Search

On a worldwide scale, land use and land cover changes (LULCC) is a major driver of global change and biodiversity erosion. This study aims to monitor at the scale of Sri Lanka, LULCC and vegetation dynamics, to identify the main changes and their drivers. It places emphasis on multiscale geospatial monitoring with satellite data but also mobilises the interdisciplinary knowledge of a research programme. First, national scale data allows the identification of major changes with the MODIS NDVI dataset using Mann-Kendall tests and time profile analysis. A second local scale was mobilised with a systematic diachronic visual interpretation of high-resolution images on Google Earth. The third step, a macro-regional scale focus on the South and East coasts, used LANDSAT imagery (Stacked K-means) verified by field studies (botanical and vegetation analysis, and interviews). About 92.5% of the island of Sri Lanka is stable or presents no significant trends in the vegetation cover. 5% show a significant positive (greening) trend between 2000 and 2020 around the Puttalam lagoon, west of the Samanalawewa Reservoir, in the Udawalawe National Park, east and north of Ella, and the Nuwaragala Forest Reserve. Only about 2.5% (165,000 ha) of the Island shows a negative significant trend mainly in the periphery of Colombo and Trincomalee. The first driver is a set of national planning decisions in terms of infrastructure development (including urban growth, housing programmes and agricultural fields, and the management of protected areas). The second driver comes under rural dynamics with increasing tree density in rural landscapes over the Uva Province. Infrastructure development initiated by the state, creates both underlying conditions for other activities and negative impacts on coastal ecosystems, such as degradation of wetlands (including protected areas). [ABSTRACT FROM AUTHOR]

Efficient management of land use/land cover (LULC) features is vital for a balanced sustainable ecosystem. Thus, this work aimed to document the LULC changes in the less studied El Peñol-Guatapé reservoir, Antioquia, Colombia, especially in the reservoir area due to the construction of a hydro-electric power plant. For this study, Landsat images of 1977, 1986, 1997, and 2017 were used and the results indicated an increase in the settlement area and road networks by 0.10 and 0.60%, respectively, while during 1986 to 2017, cropland, plantation, dense forest, and open forest areas presented an increase of 0.52, 1.06, 2.87 and 2.61%, respectively. However, the marshy vegetation, scrub forest and fallow land decreased to − 0.51, − 3.79 and − 4.29%, respectively, in the same period. The water body before and after the completion of reservoir project denoted an increase from 13.1 km2 in 1977 to 45.7 km2 in 1986. This study provides a first-hand report on LULC dynamics in this tourism dominated municipalities that will serve as a reference for ecosystem management to reconcile the conflicts between different LULC classes in ecologically enriched regions. [ABSTRACT FROM AUTHOR]

The southern coastal zone of Sri Lanka has been subjected to a variety of natural and anthropogenic influences over the past three decades. Understanding impacts of such influences on Land Use Land Cover (LULC) is vital for proper management of the coastal zone. This study, therefore, focused on mapping the change/s in the distribution of selected LULC in the selected sites, Bundala, Galle, Kalametiya, and Hambantota of the southern coastal zone, over last 24 years using satellite imagery. LULC maps of nine classes (mangrove, inland vegetation, marsh and grass, sand, bare land, built-up, cultivation, water, and unclassified) were created by employing an onscreen digitization technique achieving an accuracy of >70%. Trend analysis and two-sample proportion tests were used for statistical analyses, whereas geometric calculations were used for descriptive analyses. The results showed the highest overall change in LULC in Kalametiya, followed by Hambantota, Galle, and Bundala. The changes in the LULC classes are mainly attributed to the conversion of water to mangroves, marsh and grass areas in Kalametiya, water to built-up areas in Hambantota, cultivations to built-up areas in Galle, and marsh and grass areas to bare lands in Bundala. The causes of LULC changes were site specific. Trend analyses indicate the least LULC changes in Bundala possibly by 2025. The study highlights the significance of taking into account geographical dislocations when considering and anticipating the potential impacts of development projects over broader extents. [ABSTRACT FROM AUTHOR]

The aim of the study is to address the issues and associated health risks due to consumption of high-fluoride water supplied for drinking in a rural part of Shanmuganadhi River basin, Tamil Nadu, India. In this study, 61 groundwater samples were gathered from various tube and open wells and analysed for fluoride and other physicochemical parameters. The abundance of cations is Na+ > Ca2+ > Mg2+ > K+, and that of anions is HCO3− > SO42− > Cl− > F−. The fluoride concentration in drinking groundwater varied from 0.10 to 3.3 mg/l. According to the WHO standards, about 26% of the samples were unfit for drinking requirements (16 out of 61 samples) Water quality index (WQI) method was adopted to categorize the water into different classes to understand its suitability for drinking requirements. WQI signified that nearly 52% of the samples denoted poor, very poor and not suitable categories, whereas 48% of samples denoted good and excellent categories for consumption. Health risks associated with high-fluoride drinking water were assessed for various age groups of inhabitants such as children, teens and adults. The hazard quotient estimated based on the oral intake ranged from 0.00E+00 to 5.50E+00, from 0.00E+00 to 4.22E+00 and from 0.00E+00 to 3.45E+00 for children, teens and adults, respectively. It suggested that the health risks are associated with 75%, 59% and 43% of samples, respectively, among children, teens and adults. Therefore, children are more inclined towards risk than teens and adults in this region based on the intake of fluoride-rich drinking water. To improve the present scenario, groundwater should be either treated before drinking water supply or must be artificially recharged to lower the concentration of ions. [ABSTRACT FROM AUTHOR]

ABSTRACT Muthusankar, G.; Proisy, C.; Balasubramanian, D.; Bautès, N.; Bhalla, R S.; Mathevet, R.; Ricout, A.; Senthil Babu, D., and Vasudevan, S., 2018. When socio-economic plans exacerbate vulnerability to physical coastal processes on the south east coast of India. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1446–1450. Coconut Creek (Florida), ISSN 0749-0208. Industrial and urban development along the coast may exacerbate the changes induced by oceano-climatic processes to such an extent that the coast becomes uninhabitable. This paper presents a baseline study carried out on the 360 km-long Coromandel coast of Tamil Nadu's (TN) Bay of Bengal coast, Southeast India. About 30% of the 72 million inhabitants of the state of TN live in low-lying coastal areas within a variety of ecosystems such as sandy beaches and dunes, wetlands, mudflats and mangroves. Exponential demographic growth combines with dense urban agglomerations, ever-growing industrial and harbour areas, aquaculture and luxury tourism expansion increasing vulnerabilities to coastal erosion and extreme meteorological events. We report here how very high spatial resolution satellite (VHSRS) images, freely provided by Google Earth® engine or from the public database offered by GIS software, may be used to impartially and significantly survey coastal land cover (LC) transformations at fine scales over a number of years using preliminary visual interpretation. The study also gathered demographic data, historical records on strength and trajectories of the cyclones that have hit the TN coast since 1900, and decadal series of daily ERA-Interim/ECMWF waves and Mercator-Ocean oceanic currents. Our results demonstrate a tangle of environmental and human activities and situations subject to specific coastal hazards, particularly severe during the Northeast monsoon season. The potential risks for coastal ecosystems and local communities are finally discussed. [ABSTRACT FROM AUTHOR]

Muthusankar, G.; Proisy, C.; Balasubramanian, D.; Bautès, N.; Bhalla, R S.; Mathevet, R.; Ricout, A.; Senthil Babu, D., and Vasudevan, S., 2018. When socio-economic plans exacerbate vulnerability to physical coastal processes on the south east coast of India. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1446–1450. Coconut Creek (Florida), ISSN 0749-0208. Industrial and urban development along the coast may exacerbate the changes induced by oceano-climatic processes to such an extent that the coast becomes uninhabitable. This paper presents a baseline study carried out on the 360 km-long Coromandel coast of Tamil Nadu's (TN) Bay of Bengal coast, Southeast India. About 30% of the 72 million inhabitants of the state of TN live in low-lying coastal areas within a variety of ecosystems such as sandy beaches and dunes, wetlands, mudflats and mangroves. Exponential demographic growth combines with dense urban agglomerations, ever-growing industrial and harbour areas, aquaculture and luxury tourism expansion increasing vulnerabilities to coastal erosion and extreme meteorological events. We report here how very high spatial resolution satellite (VHSRS) images, freely provided by Google Earth® engine or from the public database offered by GIS software, may be used to impartially and significantly survey coastal land cover (LC) transformations at fine scales over a number of years using preliminary visual interpretation. The study also gathered demographic data, historical records on strength and trajectories of the cyclones that have hit the TN coast since 1900, and decadal series of daily ERA-Interim/ECMWF waves and Mercator-Ocean oceanic currents. Our results demonstrate a tangle of environmental and human activities and situations subject to specific coastal hazards, particularly severe during the Northeast monsoon season. The potential risks for coastal ecosystems and local communities are finally discussed. [ABSTRACT FROM AUTHOR]

Remote sensing images of AD 1991-2011 and field observations help evaluate shoreline changes (erosion and accretion) in Puducherry and Tamil Nadu states of southeastern India. A minor harbor was constructed during AD 1986-1989 in the coast of Puducherry, and it initiated the gradual process of shoreline modification. In the subsequent years, beaches located toward the north of the harbor suffered erosion (−0.12-−4.19 m/year) and there was accretion (0.27-7.25 m/year) in the southern beaches. However, the man-made structures (seawall and groin) have reduced the shoreline changes after AD 2004. In the last two decades, the rate of erosion area-wise gradually decreased (0.24-0.013 km/year) and accretion remained constant (0.019 km/year). Our results suggest that accretion happened in the southern side of the breakwaters and erosion occurred in the northern part. Presence of groins structures in the region in the northern part has also provoked accretion in the south and erosion in the northern side close to the State of Tamil Nadu. [ABSTRACT FROM AUTHOR]

Key message : Subjective and anatomy-based quantitative indices of distinctness of growth rings in tropical trees were related to deciduousness, species maximum height, and also potentially to local topography, independent of phylogenetic relationships. Abstract: Most tropical tree species do not produce distinct growth rings, and the causes of this phenomenon have not received sufficient quantitative study. It has been shown that rainfall seasonality influences the formation of growth rings in some deciduous taxa. However, the numerous exceptions observed call for an examination of additional drivers of the phenomenon. We therefore hypothesized that in addition to seasonal climatic stress, functional and phylogenetic constraints may determine growth-ring distinctness. Ten potentially influential factors were examined in 38 Indian tropical tree species. Distinctness of growth rings was quantitatively assessed based on both subjective visual criteria and objective measures of anatomical characters. Multivariate and phylogenetically constrained analyses were used to test for functional, environmental, and phylogenetic effects. First, subjective scores of growth-ring distinctness correlated with objective anatomical measurements of vessel size and porosity related to water conductance, but also with additional anatomical characteristics unrelated to water dynamics. Second, ring distinctness variables were primarily related to deciduousness and species maximum height, and also weakly influenced by the topographic slope. A phylogenetic signal was detected in wood specific gravity values, the climatic variable of dry season rainfall, and the subjective distinctness score of growth rings, but accounting for phylogenetic structure did not significantly improve the prediction of ring distinctness. Thus, there was no evidence of an evolutionary constraint on the relationship in our sample of species. Our study thus demonstrates how distinctness of growth rings in tropical trees can be objectively represented on a continuous scale, and provides a quantitative explanation for its variability. [ABSTRACT FROM AUTHOR]

Growing pressures on mangroves throughout the world, highlight the need for studies of vegetation across spatio-temporal scales even in relict patches for ecosystem conservation. Mangroves experience human pressure due to coastal development and are also subjected to environmental stress such as cyclones, tsunami, floods, and sea-level rise, often taking decades to recover from these stresses. We estimated changes in mangrove vegetation in the Ariankuppam estuary on the southeastern coast of peninsular India after two phenomenal perturbations, the 2004 tsunami and 2011 cyclone Thane. We compared land cover maps of mangroves from 2005, 2010, and 2011 with 2004 mangrove vegetation maps to detect change in areal extent of mangrove zones. We inventoried all stems ≥ 10 cm gbh in 34 quadrats (5 m 5 m) prior to the 2011 cyclone, immediately following the cyclone, and eighteen months later to document damages and recovery. The site harbours 2988 trees ha-1 for stems ≥ 10 cm gbh. We found four distinct mangrove zones in 2005 (15.54 ha), and five distinct mangrove zones in 2010 (41.73 ha) and 2011 (40.65 ha). The tsunami and subsequent activities such as dragging the boats swept ashore and dredging resulted in 48% loss of mangroves. The increase in mangrove area observed during 2010 and 2011 was due to the recovery potential of Avicennia and restoration programs. Cyclonic impact and recovery status inventories revealed that among the different zones, the monodominant Avicennia zone experienced severe damage and the mixed Avicennia zone showed slow recovery. The full impacts on the ecosystem from extreme stochastic events; however, can only be determined with long-term monitoring. [ABSTRACT FROM AUTHOR]

A study on the possible inundation limit in SE coast of India was carried out using various physical, geological and satellite imageries. The coastal inundation hazard map was prepared for this particular region as it was affected by many cyclones, flooding, storm surge and tsunami waves during the last six decades. The results were generated using various satellite data (IRS-P6 LISS3; LANDSAT ETM; LANDSAT-5 ETM; LANDSAT MSS) and digital elevation models (ASTER GLOBAL DEM), and a coastal vulnerability index was generated for the entire coastal stretch of Nagapattinam region in SE coast of India. The coastal area which will be submerged totally due to a 1-5 m rise in water level due to any major natural disaster (tsunami or cyclone) indicates that 56-320 km will be submerged in this particular region. The results suggest that nearly 7 towns and 69 villages with 667,477 people will be affected and indicate that proper planning needs to be done for future development. [ABSTRACT FROM AUTHOR]

In spatial ecology, detailed covariance analyses are useful for investigating the influences of landscape properties on fauna and/or flora species. Such ecological influences usually operate at multiple scales, involving biological levels from individual to group, population or community and spatial units from field to farms and regions. The aim of this work was to analyze possible multiscale influences of some landscape properties on elephant distribution in the Western Ghats, India, by applying a recent and simple mathematical method to quantify such ecological relationships across space and scales. This method combines a moving window with various correlation indices to investigate the relationship between two mapped variables. Maps of landscape heterogeneity (quantified here at all locations of the landscape with a modified Shannon index) and Asian elephant presence (a two-dimensional presence probability) were significantly correlated. This correlation systematically decreased with increasing scales (i.e. sizes of the reference moving window). Yet, this global relationship includes both positive and negative correlations located at distinct places. We documented a positive feedback (reinforcement) because elephants appeared to seek greater habitat heterogeneity, in heterogeneous areas, such as along the interface between natural and a human-disturbed habitat or in the natural part of the studied landscape. In parallel, we observed a negative feedback (compensation) making elephants seeking more homogeneous places in some relatively heterogeneous zones. Such negative feedbacks corresponded to higher than average probabilities of elephant presence. Finally, when elephant density varied according to landscape heterogeneity (corresponding to significant correlations), it pointed towards swamps and grasslands, but not towards semi-evergreen or secondary forests (as it may have been expected). Land cover information appeared to be less relevant than an integrated heterogeneity index computed at all scales. [ABSTRACT FROM AUTHOR]

This study aims to report the short-term coastline dynamics and inundation limits of coastal cities along the Eastern Pacific due to the sea swell events that occurred during April to May 2015. The multi-temporal satellite datasets from Landsat such as Enhanced Thematic Mapper (L7 ETM+) and Operational Land Imager/Thermal Infrared Sensor (L8 OLI/TIRS) of different periods before and after the swell events were used to identify the shoreline changes. The satellite images were pre-processed using ERDAS imagine 9.2, and the coastline was digitized in ArcGIS 10.4.1 for ten cities spread across from Mexico to Chile (in Pacific coast) using the spectral water indices, and the shoreline change rate and erosion/accretion pattern at each transect were estimated using the statistical parameters embedded in Digital Shoreline Analysis System (DSAS). The maximum erosion and accretion were observed in El Salvador (268 m) and Huatulco (Mexico) (115 m), respectively. Likewise, the maximum inundation was observed in El Salvador with 268 m and Acapulco (Mexico) with 254 m, and the tide gauge data suggest a possible relation to the bathymetry and the geomorphological conditions of the coast. Overall, the results indicate that the Eastern Pacific Ocean side sea swell events has led to extreme coastal flooding in recent years due to the increase in the mean sea level and the unpredictable variation in El Niño/Southern Oscillation events. [ABSTRACT FROM AUTHOR]