Water Resources Management Strategies Research Articles

The calculation of estuarine flushing times in convergent estuaries using fresh-water fraction method

ABSTRACT The flushing time in an estuary is important for water quality analysis, and it is one of the major transport time scales used in estuaries to quantify the hydrodynamic processes and for water resources management strategies. The purpose of this paper is to investigate the influence of tidal amplitude, river discharge, and salinity stratification on the spatially varying flushing time of the two selected Moroccan Atlantic semi-closed estuaries, i.e. Bouregreg and Loukkos. A freshwater fraction method (FFM) was used to calculate flushing time for both estuaries using a spatially varying freshwater fraction. The results showed that the flushing time varies from 2.7 to 6.3 days for a river discharge ranges from 17 to 22 m3s−1 during spring tide, and from 3.4 to 11.2 days for a river discharge ranges from 17 to 31 m3s−1 during neap tide in Bouregreg estuary, and varies from 10 to 13.6 days for a river discharge ranges from 3.47 to 5.12 m3s−1 during spring tide, and from 9.11 to 13.1 days for a river discharge ranges from 3.47 to 5.48 m3s−1 at neap tide in Loukkos estuary. In addition, the flushing time near the mouth for both estuaries is shorter during spring tide than during neap tide because of the larger amplitude of the spring tide. At the estuary mouth (e.g. Bouregreg estuary), the potential energy anomaly of the water column is negligible (<4 J m−3).

Investigation of potential human health risks from fluoride and nitrate via water consumption in Sabzevar, Iran

ABSTRACT High concentrations of fluoride and nitrate in drinking water cause significant impacts on human health. The aim of this research was to estimate the risk to human health induced by fluoride and nitrate due to the intake of the groundwater through drinking water in Sabzevar city, Iran. Eighteen groundwater samples were collected from nine wells in the region during 2018 to determine the fluoride and nitrate concentrations. The non-cancer risk, reflected by the hazard quotient (HQ) and the hazard index (HI), was assessed for adults, children and infants. The water samples had overall mean fluoride and nitrate levels in the range of 0.197–1.32 mg/L and 8.8–47.2 mg/L, respectively. All the wells had fluoride levels below the WHO guideline of 1.5 mg/L. For nitrate, all the wells were within the standard. Among the nine groundwater samples, the total HI values at 22%, 55% and 55% of wells exceeded safe levels of 1 for adults, children and infants, which indicates that the local groundwater is detrimental to these age groups in the mentioned locations. The results of this research could help to develop proper strategies for comprehensive water resource management, particularly by providing scientific documents for decision and management of groundwater sources applied for drinking water supply.

Water 222Rn for evaluating the variation in groundwater inflows to discharge of the Big Sioux River in different flow periods

Knowledge of seasonal water sources can help for improved management strategies to sustain agricultural productivity and ecosystem-services in a basin. This study defines the distribution of gaining reaches and evaluates groundwater inflows into the Big Sioux River located in eastern South Dakota using 222Rn mass balance approach during two distinctly different flow periods. The groundwater inflows estimated for the middle catchment were higher (up to 12.8 m3/m/day) compared to the values estimated for the upper catchment (up to 0.3 m3/m/day) in the Big Sioux River basin during both low- and high-flow periods. During low-flow period, the overall cumulative groundwater inflow ranged between 2529 and 211,166 m3/day that corresponded to 5 and 53% contribution to the total flow rate. The inflow during high-flow period ranged between 2467 and 332,740 m3/day corresponding to 2 and 55% of the total flow rate. Despite having elevated cumulative groundwater inflow during high-flow period, the relative contribution of groundwater inflow into the river was high during the low-flow period (a mean of 24% evaluated for the low-flow period vs. 18% for the high-flow period), potentially associated with high meltwater contribution derived from the spring snowmelt during that period. These estimations are expected to provide a better knowledge on seasonal water resource allocations that may be crucial for better water resource management strategies for the Big Sioux River basin.

Human Activity and Hydrogeochemical Processes Relating to Groundwater Quality Degradation in the Yuncheng Basin, Northern China.

Groundwater quality degradation has raised widespread concerns about water supplies and ecological crises in China. In this study, hydrogeochemistry, environmental stable isotopes (δ18O, δD), and principal component analysis were conducted together to reveal the mechanism’s response to the hydrogeochemical and quality degradation of groundwater in Yuncheng Basin, Northern China, so that reasonable water resource management strategies can be developed. The study reveals that groundwater faces a tremendous risk of quality decrease during the past decade: (1) the hydrochemical facies of groundwater shows that the bicarbonate and chloride type water was replaced with sulfate type water and the occupying area of SO4·Cl-Na, SO4·HCO3-Na type water expanded dramatically in shallow and intermediate-deep aquifers. (2) Major ion chemistry and hydrogen and oxygen isotope compositions indicate that the major hydrogeochemical processes responsible for groundwater quality deterioration include the dissolution of evaporates (i.e., halite, gypsum, and mirabilite), ion exchange, and evaporation process. Additionally, (3) anthropogenic activities (overutilization of fertilizer) have resulted in nitrate contamination, and have thereby led to groundwater quality degradation.

Vegetation response to precipitation anomalies under different climatic and biogeographical conditions in China

Understanding precipitation-vegetation interaction is of great importance to implementing adaptation and mitigation measures for terrestrial ecosystems. Many studies have explored the spatial pattern of precipitation-vegetation correlation along the precipitation amount gradient. While the impacts of other precipitation characteristics remain poorly understood. Here, we provided a comprehensive investigation of spatiotemporal patterns of vegetation response to precipitation anomalies in China, using satellite-derived vegetation index and multi-source climate datasets for the years 1982–2015. Subsequently, we attempted to examine in detail what specific factors, climatic or biogeographic, are responsible for spatiotemporal patterns of precipitation-vegetation relationship. Results show that vegetation in Inner Mongolia Plateau is strongly affected by precipitation anomalies. Vegetation has a 1–2 month lag response to precipitation anomalies and is significantly correlated with 2–6 month cumulative precipitation anomalies. Seasonal differences of vegetation response are also remarkable. Moreover, the largest NDVI-precipitation correlation appears in areas with 150–500 mm of mean annual precipitation, 0.075–0.275 of fraction of precipitation days, and 19–23 of precipitation concentration index. More locally, the spatial distribution of NDVI-precipitation correlations is closely related to the vegetation type and elevation. The results can provide technical basis and beneficial reference to water resource and ecological management strategies in China for associated policymakers and stakeholders.

Trend and change points of streamflow in the Yellow River and their attributions

Abstract The impacts of climate change and human activity, combined with streamflow reduction in the Yellow River Basin, have presented significant challenges to water resource management strategies. Here, the trends and change points of streamflow were determined for the period 1956–2017 via five statistical methods. A runoff-sensitive coefficients method (the Budyko hypothesis) and a conceptual rainfall–runoff model (the TUW model) were applied to assess the streamflow variation. The following conclusions were ascertained: (1) 1989, 1986, and 1990 were the change points for streamflow in the upstream Tang-Nai-Hai and Lan-Zhou stations and the downstream Hua-Yuan-Kou hydrological station; (2) the streamflow showed statistically significant decreasing trends with spatiotemporal variations in the Yellow River Basin; (3) the relationship between runoff and precipitation showed a downward trend over time; (4) comparisons of the Budyko and TUW models show that human activity is responsible for more than 65% of streamflow reduction, while climate change contributes to less than 35% of the reduction. Therefore, human activity is the main reason for streamflow reduction in the Yellow River Basin. This finding is of critical importance for water resources management under changing environment.

Modelling Estimation of the Available Rainwater Resource in Gb&amp;#233;dji-Kotovi Clay Area for Supplying Dikes and Dams

Floods and flows data are useful for dimensioning of dikes and dams which often include evacuation devices that regulate flows to ensure the volumes of water. The objective of this study is to estimate the available water resource in the village of Gbédji-Kotovi, located in the watershed of Couffo river in Benin by using sequentially, the HBV (Hydrologiska Byrans Vattenbalansavdelning) and GR4J (Rural Engineering model with 4 daily parameters) climate models. Hydrographs of water levels are simulated according to the calibration period (1994-1999) different from the validation one (1982-1988). Considering the Nash-Sutcliffe model Efficiency coefficient (NSE), the performance of GR4J model during calibration is slightly higher than the performance of the HBV model, while during the validation, the contrary is noticed. The annual rainfall average simulated is 1117.7 mm/year while the average observed is 1104.6 mm/year over the period 1981-2005. By 2050, on one hand, the annual flow rate values will vary from -19.2 to -11.9%, while the actual evapotranspiration will vary between 0.5 and -5.8; on another hand, the potential evapotranspiration and the annual precipitation remain constant. An average flow of 187 millions m3/year for annual average water depth of 1094 mm is obtained at Lanta rain station, which covers an area of 1664.47 km2, while this flow enabled an average flow of 327.5 millons m3/year to be obtained at the virtual station of our study area of 2908.15 km2. The flow rates corresponding to the return periods of 10, 25 and 50 years vary from 5.51 to 12.67 m3/s at the outlet of the virtual station; while those at the outlet of Lanta station vary from 3.6 to 6.6 m3/s. However, the simulated water quantiles cannot be fully mobilized; because of the uses, they undergo upstream and downstream. Thus, Gbédji-Kotovi locality requires the implementation of an integrated water resource management strategy that includes the construction of dikes and dams.

Assessment of climate change impact on the water footprint in rice production: Historical simulation and future projections at two representative rice cropping sites of China

As one of the most important crops cultivated in China, rice contributes to approximately 28% of total yield. In despite of the substantial production, rice productivity is gravely affected by ongoing climate change and reduction of available water resources. Thus, assessing the responses of rice water consumption and productivity to more pronounced climate change is of great significance to water resources management in terms of relieving the resources shortage and meeting the food demand. In this study, the yield and water resources utilization during 1961–2010 in two typical rice plantation regions of China were evaluated using validated rice model ORYZA2000. Subsequently, their responses to future climate scenarios of 21 century were investigated through driving ORYZA2000 with downscaling climatic projections from GCMs under four RCPs emission scenarios. To quantify the water resources utilization in rice production from multiple perspectives, the water footprint (WF) and three water productivity indices (WPI, WPU and WPET) were integrated for assessing the regional agricultural water stress in this paper. The results revealed that the annual average linear inclining rates of WF in two stations (Kaifeng and Kunshan) were 3.86 m3/ t and 2.62 m3/ t, respectively. Moreover, compared with the green water footprint (WFg), the blue water footprint (WFb) is projected to significantly increase in future. The water productivity (WP) would decrease in two stations under four RCPs scenarios except that the WPu and WPET of Kunshan under RCP2.6 and RCP4.5 scenario in 2020s, 2050s and 2080s. Hence, this study provides insights into comprehensively understand the influences of climate change on food security and sheds lights on the regional strategy for future water resource management.

Influence of mulched drip irrigation on landscape scale evapotranspiration from farmland in an arid area

Water-saving irrigation measures in arid areas affect evapotranspiration (ET) processes while conserving water. Mulched drip irrigation is considered the most efficient irrigation method because it distributes water uniformly in the soil, restricts deep percolation, and minimizes unproductive evaporation from soil. The effect of mulched drip irrigation on farmland ET during the growing season at a landscape scale remains unclear, despite being vital for developing optimal water resource management strategies in arid areas. To compare the effects of mulched drip irrigation and mulched border irrigation on ET, based on Landsat satellite imagery (2007–2009 with mulched border irrigation, and 2014–2016 with mulched drip irrigation), an improved Surface Energy Balance Algorithm for Land (SEBAL) model was used to evaluate ET for the two periods of an oasis at Sangong River Basin in the arid region of Northwest China. The results show that daily ET rates from farmland managed under mulched drip irrigation were on average 0.2–1 mm.d−1 higher than under mulched border irrigation between June and August. Correspondingly, the net radiation flux (R) increased 73.32 W·m-2 on average, and R was found to be the main determinant of the ET differences. Meanwhile, the average land surface albedo decreased by 20%, and negatively correlated with R (P < 0.05), indicating that the land surface albedo was the main factor affecting R. Furthermore, the Normalized Difference Vegetation Index (NDVI) exhibited a significant correlation with land surface albedo. More importantly, the Temperature–Vegetation Dryness Index (TVDI) under mulched drip irrigation was found to be approximately 21% lower than that under mulched border irrigation, indicating that the soil moisture conditions of the farmland under mulched drip irrigation was significantly improved compared to mulched border irrigation. Namely, less water stress resulted in better developed canopy of the crops, which in turn captured more radiation and thus increased ET. In the end, the observed increases in landscape-scale ET under mulched drip irrigation in arid area resulted from enhanced productivity of the crops due to lessened drought stress.

Impact of climatic variation on infiltration rate under an arid climate: case of Northern Gafsa Watershed, Tunisia

The assessment of the impact of climate change on hydrological systems and their water resources, whether at regional or global scale, presents a major challenge in the twenty-first century. Indeed, scientists need to present response elements regarding this climatic variation in order to establish adequate strategies for water resources management. In this context, this study examines the temporal variation of rainfall and its impact on infiltration in the Northern Gafsa Watershed (southwestern Tunisia), characterized by an arid climate. The analysis of the temporal variation of rainfall is based on daily data recorded over the period (1960–2015) at 6 rainfall stations, regularly spread over the study basin. The different components of the hydrological cycle (initial abstraction, infiltration, actual evapotranspiration and runoff) are estimated by WetSpass-M model. The analysis of the daily rainfall data showed that more than half of the daily rainfall contributions are less than 5 mm/day. On the other hand, the results of the WetSpass-M model show that the minimum infiltration rates exceed 40 mm/year, while the maximum actual evapotranspiration does not exceed 108 mm/year despite arid conditions. The maximum runoff and interception rates are 80.1 and 16.9 mm/year successively. Regression models relating monthly infiltration to rainfall and infiltration of previous months were developed. Both calibration and validation phases resulted in reasonably good agreements between infiltration rates estimated by the proposed regression equations and WetSpass-M model.

GIS based water balance components estimation in northern Ethiopia catchment

A tool to understand water balance components is crucial for developing water resources management strategies. However, there are inadequate reports on the application of water balance models integrated with Geographical Information System (GIS) at ungauged sub-catchment scale. The objective of this study was to estimate hydrological water balance components using a flexible, physically and GIS based WetSpass water balance model for the Dura sub-catchment, northern Ethiopia. WetSpass model input data included grid files of soil types, topography, slope, land use, temperature, precipitation, potential evapotranspiration (PET), wind-speed and groundwater, and parameter tables (dbf file). Descriptive and Inverse Distance Weighted were used to analyze the different data. Model outputs included actual evapotranspiration (ET), surface runoff and groundwater recharge. The PET of the area was computed using different methods and performance assessment showed < 2% of error, indicating all are robust for supporting decision making. In the study sub-catchment, the mean annual PET and actual ET were found to be 1560 and 576 mm, respectively. The model-estimated annual actual ET was calculated to be 78.4% of the mean annual rainfall. However, there is spatial and temporal variability in ET across the sub-catchment. About 77.5% of the annual actual ET was estimated during the summer season. In the study sub-catchment, about 7.9% and 13.7% of the mean annual precipitation are effective in contributing to groundwater recharge and surface runoff, respectively. On the basis of the model results, the majority of the Dura sub-catchment is generally characterized by low groundwater recharge and high actual ET. The water balance components estimated using the WetSpass model are closely comparable to the observed data as their fitness was showed using R2> 0.90 and D < 5%, indicating that the model outputs are important for supporting decision making. On the basis of the model results, it is thus suggested to introduce and implement appropriate site-specific integrated soil and water management schemes such as water conservation structures that enhance groundwater and reduce runoff in the study catchment conditions.

Simulation modelling for integration of hydropower, irrigation water and water supply potentials of Lweya Basin, Malawi

ABSTRACT The Nkhata Bay district in Northern Malawi faces rapid population growth, thus rising water demands for services such as agriculture production, water supply and electricity. Lweya River basin covers about two-thirds of the district and is the main water source for gravity-fed irrigation, water supply schemes, and a potential of gravity hydropower generation. However, there is no framework to support the decisions on water uses in the basin without adversely affecting downstream uses. Therefore, this study used simulation modelling to integrate the development and management of the surface water resources projects in a sustainable manner in the basin. The Soil and Water Assessment Tool (SWAT) model calibration results gave NS = 0.71 and R 2 = 0.76, and NS = 0.80 and R 2 = 0.86 on a daily and monthly basis, respectively. The model was used for integration where the simulated flow enabled estimation of Flow Duration Curve indices at short records and ungauged project sites, which were compared with potential water demands of 0.73, 8.61 and 20.52 m3/s for water supply, irrigation and hydropower, respectively. The integration of potentials used priorities set in Malawi's Water Resources Management Policy and Strategy (1994). Between the options, the best scenario was hydropower development located upstream of other uses on the main Lweya River.

Understanding Public Views on a Dam Construction Boom: the Role of Values

Large numbers of dams for hydroelectric power production are currently planned or under construction in many areas around the world. While positive and negative social and environmental impacts of dams are increasingly well understood, little is known about attitudes of the general public towards dams, even though benefits to wider society are often cited to legitimise their construction. In Brazil’s Upper Paraguay River Basin, more than 100 mostly small-scale hydropower dams are planned or under construction in what can be considered a regional dam construction boom. Here we analyse public preferences for strategies to manage dam impacts in the area by investigating the value base that underpins such preferences, drawing on the recently proposed Value Landscapes Approach as our theoretical framework and data from a large representative household survey (N = 1067). We find that contrasting attitudes towards dams, expressed in preferences for economically or ecologically oriented water policies are informed by opposing underlying value landscapes, that is, groups of closely related fundamental, governance-related, and assigned (water) values. While such tensions between opposing values can never be fully eliminated, our research nevertheless gives insights to policy-makers seeking to minimise value conflict and to improve the political legitimacy of public decision-making on dam construction. Moreover, we find that a majority of members of the general public would prefer concentrating dam construction on some rivers while keeping others free-flowing, with direct implications for ecosystems and inland fisheries. This finding may guide policy-makers wishing to develop publicly supported water resources management strategies.

Runoff Predicting and Variation Analysis in Upper Ganjiang Basin under Projected Climate Changes

Catchment runoff is significantly affected by climate condition changes. Predicting the runoff and analyzing its variations under future climates play a vital role in water security, water resource management, and the sustainable development of the catchment. In traditional hydrological modeling, fixed model parameters are usually used to transfer the global climate models (GCMs) to runoff, while the hydrologic model parameters may be time-varying. It is more appropriate to use the time-variant parameter for runoff modeling. This is achieved by incorporating the time-variant parameter approach into a two-parameter water balance model (TWBM) through the construction of time-variant parameter functions based on the identified catchment climate indicators. Using the Ganjiang Basin with an outlet of the Dongbei Hydrological Station as the study area, we developed time-variant parameter scenarios of the TWBM model and selected the best-performed parameter functions to predict future runoff and analyze its variations under the climate model projection of the BCC-CSM1.1(m). To synthetically assess the model performance improvements using the time-variant parameter approach, an index Δ was developed by combining the Nash–Sutcliffe efficiency, the volume error, the Box–Cox transformed root-mean-square error, and the Kling–Gupta efficiency with equivalent weight. The results show that the TWBM model with time-variant C (evapotranspiration parameter) and SC (water storage capacity of catchment), where growing and non-growing seasons are considered for C, outperformed the model with constant parameters with a Δ value of approximately 5% and 10% for the calibration and validation periods, respectively. The mean annual values of runoff predictions under the four representative concentration pathways (RCPs) exhibited a decreasing trend over the future three decades (2021–2050) when compared to the runoff simulations in the baseline period (1982–2011), where the values were about −9.9%, −19.5%, −16.6%, and −11.4% for the RCP2.6, RCP4.5, RCP6.0, and RCP8.5, respectively. The decreasing trend of future precipitation exerts impacts on runoff decline. Generally, the mean monthly changes of runoff predictions showed a decreasing trend from January to August for almost all of the RCPs, while an increasing trend existed from September to November, along with fluctuations among different RCPs. This study can provide beneficial references to comprehensively understand the impacts of climate change on runoff prediction and thus improve the regional strategy for future water resource management.

A hybrid multi-criteria decision making method for site selection of subsurface dams in semi-arid region of Iran

Water shortage is one of the most critical problems all around the world, especially in arid and semi-arid regions. Using groundwater can be an efficient solution in such lands. Although significant care and appropriate water resource management strategies are required to be implemented. Nowadays, subsurface dams (SSD) are widely used worldwide since they are proved to have advantages over surface dams in some cases. Selection of the suitable site for SSD construction is critical. This selection is made based on advantages and disadvantages of each location. Multi-criteria decision-making methods (MCDM) is an efficient method for optimum site selection. In this study, 10 regions were chosen as alternatives for construction of subsurface dams in Isfahan province of Iran. These alternatives were then ranked using ELECTRE I, II and modified ELECTRE III based on geological, hydrological, climatological and socio-economical criteria. Results from different ELECTRE methods are combined by applying the grade average, and Borda and Copeland ranking strategies. Application of an advanced MCDM method reduced uncertainties in subsurface dams (SSD) site selection. Alternative 5 (Hoseinabad) was introduced as the best location for subsurface dam construction. This methodology can be used as a basis for more detailed field investigations.

Challenges to Implementing an Environmental Flow Regime in the Luvuvhu River Catchment, South Africa.

Rivers are now facing increasing pressure and demand to provide water directly for drinking, farming and supporting industries as a result of rapidly growing global human population. Globally, the most common practice for catchment managers is to limit water abstraction and changes to stream flow by setting environmental flow standards that guard and maintain the natural ecosystem characteristics. Since the development of the environmental flow concept and methods in South Africa, very few studies have assessed the institutional constraints towards environmental flow implementation. This study determined stream flow trends over time by fitting simple linear regression model to mean daily stream flow data at three selected stations in the Luvuvhu River Catchment (LRC). We also conducted a literature search to review, firstly the response of aquatic organisms (fish and macroinvertebrate) to changes in habitat conditions and secondly on local challenges affecting the sustainable implementation of environmental flow regime and related water resources management strategies. All the three stream flow stations show decreasing stream flow volume of 1 and 2 orders of magnitude faster in some stations with the possibility that flow will cease in the near future. Qualitative analyses from both local and international literature search found that the main challenges facing the implementation of sustainable flow strategies and management are absence of catchment management agency, lack of understanding of environmental flow benefits, limited financial budget, lack of capacity and conflict of interest. Rivers with changing stream flows tend to lose sensitive species. The development of scientifically credible catchment-wide environmental flow and abstraction thresholds for rivers within the LRC would make a major contribution in minimizing the declining stream flow volumes. Monitoring and reporting should be prioritized to give regular accounts of the state of our rivers.

Assessment of Water Resources Management Strategy under Different Evolutionary Optimization Techniques

Competitive optimization techniques have been developed to address the complexity of integrated water resources management (IWRM) modelling; however, model adaptation due to changing environments is still a challenge. In this paper we employ multi-variable techniques to increase confidence in model-driven decision-making scenarios. Here, water reservoir management was assessed using two evolutionary algorithm (EA) techniques, the epsilon-dominance-driven self-adaptive evolutionary algorithm (-DSEA) and the Borg multi-objective evolutionary algorithm (MOEA). Many objective scenarios were evaluated to manage flood risk, hydropower generation, water supply, and release sequences over three decades. Computationally, the -DSEA’s results are generally reliable, robust, effective and efficient when compared directly with the Borg MOEA but both provide decision support model outputs of value.

Evaluating Evaporation Methods for Estimating Small Reservoir Water Surface Evaporation in the Brazilian Savannah

Small reservoirs play a key role in the Brazilian savannah (Cerrado), making irrigation feasible and contributing to the economic development and social well-being of the population. A lack of information on factors, such as evaporative water loss, has an impact on the design and management of these reservoirs, as well as on regional water safety. Acquiring this information is crucial for hydrologists to develop more effective water resource management strategies and policies. This study assesses the performance of a diverse number of methods that are used to estimate evaporation and provides evaporation probability curves on a fortnightly period for small reservoirs in the Brazilian savannah region. Evaporation data were collected for a small water reservoir located in the Buriti Vermelho watershed, a typical dam of the Brazilian savannah region. Among the assessed methods, those of Kohler et al. (1955) and Linacre (1993) presented the best performances on both the daily and monthly scales for evaporation estimates. By simulating the evaporation rates for a timeseries, an increasing trend in evaporation was observed for the transition between the dry and wet seasons, jeopardizing double cropping in the region. The developed probability curves are an important tool for improving water resource planning and increasing the local water availability.

Climate-induced hydrological impact mitigated by a high-density reservoir network in the Poyang Lake Basin

The Poyang Lake Basin (PLB) is expected to see more precipitation and higher temperature by 2050. Due to climate change, it is advisable to identify the vulnerable area and to investigate if the local reservoir network of hundreds of larger reservoirs and thousands of smaller reservoirs can effectively mitigate the climate-induced hydrologic variation. Therefore, the local high-density reservoir network is integrated into a distributed hydrologic model (HMS) through a fully coupled reservoir module. We then apply the extended HMS in a one-way coupled mode to the bias corrected Coordinated Regional Downscaling Experiment in East Asia (CORDEX-EA) regional climate simulations under two Representative Concentration Pathways – RCP4.5 and RCP8.5. Results indicate that climate change poses new challenges to water resources management for the PLB, with a likely decrease of water availability in the dry season but an increase of water availability, flood magnitude and flood frequency in the flood season till 2049. The local reservoir network can mitigate climate impacts by displacing excessive water resources in the flood season to the dry season and mitigating floods across the basin. Despite that, much of the southern basin is likely to see a higher risk of water shortage in the dry season, while most of the northern basin is expected to see a higher flood risk. The approach and findings are expected to improve the understanding of the role of reservoirs in the context of climate change, and provide implications for water resources management and climate change adaptation strategies on a regional scale.

Water scarcity assessment based on estimated ultimate energy recovery and water footprint framework during shale gas production in the Changning play

Abstract Shale gas extraction has attracted great attention, especially in China, following its energy transition toward decarbonization, while the fast-expanding shale gas industry faces serious challenges related to water scarcity and water contamination. Quantitative investigations of the impacts of shale gas production on water scarcity and water contamination contribute to public awareness that shale gas production will worsen the water resource shortage. This paper presents a comprehensive water footprint (WF) assessment to improve understanding of the water sustainability and availability in shale gas industry. A detailed process water footprint model was used to quantify precisely the potential water consumption and environmental impacts. The full water use chain in the shale gas industry was examined, from the water used for well drilling and equipment maintenance, to the injection of hydraulic fracturing fluids and the disposal of the produced water. The results indicate that the historical water consumption ranged from 633.23 m3/segment to 2,292.90 m3/segment, totaling nearly 4.54 × 106 m3 for 120 wells. The projections of the estimated total WF for the constructed production period 2018–2020 and stable production period 2021–2030 were 3.30 × 107 m3/year and 5.21 × 107 m3/year in the Changning play, accounting for 10.12% and 15.98% of the average annual runoff of the Changning River, respectively, and 3.19 × 108 m3/year and 6.38 × 108 m3/year in all of the plays in China, accounting for 0.25% and 0.50% of the total national industrial water consumption in China in 2017 (1.28 × 1011 m3), respectively. The grey WF was the main contributor, accounting for 94.50% to the total WF, suggesting that water quality issues should be highly emphasized and that this footprint has a significant impact on the pollution of the water bodies near shale gas sites. These findings provide a valuable insight in understanding water consumption process in shale gas industry that can be employed to develop water resource and wastewater treatment management strategies and indicate that water resource contamination will restrict shale gas development and different effective alternative forms of management strategies, laws or regulations regarding water resources should be implemented to alleviate water resource and environmental burdens.