Regional Water Security Research Articles

From narratives to numbers: Spatial downscaling and quantification of future water, food & energy security requirements in the Indus basin

Integrated adaptation strategies are needed to achieve the highly interlinked Sustainable Development Goals (SDGs) for water, food- and energy security in the Indus basin. However, detailed quantitative scenarios for the plausible dimensions of future resource security requirements under socio-economic development are lacking. Here we define three quantitative and spatially downscaled scenarios for future water, food and energy requirements in the Indus basin and we assess the implications of socio-economic development for the integrated resource security challenge. High-resolution gridded scenarios for resource security requirements are developed by combining three regionalised and spatialised Shared Socioeconomic Pathways (SSPs) with quantitative regional water, food and energy security thresholds. The results demonstrate that by 2080 basin level water- and energy security requirements are likely to at least double and potentially triple compared to the current situation. Food requirements could increase only marginally and double at most. Migration and urbanisation additionally drive the growing requirements to spatially converge around the largest cities of the basin. This demonstrates that socio-economic development increases the complexity of the water-food-energy security challenge by increasing its magnitude and spatial concentration. Future research and policymaking should anticipate for this heterogeneous growth of resource security challenges when developing adaptation strategies.

Algal Boom Characteristics of Yeongsan River Based on Weir and Estuary Dam Operating Conditions Using EFDC-NIER Model

A number of hydraulic structures have been installed along the Yeongsan River, including an estuary dam and two weirs (Seungchon and Juksan). While these structures aid in regional water security and use and reduce flooding, they reduce water flow in the summer, thereby frequently causing algal blooms. This study simulated algal bloom and water quality characteristics of sections of the Yeongsan River in South Korea under different weir and estuary dam operating conditions using the Environmental Fluid Dynamics Code—National Institute of Environment Research (EFDC-NIER) model. Results showed that when the management levels of the Juksan Weir and estuary dam were maintained, simulated water levels were EL. 3.7 m in the weir section and EL. −1.2 m (below average water level of the Yellow Sea) in the dam section. When both the weir and dam were open, the water levels varied with the tide; in contrast, when the Juksan Weir alone was open, the water level was between EL. −1.2 and −0.9 m, in line with the management level of the estuary dam. Opening the weir alone reduced algal blooms by 72–84% in the weir region, and opening the estuary dam alone reduced the algal blooms by 83% in the dam region. This improvement was attributed to the reduced water retention time and dilution due to seawater inflows.

Glacial Change and Its Hydrological Response in Three Inland River Basins in the Qilian Mountains, Western China

Glacial changes have great effects on regional water security because they are an important component of glacierized basin runoff. However, these impacts have not yet been integrated and evaluated in the arid/semiarid inland river basins of western China. Based on the degree-day glacier model, glacier changes and their hydrologic effects were studied in 12 subbasins in the Shiyang River basin (SYRB), Heihe River basin (HHRB) and Shule River basin (SLRB). The results showed that the glacier area of each subbasin decreased by 16.7–61.7% from 1965 to 2020. By the end of this century, the glacier areas in the three basins will be reduced by 64.4%, 72.0% and 83.4% under the three climate scenarios, and subbasin glaciers will disappear completely after the 2070s even under RCP2.6. Glacial runoff in all subbasins showed a decreasing–increasing–decreasing trend, with peak runoff experienced in 11 subbasins during 1965~2020. The contribution of glacial meltwater to total runoff in the basin ranged from 1.3% to 46.8% in the past, and it will decrease in the future due to increasing precipitation and decreasing glacial meltwater. However, the scale differences in glacier runoff are significant when aggregated over the region/basin/subbasin. This suggests that the results of large-scale generalization may be misleading for subbasin glacier water resource evaluations. Therefore, the hydrological effects of glaciers should be studied more in subbasins to provide an accurate reference for practical water resource management.

Counterion Effects in Metal Hybrid Biopolymer Materials for Sulfate Adsorption: An Experimental and Computational Study

Modification of biomaterials is an active research area in materials and environmental science, where the controlled removal of sulfate is a key goal toward achieving global water security in regions with saline aquifers. In this study, biopolymer-based ternary metal composites (TMCs) were prepared that contain alginate/chitosan/Al(III) with variable counterions: chloride (C), nitrate (N), and sulfate (S), denoted as TMC-C, TMC-N, and TMC-S, respectively. The structure and physicochemical properties of the TMCs were characterized by spectroscopy (NMR, FT-IR, Raman, and XPS) and other complementary methods (thermal gravimetry, potentiometry, and zeta potential) to gain insights on the role of counterion effects related to the adsorption properties of TMCs with inorganic and organic anions in aqueous media. Both equilibrium and dynamic adsorption properties of the TMCs were evaluated with inorganic sulfate (Na2SO4) and two types of anionic organic dyes (methyl orange, MO,; and reactive black-5, RB5) at pH 7 and 295 K. A computational study was carried out to evaluate the structural features of the TMCs related to the coordination of sulfate with the TMC-N system. The charge state of the TMCs for the various counterion systems was estimated according to the pHPZC (5.0 to 5.9) and zeta potential (+8.31 to +35.7 mV) of the composites in aqueous media. The presence of variable counterions (chloride, nitrate, and sulfate) revealed the effects on the equilibrium and kinetic uptake of sodium sulfate and RB5. The Sips isotherm model for sulfate adsorption revealed a value of Qe from 87 to 120 mg/g, which depends on the counterion. The uptake of RB5 (Qm = 77 to 208 mg/g) by the TMCs varied over a wider range due to the role of secondary biopolymer adsorption sites. The incorporation of switchable counterions in TMCs offer a low-cost and bottom-up approach for the design of tailored biopolymer adsorbents with tunable anion uptake properties toward organic and inorganic anions in aqueous media.

Potential catastrophic water outflow from Lake Dian, China: Possible hydrological and ecological risks

Lake Dian, the largest lake on South China’s Yunnan-Guizhou Plateau, exhibits two abnormal funnel-like features in the deepest part of the lake. Nevertheless, how and when these funnels formed and their implications and potential environmental and ecological effects remain unclear. To address these questions, we carried out a detailed multi-method survey including underwater topographic monitoring, extraction of sediment records, and geophysical exploration across the funnel areas. Sediment records revealed a significant sedimentation hiatus around these features. For example, sediments with thicknesses of ca. 69.24 cm and 83.56 cm in cores D4 and D6 were eroded based on the calculated of sedimentation rates. Deformed sedimentary structures and a hiatus, together with large-scale funnel-shaped topography, prove that underlying karst collapse may trigger massive water outflow through these funnels, which could result in an erosional hiatus in the local lakebed. Continuous clay deposits in the upper part of the sedimentary column suggest that water leakage may have ceased since the 1930s. However, bathymetric surveys conducted in October 2015 and September 2019 indicated that the maximum lake depth increased by 0.97 m and 0.2 m in the large and small funnels, respectively, over this 4-year period. The corresponding increased volumes were 1520 m3 and 375 m3 in the large and small funnels, respectively. Numerous pits were distributed around the funnels. Cumulatively, these underwater topographic changes reveal that small-scale, slow water leakage has been developing, which could potentially trigger catastrophic water discharge due to increasing hydraulic pressure and/or underlying karstification. If catastrophic water outflow occurs, ~14.05 × 108 m3 of highly polluted water would not only contaminate the upper reaches of the large river and/or the lake itself, but would also endanger regional water security and induce widespread negative ecological impacts.

Long-term study on the seasonal water uptake of Platycladus orientalis in the Beijing mountain area, northern China

Understanding how extreme drought and precipitation influence the water uptake patterns of vegetation is essential to assessing the responses of vegetation to climate change and evaluating regional water security. We introduced stable hydrogen and oxygen isotopes to determine the seasonal pattern of water uptake by the evergreen coniferous species Platycladus orientalis from June 2011 to June 2014 in the semiarid rocky areas of North China with shallow soil. Temporal variations in the soil water content (SWC), transpiration and root distribution were examined to analyze the key role of groundwater in plant water sources during the extreme drought. Platycladus orientalis showed great dependence on the surface soil water (0–20 cm) and a water uptake proportion greater than 50% in all rainy seasons (June–September) was observed. Our study also revealed that P.orientalis preferred to use upper soil moisture (0–40 cm) in the dry seasons as long as the supply met the demand, and it would turn to deep soil water and groundwater under dramatic reduction in the surface soil water content. During prolonged extreme drought, groundwater use increased from 25.3% in the early period to 61.3% in the late period. These findings suggest that P. orientalis water uptake has great plasticity and that its water uptake depth varies with a decline in soil water. In addition, a long extreme drought period will lead to a preference for and an increase in groundwater use, which means that P. orientalis can adapt well to extreme climates.

Regional water security evaluation with risk control model and its application in Jiangsu Province, China.

To reduce losses from the various disasters, regional water security evaluation and risk control model is studied. The model is built upon different kinds of indices in water security system, proceeding from the whole structure and its parts of evaluation, forewarning and decision making analysis. Based on China's national conditions, this study firstly advances an evaluation index system of regional water security, which includes three subsystems of water resource security, water environment security, and water disaster control security. Secondly, fuzzy analytic hierarchy process based on accelerating genetic algorithm (AGA-FAHP) combines with entropy weight method (EW) to determine the objective weights of evaluation indexes. The subjective and objective weights can be integrated by the principle of minimum relative information entropy. The subsystem weights are obtained by using AGA-FAHP. Then regional water security evaluation model is established. Thirdly, the comparison judging method is adopted to divide warning degree of water security with the comprehensive evaluation index and forewarning standards, and then the local conditions for proposing planning schemes. Finally, decision making analysis is employed to find the effective indices based on projection pursuit technique with the ideal point method in multi-index decision. This study takes Jiangsu province, China as an example. The evaluation results from 2000 to 2015 show that the development trend of water security is increasing on the whole except in several individual years. Risk forewarning doesn't take place in recent years. But risk is always there. So, project and non-project measures are proposed for the corresponding forewarning levels. From light warnings for three times and moderate warning for once in 2000, 2001, 2002, and 2004, index 1, 3, 4, 11, 13, 17, and 18 are selected as the effective indices to decision making analysis in common. Then, the solution schemes are given as the processing method accordingly. This conclusion is reasonable and its method is practical that match the reality. It suggests that the presented model is feasible with theory and application, which can offer advice in regional water security management to some extent.

Hybrid power generation for increasing water and energy securities during drought: Exploring local and regional effects in a semi-arid basin

Reservoirs of hydropower plants (HPP) can amend water, energy, and food security in semi-arid regions. However, during severe droughts, the priority of energy demand leads to critical conditions of water availability. To reduce water use for energy, one possible measure is the adoption of solar power, an abundant energy source in semi-arid regions. This study assessed the influence of adding floating photovoltaic power (PV) in the large-scale reservoir of Sobradinho HPP, located in the São Francisco River (SFR), in Brazil, from 2009 to 2018. The simulated scenarios varied the installed PV power capacity from 50 to 1000 MW. For each scenario, water allocation was modified based on the solar-hydro equivalence that restrained the historical outflow of Sobradinho to maintain water in the reservoir. Besides, a diverse operation rule for the reservoirs in cascade of SFR was adopted to avoid ecological impacts of low streamflow. The scenarios were assessed in water security, solar-hydro electricity output, capacity factor of the powerplant, water and energy losses by evaporation and spilled water. Results show that a PV system starting from 250 MW was necessary to improve water security during the severe drought, reserving 0.7–2.3 of the annual water demand. In addition, the capacity factor was optimized from 29% to 34–47%. However, as the HPPs installed at SFR work as one system, the constrain of the river flow reduced the hydroelectricity by 4.4% for 750 MW. We concluded that PV significantly influenced water security and ecological conditions of SFR, with benefits in the range of 250–750 MW. The research provides assessment on substituting hydro for solar power on the operation of reservoirs in cascade and identifies the correlated benefits in social and ecological aspects. This information can support decisions of water and energy supply system operators and public policies focused on integrated resources management in semi-arid regions.

Agricultural Drought Risk Assessment: A Spatial Analysis of Hazard, Exposure, and Vulnerability in Zacatecas, Mexico

Drought is one of the major threats to water and food security in many regions around the world. The present study focuses on the evaluation of agricultural drought risk from an integrated perspective, that is, emphasizing the combined role of hazard, exposure, and vulnerability to drought. For this purpose, we used the Mexican state of Zacatecas as a case study. This state is one of the most vulnerable to the adverse effects of agricultural drought in the country. The proposed method includes three stages: first, we analyzed the risk of agricultural drought at the municipal scale using the FAO Agricultural Stress Index System (ASIS) in its country version (Country-Level ASIS) and also determined a Drought Hazard Index (DHI). Subsequently, we conducted a municipal assessment of exposure and vulnerability to drought based on a set of socioeconomic and environmental indicators, which we combined using an analytical procedure to generate the Drought Exposure Index (DEI) and the Drought Vulnerability Index (DVI). Finally, we determined a Drought Risk Index (DRI) based on a weighted addition of the hazard, exposure, and vulnerability indices. Results showed that 32% of the state’s municipalities are at high and very high risk of agricultural drought; these municipalities are located mainly in the center and north of the state, where 75.8% of agriculture is rainfed, 63.6% of production units are located, and 67.4% of the state’s population depends on agricultural activity. These results are in general agreement with those obtained by other studies analyzing drought in the state of Zacatecas using different meteorological drought indices, and the results are also largely in line with official data on agricultural surfaces affected by drought in this state. The generated maps can help stakeholders and public policymakers to guide investments and actions aimed at reducing vulnerability to and risk of agricultural drought. The method described can also be applied to other Mexican states or adapted for use in other states or countries around the world.

Refined water security assessment for sustainable water management: A case study of 15 key cities in the Yangtze River Delta, China

Water security represents ecological security and a policy priority for sustainable development; however, un-gridded assessment results cannot be used to support urban environmental management decisions. This study proposes a systematic framework to obtain a gridded regional water security assessment, which reflects the regional natural resource, based on the index system derived from the Pressure-State-Response (PSR) model and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The results were applied to sustainable water management. Using 15 key cities in the Yangtze River Delta (YRD) region as a case study to apply the methodology, we found that the comprehensive water security was relatively high and high-value areas were widely distributed, accounting for about two-thirds of the study area. Low-value areas were mainly distributed in central and eastern regions, such as Shanghai, Suzhou, and Nanjing. There was evidence of a water resource shortage during the twelve-month period studied, particularly in August. The proportions of comprehensive water security in each administrative unit and the differences between simulated and target water quality could be used in the spatial planning and the exploration of payments for ecosystem services (PES) mechanism in county-level or smaller administrative units. Despite the premise requirement and the grid resolution problems of the InVEST model, it can be concluded that our assessment method proves capable of matching spatial and temporal differences in water supply and demand at a fine scale, and results can be used to supply useful information for urban management decision making.

Spatio‐temporal dynamics of water quality and eutrophication in Lake Taihu, China

AbstractWater quality evaluation in Lake Taihu, China, is vital for the regional water security. Recent studies have focused on understanding the spatio‐temporal dynamics of water conditions using long‐term data series. In this study, water conditions of Lake Taihu during non‐cyanobacterial/cyanobacterial growth periods were assessed based on water quality index (WQI), trophic level index (TLI), chlorophyll a concentration, and algal density; the spatio‐temporal changes in water quality were quantified, and their corresponding driving forces were discussed. The study employed water quality data from 2013 to 2018 and algal density data from 2013 to 2017. The results revealed that the water conditions varied over the years; it was the poorest in 2013, improved slightly in 2014, deteriorated during 2015–2017, and improved again in 2018. Slow algal growth was observed from May to July, which accelerated from August–September. The TLI in Lake Taihu may increase due to significant inflow during wet years, which may increase the eutrophication area and algae density in the following year, necessitating extreme caution. The northwestern part of Lake Taihu exhibited a lower WQI and higher TLI than its southeastern part. In the bays with high TLI, the WQI during the cyanobacterial growth period was lower than the non‐cyanobacterial growth period; the converse was observed in bays with low TLI. The results of this study imply that water conditions of Lake Taihu could be enhanced by reducing the nutrient load in wet seasons and wet years and improving the hydrodynamic conditions through water diversion, especially in Zhushan and Meiliang bays.

Hydrological significance of Himalayan surface water and its management considering anthropogenic and climate change aspects

Water plays a key role in maintaining different ecosystem services. The anthropogenic and climate change impacts studies on Himalayan water resources has been trending in recent years. The Indian Himalayan region cover several states like Jammu & Kashmir, Ladakh (Union territory), Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh and the hilly regions of Assam and West Bengal. Water resources in this region are the life support for humankind and rich biodiversity. Researchers has reported that the warming in the Himalayas is more than the global average, thereby climate change can affect significantly in the mountainous water resources so as the snow and glacial melt is the main lifeline of the perennial rivers’ flow. Almost every year, the heavy monsoon rainfall brings floods on the upstream highlands and then the downstream plains causing enormous human suffering, loss of property, loss of life, agricultural crops damage as well as increased economic losses. The main challenges being associated to the frequency and magnitude of extreme weather events like monsoon rainfall which leads to flash floods, landslides and debris flow; and then the drought during dry season also, has had huge impacts on regional water security. Human actions like economic development and population growth have also brought changes in land cover/use to Himalayan watersheds recently. As a result of farming, grazing, tree planting, urbanization, etc., the changes in land cover have altered the water balance and transformed the water-flow paths in the global hydrological cycle. In contrast to freshwater ecosystems, demand is high, but their supply is limited, also depend on the specific flow pattern of rivers. Although, with interference of various infrastructure development upstream results in changes in flow pattern downstream causing non-availability of water to support aquatic life and communities that depend on for livelihoods. Initiation of monitoring and observation system for water resources and use of appropriate hydrological model are preferable to better understand the hydrological processes of the Himalayas.

The Impacts of Climate Variability on Crop Yields and Irrigation Water Demand in South Asia

Accurate (spatio-temporal) estimation of the crop yield relation to climate variables is essential in the densely populated Indus, Ganges, and Brahmaputra (IGB) river basins of South Asia for devising appropriate adaptation strategies to ensure regional food and water security. This study examines wheat (Triticum aestivum) and rice (Oryza sativa) crop yields’ sensitivity to primary climate variables (i.e., temperature and precipitation) and related changes in irrigation water demand at different spatial (i.e., province/state, districts and grid cell) and temporal (i.e., seasonal and crop growth phase) scales. To estimate the climate driven variations in crop yields, observed and modelled data applying the Lund-Potsdam-Jena managed Land (LPJmL) model are used for six selected study sites in the IGB river basins over the period 1981–2010. Our statistical analysis underscores the importance of impacts assessments at higher spatio-temporal scales. Our grid cell (aggregated over study sites) scale analysis shows that 27–72% variations in wheat and 17–55% in rice crop yields are linked with temperature variations at a significance level of p < 0.001. In the absence of irrigation application, up to 39% variations in wheat and up to 75% variations in rice crop yields are associated with precipitation changes in all study sites. Whereas, observed crop yields show weak correlations with temperature at a coarser resolution, i.e., up to 4% at province and up to 31% at district scales. Crop yields also showed stronger sensitivity to climate variables at higher temporal scale (i.e., vegetative and reproductive phases) having statistically strong negative relationship with temperature and positive with precipitation during the reproductive phase. Similarly, crop phase-specific variations in climate variables have considerable impacts (i.e., quantity and timing) on irrigation water demand. For improved crop water planning, we suggest integrated climate impact assessments at higher spatio-temporal scales which can help to devise appropriate adaptation strategies for sustaining future food demand.

Healthy waterways and ecologically sustainable cities in Beijing‐Tianjin‐Hebei urban agglomeration (northern China): Challenges and future directions

AbstractThe cities across the northern dry region of China are exposed to multiple sustainability challenges. Beijing‐Hebei‐Tianjin (BTH) urban agglomeration, for example, experiences severe water shortages due to rapidly expanding urban populations, industrial use, and irrigation‐intensive agriculture. Climate change has further threatened water resources security. Overuse of water resources to meet the demand of various water sectors has far‐reaching health and environmental implications including ecosystem sustainability. Surface water and groundwater pollution present public health risks. Despite the extraordinary policies and efforts being made and implemented by the Government of China, the BTH region currently lacks coordination among stakeholders leading to poor water governance. Consultation among scientists, engineers and stakeholders on regional water security issues is crucial and must be frequent and inclusive. An international symposium was held in Shijiazhuang in early November 2019 to identify some of the key water security challenges and scope of an idealized future eco‐city in the region by developing a sustainability framework. This work drew on experiences from across China and beyond. Scientists agree that integration of science, technology, and governance within an appropriate policy framework was particularly significant for combating the issue of water insecurity, including in the region's newly developed city, Xiong'an New Area. An emerging concept, “Healthy Waterways and Ecologically Sustainable Cities” which integrates social, ecological and hydrological systems and acts as an important pathway for sustainability in the 21st century was proposed in the symposium to tackle the problems in the region. This high level biophysical and cultural concept empowers development goals and promotes human health and wellbeing. The framework on healthy waterways and ecologically sustainable cities can overcome sustainability challenges by resolving water resource management issues in BTH in a holistic way. To implement the concept, we strongly recommend the utilization of evidence‐based scientific research and institutional cooperation including national and international collaborations to achieve the Healthy Waterways and Ecologically Sustainable Cities goal in the BTH in future.This article is categorized under: Water and Life > Conservation, Management, and Awareness

Evaluation of water security based on capacity for socio-economic regulation

Abstract From the perspective of social and economic regulation, the development trend of regional water security in different periods and under different regulation strengths is evaluated by using the fuzzy set pair analysis method. The results show: the degree of regional water resources security changes from insecurity in the pilot period of water-saving society construction to basic security, and then to security in the planning period, with the enhancement of economic and social regulation. The order of importance of each index is C19 > C1 = C5 > C18 > C14 > C10 > C13 > C3 = C4 > C8 > C7 > C15 > C16 > C12 > C2 > C11 > C17 > C6 > C9, the long-term shortage of water resources is the most important factor, the contribution rate is 60%, but the index weight of economic and social coordination ability is large, and its rapid change causes the improvement of water resources security; the contradiction between the regulation intensity of social and economic indicators in the planning year and the demand for water resources is not matched, and the degree of water security is mainly restricted by the shortage of regional water resources.

Determination of groundwater recharge mechanisms using stable isotopes in small watersheds of the Loess Plateau, China

Water sustainability is a major challenge on the Loess Plateau of China, since the drying of soil and loss of surface water is threatening regional water security. Fundamental to effective water management is an understanding of groundwater recharge mechanisms. Based on a time series of stable isotopes data for precipitation, surface water and groundwater, the groundwater recharge ratios and water transmission times were quantitatively identified for the studied region. The results showed that groundwater discharge to surface water was a common phenomenon during the dry and wet seasons. However, groundwater could also be recharged by precipitation and surface water during specific months when experiencing large precipitation events. Over shorter time scales ( 1 year), precipitation was the primary recharge source of groundwater in small watersheds due to the general flow direction of groundwater to surface water. Groundwater recharge by precipitation mostly occurred through a combination of piston flow and preferential flow, where preferential flow was the primary recharge mechanism for groundwater replenished by precipitation in this region. Surface water could quickly recharge groundwater by lateral flow through fractures in the aquifer and vertical piston flow. These findings could, therefore, be used to provide a reference for the utilization and protection of groundwater resources in the small watersheds of the loess hilly regions of the Loess Plateau.

Separating the effects of revegetation and sediment-trapping dams construction on runoff and its application to a semi-arid watershed of the Loess Plateau

Runoff decrease triggered or exacerbated by human activities over the past decades on the Loess Plateau has been drawing nationwide concerns; quantifying human-induced runoff-altering factors is of great significance for decision-making on maintaining regional water, ecological and economic security. Sediment-trapping dams (STDs) construction and revegetation are the two major soil-water conservation practices regarded to have caused runoff reduction, while their hydrologic effects on the basin scale have not been separated quantitatively. In this study, we chose the Huangfuchuan River Basin as a case study area, and proposed a physically-based attribution framework with the ability to account for the hydrologic effects of STDs, revegetation, and climate change simultaneously and attribute runoff decrease of the basin among these factors. The model-based attribution results revealed that STDs construction caused a 45% (48%) runoff reduction from 1976 to 1988 to 1989–2000 (2001–2014) and revegetation was responsible for a 30% runoff decrease from 1976 to 1988 to 2001–2014, while the daily simulation implied that the hydrologic effect of revegetation affected daily runoff magnitudes more consistently than that of STDs. Our study demonstrates that STDs construction was the prime contributor to runoff decrease in the case study area and suggests that STDs should be taken into account in similar studies on the Loess Plateau in the future.

Precipitation Dominates Long-Term Water Storage Changes in Nam Co Lake (Tibetan Plateau) Accompanied by Intensified Cryosphere Melts Revealed by a Basin-Wide Hydrological Modelling

Lakes on the Tibetan Plateau (TP) have changed dramatically as a result of climate change during recent decades. Studying the changes in long-term lake water storage (LWS) is of great importance for regional water security and ecosystems. Nam Co Lake is the second largest lake in the central TP. To investigate the long-term changes in LWS, a distributed cryosphere-hydrology model (WEB-DHM) driven by multi-source data was evaluated and then applied to simulate hydrological processes across the whole Nam Co Lake basin from 1980 to 2016. Firstly, a comparison of runoff (lake inflow), land surface temperature, and snow depth between the model simulations and observations or remote sensing products showed that WEB-DHM could accurately simulate hydrological processes in the basin. Meanwhile, the simulated daily LWS was in good agreement with satellite-derived data during 2000–2016. Secondly, long-term simulations showed that LWS increased by 9.26 km3 during 1980–2016, reaching a maximum in 2010 that was 10.25 km3 greater than that in 1980. During this period, LWS firstly decreased (1980–1987), then increased (1988–2008), and decreased again (2009–2016). Thirdly, the contributions of precipitation runoff, melt-water runoff, lake surface precipitation, and lake evaporation to Nam Co LWS were 71%, 33%, 24%, and -28%, respectively. Snow and glacier melting have significantly intensified during recent decades (2.96 m3 s−1/decade on average), contributing a mean proportion of 22% of lake inflows. These findings are consistent with the significant increasing trends of annual precipitation and temperature in the lake basin (25 mm/decade and 0.4 K/decade, respectively). We conclude that long-term variations in Nam Co LWS during 1980–2016 were largely controlled by precipitation; however, the contribution of precipitation runoff to total lake inflow has decreased while the contribution from warming-induced snow and glacier melting has significantly increased.

Introduction

Introduction

Evaluating water ecological achievements of leading cadres in Anhui, China: Based on water resources balance sheet and pressure-state-response model

Water scarcity has become a common problem worldwide. To realize the sustainable development of water resources, exploring the compilation of the water resources balance sheet and implementing outgoing audits of water resource assets for leading cadres is of great significance. To evaluate regional water security, this study took the water resources balance sheet as the data carrier of outgoing audits and organically combined the results with the evaluation of leading cadres’ water ecological achievements. The water ecological achievements of the three provincial governors in Anhui province from 2013 to 2017, including those who have left office (leading cadres A and B) and who is currently in office (leading cadre C), were evaluated. The results indicate the following. (1) Both A and B’s water ecological achievements were “good,” and the water security level changed from “relatively unsafe” to “proximity safe” during A’s tenure, while it improved from “proximity safety” to “relatively safe” during B’s tenure. (2) The water security level in 2017 was stable at “relatively safe,” and the current leading cadre C’s water ecological achievement was “good,” but the performance in improving the state of water resources still needs to be strengthened. The results of this research have some implications for water resource management in other regions, especially countries where the governance system is similar to that of China.