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Reservoir expansion over the last century has largely affected downstream flow characteristics. Yet very little is known about the impacts of reservoir expansion on the climate. Here, we implement reservoir construction in the Community Land Model by enabling dynamical lake area changes, while conserving mass and energy. Transient global lake and reservoir extent are prescribed from the HydroLAKES and Global Reservoir and Dam databases. Land‐only simulations covering the 20th century with reservoir expansion enabled, highlight increases in terrestrial water storage and decreases in albedo matching the increase in open water area. The comparison of coupled simulations including and excluding reservoirs shows only limited influence of reservoirs on global temperatures and the surface energy balance, but demonstrates substantial responses locally, in particular where reservoirs make up a large fraction of the grid cell. In those locations, reservoirs dampen the diurnal temperature range by up to −1.5 K (for reservoirs covering >15% of the grid cell), reduce temperature extremes, and moderate the seasonal temperature cycle. This study provides a first step towards a coupled representation of reservoirs in Earth System Models. Key Points: Global reservoir expansion is implemented in the Community Land Model as growing lakesDuring the 20th century, reservoir expansion increases the terrestrial water storage and decreases the albedoLocally, reservoirs dampen the diurnal temperature range and mute temperature extremes [ABSTRACT FROM AUTHOR]

• The nanoscale storage spaces of the Da'anzhai carbonates are well developed. • The nanopore structure of the Da'anzhai carbonates is more complex than other rocks. • The Da'anzhai nanoscale storage spaces are mainly from terrestrial minerals. • The authigenic CaCO 3 minerals are negatively correlated with the nanoscale pores. • Weathering, salinity, climate and hydrodynamic conditions can control nanoscale pores. Compared with the studies of nanoscale pores in shale, coal, and tight sandstone, studies associated with lacustrine tight carbonate nanoscale pores and their control mechanisms, particularly quantitative studies combining reservoir evaluation and geochemistry, remain scarce. To address this disparity, lacustrine tight carbonate samples collected from the Jurassic Da'anzhai Member in the central Sichuan Basin of China were quantitatively investigated. Similar to other unconventional reservoirs, lacustrine tight carbonate reservoirs contain well-developed intraparticle pores, interparticle pores, and micro-cracks with nanoscale storage spaces that dominate the full-scale reservoirs. The relatively small pores (3–5 nm) make a dominant contribution to the nanoscale storage space. Isotherms and hysteresis loops are Type II and Type H 3 , respectively, indicating wedge-shaped pores. However, the hysteresis loops indicate more dead-end pores, larger pores, and more complex microstructures than those found in other unconventional reservoirs. The mineral in lacustrine carbonate provides a link between the reservoir and the formation environment. Strong paleo-weathering, low salinity, a humid (rainy) paleo-climate and poor hydrodynamic conditions are favorable to improve the storage spaces and terrestrial mineral contents but harmful to the formation of authigenic minerals. Terrestrial minerals, including primarily quartz, clay, and dolomite, have well-developed nanoscale pores and are positively correlated with the nanoscale storage space, whereas authigenic minerals, primarily calcite, have strong cementation and filling effects and are negatively correlated with the nanoscale storage space. [ABSTRACT FROM AUTHOR]

World Bank Loan Project (WBLP) for schistosomiasis control conducted from 1992 to 2001, resulted in significant reduction of schistosomiasis morbidity and mortality in People's Republic of China (P.R. China), with implementation of morbidity control. Thereafter, an integrated control strategy, which targeted blocking disease transmission from reservoir hosts to the environment, was initiated in order to conquer schistosomiasis rebound after WBLP completion. Data obtained from the national schistosomiasis control reporting systems was collected and analyzed. The number of confirmed cases and infected cattle decreased significantly from 2002 to 2017, while no infected snails were found by dissection for four consecutive years. However, lake and marshland regions and some parts areas of Yunnan Province require attention for rigorous schistosomiasis control efforts. There is need to strengthen precise interventions and sensitive surveillance to achieve schistosomiasis elimination in P.R. China. [ABSTRACT FROM AUTHOR]

Proppant crushing, a major proppant failure mechanism, occurs in geothermal energy and oil/gas stimulation production stages when the level of net stress exerted on the proppant exceeds the actual crush resistance of the material. Loss of effective reservoir conductivity due to proppant crushing can result in significant loss in productivity, and so it is crucial to understand the realistic proppant mechanical performances under deep reservoir conditions. This review provides a comprehensive overview of proppant crushing at the micro- to macro-levels by analyzing single proppant breakage, as well as re-arrangement and breakage mechanisms of proppant packs under in situ fracture environments. The choice of an appropriate proppant type based on the fracture treatment plays a key role in effective geothermal and oil/gas recovery. In addition, injection of proppants with better characteristics (higher sphericity, lower size, better gradation and lower granular porosity) can significantly influence the reduction of the extent of proppant crushing. Moreover, this study compares the performances and responses of different types of proppants upon proppant interaction with geothermal and oil/gas reservoir environments. Furthermore, this paper discusses various proppant types and their enhanced characteristics, which can be utilized as controlling measures for proppant crushing during unconventional energy extraction. [ABSTRACT FROM AUTHOR]

Summary: Lignin is one of the largest carbon reservoirs in the environment, playing an important role in the global carbon cycle. However, lignin degradation in bacteria, especially non‐model organisms, has not been well characterized either enzymatically or genetically. Here, a lignin‐degrading bacterial strain, Pseudomonas putida A514, was used as the research model. Genomic and proteomic analyses suggested that two B subfamily dye‐decolorizing peroxidases (DypBs) were prominent in lignin depolymerization, while the classic O2‐dependent ring cleavage strategy was utilized in central pathways to catabolize lignin‐derived aromatic compounds that were funnelled by peripheral pathways. These enzymes, together with a range of transporters, sequential and expression‐dose dependent regulation and stress response systems coordinated for lignin metabolism. Catalytic assays indicated these DypBs show unique Mn2+ independent lignin depolymerization activity, while Mn2+ oxidation activity is absent. Furthermore, a high synergy between DypB enzymes and A514 cells was observed to promote cell growth (5 × 1012 cfus/ml) and lignin degradation (27%). This suggested DypBs are competitive lignin biocatalysts and pinpointed limited extracellular secretion capacity as the rate‐limiting factor in bacterial lignin degradation. DypB production was, therefore, optimized in recombinant strains and a 14,141‐fold increase in DypB activity (56,565 U/l) was achieved, providing novel insights for lignin bioconversion. [ABSTRACT FROM AUTHOR]

Abstract Using numerical simulations of the paleostress field during the time of fracture formation, we predict the occurrence of fractures in the reservoirs of the second member of the Funing Formation in the Tongcheng fault zone, Subei basin, East China. We use sonic velocity measurements from rock cores and microseismic monitoring to determine the in situ stress, which is combined with fracture data to calculate the magnitude of the in situ stress at the well site. By determining the mechanical parameters of the rock, we use the finite element method (FEM) to develop a geomechanical model and conduct numerical simulations of the in situ stress field. Based on the occurrence of fractures and the numerical simulation results of the in situ stress field, we predict the opening pressure and opening sequence of natural fractures in the reservoirs. The results indicate that the maximum horizontal principal stress in the second member of the Funing Formation in the Tongcheng fault zone is oriented ENE. During the injection process, the ENE-trending fractures open first, and the ESE-trending fractures open later. The opening pressure of the fractures increases as the angle between the fracture strike and the maximum horizontal principal stress increases, and the burial depth of the fractures also has a relatively positive correlation with the opening pressure. At the structurally high site (1850 m–2350 m), the opening pressure of the fractures is in the range of 25 MPa–50 MPa, and at the structurally low site (3300 m–4000 m), the opening pressure of the fractures is in the range of 45 MPa–75 MPa. By calculating the actual fracture pressure of the reservoirs, we propose using different injection pressures in different blocks to ensure the high and stable production of oil from wells. Highlights • Quantitative prediction of reservoir fracture pressure using finite element method. • A method for predicting opening pressure of natural fractures in different directions. • Suggestion on reservoir development by combination of paleo and current stress field. [ABSTRACT FROM AUTHOR]

Antibiotic resistant bacteria are a threat to human life. Recently, sewers have been identified as potential reservoirs. The intermittent injection of sewage into adjacent surface waters is inevitable, due to capacity limitations of the urban drainage system. Information regarding the effect to natural freshwater biofilms (NFB) due to the intermittent contaminations are scarce. Therefore, a fundamental screening is necessary. In April, we placed NFB-attachment constructions in a brook upstream and downstream from urban drainage overflow constructions. In meanwhile two sampling campaigns were conducted. The sewage and the brook water were collected to gather information about antibiotic background exposure of ciprofloxacin (CIP), clarithromycin (CLA) and doxycycline (DOX). Six months later we experimentally determined the oxygen uptake rate (OUR) of the NFB-communities after a 24 h lasting exposure with additionally dosed antibiotics. Concentrations of 0.1, 1.0 and 10.0 mg L −1 were selected. CIP, CLA and DOX were individually dosed, and also in mixtures. The mean antibiotic background concentration in sewage was in a range of 575.5–1289.1 ng L −1 , which mainly exceeded the concentrations published in literature. The determined mean concentration in the brook was in a range of 4.6–539.0 ng L −1 . The first significant inhibition of the OUR with individually dosed antibiotics started mainly at a concentration of 1.0 mg L −1 . Antibiotics in a mixture with concentrations of 0.1 and 1.0 mg L −1 were as effective as single dosed antibiotics with a concentration of 10.0 mg L −1 . The increased antibiotic tolerance and resistance of NFB-communities downstream of the combined sewer overflow (CSO) structure was a consequence of a severe impact due to urban drainage overflows. Hence, NFB-communities downstream of CSO-constructions are hot spots of antibiotic tolerant and resistant subpopulations and access restrictions should be announced, if an infection risk is present. [ABSTRACT FROM AUTHOR]

The article presents an editorial on the impact of large scale dams and water reservoirs on the society and on the water-land nexus in Brazil. Also included are the negative impacts of dams and reservoirs on the local community and environment and the additional impact of climate change on river basins and rainfall.

Reservoir operation and management are complex engineering problems, due to the stochastic nature of inflow, various demands and as well as tailwater in the downstream. The complexity increases when the number of reservoirs gets increased such as multi-reservoir system or chain system. To obtain optimal operation in such condition become more difficult. It requires powerful optimization algorithm to solve aforesaid problems. Teaching Learning Based Optimization (TLBO) algorithm and Jaya Algorithm (JA) are recently developed advanced optimization techniques a novel approach comparatively simple, easy, and robust. The main advantages of these algorithms are it only requires the common control parameters such as number of iterations and population size. In the present study, three different benchmark problems were evaluated to check the applicability and performance of TLBO and JA in multi-reservoir operation problems. The benchmark problems are the discrete time four-reservoir operation (DFRO), the continuous time four-reservoir operation (CFRO), and the ten-reservoir operation (TRO). The results from the TLBO and JA are compared with different approaches from the literature. The optimal net benefits obtained from JA for DFRO, CFRO and TRO problems are 401.44, 308.40 and 1194.59, respectively, and that of TLBO algorithm are 401.33, 308.30 and 1194.44, respectively. It is found that both JA and TLBO algorithms provided a satisfactory solution as other optimization techniques, from literature. In conclusion, JA outperformed over TLBO. [ABSTRACT FROM AUTHOR]

Metalimnetic oxygen minimum zones (MOMs) commonly develop during the summer stratified period in freshwater reservoirs because of both natural processes and water quality management. While several previous studies have examined the causes of MOMs, much less is known about their effects, especially on reservoir biogeochemistry. MOMs create distinct redox gradients in the water column which may alter the magnitude and vertical distribution of dissolved methane (CH 4 ) and carbon dioxide (CO 2 ). The vertical distribution and diffusive efflux of CH 4 and CO 2 was monitored for two consecutive open-water seasons in a eutrophic reservoir that develops MOMs as a result of the operation of water quality engineering systems. During both summers, elevated concentrations of CH 4 accumulated within the anoxic MOM, reaching a maximum of 120 μM, and elevated concentrations of CO 2 accumulated in the oxic hypolimnion, reaching a maximum of 780 μM. Interestingly, the largest observed diffusive CH 4 effluxes occurred before fall turnover in both years, while peak diffusive CO 2 effluxes occurred both before and during turnover. Our data indicate that MOMs can substantially change the vertical distribution of CH 4 and CO 2 in the water column in reservoirs, resulting in the accumulation of CH 4 in the metalimnion (vs. at the sediments) and CO 2 in the hypolimnion. [ABSTRACT FROM AUTHOR]

Keban Dam Reservoir (KDR), located on the Euphrates River (Turkey), is an internationally important reservoir. In this study, levels of ten metals in 220 muscle samples of five fish species (mangar, common carp, Tigris scraper, Euphrates barbell and trout barb) taken from 11 sampling sites in the KDR were determined and compared with the results of previous studies carried out in other countries and Turkey. In addition, multiple approaches were used to assess human health risks from fish consumption. The significant spatial differences in concentrations of studied metals except As and Ni in Euphrates barbell were not found. However, concentrations of all metals except Cd showed significant seasonal differences. The concentrations of ten metals in fish species were lower than or comparable to those in fish species from other freshwater bodies. The metal concentrations in all fish species were found below the maximeavyum permissible concentrations. No health risks of studied heavy metals on human were found by daily fish intake. The target hazard quotient (THQ) and total THQ values were below 1, which suggests there are no significant non-carcinogenic health risks for fish consumers. The cancer risk values calculated for inorganic arsenic in all fish species except Euphrates barbell did not exceed the 10 −6 threshold. The allowable number of fish meals per month can be categorized as safe fish consumption. The results of this study revealed that the consumption of the examined fish species does not pose a significant risk to human health. [ABSTRACT FROM AUTHOR]

Abstract: A structural interpretation of the Ziarat block in the Balochistan region (a part of the Suleiman Fold and Thrust Belt) has been carried out using seismic and seismological data. Seismic data consists of nine 2.5D pre‐stack migrated seismic lines, whereas the seismological data covers the Fault Plane Solution and source parameters. Structural interpretation describes two broad fault sets of fore and back thrusts in the study area that have resulted in the development of pop‐up structures, accountable for the structural traps and seismicity pattern in terms of seismic hazard. Seismic interpretation includes time and depth contour maps of the Dungan Formation and Ranikot group, while seismological interpretation includes Fault Plane Solution, that is correlated with a geological and structural map of the area for the interpretation of the nature of the subsurface faults. Principal stresses are also estimated for the Ranikot group and Dungan Formation. In order to calculate anisotropic elastic properties, the parameters of the rock strength of the formations are first determined from seismic data, along with the dominant stresses (vertical, minimum horizontal, and maximum horizontal). The differential ratio of the maximum and minimum horizontal stresses is obtained to indicate optimal zones for hydraulic fracturing, and to assess the potential for geothermal energy reservoir prospect generation. The stress maps indicate high values towards the deeper part of the horizon, and low towards the shallower part, attributed to the lithological and structural variation in the area. Outcomes of structural interpretation indicate a good correlation of structure and tectonics from both seismological and seismic methods. [ABSTRACT FROM AUTHOR]

Abstract: The Kimmeridgian‐Tithonian aged Arab Formation, as the main reservoir of the Jurassic succession in the Balal oilfield, located in the offshore region of the Iranian sector of the Persian Gulf, is investigated in this study. The formation is composed of dolomites and limestones with anhydrite interbeds. Based on detailed petrographic studies, six microfacies are recognized, which are classified in four sub‐environments including supratidal, intertidal, lagoonal and the high energy shoal of a homoclinal carbonate ramp. The main diagenetic features of the studied succession include dolomitization, anhydritization, cementation, micritization, fracturing and compaction. Based on stable isotope data, dolomitization of the upper Arab carbonates is related to sabkha settings (i.e. evaporative type). In terms of sequence stratigraphy, three shallowing‐upward sequences are recognized, based on core and wireline log data from four wells of the studied field. Considering depositional and diagenetic effects on the reservoir quality, the studied facies are classified into eight reservoir rock types (RRT) with distinct reservoir qualities. Dolomitization has played a major role in reservoir quality enhancement, whereas anhydritization, carbonate cementation, and compaction have damaged the pore throat network. Distribution of the recognized RRTs in time and space are discussed within the context of a sequence stratigraphic framework. [ABSTRACT FROM AUTHOR]

Abstract: The late Jurassic Arab Formation, a significant carbonate‐evaporite reservoir rock in the Persian Gulf, is characterized by frequent grainstone facies. For rock type identification and reservoir characterization, core description, petrographic studies and pore system evaluation are integrated for Balal oil field in the Persian Gulf. The grainstone facies are developed into three shoal subenvironments on a carbonate ramp platform: leeward, central and seaward. Compaction, dissolution, cementation, anhydrite mineralization and dolomitization are the main diagenetic processes affecting the depositional pore system. Considering depositional and diagenetic features and pore types, the grainstones are classified into six rock types (RT 1 to RT6). Rock types 1, 2 and 5 have large pore throat sizes with intergranular and touching vug pore types. In rock type 3, moldic pores lead to high porosity and low permeability. Rock types 4 and 6 are cemented by anhydrite, calcite and dolomite. Generally, RTs 1, 2, 3 and 5 are related to late Transgressive systems tract (TST) and early Highstand systems tracts (HST) and show fair to good reservoir quality. In contrast, RTs 4 and 6 of late HST system tract show lower poroperm values, due to evaporite mineralization. Characterization of the grainstone facies provides a comprehensive understanding of the reservoir zones of the Arab Formation. [ABSTRACT FROM AUTHOR]

Abstract: Multireservoir systems require robust and adaptive control policies capable of managing hydroclimatic variability and human demands across a range of time scales. This is especially true for river basins with high intraannual and interannual variability, such as monsoonal systems that need to buffer against seasonal droughts while also managing extreme floods. Moreover, the timing, intensity, duration, and frequency of these hydrologic extremes may evolve with deeply uncertain changes in socioeconomic and climatic pressures. This study contributes an innovative method for exploring how possible changes in the timing and magnitude of the monsoonal cycle impact the robustness of reservoir operating policies designed assuming stationary hydrologic and socioeconomic conditions. We illustrate this analysis on the Red River basin in Vietnam, where reservoirs and dams serve as important sources of hydropower production, multisectoral water supply, and flood protection for the capital city of Hanoi. Applying our scenario discovery approach, we find that reservoir operations designed assuming stationarity provide robust hydropower performance in the Red River but that increased mean streamflow, amplification of the within‐year monsoonal cycle, and increased interannual variability all threaten their ability to manage flood risk. Additionally, increased agricultural water demands can only be tolerated if they are accompanied by greater mean flow, exacerbating food‐flood trade‐offs in the basin. These findings highlight the importance of exploring the impacts of a wide range of deeply uncertain socioeconomic and hydrologic factors when evaluating system robustness in monsoonal river basins, considering in particular both lower‐order moments of annual streamflow and intraannual monsoonal behavior. [ABSTRACT FROM AUTHOR]

In a changing climate with a warming trend in air temperature, river water temperature increases as a result of heat exchange with the atmosphere. Moreover, of the different types of anthropogenic activity impacting rivers, the construction of dams appears to have multi-dimensional effects on the river environment, and it especially affects the thermal condition of rivers. The aim of the study is to identify and assess the impact of these two distinct sources of water temperature distortion in relation to the natural thermal conditions of rivers. In the study, linear trend analysis and a complex wavelet transform are used. The analysis focuses on daily river water temperature data for time periods before and after the construction of selected reservoirs in the Polish Carpathians, and on daily air temperature data for neighboring meteorological stations. Three rivers were selected for analysis: (1) Dunajec River, 22 km downstream of the Czorsztyn–Sromowce Wyżne reservoir complex, (2) Ropa River, 16 km downstream of the Klimkówka Reservoir, and (3) Wisłok River, 33 km downstream of the Besko Reservoir. Research has shown that the significant increasing trends identified for water temperature are weaker than analogous trends in air temperature. The Czorsztyn–Sromowce Wyżne and Klimkówka reservoirs appear to exert considerable influence on natural air–water temperature synchronization, because the phase difference increases 5-fold in comparison with conditions prior to the construction of the reservoirs. The weakening of the natural air–water temperature synchrony implies diminished impact of air temperature on stream water temperature. However, this creates an opportunity for preparing appropriate management practices mitigating an increasing temperature trend in order to shape more favorable (natural) thermal conditions for native aquatic biota in impounded rivers. [ABSTRACT FROM AUTHOR]

In regions where the Mediterranean climate prevails, the agricultural sector and agricultural-operated dam reservoirs are threatened by climate change. In this respect, the prediction of hydro-meteorological changes that may occur in surface water resources under climate change scenarios is essential to examine the sustainability of reservoirs. In this paper, Demirköprü reservoir in the Gediz Basin/Turkey, a reservoir operated for irrigation purposes, was analyzed against the RCP4.5 and RCP 8.5 scenarios specified in the AR5 report of the IPCC. Projection period was evaluated as 2016-2050 water year period. First, statistical downscaling, Bayesian model averaging and quantile delta mapping bias correction techniques were respectively applied to monthly total precipitation and monthly average temperatures of meteorological stations in the region using 12 GCMs. According to RCP4.5 and RCP8.5, negligible reductions in precipitation are foreseen, while significant increases of 1.3 and 1.8 °C, respectively, are projected for temperatures under the same scenarios. Following the calibration of rainfall-runoff models for the sub-basins feeding the reservoir, streamflow simulations were also performed with projected precipitation and temperatures. In particular, according to the RCP 8.5 scenario, reservoir inflows during the period 2016-2050 could be reduced by 21% compared to the reference scenario results. Finally, the projected crop water demands and hydro-meteorological changes are evaluated together and the reservoir performances are examined using various indices. Assuming that the performance of the past irrigation yields will not change in the future, it is foreseen that reservoir’s sustainability will decrease by 16% under the RCP8.5 scenario. Even if the irrigation efficiency is increased by 40%, the reservoir cannot reach past sustainability characteristics. [ABSTRACT FROM AUTHOR]

Quantitative assessment of the Aquistore CO 2 storage reservoir has been conducted using a 30 km 2 3D seismic volume and a suite of well logs. 3D porosity was calculated using acoustic impedance from model-based seismic inversion and a log-based porosity-impedance relation. The reservoir has a mean thickness of 219 m ±ơ = 3% comprising 51% of pay . Strata dip at ∼1.75% SSE and include a prominent SSE-NNW structural fabric dominated by a ridge that corresponds to a Precambrian basement fault and overlying flexure. Porosity maps for Black Island and Deadwood reservoir zones show mean interval porosities of 0.071 ± ơ = 18% and 0.075 ± ơ = 9%, respectively with a weak degree of directionality that is sub-parallel to the strong NNW-SSE structural trends. Lateral spread of injected CO 2 will be strongly affected by the NNW-trending structural relief and bulk porosity/permeability trends. Local topographic channels may control CO 2 flow particularly when injection rates are low and local closed topographic structures may constitute traps for CO 2 . CO 2 static capacity estimates from well-based mean values are less than comparable seismic-based estimates by <15% due to porosity differences and <5% due to thickness differences. Variations in the Deadwood thickness of up to 25 m from the mean value would have resulted in capacity estimate differences of up to 25% if an alternate well location had been chosen. [ABSTRACT FROM AUTHOR]

An editorial is presented which focuses on freshwater biodiversity conservation and the role of artificial ponds in the 21st century. Topics discussed include current trends in wetland loss and creation; functioning of artificial ponds as effective conservation tools; and ways to enhance the capacity of these systems to support wildlife.

Tropical reservoirs are main carbon sources to the atmosphere, and bacterial metabolism is a key process in these emissions. Here, we explored the drivers of bacterial metabolism in four tropical cascading reservoirs forming a trophic state gradient, and compared them with those found in the literature (mainly from temperate regions). Bacterial production (BP) and growth efficiency (BGE) responded to trophic state-related variables, while bacterial respiration (BR) was weakly and negatively correlated to dissolved organic carbon (DOC). BP and BGE were higher in reservoirs with higher primary production, while BR (high throughout the whole study period) was greater in less productive reservoirs, where planktonic communities were often limited by phosphorus. The high BR and low BGE observed in less productive downstream reservoirs (i.e., less nutrients and organic matter availability) may be explained by increasing nutrient limitation and proportion of recalcitrant DOC along the cascade. Despite the lower productivity, oligotrophic reservoirs may be more important in terms of carbon biogeochemistry, considering that microbes in those systems mineralize more carbon than upstream productive reservoirs. Moreover, the drivers of bacterial metabolism may act differently according to latitude, as seasonality in the tropics is determined mainly by rainfall rather than temperature. [ABSTRACT FROM AUTHOR]

Abstract: Founder effects introduce stochasticity in the genetic structure of species at the regional scale. To the extent that founder effects are important, they will result in a reduced signature of space, time, and environmental variation in landscape genetic data. We studied the metapopulation genetic structure of recently founded populations of the microcrustacean Daphnia sinensis in 10 Ethiopian water reservoirs. We used three different approaches to estimate the number of effective founders and applied them to two independent genetic marker sets in an effort to investigate the role of founder effects and to estimate effective size of the founding population. Estimates of founding sizes rarely exceeded eight individuals but were most often limited to less than four individuals. No associations of genetic identities, gene frequencies, measures of genetic diversity, or differentiation with environmental and spatial variables were found. Age and size of the reservoirs were not correlated with genetic diversity measures or number of founders in these reservoirs. These findings indicate that neither strong selection, nor dispersal limitation are responsible for the observed pattern of genetic variation. Our results suggest a regional population structure that is strongly impacted by founder events, reflecting colonization by just a few founders per waterbody, and not noticeably influenced by subsequent dispersal and gene flow. Our results show that rapid colonization of empty habitats and fast population growth by a handful of founders can result in strong founder effects, even in relatively large habitats that are likely regularly reached by new immigrants. [ABSTRACT FROM AUTHOR]

Abstract: Naturally Fractured Reservoirs (NFR's) have received little attention as potential CO2 storage sites. Two main facts deter from storage projects in fractured reservoirs: (1) CO2 tends to be nonwetting in target formations and capillary forces will keep CO2 in the fractures, which typically have low pore volume; and (2) the high conductivity of the fractures may lead to increased spatial spreading of the CO2 plume. Numerical simulations are a powerful tool to understand the physics behind brine‐CO2 flow in NFR's. Dual‐porosity models are typically used to simulate multiphase flow in fractured formations. However, existing dual‐porosity models are based on crude approximations of the matrix‐fracture fluid transfer processes and often fail to capture the dynamics of fluid exchange accurately. Therefore, more accurate transfer functions are needed in order to evaluate the CO2 transfer to the matrix. This work presents an assessment of CO2 storage potential in NFR's using dual‐porosity models. We investigate the impact of a system of fractures on storage in a saline aquifer, by analyzing the time scales of brine drainage by CO2 in the matrix blocks and the maximum CO2 that can be stored in the rock matrix. A new model to estimate drainage time scales is developed and used in a transfer function for dual‐porosity simulations. We then analyze how injection rates should be limited in order to avoid early spill of CO2 (lost control of the plume) on a conceptual anticline model. Numerical simulations on the anticline show that naturally fractured reservoirs may be used to store CO2. [ABSTRACT FROM AUTHOR]

The middle catchment of the Nu River is highly susceptible to debris flows. Differences in flow and substratum conditions among mainstem reaches correlate with debris flow depositions from lateral tributaries. We studied the impacts of debris flows on macroinvertebrates, especially responses in their diversity and assemblage structure to habitat modification at 22 sites in three habitats: barrier lakes and debris dams, formed by debris flow deposits barring the river, and unaffected mainstem sections. Unaffected mainstem sites supported the most diverse macroinvertebrate assemblage, with mean taxon richness, density and biomass 1.4, 1.1, and 23.6 times higher than those of debris dam sites, and 2.1, 4.2, and 7.4 times higher than those of barrier lake sites, respectively. Variance analysis revealed significant differences in diversity indices, and both taxonomic and functional feeding group composition among habitats. Although barrier lakes and debris dams had lower taxon richness, the two affected habitats contributed 17 and 16 exclusive taxa, respectively, to total taxon richness. Redundancy analysis identified habitats could be characterized by water temperature, electrical conductivity, flow velocity, and median particle size of substratum type. Significant differences in flow velocity and substratum median particle size among habitats were attributed to debris flows. Distinct assemblages within barrier lakes were associated with fine sediments. By altering habitat conditions, debris flows affect macroinvertebrate assemblages, reducing diversity locally in affected reaches, contributing to variation in diversity and assemblage structure throughout the catchment. Three genera ( Cricotopus sp., Pseudocloeon sp. and Monodiamesa sp.) are proposed as potential indicator taxa for unaffected mainstem, debris dam and barrier lake habitats, respectively. [ABSTRACT FROM AUTHOR]

The magnitude of diffusive carbon dioxide (CO2) and methane (CH4) emission from man-made reservoirs is uncertain because the spatial variability generally is not well-represented. Here, we examine the spatial variability and its drivers for partial pressure, gas-exchange velocity (k), and diffusive flux of CO2 and CH4 in three tropical reservoirs using spatially resolved measurements of both gas concentrations and k. We observed high spatial variability in CO2 and CH4 concentrations and flux within all three reservoirs, with river inflow areas generally displaying elevated CH4 concentrations. Conversely, areas close to the dam are generally characterized by low concentrations and are therefore not likely to be representative for the whole system A large share (44-83%) of the within-reservoir variability of gas concentration was explained by dissolved oxygen, pH, chlorophyll, water depth, and within-reservoir location. High spatial variability in k was observed, and k CH4, was persistently higher (on average, 23 times more) than kCO2 Not accounting for the within-reservoir variability in concentrations and k may lead to up to 80% underestimation of whole-system diffusive emission of CO2 and CH4. Our findings provide valuable information on how to develop field-sampling strategies to reliably capture the spatial heterogeneity of diffusive carbon fluxes from reservoirs. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing requires a large volume of fresh water, which is difficult and expensive to obtain in the desert area such as Tarim Basin. Currently, flowback fluid is typically transported to the sewage treatment plant and then discharged after reaching environmental requirements; however, this is not only costly, but also a waste of water resource. Therefore, it is imperative to understand the potential interactions between fracturing fluid and reservoir rock, and then find solutions to reuse the flowback water for subsequent fracturing. In this study, once flowback fluid was directly collected from the field, its chemical compositions were analyzed; then, filtering, decoloring, and chelating methods were chosen to effectively remove or shield the unfavorable reintroduced components. Moreover, pH value was further tuned during different stages of the recycling process to ensure good gelation and cross-linking properties of guar. Cross-linked guar synthesized with the flowback fluid was evaluated in the lab through shear resistance tests and coreflood tests under the reservoir conditions; results indicated the recycled gel behaved similarly as the original gel, or even better. From this work, a cheap and effective treatment process was proposed to reuse the flowback fluid in the desert area. [ABSTRACT FROM AUTHOR]

Reservoir impoundment and water fluctuations have endangered the stability of the reservoir bank slopes, which have experienced several small-scale shallow slides/collapses and few large-scale slopes with failures/deformations. Field investigations, unmanned aerial vehicle technology and site displacement monitoring dates are used to study the spatiotemporal distribution and mechanisms of the reservoir landslides within the Dagangshan reservoir. The reservoir landslides can be divided into two main types: shallow small-scale slides and unstable deformation slopes, which are clearly associated with reservoir impoundment and fluctuations of the water level. Small-scale slides/collapses are continually distributed along the river banks nearest to the water level, but deep-seated landslides have usually experienced a long history, and some obvious precursor phenomena may exist in the slopes. According to the recognition of deformational and failure evolutionary processes of large-scale slopes, and based on hydrology and geomechanics, two types of potential failure models (creep-shear-tension failure and toppling-tensile-shear model) are proposed to interpret the mechanisms of the deformation slopes in the Dagangshan reservoir. Furthermore, some preliminary discussion is presented concerning the non-significant development of landslides in the Dagangshan reservoir that are also associated with smaller water fluctuations due to the daily regulation type of the reservoir. [ABSTRACT FROM AUTHOR]

Glaciers were solid reservoirs and important water resources in western China, but they were retreating significantly in context of global warming. Laohugou Glacier No. 12 was the largest valley glacier in Qilian Mountains. In this study, realtime kinematic (RTK) data, topographic map and WorldView-2 satellite imagery were used to measure changes in terminus, extent and volume of Laohugou Glacier No. 12. Results showed that Laohugou Glacier No. 12 was shrinking significantly since 1957. From 1960 to 2015, the terminus reduction of Laohugou Glacier No. 12 was 402.96 m (3.99%) in total, and glacier length decreased to 9.7 km from 10.1 km. Reduction of glacier area and volume were the most obvious. From 1957 to 2015, glacier area and volume decreased by 1.54 km2 (7.03%) and 0.1816 km3, respectively. Reduction trend of terminus and area was slowing in 1950 -1980s, even stable for a period in the mid-1980s, and then accelerated. Ice core analysis result and nearly meteorological station data shown an increasing trend of temperature in 1957 -2015, it was a main reason of continuous retreating of Laohugou Glacier No.12. [ABSTRACT FROM AUTHOR]

Observed changes in precipitation patterns, rising surface temperature, increases in frequency and intensity of floods and droughts, widespread melting of ice, and reduced snow cover are some of the documented hydrologic changes associated with global climate change. Climate change is therefore expected to affect the water supply-demand balance in the Northeast United States and challenge existing water management strategies. The hydrological implications of future climate will affect the design capacity and operating characteristics of dams. The vulnerability of water resources systems to floods and droughts will increase, and the trade-offs between reservoir releases to maintain flood control storage, drought resilience, ecological flow, human water demand, and energy production should be reconsidered. We used a Neural Networks based General Reservoir Operation Scheme to estimate the implications of climate change for dams on a regional scale. This dynamic daily reservoir module automatically adapts to changes in climate and re-adjusts the operation of dams based on water storage level, timing, and magnitude of incoming flows. Our findings suggest that the importance of dams in providing water security in the region will increase. We create an indicator of the Effective Degree of Regulation (EDR) by dams on water resources and show that it is expected to increase, particularly during drier months of year, simply as a consequence of projected climate change. The results also indicate that increasing the size and number of dams, in addition to modifying their operations, may become necessary to offset the vulnerabilities of water resources systems to future climate uncertainties. This is the case even without considering the likely increase in future water demand, especially in the most densely populated regions of the Northeast. [ABSTRACT FROM AUTHOR]

Soil heavy metal contents were measured in newly submerged areas of the Danjiangkou Reservoir, China. We aimed to determine the heavy metal distribution in this area and the associated ecological risk. Most of these heavy metal contents (except Pb and Mn) suggest enrichment compared with the background values of soils from Henan Province, especially As and Cd with mean geo-accumulation index ( I geo ) values of 0.84 and 0.54. The spatial analysis results indicated that the highest heavy metal contents were distributed in the arable soils above 160 m elevation, whereas low heavy metal contents were observed under other land-use types above 160 m elevation. According to I geo and EF values, Cd was the major heavy metal contaminant in the newly submerged area, Cr, Pb and Mn mainly originated from natural geochemical sources. In contrast, Ni, Cd, As, Cu, and Zn mainly originated from anthropogenic sources. Evaluation using the potential ecological risk (PER) method indicated that PER of individual elements were low in the studied soils, and the comprehensive PER index was at a moderate level, indicating heavy metals in the soils of newly submerged areas may not threaten the water quality of Danjiangkou Reservoir, especially in winter. [ABSTRACT FROM AUTHOR]

The United States is home to 2198 dams actively used for hydropower production. With the December 2015 consensus adoption of the United Nations Framework Convention on Climate Change Paris Agreement, it is important to accurately quantify anthropogenic greenhouse gas emissions. Methane ebullition, or methane bubbles originating from river or lake sediments, has been shown to account for nearly all methane emissions from tropical hydropower reservoirs to the atmosphere. However, distinct ebullitive methane fluxes have been studied in comparatively few temperate hydropower reservoirs globally. This study measures ebullitive and diffusive methane fluxes from two eastern Washington reservoirs, and synthesizes existing studies of methane ebullition in temperate, boreal, and tropical hydropower reservoirs. Ebullition comprises nearly all methane emissions (>97%) from this study's two eastern Washington hydropower reservoirs to the atmosphere. Summer methane ebullition from these reservoirs was higher than ebullition in six southeastern U.S. hydropower reservoirs, however it was similar to temperate reservoirs in other parts of the world. Our literature synthesis suggests that methane ebullition from temperate hydropower reservoirs can be seasonally elevated compared to tropical climates, however annual emissions are likely to be higher within tropical climates, emphasizing the possible range of methane ebullition fluxes and the need for the further study of temperate reservoirs. Possible future changes to the Intergovernmental Panel on Climate Change and UNFCCC guidelines for national greenhouse gas inventories highlights the need for accurate assessment of reservoir emissions. [ABSTRACT FROM AUTHOR]

In order to understand the effect of river impoundment on carbon dynamics, a large reservoir in a subtropical area, the Xinanjiang Reservoir, was investigated in detail. CO emissions from the water-air interface was studied, as was organic carbon burial in sediment. The results show a significant seasonal difference in CO emissions. River impoundment led to the enhancement of aquatic photosynthesis, generating large amounts of authigenic organic carbon that was then buried in sediment. [ABSTRACT FROM AUTHOR]

Increasing demand for water and a desire for greater human water security has facilitated the global expansion of dams, with river regulation acknowledged as the leading cause of biodiversity decline in rivers. Native biota within these stressed systems are also impacted by reductions in habitat availability, decreased hydraulic diversity, increased sedimentation, movement barriers, invasive species and altered flows that may profoundly change the character and functioning of rivers. Construction or enlargement of reservoirs is continuing, and whilst downstream impacts are often considered, upstream impacts receive far less attention. We develop a population model to examine the impacts of reservoir expansion on a threatened riverine species in South Eastern Australia: the two-spined blackfish. We examined two processes, loss of breeding habitat and increased predation, directly linked to reservoir expansion as well as a broader threat of recruitment failure due to sedimentation. These threatening processes were assessed using the expected minimum population size as an indicator of risk. As is often the case for threatened species, limited data were used to parameterise the model and sensitivity analysis performed to assess the appropriateness of the model parameterisation. The outcomes indicate that the two-spined blackfish population is vulnerable to the loss of breeding habitat particularly if two-spined blackfish are unable to spawn in the larger dam, although this vulnerability is ameliorated if the whole river is accounted for. Including possible impacts from the resident trout population for the whole river, indicates the two-spined blackfish to be vulnerable to low level predation particularly if the trout population have a high growth rate. Population modelling has rarely been used to predict the consequences of dam construction on aquatic species/communities. The example here shows it to be a powerful tool to visualise and quantify potential biodiversity outcomes. [ABSTRACT FROM AUTHOR]

Artificial water bodies like reservoirs are unique in sense that they encompass hybrid characters of both lakes and streams. Detailed study of reservoir ecosystem is necessary in order to understand and evaluate the health of such systems. A universal characteristic of any ecosystem is its ability to counter stress conditions and this ability is termed robustness which signifies the systems sustainability. Exergy or eco-exergy, measuring the amount of stored workable energy in the system is another important descriptor of an ecosystem. Both robustness and eco-exergy are good indicators of ecosystem health and also they are dependent on the magnitude and type of the inflicted stress. Robustness of Bakreswar reservoir system has been studied here following hypothetical perturbation scenarios that represent possible real situations of eutrophication (nutrient loading) and overfishing. Quite a few descriptive ecosystem indices have also been considered for the current study including Total System Throughflow ( TST ), Finn Cycling Index ( FCI ), Redundancy ( R ), Ascendancy ( A ), Developmental capacity ( C ), Total Primary Production to Total Respiration ratio ( TPP/TR ), Total Primary Production to Total Biomass Ratio ( TPP/TB ), detritivory to herbivory ratio and also the Exergy of the system. It is concluded from this study that the Bakreswar reservoir is a moderately stable ecosystem with fair maturity level and is able to withstand stress for a reasonable extent. The network indices revealed that variation in robustness of the system is related more with fish biomass perturbation scenario rather than that for the autotroph biomass perturbations. This is confirmed by the network indices as well as the change in the system exergy values which shows more variation in the fish biomass scenario. [ABSTRACT FROM AUTHOR]

In the reservoir exploration phase, different types of information are gathered and used for a reliable geological description. Combining seismic data, well log analysis, statistical rock physics or even paleobathymetry ranges, several methods have been proposed to estimate a probability field for each facies type in the reservoir model. However, these probability fields are typically not conditioned to the reservoir production history. Once the reservoir starts production new information becomes available, and an update of the probability fields is needed. The work presented here introduces a new framework for simulation of facies fields in the context of plurigaussian simulation where the facies fields are conditioned to the prior probability fields provided. The methodology is based on the probability integral transform and the topological characteristics of the facies types (number of the facies type and relative position among facies types). The developed method generates an ensemble of facies fields that honor the facies distribution as described by a probability field. The proposed method can easily condition the facies field to hard data and preserve the facies field during history matching in an ensemble based framework. A demonstration with the adaptive Gaussian mixture filter is presented here. [ABSTRACT FROM AUTHOR]

The spatial footprint of individual run-of-river (RoR) hydropower facilities is smaller than reservoir-storage hydroelectric projects and their impacts to aquatic ecosystems are often assumed to be negligible. However, these effects are poorly understood, especially for salmonids whose freshwater habitat often overlaps with RoR hydropower potential. Flow regulation for RoR hydropower is unique in how it influences the seasonality and magnitude of flow diversion and because low-head dams can be overtopped at high flows. Based on a review of the primary literature, we identified three pathways of effects by which RoR hydropower may influence salmonids: reduction of flow, presence of low-head dams impounding rivers, and anthropogenic flow fluctuations. We synthesized empirical evidence of effects of RoR hydropower on river ecosystems from 31 papers, of which only 10 explicitly considered salmonids. We identified key research gaps including impacts of extended low-flow periods, anthropogenic flow fluctuations, and cumulative effects of multiple RoR projects. Filling these gaps is necessary to help manage and conserve salmonid populations in the face of the growing global demand for small-scale hydropower. [ABSTRACT FROM AUTHOR]

Reconciling simultaneous water quantity and quality aspects in drawing optimal reservoir operational strategy involves extensive computational burdens. Surrogate based optimization techniques (SBOTs) are common approaches to overcome computational bottlenecks of numerical hydrodynamic simulation models coupling evolutionary algorithm in simulation-optimization approaches. In this study, the reservoir high resolution CE-QUAL-W2 model is replaced by the lower resolution CE-QUAL-W2 and/or static ANN to speed up the optimization process. These surrogate models could consider the complex relationships to emulate the main dynamics of HR CE-QUAL-W2 model due to various reservoir operational strategies. The performance of various SBOTs, based on adaptive and sequential surrogate models coupled with particle swarm optimization algorithm, are evaluated in deriving optimal reservoir operational strategies. Then adaptive surrogate model, as the more efficient and accurate one, is applied to derive long term optimal reservoir operational strategy in the selective withdrawal scheme. The results show application of the proposed approach could enhance downstream water temperature, water demand satisfactions, and hydropower peak energy generation compared with the standard operation policy (SOP) in Karkheh reservoir during 15-year-time horizon. [ABSTRACT FROM AUTHOR]

Under climate warming and impoundment conditions of the Three Gorges Reservoir (TGR), spatial distribution and temporal trend of pan evaporation in the Three Gorges Reservoir Area (TGRA) and its surroundings offer valuable information about regional hydrology and ecosystem succession. In this study, pan evaporation measured by a pan of 20 cm diameter at 27 meteorological stations during 1952-2013 in the TGRA and its surroundings were calculated, compared and analyzed. Their spatial distribution and temporal trend were examined and the causes for the variations are discussed. The results show that: (1) The average annual pan evaporation in the TGRA and its surroundings is 1208.03 mm, and it appears an east-west downward gradient. (2) Examined by Mann-Kendall (MK) test, pan evaporation significantly declined at the rate of -40.8 mm/decade during 1952-2013. It shows upward trend in 1960s, 1970s, but downward trend in 1980s and 2000s. (3) The decreasing of pan evaporation is the results of comprehensive influences of air temperature (TEM), wind speed (WIN), sunshine duration (SSD) and relative humidity (RHU). Among them, SSD is the largest contributor. [ABSTRACT FROM AUTHOR]

Pre-dams are small reservoirs constructed upstream of the main drinking water reservoirs and are used for nutrient removal and sediment trapping. Little is known about the role of pre-dams regarding the production and decomposition of dissolved organic carbon (DOC) in relation to discharge and how this affects the quality of DOC in the water. We combined quantitative and qualitative investigations under different hydrological conditions at three pre-dams exhibiting a gradient from oligotrophic/high-DOC to eutrophic/low-DOC. All pre-dams were mainly autotrophic in their upper water layers. The ratio of OC production to total gained OC (i.e. OC import + OC production) decreased with increasing discharge. On average, 0–30% of the total gained OC was produced within the pre-dams. The amount of microbially decomposed DOC increased with the average water residence time (WRT) and with the trophic status of the pre-dams. Radiocarbon analyses of respired CO 2 revealed that heterotrophic bacteria preferentially utilized old DOC components (195–395 years before present) under base flow conditions, whereas younger components (modern, i.e. OC produced after 1950) were utilized at high discharge. DOC quality changed significantly over the year within the pre-dams: High proportions of algae-derived DOC were observed during base flow in summer, and the freshness index (β/α ratio) decreased significantly with higher discharges. DOC production and quality changes in response to hydrological conditions should be considered for future water quality management in reservoirs, as climate scenarios for temperate regions predict decreased runoffs leading to longer WRT and increased eutrophication and production of algae-derived OC. [ABSTRACT FROM AUTHOR]

ABSTRACT Radiocarbon (14C) dating is a widely used and powerful tool for determining the ages of samples in studies of palaeoclimatology, palaeoseismology and archaeology. 14C ages of marine samples often require correction for local reservoir age (Δ R). Although Δ R in the mid- to low latitudes has varied through time, few spatiotemporal reconstructions of Δ R have been published for those regions. Here we report on new and previously published Δ R data for the early 1900s to 1950 obtained from coral skeletons from the Kuroshio region off southern Japan. The data presented here show a marked positive-to-negative shift of Δ R from the early 1900s to the 1940s, which has important implications for calibration of radiocarbon ages in the region and for understanding the relationship of Δ R in the western Pacific with both the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. [ABSTRACT FROM AUTHOR]

Sand hazards are serious at the Danghe Reservoir of Dunhuang, and efforts to control sand are ineffective because disaster-causing mechanisms are currently unclear. The source of sandy materials, dynamic environment of blown sand, and controlling measures of the reservoir area are investigated using different methods, such as granularity analyses, wind regime and sand transport field observation and analyses, sand drift potential calculation. Accordingly, the sandy materials are found to derive chiefly from the Mingsha Mountain on the north side of the reservoir area. In addition, sand grain in the range of 0.50-0.25 mm and 0.25-0.10 mm are dominant. The prevailing sand-moving wind originates from the N direction, accounting for 15.38% of the yearly total, which coincides in the same direction with sand source, thereby increasing the severity of sand hazards in the reservoir area. The yearly sand DP is 1386.59 VU, the yearly RDP is 567.31 VU, the yearly RDP/DP is 0.41, and the yearly RDD is 183.15°. In the windy season (mainly in summer), sand materials are blown by wind from north to south, and then blocked by the Danghe River. The sand materials then move with an approximate east-west trend into the river channel and produce sediment, thereby causing a disaster. We propose that the sand-controlling pattern of the Danghe Reservoir is dominated by sand blocking in the outer fringe and sand fixing in the inner fringe. Applying windbreak and sand fixation to control sandy material movement into the river channel plays an important role in retarding sedimentation and extending the useful life of the Danghe Reservoir. [ABSTRACT FROM AUTHOR]

Energy systems are not only intrinsically interesting, because power is itself of importance; they raise fascinating trade-offs in other areas particularly since there are almost invariably technical, economic, and ecological dimensions to these considerations. This paper illustrates this interplay through a staged process that starts with a direct optimization approach for a pumped-storage facility with the simple goal of achieving an optimal profit given well-forecasted flows and energy prices. Sir Adam Beck Pumping Generating Station, located on the Niagara River, is selected as the subject of the model application. When analyzed for probable changes in current electricity rates, a 1–24% reduction in profit is realized depending on the month. Interestingly, relative to current design the model predicts only modest profit throughout the year with an increasing reservoir footprint. Since considerations other than the purely technical quickly arise, this paper considers the trade-off between hydropower and ecological targets imposed by the 1950 Niagara River Treaty. This exploratory study makes no pretense to forecast likely or advisable developments, but rather considers a possible role that a pumped-storage operation might hypothetically play in the Ontario spot market. [ABSTRACT FROM AUTHOR]

Response strategies determine the resilience of an area to effects of sea level rise. Strategies that are sustainable are those that do not negatively affect the environment, biodiversity and community life of the people. The paper discusses response strategies practiced in the Niger delta to combat effects of sea level rise like: flooding, erosion, inundation, storm surge, and intrusion of sea salt. Local responses to these natural hazards and the degree of effectiveness of the methods in enabling the people return to their normal lives are reviewed for their suitability as future adaptation strategies. GIS and remote sensing analysis of slope and topography show the Niger delta is vulnerable to further flooding, inundation, and erosion as a result of sea level rise. Based on a ‘business as usual’ scenario, the GIS based bathtub approach is used to calculate and map possible inundation extents for the Niger delta under sea level rise conditions. As the Niger delta is subsiding due to oil and gas exploitation, relative sea level rise (RSLR) values for the Niger delta are obtained by adding measured subsidence values (7 mm and 25 mm) to predicted eustatic sea level rise values (19 mm by 2030 and 35 mm by 2050); resulting in RSLR of 0.14–0.96 m by 2030 and 2050. With subsidence at 7 mm/year and a RSLR of 0.14 m, results for 2030 shows an inundation extent of 1119.3 km 2 which is 4.6% of the total surface area; subsidence of 25 mm/year (SLR = 0.44 m) gives an inundation extent of 1254.0 km 2 which is 5.2% of the surface area. Results for 2050 show that a rise of 0.29 m (subsidence = 7 mm/year) will cause an inundation extent of 1175.9 km 2 which is 4.9% of the total surface area, and RSLR of 0.96 m (subsidence = 25 mm/year) inundates 1633.0 km 2 which is 6.8% of the surface area. Although the literature shows local practices have helped people to cope with the challenges posed by flooding, erosion, inundation, and inland intrusion of sea salts, however some of the practices have disadvantages that make them undesirable for inclusion in future planning. Sustainable local practices in the Niger delta include: planting of Bamboo trees for erosion control, use of sandbags as bridges and dikes (flood control), use of flood receptor pits as temporary flood water reservoirs, and community legislation against sand mining and indiscriminate tree felling. Further studies on the limitations of the local resilience practices in the Niger delta is recommended. [ABSTRACT FROM AUTHOR]

Construction of dams causes reduced flow velocities, inducing gradual deposition of sediments carried by the inflowing stream, and resulting in sedimentation and ultimately diminishing reservoir storage capacity. This study focuses on sedimentation of Hirakud Reservoir in Odisha, India, using available reservoir capacity and numerical simulation data. Reduced trap efficiency, observed and projected capacity curves, rising reservoir bed level and the capacities of the different storage zones for various projected years are analysed. The area-reduction method indicates the loss in the live, gross and dead storage will be 58%, 63% and 100%, respectively, of their original capacities by 2057, which represents 100 years of impounding of water in the reservoir. If the present sediment inflow rate continues without regular flushing of the deposited sediment, it is predicted the reservoir bed level will rise to the full reservoir level of 192.02 m by the year 2110. Brune's trap efficiency and step method indicate the gross storage zone of Hirakud Reservoir will be completely depleted by the end of 2110, with the trap efficiency reduced to zero. The empirical area-reduction method is found to be more suitable for determining the storage capacities of Hirakud Reservoir in the absence of sedimentation survey data. An attempt was also made to solve the combined hydrodynamic and sediment transport equations numerically to predict morphological changes in Hirakud Reservoir. The finite-element code TELEMAC-2D and finite-volume code for SISYPHE, respectively, were applied to solve the above set of equations in order to predict the bed profiles at different reservoir cross sections for the period of 1958-2008. Analysis of the simulated results demonstrates that, considering the model inputs, the model performs well in simulating the morphology and dynamic characteristics of a reservoir. Projection of the numerical results indicates a complete loss of reservoir operational life due to sedimentation by around 2150. [ABSTRACT FROM AUTHOR]

Recent year, reducing of open area and the extreme rainfall are reason for the flood in some city in Indonesia. The drainage and infiltrated well were constructed in some parts of the city could not solve the problem yet. The porous pavement can be applied to reduce run off, rate and pollutants. Reservoir base or sub base is an important layer as part of structure and also temporary store rainfall water before infiltrate to the subgrade. This study assessed characteristic and gradation some types of materials as stone crush, limestone and steel slag for porous pavement and evaluate this performance based on California Bearing Ratio (CBR) and porosity. Naturally these characteristics are contrary, in which for high porosity materials will have low bearing capacity. There are 7 gradations consist of 4 gradations in coarse aggregate and 3 gradations based on Bina Marga (Indonesian Highway Agency). The result showed that CBR of stone crush is high in uniform course material gradation than limestone and steel slag. In the term of porosity, the result completely the same for all materials in which the uniform gradation give the high porosity. It makes sign the influence of hardness and gradation of material will give contribution for bearing capacity and only gradation influence to porosity. The material are suitable for reservoir layer of porous pavement for light traffic load. Gradation band is lied between Bina Marga and NAPA and AASHTO specification. [ABSTRACT FROM AUTHOR]

Sediments play important roles, as nutrient reservoir, especially in shallow lake ecosystem. The water column of large shallow lakes is often stable but also disturbed by turbulence causing resuspension of sediments. While considerable research has been carried out to investigate the influence of sediment resuspension on nutrient release, fewer studies have been done to understand the contribution of alkaline phosphatase activity (APA) in water as a response to the two conditions (turbulence and stability). Also, effects of the two lake conditions on photosynthetic efficiency of phytoplankton are still poorly understood. This study will evaluate the effect of these two conditions on photosynthetic efficiency and APA. Sediments used in the indoor experiments were collected from Zhushan Bay in Lake Taihu. Turbulence was generated by rotors to simulate the strong wind-induced disturbance in Lake Taihu. Results of the experiments showed that TN and TP in the stable and episodically turbulent conditions were not significantly different, with TN ranging from 1.34 to 1.90 mg/L and TP from 0.08 to 0.18 mg/L. Whereas, the soluble reactive phosphorus in the episodically turbulent condition was significantly higher than in the stable condition. Episodic turbulence could enhance P cycling by resuspending sediment-associated P, which alleviated algal P limitation. In stable conditions, P deficiency induced the production of high APA, which enhanced the availability of P. Although episodic turbulence could also cause increased algal biomass, photosynthetic efficiency of the algae was also affected not only by the nutrients but also by many other factors, especially light availability. Our results suggest that episodic turbulence is an important driver of biogeochemical cycling in large shallow hypertrophic lake ecosystem. [ABSTRACT FROM AUTHOR]

The widespread use of detergents increases the concentration of surfactant in lakes and reservoirs. High surfactant loads produces toxicity to algae; however, the influence of the increasing surfactant on the competition between algae is not clear. In this paper, different amounts of linear alkylbenzene sulfonate (LAS) were added to test the effects of LAS on the competition between Microcystis aeruginosa and Scenedesmus obliquus under eutrophic condition. In single culture, the growth of S. obliquus was promoted under lower LAS concentrations (1 and 20 mg L), but cell density of S. obliquus reduced when treated with higher LAS concentration (100 mg L). The growth of M. aeruginosa was inhibited markedly with 20 and 100 mg L LAS. Compared with single culture, the result was opposite in co-cultures and the cell density of S. obliquus increased significantly when treated with LAS of 1, 20, and 100 mg L. The specific growth rates of S. obliquus and M. aeruginosa in both cultures were 0.4-0.5 day and 0.6-0.7 day, respectively, except that the specific growth rate of M. aeruginosa in both cultures treated with 100 mg L LAS was about 0.2 day. M. aeruginosa dominated over S. obliquus in the co-culture without LAS, while the competition was completely opposite with the addition of 20 mg L LAS. The growth of S. obliquus treated with 20 mg L LAS was not affected significantly in single culture but was promoted by 75 % in co-culture. Moreover, the growth of S. obliquus in co-culture treated with 100 mg L LAS was promoted by more than 97 %. These results suggested that the increasing LAS would overturn the competition of algae in freshwater ecosystems. [ABSTRACT FROM AUTHOR]