact when interacting with other factors, demonstrating that precipitation and temperature were also key factors affecting MRSEI. Overall, climate change and the implementation of ecological restoration projects have led to an improvement in the quality of the ecological environment in Lanzhou. This study provides a reference for understanding the spatiotemporal changes in the ecological environment in semi-arid Lanzhou and is conducive to formulating proper protection strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. Groundwater storage changes using GRACE observations.
- Author
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Maksoud, Tala and Mohamed, Mohamed M.
- Subjects
GROUNDWATER ,LITERATURE reviews ,GROUNDWATER monitoring ,HYDROLOGIC cycle ,ARID regions ,WATER table ,WATER levels - Abstract
Groundwater is vital for the global water cycle, but it is being depleted at an alarming rate, especially in arid regions. Researchers are looking into new techniques for monitoring changes in groundwater levels in order to evaluate groundwater storage. Different approaches take into account temporal differences in total water storage (TWS). The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) are two satellite missions that are able to monitor water mass changes in a basin and calculate changes in water levels by measuring water variations. The GRACE satellite system has allowed for significant advances in monitoring changes in groundwater levels over large regions. This paper reviews recent studies that used the GRACE mission to show how improved analysis techniques provide greater accuracy in the estimation of mass changes. Moreover, several studies compared the findings of the different GRACE estimates. The findings of these studies are summarized in this paper in order to validate the results of GRACE estimates. The main findings of the literature review showed that aquifer depletion is widespread in areas such as the Middle East, India, China, the United States, and Australia to estimate the change in groundwater level storage in these areas. The California Central Valley and west Africa regions show the most significant groundwater depletion over the past decade, with rates of 24.42± 9.3 km3/year and 14 km3/year respectively, for the period 2003–2015. The middle east experienced a groundwater depletion of around 13±1.5 km3/year from 2002 to 2014. Further investigation will be carried out to understand and evaluate the changes in groundwater levels over large regions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Optimizing the design of courtyard houses for passive cooling in hot, dry regions.
- Author
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Khan, Hayder M., Lane-Serff, Gregory F., and Dewsbury, Jonathan
- Subjects
COOLING ,ARCHITECTURAL details ,NATURAL ventilation ,SOLAR radiation ,ARID regions ,COURTYARDS ,VENTILATION - Abstract
The courtyard is an architectural element found in hot arid regions due to its thermal performance that gives it cooler temperatures than the outside resulting from shading and night cooling. Previous papers focus only on either shading or ventilation and never together. This paper employs CFD techniques to simulate heat transfer in the courtyard. The results are presented through time constants showing the response of the thermal mass of the building containing the courtyard toward solar radiation and night cooling and the effect of both being combined in a factor called the Night-Time Effectiveness Ratio (NTER). The research includes simulation for different courtyard sizes and other building elements around the courtyard, like galleries. The results show the importance of the courtyard's width in changing the performance of night ventilation. Adding extra shading elements such as galleries can enhance thermal performance by 30–60%. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. Spatiotemporal Characteristics of Watershed Warming and Wetting: The Response to Atmospheric Circulation in Arid Areas of Northwest China.
- Author
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Li, Taohui, Lv, Aifeng, Zhang, Wenxiang, and Liu, Yonghao
- Subjects
EL Nino ,ARID regions ,NORTH Atlantic oscillation ,CLIMATE change ,ARCTIC oscillation ,ATMOSPHERIC circulation - Abstract
The Tarim Basin is a large inland arid basin in the arid region of northwest China and has been experiencing significant "warming and wetting" since 1987. As a result, the purpose of this paper is to determine whether the climate transition phenomenon occurred in the Tarim Basin as well as the role of atmospheric circulation in this process. We use meteorological data and atmospheric circulation indexes to study the seasonal trends of climate change in this region from 1987 to 2020 to understand how they are affected by atmospheric circulation. The findings show that, from 1987 to 2020, the Tarim Basin experienced significant warming and wetting; with the exception of the winter scale, all other seasonal scales exhibited a clear warming and wetting trend. From the perspective of spatial distribution, most of the areas showed a significant warming trend, and the warming amplitude around the basin is greater than that in the central area of the basin. However, there are significant regional differences in precipitation change rates. Meanwhile, wavelet analysis shows that there is a significant oscillation period of 17–20 years between climate change and the atmospheric circulation index during 1987–2020. The correlation analysis shows that the Pacific decadal oscillation (PDO) and El Niño-Southern Oscillation (ENSO) are the main influencing factors of climate change in the Tarim Basin at different seasonal scales, while the teleconnection of the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) is low and the PDO dominates the summer and autumn temperature changes in the Tarim Basin. The research results of this paper show that, despite the warming and wetting trends since 1987 in the Tarim Basin, the climate type did not change. From 1987 to 2020, the main teleconnection factors of climate change in the Tarim Basin were PDO and ENSO. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. A review of fusion framework using optical sensors and Synthetic Aperture Radar imagery to detect and map land degradation and sustainable land management in the semi-arid regions.
- Author
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Sengani, David, Ramoelo, Abel, and Archer, Emma
- Subjects
SYNTHETIC apertures ,OPTICAL sensors ,SYNTHETIC aperture radar ,LAND degradation ,IMAGE fusion ,ARID regions ,LAND management - Abstract
This paper examines a feature-level fusion framework for detecting and mapping land degradation (LD) and enabling sustainable land management (SLM) in semi-arid areas using optical sensors and Synthetic Aperture Radar (SAR) satellite data. The objectives of this review were to (i) determine the trends and geographical location of land degradation mapping publications, (ii) to identify and report current challenges pertaining to mapping LD using multiscale remote sensing data, (iii) to recommend a way forward for monitoring LD using multiscale remote sensing data. The study reviewed 78 peer-reviewed research articles published over the past 24 years (1998–2022). Image fusion has the potential to be more useful in various remote sensing applications than individual sensor image data, making it more informative and valuable in the interpretation process. In addition, this review discusses the importance of SAR and optical image fusion, pixel-level techniques, applications, and major classes of quality metrics for objectively assessing fusion performance. The literature review alluded that the SAR and optical image fusion in the detection and mapping of land degradation and enabling sustainable land management has not been fully explored. Advanced techniques such as the fusion of SAR and optical satellite imageries need to be incorporated for the detection and mapping of LD, as well as the promotion of SLM in halting LD in South African drylands and around the world. We conclude that there is scope for further research on the fusion of SAR and optical images, as new micro-wave and optical sensors with higher resolution are introduced on a regular basis. The results of this review contribute to a better understanding of the applications of SAR and optical image fusion in future research in the severely degraded drylands of southern Africa. The fusion of SAR and optical data still remains an open challenge. The future of different remote sensing applications lies in this kind of fusion. Land degradation is one of the greatest challenges amongst the environmental problems in South Africa, causing a reduction in the capacity of the land to perform ecosystem functions and services that support society and development. Yet, in South Africa, there are no studies that have widely investigated the potential for a fusion of SAR and optical data to detect and map land degradation and SLM practices. This paper established a baseline for understanding the application of a fusion of SAR and optical data as rapid tools for mapping, monitoring, and evaluating LD, as well as the impacts of SLM practices in South Africa's degraded drylands. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
46. Aspidosperma pyrifolium seeds treated with ultrasound and microwave.
- Author
-
Costa Ferreira, Thiago, Silva Ribeiro, Fábia Shirley, Gomes de Oliveira, Manoel Rivelino, and Martin Pérez-Marin, Aldrin
- Subjects
PEARSON correlation (Statistics) ,FOREST productivity ,SEEDS ,ARID regions ,ULTRASONIC imaging - Abstract
Copyright of Brazilian Journal of Forest Research / Pesquisa Florestal Brasileira is the property of Brazilian Journal of Forest Research / Pesquisa Florestal Brasileira and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
47. No-tillage lessens soil CO2 emissions the most under arid and sandy soil conditions: results from a meta-analysis.
- Author
-
Abdalla, K., Chivenge, P., Ciais, P., and Chaplot, V.
- Subjects
TILLAGE ,CARBON dioxide ,SOIL composition ,ARID regions ,SANDY soils ,META-analysis ,ENVIRONMENTAL impact analysis - Abstract
The management of agroecosystems plays a crucial role in the global carbon cycle with soil tillage leading to known organic carbon redistributions within soils and changes in soil CO
2 emissions. Yet, discrepancies exist on the impact of tillage on soil CO2 emissions and on the main soil and environmental controls. A meta-analysis was conducted using 46 peer-reviewed publications totaling 174 paired observations comparing CO2 emissions over entire seasons or years from tilled and untilled soils across different climates, crop types and soil conditions with the objective of quantifying tillage impact on CO2 emissions and assessing the main controls. On average, tilled soils emitted 21% more CO2 than untilled soils, which corresponded to a significant difference at P < 0.05. The difference increased to 29% in sandy soils from arid climates with low soil organic carbon content (SOCC < 1%) and low soil moisture, but tillage had no impact on CO2 fluxes in clayey soils with high background SOCC (> 3%). Finally, nitrogen fertilization and crop residue management had little effect on the CO2 responses of soils to no-tillage. These results suggest no-tillage is an effective mitigation measure of carbon dioxide losses from dry land soils. They emphasize the importance of including information on soil factors such as texture, aggregate stability and organic carbon content in global models of the carbon cycle. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
48. The abiotic contribution to total CO2 flux for soils in arid zone.
- Author
-
Ma, J., Li, Y., and Liu, R.
- Subjects
ABIOTIC environment ,CARBON dioxide ,SOIL composition ,ARID regions ,ECOSYSTEMS ,SOIL temperature ,LANDSCAPES ,ECOTONES - Abstract
As an important component of ecosystem carbon budgets, soil carbon dioxide (CO
2 ) flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence that the abiotic component can be important in total soil CO2 flux, its relative importance has never been systematically assessed. In this study, the total soil CO2 flux (Rtotal ) was partitioned into biotic (Rbiotic ) and abiotic (Rabiotic ) components over eight typical landscapes in a desert-oasis ecotone, including cotton field, hops field, halophyte garden, reservoir edge, native saline desert, alkaline soil, dune crest and interdune lowland in the Gurbantunggut Desert, and the relative importance of these two components was analyzed. Results showed that Rabiotic always contributed to Rtotal for the eight landscapes, but the degree of contribution varied greatly. In the cotton and hops fields, the ratio of Rabiotic to Rtotal was extremely low (< 10%); whereas Rabiotic was dominant in the alkaline soil and dune crest. Statistically, Rabiotic =Rtotal decreased logarithmically with rising Rbiotic , suggesting that Rabiotic strongly affected Rtotal when Rbiotic was low. This pattern confirms that soil CO2 flux is predominantly biological in most ecosystems, but Rabiotic can dominate when biological processes are weak. On a diurnal basis, Rabiotic resulted in no net gain or loss of carbon but its effect on instantaneous CO2 flux was significant. Temperature dependence of Rtotal varied among the eight landscapes, determined by the predominant components of CO2 flux: with Rbiotic driven by soil temperature and Rabiotic regulated by the rate of change in temperature. Namely, declining temperature resulted in negative Rabiotic (CO2 went into soil), while rising temperature resulted in a positive Rabiotic (CO2 released from soil). Furthermore, without recognition of Rabiotic , Rbiotic would have been either overestimated (for daytime) or underestimated (for nighttime). Thus, recognition that abiotic component in total soil CO2 flux is ubiquitous in soils has widespread consequences for the understanding of carbon cycling. While the abiotic flux will not change net daily soil CO2 exchange and not likely directly constitute a carbon sink, it can alter transient soil CO2 flux significantly, either in magnitude or in its temperature dependency. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
49. Dam tailwaters compound the effects of reservoirs on the longitudinal transport of organic carbon in an arid river.
- Author
-
Ulseth, A. J. and Hall Jr., R. O.
- Subjects
RESERVOIRS ,DAMS ,ORGANIC compounds ,ARID regions ,LONGITUDINAL method ,COMPARATIVE studies - Abstract
Reservoirs on rivers can disrupt organic carbon (OC) transport and transformation, but less is known how downstream river reaches directly below dams contribute to OC processing than reservoirs alone. We compared how reservoirs and their associated tailwaters affected OC quantity and quality by calculating particulate (P) OC and dissolved (D) OC fluxes, and measuring composition and bioavailability of DOC. We sampled the Yampa River near Maybell, Colorado, USA and the Green River above and below Fontenelle and Flaming Gorge reservoirs, and their respective tailwaters from early snowmelt to base flow hydrological conditions. In unregulated reaches (Yampa River, Green River above Fontenelle reservoir), DOC and POC concentrations increased with snowmelt discharge. POC and DOC concentrations also increased with stream discharge below Fontenelle reservoir, but there was no relationship between DOC and stream flow below Flaming Gorge reservoir. The annual load of POC was 3-fold lower below Fontenelle Reservoir and nearly 7-fold lower below Flaming Gorge reservoir, compared to their respective upstream sampling sites. DOC exported to downstream reaches from both reservoirs was less bioavailable, as measured with bioassays, than DOC upriver of the reservoirs. Lastly, tailwater reaches below the reservoirs generated OC, exporting 1.6-2.2 g Cm
-2 d-1 of OC to downstream ecosystems. Changes in total fluxes from upstream to downstream of reservoirs and their tailwaters do not represent the simultaneous transformation and production of OC, which may lead to the underestimation of the quantity of OC mineralized, transformed, or retained in coupled river-reservoir-tailwater ecosystems. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
50. A Hybrid Model Coupling Physical Constraints and Machine Learning to Estimate Daily Evapotranspiration in the Heihe River Basin.
- Author
-
Li, Xiang, Xue, Feihu, Ding, Jianli, Xu, Tongren, Song, Lisheng, Pang, Zijie, Wang, Jinjie, Xu, Ziwei, Ma, Yanfei, Lu, Zheng, Wu, Dongxing, Wei, Jiaxing, He, Xinlei, and Zhang, Yuan
- Subjects
WATERSHEDS ,MACHINE learning ,COUPLINGS (Gearing) ,EVAPOTRANSPIRATION ,STANDARD deviations ,ARID regions - Abstract
Accurate estimation of surface evapotranspiration (ET) in the Heihe River Basin using remote sensing data is crucial for understanding water dynamics in arid regions. In this paper, by coupling physical constraints and machine learning for hybrid modeling, we develop a hybrid model based on surface conductance optimization. A hybrid modeling algorithm, two physical process-based ET algorithms (Penman–Monteith-based and Priestley–Taylor-based ET algorithms), and three pure machine learning algorithms (Random Forest, Extreme Gradient Boosting, and K Nearest Neighbors) are comparatively analyzed for estimating the ET. The results showed that, in general, the machine learning model optimized by parameters was able to better predict the surface conductance of the hybrid model. Driver analyses showed that radiation, normalized difference vegetation index (NDVI), and air temperature had high correlations with ET. The hybrid model had a better prediction performance for ET than the other five models, and it improved the R
2 of the two physical process-based algorithms to 0.9, reduced the root mean square error (RMSE) to 0.5 mm/day, reduced the BIAS to 0.2 mm/day, and improved the Kling–Gupta efficiency (KGE) to 0.9. The hybrid model outperformed the others across different time scales, displaying lower BIAS, RMSE, and higher KGE. Spatially, its ET patterns aligned with regional vegetation changes, with superior accuracy in annual ET estimation compared to the other models. Comparison with other ET products shows that the estimation results based on the hybrid model have better performance. This approach not only improves the accuracy of ET estimation but also improves the understanding of the physical mechanism of ET estimation by pure machine learning models. This study can provide important support for understanding ET and hydrological processes under different climatic and biotic vegetation in other arid and semi-arid regions. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
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