Model-based water accounting for integrated assessment of water resources systems at the basin scale

Accounting and system dynamics simulation of water resource liabilities in the Yangtze River Economic Zone, China

Based on the concept of sustainable water resources management, this study defines water resources liability (WRL) as the compensation liability formed in the process of unreasonable utilization of water resources, which will lead to the damage of resources and environment. Combined with system dynamics (SD) method, a simulation model of WRL is constructed to analyze the WRL of the Yangtze River Economic Zone (YREZ) from 2021 to 2030 in three development modes, which are status quo continuation mode, economic development mode, and resource and environment-friendly mode. The results reveal that: (1) In the status quo continuation mode, the scale of WRL can be effectively controlled, and the WRL will be reduced to 11.20 billion m3 in 2030. However, the WRL of Jiangsu, Jiangxi and Hunan show a rapid growth trend. (2) In the economic development mode, agricultural and domestic water consumption increase significantly, and the WRL will be close to 50 billion m3 in 2030, indicating that excessive pursuit of economic development in terms of speed and scale will lead to increased demand for water resources and aggravate water environment pollution. (3) In the resource and environment-friendly mode, the WRL is estimated to be 1.09 billion m3 in 2021 and would decrease to 0 billion m3. This mode can alleviate the situation of water shortage and pollution, and the impact of water resources utilization on the environment will be minimized. This study provides a theoretical basis for the government to formulate countermeasures to promote the coordinated development of the social economy and water resource system.

Enhancing water security: Statistical measurement and spatiotemporal analysis

Water security is essential for ensuring energy security, sustainable development, and human survival. However, due to a series of challenges, including rising water demand, environmental pollution, and water resource shortages, the global water security situation remains concerning and poses a threat to global sustainable development. To assess water security in China, this study uses data from 30 provinces in China from 2012 to 2021. A comprehensive evaluation method was applied to determine the level of water resource security in China. The Dagum Gini coefficient, Moran index, and spatial model were used to clarify regional differentiation characteristics and the driving factors. The results indicate that while China's water resource security is relatively low, it has shown steady improvement in recent years. Significant regional disparities exist in water resource security across China, with notable spatial characteristics, and socio-economic factors are the primary causes of these differences. Based on the above research, we put forward policy recommendations from the aspects of water resources management, public participation and inter-regional water resources cooperation, to provide reference for water resources security in developing countries.

Trade-offs and synergies among ecosystem services in Inland River Basins under the influence of ecological water transfer project: A case study on the Tarim River basin

Ecosystem services (ESs) are the largest benefits that humans derive directly or indirectly from ecosystems. Inland river basins in arid zones have a variety of key ecosystem functions. At present, inland river basins are experiencing a decline in ESs, such as shrinking lakes, land degradation, and rapid biodiversity loss. In order to address these problems, several ecological restoration projects (ERPs) have been implemented. Therefore, this study selected the Tarim River Basin (TRB), which is highly affected by the ecological water transfer project (EWTP), as the study area, and quantified the differences in ESs caused by the implementation of the EWTP through different scenarios of simulation, and discussed the impact of the EWTP in changing the ESs of the basin. Compared to the pre-EWTP period (1990-1999), the major ESs within the basin showed varying degrees of improvement. Water yield increased by 18 %, carbon sequestration increased by 2 %, wind prevention and sand fixation increased by 13 %, habitat quality increased by 8 %, and food production increased by 35 %. EWTP has shown positive impacts by directly or indirectly affecting runoff, vegetation, evapotranspiration, and landscape patterns, which in turn improves the comprehensive benefits of ESs in the TRB. The implementation of EWTP plays an important role in restoring ESs in inland river basins, and this study provides a key reference for the restoration of ESs in inland river basins in arid zones.

Satellite-based soil moisture enhances the reliability of agro-hydrological modeling in large transboundary river basins

Satellite-based observations of soil moisture, leaf area index, precipitation, and evapotranspiration facilitate agro-hydrological modeling thanks to the spatially distributed information. In this study, the Climate Change Initiative Soil Moisture dataset (CCI SM, a product of the European Space Agency (ESA)) adjusted based on Soil Water Index (SWI) was used as an additional (in relation to discharge) observed dataset in agro-hydrological modeling over a large-scale transboundary river basin (Odra River Basin) in the Baltic Sea region. This basin is located in Central Europe within Poland, Czech Republic, and Germany and drains into the Baltic Sea. The Soil and Water Assessment Tool+ (SWAT+) model was selected for agro-hydrological modeling, and measured data from 26 river discharge stations and soil moisture from CCI SM (for topsoil and entire soil profile) over 1476 sub-basins were used in model calibration for the period 1997-2019. Kling-Gupta efficiency (KGE) and SPAtial EFficiency (SPAEF) indices were chosen as objective functions for runoff and soil moisture calibration, respectively. Two calibration strategies were compared: one involving only river discharge data (single-objective - SO), and the second one involving river discharge and satellite-based soil moisture (multi-objective - MO). In the SO approach, the average KGE for discharge was above 0.60, whereas in the MO approach, it increased to 0.67. The SPAEF values showed that SWAT+ has acceptable accuracy in soil moisture simulations. Moreover, crop yield assessments showed that MO calibration also increases the crop yield simulation accuracy. The results show that in this transboundary river basin, adding satellite-based soil moisture into the calibration process could improve the accuracy and consistency of agro-hydrological modeling.

Regulating the concentration of dissolved oxygen to achieve the directional transformation of reactive oxygen species: A controllable oxidation process for ciprofloxacin degradation by calcined CuCoFe-LDH

Different reactive oxygen species (ROS) tend to attack specific sites on pollutants, leading to the formation of intermediates with different toxic effects. Therefore, regulating the directional transformation of ROS is a new effective approach for safe degradation of refractory organic compounds in wastewater. However, the regulation mechanism and transformation path of ROS remain unclear. In this work, the dissolved oxygen (DO) content was controlled by aeration to generate different ROS through the activation of O₂ on the calcined CuCoFe-LDH (CuCoFe-300). ROS quantitative experiments and electron paramagnetic resonance proved that O₂ was mainly activated to superoxide radical (•O₂^-) and singlet oxygen (¹O₂) under low DO concentration (0.231 mmol/L) (O₂ → •O₂^- → ¹O₂). With the increasing of DO concentration (0.606 mmol/L), O₂ was inclined to convert into hydroxyl radicals (•OH) (O₂ → •O₂^- → H₂O₂ → •OH). The density functional theory and function model of active sites utilization and DO concentration built a solid proof for ROS conversion mechanism that increasing the DO concentration promotes the increase of active sites utilization on the CuCoFe-300 system. That is, the •O₂^- was more prone to convert to •OH, not ¹O₂ in thermodynamics under high active sites utilization condition. Hence, the ROS generation was controlled by regulating DO concentration, and the nontoxic degradation pathway of ciprofloxacin was well-designed. This work is dedicated to the in-depth exploration of the mechanism between DO concentration and ROS conversion, which provides an extremely flexible, low energy consumption, and environmentally friendly wastewater treatment method in a new perspective.

A quantitative approach on environment-food nexus: integrated modeling and indices for cumulative impact assessment of farm management practices

Background

Best management practices (BMPs) are promising solutions that can partially control pollution discharged from farmlands. These strategies, like fertilizer reduction and using filter strips, mainly control nutrient (N and P) pollution loads in basins. However, they have secondary impacts on nutrition production and ecosystem. This study develops a method to evaluate the cumulative environmental impacts of BMPs. It also introduces and calculates food's environmental footprint (FEF) for accounting the total environmental damages per nutrition production.

Methods

This study combines the soil and water assessment tool (SWAT) for basin simulation with the indices of ReCiPe, a life cycle impact assessment (LCIA) method. By these means, the effectiveness of BMPs on pollution loads, production yields, and water footprints (WFs) are evaluated and converted as equivalent environmental damages. This method was verified in Zrebar Lake, western Iran. Here, water consumption, as WFs, and eutrophication are the main indices that are converted into equivalent health and ecological impairments. Two methods, entropy and environmental performance index (EPI), are used for weighting normalized endpoints in last step.

Results

Results showed that using 25-50% less fertilizer and water for irrigation combined with vegetated filter strips reduce N and P pollution about 34-60% and 8-21%, respectively. These can decrease ecosystem damages by 5-9% and health risks by 7-14%. Here, freshwater eutrophication is a more critical damage in ecosystem. However, using less fertilizer adversely reduces total nutrition production by 1.7-3.7%. It means that BMPs can decline total ecological damages and health risks, which threatens nutrition production. FEF presents a tool to solve this dilemma about the sustainability of BMPs. In the study area, a 4-9% decrease in FEF means that BMPs are more environmental friendly than nutrition menacing. Finally, this study concludes that SWAT-ReCiPe with FEF provides a quantitative framework for environment-food nexus assessment. However, due to the uncertainties, this method is recommended as a tool for comparing management strategies instead of reporting certain values.

Detecting characteristics of extreme precipitation events using regional and satellite-based precipitation gridded datasets over a region in Central Europe

Perception of the spatio-temporal events of extreme precipitation and their variations is essential for diminishing the natural hazards linked with extreme events. In this research, a satellite-based precipitation dataset derived from remotely sensed soil moisture (SM2RAIN-ASCAT, obtained from ASCAT satellite soil moisture data through the Soil Moisture to Rain algorithm) was selected to evaluate the accuracy of daily precipitation and extreme events estimations against a regional gridded weather dataset by employing various performance indicators, and ETCCDI indicators (CDD, and CWD, SDII, R10mm, R20mm, R95p, R99p, Rx1day, and Rx5day). The study area includes entire Poland as well as small parts of Ukraine, Belarus, Slovakia, the Czech Republic, Russia, and Germany. According to PBIAS (~ -3.9 %) and coefficient of correlation (~0.74), SM2RAIN-ASCAT has good accuracy in the study area. Assessments reveal that, in general, over southern, mountainous part SM2RAIN-ASCAT does not have accurate estimations. According to the reference dataset, during the 2007-2019 period, on average, the length of dry days was ~22 days, while SM2RAIN-ASCAT shows ~19.6 consecutive dry days. In contrast, SM2RAIN-ASCAT overestimated (16 days/year) the consecutive wet days compared to the reference dataset (~8.7 days/year). SM2RAIN-ASCAT underestimated the number of heavy precipitation days index (R10mm) over the northern part of the region, close to the Baltic Sea), but the accuracy increased in the southern parts. SM2RAIN-ASCAT underestimated the maximum 1-day rainfall total and relative max 5-day precipitation amount indices. The total precipitation divided by the amount of wet days index shows that SM2RAIN-ASCAT has relatively acceptable accuracy in the center and south of the study area. Our results show that SM2RAIN-ASCAT should be improved for relatively higher extreme indicators.

Performance evaluation and verification of groundwater balance using WA + as a new water accounting system

In this study, to increase the accuracy of determining the parameters of groundwater balance and finally the aquifer reservoir deficit, WA + as a new water accounting system has been applied by calculating six sheets in the Plasjan basin, central Iran. According to the results, the volume of rainfall and transfer flow to the basin was 548.8 MCM in the water year 2016-2017, which entered the hydrological cycle as input. Moreover, the results of FAO's Water Productivity Open-Access Portal (WaPOR) product showed that evapotranspiration was equal to 465 MCM, of which 345 and 120 MCM belonged to green water and blue water, respectively, at the basin level. The results of the WaPOR product showed that 264 MCM of evapotranspiration was beneficial, while the rest was non-beneficial in the basin. Finally, investigating the runoff and utilization of water resources showed that the return flow to surface water and groundwater resources was 35.5 MCM and 62 MCM, respectively. Therefore, the aquifer deficit was estimated to be 56.3 MCM based on the results of the WA + system. By calculating the evapotranspiration using remote sensing in WA + , the return water flow was estimated at 28%, being more accurate compared to the classical groundwater balance. Consequently, the amount of aquifer deficit calculated by the WA + method was accurate according to the balance and the aquifer hydrograph. The findings of this study show that as a suitable tool, the water accounting system can reduce the uncertainty of groundwater balance calculations.

An Assessment of the Water Resources Carrying Capacity in Xinjiang

The water resource shortage is a crucial factor in restraining the development of society and the economy in Xinjiang, where there is drought and little rain. The assessment of the water resources carrying capacity (WRCC) is a prerequisite for socioeconomic sustainable development in Xinjiang. In this paper, a convenient and effective model is established for assessing the WRCC under the influence of social welfare and water use efficiency. Meanwhile, a pedigree chart for WRCC is put forward. Then the developed approach is applied to investigate the sustainable utilization of water resources in Xinjiang. The results indicate that the WRCC of Xinjiang is not overloaded in 2018. The status of the WRCC is worse in northern Xinjiang than in southern Xinjiang, especially in Karamay, Shihezi, and Urumchi. The areas with potential water resource exploitation in Xinjiang are mainly located in the Yili Kazak Autonomous Prefecture and Altay Prefecture. The efficiency of agricultural water use is of vital importance to the WRCC in Xinjiang. The WRCC of Xinjiang can be improved by saving agricultural water, water recycling, and optimizing industrial structures. The maximum population carried by the water resources in Xinjiang is predicted to be 33.63 million and 35.80 million in 2035 and 2050, respectively. The assessment of the WRCC provides a valuable reference for the sustainable utilization of water resources in Xinjiang.