South-to-North Water Transfer Project Research Articles

Do Water Transfer Projects Promote Water Use Efficiency? Case Study of South-to-North Water Transfer Project in Yellow River Basin of China

With a huge capital and labor input influx, inter-basin water transfer (IBWT) projects have been shown to effectively mitigate water stress and ensure the water demand for social and economic development in the receiving area. Whether they have promoted the improvement of regional water use efficiency (WUE) is crucial for sustainable management of regional water resources. Targeting the South-to-North Water Transfer Project (SNWTP), the largest and most ambitious inter-basin water transfer project in China, this study establishes quantitatively econometric models to analyze the impact of different water diversion projects, specifically the eastern route of the SNWTP (ER-SNWTP), middle route of the SNWTP (MR-SNWTP), and diversion from the main stream of the Yellow River (DYR), on the regional water consumption per unit of GDP; regional water stress, water use structure, economic structure, and urbanization level are used as control variables in different types of cities in the Yellow River Basin, and some intriguing results are found. While the overall water transfer project demonstrates a positive impact on water use efficiency, the effects of the three water transfer measures vary significantly. The ER-SNWTP does not exhibit a notable positive effect on regional water use efficiency, whereas the MR-SNWTP demonstrates a significant positive impact. Interestingly, the DYR has a notable negative influence on water use efficiency in developed cities. The water use structure, shaped by the pricing, scale, and policies of different projects, emerges as a pivotal factor in explaining these differences. Finally, this paper suggests that the impact of water transfer projects on the improvement of regional water use efficiency be viewed from a more comprehensive and developmental perspective.

Spatiotemporal Variations and Sustainability Characteristics of Groundwater Storage in North China from 2002 to 2022 Revealed by GRACE/GRACE Follow-On and Multiple Hydrologic Data

North China (NC) is experiencing significant groundwater depletion. We used GRACE and GRACE-FO RL06 Level-2 data with Mascon data from April 2002 to July 2022. We fused these two types of data through the generalized three-cornered hat method and further combined them with hydrological models, precipitation, in situ groundwater-level, and groundwater extraction (GWE) data to determine and verify temporal and spatial variations in groundwater storage (GWS) in NC. We quantitatively assessed groundwater sustainability by constructing a groundwater index in NC. We further explored the dynamic cyclic process of groundwater change and quantified the impact of the South-to-North Water Transfer Project (SNWTP) on GWS change in NC. The overall GWS shows a decreasing trend. The GRACE/GRACE-FO-derived GWS change results are consistent with those shown by the in situ groundwater-level data from the monitoring well. Groundwater in NC is in various states of unsustainability throughout the period 2002 to 2022. The SNWTP affected the water use structure to some extent in NC. This study elucidates the latest spatial–temporal variations in GWS, especially in the groundwater sustainability assessment and quantitative description of the effects of the SNWTP on changes in GWS in NC. The results may provide a reference for groundwater resource management.

Estimating the Economic Effect of the South-to-North Water Transfer Project on Beijing—An Applied Computable General Equilibrium Analysis

What exactly is the contribution of the South-to-North Water Transfer Project (SNWTP)? This is a subject of much debate. There are concerns about the possible effects on the macroeconomy. Most previous studies have tried to answer this question. In order to answer this question quantitatively, it is necessary to separate the effect of SNWTP from many influencing factors. A computable general equilibrium model (SICGE) was built to estimate the economic effect of the South-to-North Water Transfer Project on Beijing. This CGE model was modified by joining the subdivided water substitution module, the total water constraints module, and the water-capital substitution module. Two scenarios were set: one with SNWTP and one without SNWTP. The what-if scenario (without SNWTP) indicates that the water reduction poses a direct threat to economic growth. Employment, capital, and GDP are lower, largely due to water shortages suffered by many industries by comparative analysis with or without SNWTP. The water utilization for the water-intensive industry will decrease the most, and its output will also decrease the most. Without SNWTP, groundwater extraction will increase, which suggests that SNWTP water will tentatively replace groundwater.

Coupled processes of groundwater dynamics and land subsidence in the context of active human intervention, a case in Tianjin, China

To address the crisis of water shortage in the North China Plain, the Chinese government implemented the South-to-North Water Transfer Project (SNWTP). In this context, Tianjin, one of the main beneficiaries of this project, has been relieved from water shortages and begun to implement Groundwater Management Plans (GMP) since 2018, which undoubtedly have a significant effect on the groundwater recovery. Meanwhile, this provides a good case for studying the coupled process of ground settlement and groundwater dynamics, especially the soil deformation pattern driven by groundwater level (GWL) rebound. To analyze these issues in detail, field well data was collected to depict groundwater flow field. Moreover, geodetic data was also collated, including leveling, GPS, and InSAR, so that a vertical deformation field with high spatiotemporal resolution could be generated. The results reveal that the GWL of the third confined aquifer which is the main exploitation layer in Tianjin recovered significantly since 2018 with a rate of 2.1 m/yr. The dynamic deformation patterns indicate that the area of land subsidence cones in Tianjin has reduced significantly, accompanied by a sharply declining subsidence rate (decreased from −32.2 mm/yr to −4.5 mm/yr.). Particularly, a significant poroelastic rebound has occurred in the Wuqing and Beichen districts since 2020. Furthermore, due to the delayed pore pressure dissipation in the aquitard, we find a time delay of 0.3–5.5 years between land subsidence and GWL time series, which is far less than that estimated by hydrogeological parameters, as the latter ignored the recharge and recovery capacity of the aquifer system. Finally, an evolution models in Tianjin was presented to illustrate interactive process among the deformation, pore pressure, and hydraulic head. In general, the SNWDP and the GMP has restored the pore pressure of aquifer, reduced the land subsidence, and alleviated the groundwater storage depletion of Tianjin.

High-latitude invasion and environmental adaptability of the freshwater mussel Limnoperna fortunei in Beijing, China.

The invasive freshwater mussel Limnoperna fortunei (Dunker, 1857) has spread widely throughout Asia and South America, especially via interbasin water diversion and navigation. The middle route of the South-to-North Water Transfer Project (SNWTP), whose terminal is Beijing, has diverted more than 60 billion m3 of water from the Yangtze River Basin to Northern China since December 2014. L. fortunei has spread north to Beijing along the SNWTP, biofouling its channels and tunnels. To determine the status of L. fortunei's invasion in Beijing, we systematically inspected the water bodies receiving southern water, including all branches of the SNWTP, water treatment plants, lakes, reservoirs, and rivers. We measured the densities of adults and veligers of L. fortunei and conducted eDNA analyses of water samples. A generalized linear model and canonical correspondence analysis were adopted to investigate the correlations between environmental (e.g., water temperature, conductivity, pH, total nitrogen, and phosphorus) and biological (e.g., chlorophyll a, plankton density, and community composition) variables and the densities of adults and veligers of L. fortunei. Water temperature is the most important factor in determining the densities of D-shaped and pediveliger veligers, with explanatory variable contributions of 56.2% and 43.9%, respectively. The pH affects the densities of D-shaped, umbonated, and pediveliger veligers. The density of plantigrade veligers is negatively correlated with the conductivity and positively correlated with the concentration of chlorophyll a. Canonical correspondence analysis shows a weak correlation between the dominant phytoplankton taxa and the density of veligers. The densities of D-shaped, umbonated, and pediveliger veligers are positively correlated with the density of small phytoplankton (12.54 ± 4.33 μm), and the density of plantigrade veligers is positively correlated with the density of large (16.12 ± 5.96 μm) phytoplankton. The density of planktonic veligers is well correlated with local abiotic variables, and that of plantigrade veligers is less correlated with local abiotic variables. This finding implies that controlling early-stage veligers by altering water temperature, pH, and food size might effectively control the establishment of further L. fortunei colonies.

Inter-basin water transfer enhances the human health risk of heavy metals in the middle and lower Han River, China

The ecological and human health issues caused by inter-basin water transfer have drawn wide attention. To illustrate the spatial and temporal distribution of heavy metals (HMs) in the middle and lower Han River (MLHR), a 1D hydro-environmental model was developed, calibrated, and validated based on the observed data. Three simulation scenarios were conducted to analyze the human health risks resulting from heavy metal pollution. The results show that the water flow reduction after water transfer enhanced the heavy metal pollution in the MLHR. The total health risk of HMs in surface water of the MLHR basin was 4.69 × 10−5 a−1 for adults and 7.82 × 10−5 a−1 for children without the water transfer, while it increased to 4.77 × 10−5 a−1 and 7.95 × 10−5 a−1 when the South-to-North Water Transfer Project (SNWTP) was put into operation. The Yangtze to Han River Water Transfer project (YHWTP) can partially offset the adverse SNWTP influences. However, the human health risk is still higher than those without SNWTP operation. The health risks in the MLHR basin are main from carcinogens As, which should be prioritized as the main targets for water environment risk management in the Han River basin.

A Quantitative Assessment on Ecological Compensation Based on Water Resources Value Accounting: A Case Study of Water Source Area of the Middle Route of South-To-North Water Transfer Project in China

As an economic means to adjust the contradiction between ecology and development, ecological compensation plays an important role in promoting the good operation of interbasin water transfer projects and the sustainable development of regional economy. The accounting of ecological compensation is the key and difficult point of ecological compensation as well as the basis of ecological compensation policy and practice. Watershed ecological compensation based on water resources value accounting is an early exploration field of ecological compensation research, and water resources value calculation needs to consider both water quantity and water quality comprehensively. Taking the water source area of the Middle Route of South-to-North Water Transfer Project (SNWTP) as an example, this article tries to establish the payment standard of watershed ecological compensation from the perspective of water resources value. The results show that: 1) The water resources value of the six core regions in the water source area has shown an overall upward trend since 2000, and the northern regions have demonstrated higher value of water resources than the southern regions. 2) The LSTM neural network model is used to forecast the value of water resources in the six regions from 2020 to 2022, and it is found that the value of water resources would increase in the next few years. 3) The compensation price of the six regions in the water source area is predicted in the range of 0.5–1.5 yuan/m3 from 2020 to 2022, and an upward trend in the ecological compensation amount is forecast. Based on the above conclusions, this article puts forward suggestions to establish an ecological compensation accounting system in line with the Middle Route water source area from the perspectives of ecological compensation legislation, allocation of ecological compensation amount, and introduction of market mechanism.

Hydro-environmental response to the inter-basin water resource development in the middle and lower Han River, China

Abstract As one of the most important influencing factors, inter-basin water resource development has been exerting an increasingly evident impact on the hydro-environment of river basins. The Han River was selected as a case study to reveal the hydro-environmental response to China's inter-basin water resource development. The hydrological changes and water-quality variations resulted from the middle route of the South-to-North Water Transfer Project (SNWTP) and the Three Gorges Reservoir (TGR) operation were examined based on a hydro-environmental model. The results indicated that the runoff reduction is obvious after the SNWTP operation, and the low-flow duration significantly increased by 4–5 months. Consequently, the flow decrease significantly contributed to the water quality deterioration in the middle and lower Han River, while the Yangtze-Han Water Diversion Project (YHWDP) can not alleviate the situation completely. Moreover, the nutrient assimilative capacity decreased after water diversion, which agrees with the hydrological changes along the middle and lower Han River. The quantitative analysis performed in this study distinguishes the spatiotemporal variation in water quality variables using the integrated model. It provides insights into water quality management under the influences of inter-basin water resource development.

Eutrophication risk assessment considering joint effects of water quality and water quantity for a receiving reservoir in the South-to-North Water Transfer Project, China

Evaluating the eutrophication risk of a receiving reservoir is crucial for scientific water transfer schemes. However mega water transfer projects would greatly affect both water quantity and water quality processes, making the eutrophication evaluation more difficult. This study assessed the eutrophication risk of a receiving reservoir (i.e., Miyun Reservoir) after the implementation of the world's largest water transfer project, namely, the South-to-North Water Transfer Project (SNWTP) in China. A new perspective of considering joint effects of water quantity indicator (i.e., water storage) and water quality indicator (i.e., Chlorophyll a concentration or Chla concentration for short) was proposed to assess the eutrophication risk. The GMM model was first introduced into the copula model to adaptively describe the marginal distribution of hydrological variables and to improve the accuracy of the marginal probability distribution for water storage. Besides, the Frank copula model was selected to establish the joint probability distribution function of water storage and Chla concentration from four candidate copula models. The eutrophication risk of the receiving reservoir was then assessed under ten water transfer scenarios concerning six amounts of water transfer in four certain periods. Results showed: 1) there was little eutrophication risk (<0.0005) in Miyun Reservoir under the selected water transfer scenarios; 2) the probability of higher Chla concentration in Miyun Reservoir would increase with larger water storage after the implementation of the SNWTP, and 3) the probability (0.00027) of water quality deterioration in the reservoir under uniform water transfer was about half (0.00045) of the centralized water transfer. These findings can contribute to the eutrophication risk assessment and adaptive management of the world's largest water transfer project.

Balancing water and food by optimizing the planting structure in the Beijing–Tianjin–Hebei region, China

In the past several decades, the irrigation of high-intensity cropping systems has caused serious groundwater depletion in the Beijing–Tianjin–Hebei region. Optimizing the planting structure is a key method for mitigating groundwater decline. However, the optimal planting structure has not been confirmed, and the effect of planting structures has not been quantified in groundwater overdraft areas. In this study, based on a model for planting structure optimization and the elitist nondominated sorting genetic algorithm, the water saving potential was estimated, and the trade-off between water resources and agricultural production was quantified. The results showed the following: (1) The current planting structure is a highly water-consuming system. The winter wheat–summer maize double-cropping system and vegetable and fruit cropping systems are the dominant contributors to crop water consumption, accounting for 90% of the total water deficit. (2) Constrained by regional water resources, it is difficult to achieve the objectives of halting groundwater decline and food self-sufficiency simultaneously unless at least 1.0 billion m3 yr-1 water from the mid-route of the South-to-North Water Transfer (SNWT) project is used for agriculture or wheat imports account for more than 25% (2.84 million ton yr-1) of the regional wheat demand. (3) It is almost impossible to achieve a balance between groundwater exploitation and replenishment only by optimizing the planting structure without decreasing the agricultural output or without using external water. When the planting structure is optimized, to coordinate grain crops, cash crops and water use, at least 81–96% (4.6–5.5 billion m3 yr-1) of the planned water from the SNWT project will need to be used for agriculture. (4) A viable option for restructuring planting should consider the regional self-sufficiency for wheat, a moderate surplus of vegetables/fruits to boost farmers’ income, and appropriate water transfer for groundwater sustainability. The results provide a compromise between food and water in severe groundwater overdraft areas and serve as a quantitative reference for making decisions regarding agricultural and water resource policies.

Pollution risk assessment of heavy metals in the sediments of upstream Hanjiang River, China

In China, the upstream Hangjing River (HJR) is an important surface water source for the South-to-North Water Transfer Project (SNWTP) because it has abundant water and better quality, which plays a crucial part in national drinking water safety and ecological sustainable development in China. This work was aimed at comprehensively studying the pollution status of heavy metals in sediments upstream of the HJR and apportioning sources. A total of 33 superficial sediment samples were collected from the main upstream of the HJR, which is located in Shaanxi and Hubei Provinces in China. The total concentrations of Zn, Cr, Ni, Cu, Cd, Pb, and As were analysed by using inductively coupled plasma mass spectrometry (ICP-MS). A standardized method was used to establish the environmental geochemical baseline concentrations (EGBCs) of the selected HMs as an alternative for local geochemical background values (LGBVs) to use for HM pollution assessment of sediment. The pollution status and potential ecological risk were assessed with the geochemical baseline factor pollution index (Ki), potential ecological risk index (RI), and sediment quality baseline evaluation (SQBEs). The source apportionment of heavy metals was performed by correlation analysis and principal component analysis (PCA). This study showed that the EGBCs of Zn, Cr, Ni, Cu, Cd, Pb, and As were 63.81 mg/kg, 23.47 mg/kg, 46.52 mg/kg, 35.26 mg/kg, 0.26 mg/kg, 6.97 mg/kg, and 6.76 mg/kg, respectively. The results indicated that Cd was the most common heavy metal pollutant. Mineral mining and smelting activities were the main sources of heavy metals in the sediments of the upstream HJR. Special attention should be paid to Cd, while Ni pollution cannot be ignored, especially in biotoxic effects. The high total Cd content affected individual and overall ecological risk indicators, indicating that Cd could represent a considerable ecological risk for upstream HJR.

Potential impact of water transfer policy implementation on lake eutrophication on the Shandong Peninsula: a difference-in-differences approach

Abstract Traditional research on lake eutrophication has failed to consider the effect of the South-to-North Water Transfer Project (SNWTP) policy; thus, the difference-in-differences (DID) model, which is usually applied to economic factors, was innovatively introduced to evaluate the effect of such policies on lake eutrophication. Nansi Lake and Dongping Lake in the Shandong Peninsula were selected as the experimental group, and Daming Lake and Mata Lake were selected as the control group. The eutrophication indices of the experimental group and the control group were calculated by the measured chlorophyll-a, total phosphorus, total nitrogen, water transparency and chemical oxygen demand data and used as the explanatory variables of the DID model. Nine environmental and socio-economic factors, such as dissolved oxygen and rural population, were selected as the control variables of the DID model to analyze the impact of the SNWTP policy on lake eutrophication. A joint consideration of environmental and socio-economic factors showed that the eutrophication degree of the experimental lakes deteriorated by 7.10% compared with the control under the influence of the implemented policy. Dissolved oxygen is the main factor affecting the eutrophication of the Shandong Peninsula. This study verifies that the DID model has the potential for use in quantitative analyses of the effect of the SNWTP policy on lake eutrophication.

Water security evaluation based on comprehensive index in Jing-Jin-Ji district, China

Abstract China has long faced the problem of uneven distribution of water resources in time and space. The state of water security is therefore a key factor in regional development. The Jing-Jin-Ji district in China, which includes Beijing, Tianjin and Hebei Province, faced severe water security problems. Therefore, to improve the management of water resources, water security should be properly evaluated. This study established a comprehensive evaluation index system for evaluation. Furthermore, it analyzed the impacts of the South-to-North Water Transfer Project (SNWTP), which fully reflects the impact of human activities on the spatial distribution of water resources and is an innovation. The results showed that the state of water security in the Jing-Jin-Ji district generally had an increasing trend, and the score of the overall evaluation was increased by 65.8%. The Middle Route of the SNWTP had played a major role in water security in resources criterion, which increased by 28.53% in 2015 and 13.64% in 2016. With social development, the general state of water security in the district was improving. These findings could provide a scientific basis for regional water resources management.

Numerical Simulation of Multi-Water-Source Artificial Recharge of Aquifer: A Case Study of the Mi-Huai-Shun Groundwater Reservoir

Artificial recharge is an effective way to alleviate water shortages and excessive groundwater exploitation. In this study, to explore environmental changes of surface water and groundwater during multi-water-sources recharge process, numerical simulation method was applied. Local reclaimed water, treated by wetland, and water from the South-to-North Water Transfer Project (SNWTP) were used to recharge groundwater reservoir in Mi-Huai-Shun District (Miyun District, Huairou District and Shunyi District). The Flow Model results showed that the accumulated loss of the groundwater resource in the Mi-Huai-Shun area from 2007 to 2016 reached – 1.784 × 109 m3. All the water sources contribute to the recharge of groundwater, raising the groundwater level and increasing the groundwater reserves. Meanwhile, the Solute Transport Model results show that different water source has different effects on the local groundwater environment. chloride concentration of reclaimed water source and wetland water source are higher than groundwater, and the artificial recharge caused the chloride concentration of groundwater in receiving area to rise. The water from the SNWTP played an important role on reducing chloride concentration due to dilution. In addition, Multi-Water-Source artificial recharge is also related to the local hydrogeological conditions. This study provides a comprehensive analysis of the impact of multi-water-source recharge on groundwater quantity and quality.

Macrozoobenthos variations in shallow connected lakes under the influence of intense hydrologic pulse changes

Hydrologic pulse represent one of the dominant factors controlling the distribution of aquatic organisms. Changes in hydrologic pulses may change the surroundings of the organism and then affect their distribution and community structure. Here, based on the data from a rainy season and a dry season, the water quality, heavy metal in the sediment and macrozoobenthos community structure in two shallow lakes, Nansihu Lake (NSH) and Dongpinghu Lake (DPH, were analyzed. The results showed that the water diversion pulse participated in the influence of runoff pulse on NSH and DPH. The macrozoobenthos community in NSH and DPH were similar after the hydrologic pulse changed, this might be due to these two lakes were connected by the South-to-North Water Transfer Project (SNWTP). Along the direction of water transfer, the macrozoobenthos communities were gradually dominated by small-size species with as water quality decreased. Compared with community structure before the SNWTP, the macrozoobenthos changed from dominant aquatic insect to dominant Mollusca in NSH, and changed from dominant Mollusca and Oligochaeta to dominant Mollusca in DPH. The water diversion pulse, in which the direction of water transfer was opposite to that of natural water flow, affected the distribution of nitrogen and phosphorous in water and heavy metals in sediment. In addition, the introduction of exogenous water caused by the SNWTP changed water quality and heavy metals content in the sediment and water depth in NSH and DPH. These changes together affected the community structure and distribution of macrozoobenthos. These findings enable a better understanding of the ecological impact of intense hydrologic pulse changes caused by water transfer projects.

Variations in stable carbon and nitrogen isotopes of particulate organic matter in surface waters of water-receiving area of Eastern Route of South-to-North Water Transfer Project, China.

The purpose of this study was to assess the water quality and variations in stable carbon and nitrogen isotopes of particulate organic matter (δ13CPOM and δ15NPOM), as well as to evaluate the sources of carbon and nitrogen that contribute to the POM pools in lakes and reservoirs located in the water-receiving area of the Eastern Route of South-to-North Water Transfer Project (SNWTP) in Northern China. During each season from October 2013 to July 2014, samples of POM from 14 lakes and reservoirs in Northern China were collected. The lakes and reservoirs were meso-eutrophic with considerably high brackish ions (SO42-, 173mg/L; Cl-, 296mg/L) in Yangtze River lake, and high total nitrogen: total phosphorus ratio (averaged with 772) or dissolved inorganic nitrogen: soluble reactive phosphorus molar ratios (averaged with 1077) in mountainous reservoirs. The δ13CPOM, δ15NPOM, carbon to nitrogen (C/N) ratios showed significant seasonal variation, with ranges of - 32.5 to - 17.4‰, - 3.6 to 13.5‰, and 5.1-13.2, respectively, while they were hard to be distinguished among types of water sources. Principal component analysis (PCA) indicated that brackish ions, nutrients, and their molar ratios were the main factors influencing variations in δ13CPOM and δ15NPOM. δ13CPOM and C/N ratios suggested autochthonous primary production mainly contributed to POM during from April to October, while exogenous organic matter might mainly contribute these carbon pools in January. The low values of δ15NPOM (< 0‰) and negative correlation between δ15NPOM and TN suggested discharge of agricultural waste water (e.g., fertilizers, irrigation tailwater) in Bailanghe, Xinan, and Taihe Reservoir during the fertilization season, while higher values indicated domestic sewage input to waterbodies (e.g., Mishan, Gengjing, Donghai Reservoir). Our results suggested that the aquatic ecosystem in water-receiving area of SNWTP would be potentially affected by the inter-basin water diversion, and thus, ecosystem-based strategies were also presented accordingly.

Changes in nutrient transport from the Yangtze River to the East China Sea linked to the Three-Gorges Dam and water transfer project

River-sea transition plays a key role in global geochemical cycles. The Yangtze River Estuary of China was selected as the research area, and the Section-Segmented Method was applied to determine the nutrient discharge from the Yangtze River to the East China Sea. A 3-D numerical model for the estuary was established and validated against the field investigated data. By numerical experiments the dynamics of hydrology and nutrient from 1950 to 2016 were simulated under four varied schemes. The individual and combined impacts on the nutrient flux induced by the Three-Gorges Dam (TGD) and the South-to-North Water Transfer Project (SNWTP) were explored. The following results were observed: (1) During the Pre-TGD period, the Yangtze River delivered the loads of 1.32 Tg/yr and 0.08 Tg/yr for TN and TP, respectively. July and Feb. were characterized by the highest and lowest monthly flux, respectively. (2) TGD played a significant role in regulating the temporal nutrient deliveries. After the closing of TGD, the discharges of TN and TP in the dry season respectively went up to 0.55 Tg and 0.032 Tg, with a mean increase of 28.3%. (3) SNWTP reduced the nutrient transport at a relatively stable level, and the total loads of 40.66 Gg and 2.4 Gg were reduced per year for TN and TP, respectively. (4) The combined impacts of TGD and SNWTP varied with seasons. October was characterized by the greatest cumulative effects. In dry seasons, the reduction caused by SNWTP was leveled by TGD-induced increase, limiting the flux variation linked to project operations.

Dynamics of nutrient export from the Yangtze River to the East China sea

River-sea transition plays a key role in global geochemical cycles. This study proposed a Section-Segmented Method (SSM) to determine the nutrient discharge from the Yangtze River to the East China Sea (ECS), against the high-density data of water flux and nutrient by the combination of artificial and tele-control monitoring. During 2012–2016, the nutrient delivery exhibited a pronounced inter annual variation, and the mean fluxes of TN and TP were respectively 1.69 Tg/yr and 0.11 Tg/yr. The year of 2016 was characterized by the highest level, with the loads of 2.00 Tg and 0.115 Tg for TN and TP, respectively. The river transported the maximum monthly flux in July, yielding 270.97 Gg and 15.62 Gg for TN and TP, respectively. The 5-year mean daily TN and TP flux were respectively 4.62 Gg and 0.27 Gg. The daily nutrient flux showed a pronounced and positive relationship with net water flux, but due to the different input modes of N and P, TP flux displayed a higher dispersion than TN. The degrees influenced by the South-to-North Water Transfer Project (SNWTP) in the nutrient delivery were stably maintained at the level of 2.50% and 2.36% for TN and TP, respectively, whereas the Three Gorges Dam (TGD) just harnessed 0.60% and 0.26%.

Changes in Ecosystem Services Value and Establishment of Watershed Ecological Compensation Standards.

Ecological compensation standards and the allocation of compensation funds have always been the core issues of watershed ecological compensation. Due to the construction of the Eastern Route of the South-to-North Water Transfer Project (SNWTP), Jiangsu Province has paid a huge cost for the protection of water resources, and local economic development has been greatly affected. Therefore, this paper takes Jiangsu Province, the water source area of the Eastern Route of the SNWTP as an example, and combines a geographic information system (GIS) and remote sensing technology, using the ecosystem services value method to calculate the ecosystem services value of Jiangsu Province from 2005 to 2018. Then the change of this ecosystem services value in Jiangsu Province from 2015 to 2018 is taken as the basis for watershed ecological compensation standards of the Eastern Route. Through a compensation fund allocation model, watershed ecological compensation funds are allocated to four cities, Yangzhou, Huai’an, Suqian and Xuzhou, which are located along the Eastern Route of this SNWTP in Jiangsu Province. The results show that: (1) The ecosystem services value of Jiangsu Province has changed greatly. Urbanization and market environment of grain crops are the main reasons for this change; (2) the relationship between ecosystem services in Jiangsu Province is mainly synergistic; (3) Suqian receives US$24.73 million; Huai’an receives US$16.49 million; Yangzhou receives US$54.88 million and Xuzhou receives US$0.95 million in watershed ecological compensation, respectively. Watershed ecological compensation standards based upon the value of ecosystem services, and the allocation of compensation funds at the municipal level, are conducive to the improvement in efficiency of watershed ecological compensation in mainland China.

Optimizing water resources allocation in the Haihe River basin under groundwater sustainability constraints

This study applies a hydroeconomic optimization method for water resources management in the highly water stressed Haihe River basin. A multi-objective, multi-temporal deterministic hydroeconomic optimization model has been built to quantify the economic trade-offs and reveal “minimum cost strategies” when reducing groundwater abstraction to sustainable levels. A complex basin representation, with ∼140,000 decision variables is formulated where each decision variable represents a flow-path from a water source to a sink. Available water sources are runoff generated by the sub-basins upstream the nine major surface water reservoirs, the inter-basin transfers from Yellow River and South to North Water Transfer Project (SNWTP) and the natural groundwater recharge to the three main groundwater aquifers. Water demands, i.e. sinks, are aggregated for each model sub-basin in categories of the major agricultural users, domestic, industrial and ecological water demands. Each demand is associated with a curtailment cost and groundwater abstraction with a pumping cost. Groundwater overdraft is constrained in each model scenario, ranging from unlimited overdraft in the plain area groundwater aquifer to sustainable abstractions over an 8-year period. Inflow upstream Yuqiao reservoir, and the inter-basin transfers from SNWTP and Yellow River are identified as the water resources with the highest increase in average shadow prices when limiting groundwater overdraft. An increase in inflow shadow prices of 37.5% indicates that these water sources will be most valuable if sustainable groundwater abstraction should be achieved. The shadow prices of water sources reveal when and where in the Haihe River basin users are curtailed if water resources are managed in the most optimal way. Average shadow prices of 1.6 yuan/m3 for all surface water sources in the sustainable abstraction scenarios shows that overdraft can be avoided by curtailment of users with a willingness-to-pay ≤1.6 yuan/m3. The shadow prices of the existing surface water reservoirs represented in the model shows that no costs can be saved from expanding their capacities. Finally, the cost of achieving sustainable groundwater abstraction with present water resource availability is found to be minimum 8.2 billion yuan/year.