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Water conservation has become a global problem as the population increases. In many densely populated cities in China, leaks from century-old pipe works have been widespread. However, entirely eradicating the issues involves replacing all water networks, which is costly and time-consuming. This paper proposed an AI-enabled water-saving control system with three control modes: time division control, flow regulation, and critical point control according to actual flow. Firstly, based on the current leaking situation of water supply networks in China and the capability level of China's water management, a water-saving technology integrating PID control and a series of deep learning algorithms was proposed. Secondly, a multi-jet control valve was designed to control pressure and reduce water distribution network cavitation. This technology has been successfully applied in industrial settings in China and has achieved gratifying water-saving results. [ABSTRACT FROM AUTHOR]

Mountainous areas in southwest China are rainy in summer. The rainfall infiltration process involves complex soil thermal-hydraulic-mechanical (THM) coupling problems. The researches on soil THM coupling are mostly focused on numerical simulations, whereas the corresponding model tests are relatively few, and the existing model test studies often ignore the effect of temperature gradients in the soil. However, temperature gradients in the soil can cause water migration and affect the THM behavior of soil, so it cannot be ignored. This paper describes an experimental device that can test the changes of temperature, moisture and displacement in unsaturated soil columns with temperature gradients under rainfall infiltration conditions. By using the apparatus, the model tests of homogeneous soil column (H), homogeneous soil column with infiltration (HI), and preferential flow soil column with infiltration (P) under different temperature gradients are respectively conducted, and the results of moisture and heat migration and deformation properties in soils under different conditions are presented and discussed. A rainfall of low intensity and long duration is applied in the experiments, and the temperature of infiltration rainwater is consistent with that of the soil upper boundary. The results show that: (1) The infiltration of rainfall will increase the temperature of the soil column. The appearance of preferential flow results in faster heat transfer within the soil column, but causes the steady-state temperature to be lower than that of the homogeneous soil (HI); (2) Under infiltration conditions, the preferential flow soil column has an earlier outflow time but a later time for water field to reach steady state, while its water distribution is different from that of the homogeneous soils, with accumulation occurring near the end of preferential flow channel; (3) Under the action of temperature gradient, water migration occurs in homogeneous soil column (H), accompanied by soil settlement, while the infiltrated columns (HI and P) exhibit an increase in both water content and top displacement. In addition, the larger the temperature gradient, the more obvious the thermally induced hydraulic-mechanical response. The research results in this paper can provide experimental evidence for the theoretical study and numerical simulation of the soil THM coupling problems. [ABSTRACT FROM AUTHOR]

To achieve the transformation of water rights institution in China from the administrative management to the property rights institution, it is of high significance to discuss the principle of rights confirmation, institution connection, and change. In this paper, we present the process, result, experience, and problems of the authors' involvement in water rights confirmation and registration in Delingha as the methods designer of water rights confirmation. The conclusions of this paper follow: (1) Equity must be the priority while considering the principles of water rights confirmation. Complying and verifying the results of historical water distribution, strengthening public participation, and selecting persuasive and scientific indicators are the main components that are embodied in the concept of equity. (2) Water rights confirmation is to recognize and revise the distribution result of the old institution. Macroscopically, based on the administrative upper limits set by the "Three Red Lines" and ecologically sustainable requirements, the dual-control method of "matching water use and the Three Red Lines" and "matching water consumption and available water resources" was used to control the total distribution of water rights. From a microscopic point of view, the water abstraction permit was the core indicator of water rights confirmation, after checking with other data. (3) The institutional logic, the responsibilities and roles of the government, and the intellection of water users have changed after the confirmation of water rights. Registration is the key to distinguishing water rights from the traditional administrative institution. [ABSTRACT FROM AUTHOR]

Assessing the risk of water leakage within urban water distribution networks (UWDN) is crucial prior to implementing any control measures. Conducting a risk assessment facilitates the development of effective water leakage management plans. By comprehensively analyzing the probability and loss factors that contribute to the risk of leakage in UWDN, this paper presents an evaluation index system for pipeline leakage risk. This index system utilized both quantitative and qualitative data on influencing factors derived from an actual pipeline network. In order to determine the precise level of pipeline leakage risk, an index theory-based pipeline leakage risk evaluation model was established. This model consisted of a single-index measure function and a multi-index comprehensive measure vector. The combined weight of evaluation indices through game theory was used to determine the weight of each index, thereby minimizing the negative effects of a single weight determination method. A risk assessment model that evaluated the leakage risk of specific pipelines was constructed based on actual data from the water distribution network in a certain area of China. The analysis showed that the risk of pipeline leakage in this area was mainly classified as a third-level risk, which is consistent with the actual evaluation results obtained from field visits. [ABSTRACT FROM AUTHOR]

Objective Water sourced from the Yellow River in China, which has been extensively used for irrigation in the northern irrigation districts of the country, is characterized by high sediment content. This paper aims to investigate the influence of sediment particle size distribution on water infiltration under surge irrigation. Method The infiltration tests encompassed four treatments with sediment content being 3%, 6%, 9%, and 12%, respectively. Each sediment treatment included four particle gradings labeled as A, B, C, and D, respectively. In each infiltration test, we meticulously measured both the infiltration rate and the variation in infiltration over time. Result The relationship between cumulative infiltration and time can be described by the Philip and Kostiakov models, regardless of sediment content and particle grading. As the number of irrigation cycles increased, the parameters K and α in the Kostiakov model, as well as the parameters S and A in the Philip model, all exhibited a declining trend. Conclusion In comparison to the infiltration of clean water, the infiltration depth of sedimentwater was inversely related to the presence of physically cohesive particles. Conversely, when the infiltration depth was the same, soil water content was negatively correlated to the quantity of physically cohesive particles in the water. [ABSTRACT FROM AUTHOR]

With the continuous development of economy and society, great changes have taken place in the national water intake situation. In order to adapt to the requirements of high-quality development of water resources management in the new situation and respond to the needs of building a smart water digital twin data base, the construction of the national water resources monitoring and measurement system needs to be strengthened. As the main water intake form in China at this stage, it is necessary to study the technical methods to improve its monitoring and measurement capacity. This paper investigates and studies the data of more than 5.5 million water intakes nationwide collected in 2021 by combining field investigation and data collection. From the national and typical provincial levels, the current situation of water intake monitoring and metering is analyzed according to different water intake scales, water intake purposes, water intake projects, monitoring and metering facilities and water transmission type, and the comparison and selection of monitoring and metering facilities, improvement of monitoring accuracy. Technical methods are proposed to improve the stability and durability of monitoring, improve the application of system platform functions, and promote the improvement of pipeline type water intake monitoring and metering capacity. The research shows that: ➀ The number and distribution of water intakes across the country are significant. The number of water intakes is huge and the spatial distribution is uneven. There are many water intakes in the north, mainly groundwater intakes, and few water intakes in the south, mainly surface water intakes. ➁ The national water intake monitoring and metering work should be further strengthened. At this stage, the focus should be on improving the pipeline type water intake monitoring and metering capacity. The monitoring and metering methods and facilities used are different due to different conditions such as water intake scale, water intake scene and water intake purpose. The error, environmental adaptability, measurement cost, advantages and disadvantages and unique application scenarios of different monitoring and measurement facilities are quite different. ➂ The monitoring and metering lifting of pipeline type water intakes is a comprehensive task. It is necessary to comprehensively improve the monitoring and metering capacity of the water intake from four aspects: metering accuracy, stability and durability, system platform application capability, and the introduction of relevant technical standards. The research findings provide an important basic data reference for comprehensively understanding the current situation of water intake monitoring and metering in China, a technical reference for improving the monitoring and metering capacity of pipeline water intakes, and a technical support for the next step of water intake supervision. [ABSTRACT FROM AUTHOR]

The construction of large-scale water diversion projects has effectively alleviated the current situation of the uneven distribution of water resources in China. However, due to the siltation of very fine sediment and organic matter on the side wall of an open channel, and the slow velocity of the side wall flow field, it is easy for epipelic algae to be produced, which affects water quality. Because prototype observation cannot be used to predict the series of flow in real time, and the calculation of the mathematical model is affected by parameter limitations, these two methods often cannot truly reflect the hydrodynamic characteristics of an open channel with epipelic algae. Therefore, by referring to the design parameters of the water diversion project channel, this study took the epipelic algae growing on the side wall of an open channel as the research object and used the scale of 1:30 to carry out a generalized flume experiment. Through the analysis of the physical characteristics of the prototype sample, and the simulation of the cohesive force between the oblique side wall and the epipelic algae, multi-group and multi-series hydrodynamic tests were carried out. The velocity distribution law and flow field distribution law were analyzed. The research results show that the presence of epipelic algae has a certain hindering effect on the flow velocity and significantly reduces the range of the peak velocity of the channel along the water depth. The position of the maximum velocity on the vertical line of the channel flow appears at the relative water depth of 0.6. In the case of small flow, the epipelic algae group only reduces the average flow rate of the channel by 5~6%; in the case of large flow, the effect of epipelic algae on the channel flow rate is minimal. This paper includes important scientific guiding significance and practical value for the regulation of water quantity and water quality safety, as well as the protection of long-distance projects. [ABSTRACT FROM AUTHOR]

Because of the continuous deterioration of water environment, it is ensured that the basic water demand of ecological environment is the key task of water resources utilization and control in China. In view of the uneven distribution of domestic water resources "more in the South and less in the north, more in the East and less in the west," it is very necessary to optimize the allocation of water resources. This paper aims to optimize the allocation of water resources through simulated annealing algorithm (SAA), hoping to optimize the allocation of water resources through diversion, water intake, and storage measures such as pipelines. Based on this, this paper proposes an improved SAA pipeline construction algorithm. Aiming at the distribution of water sources in the Yangtze River Basin, the algorithm is used to optimize the objective function path to solve the unbalanced problem of rich and lack of regional water resources. And after optimizing the annealing simulation algorithm, the simulation optimization ability is significantly improved. Experiments show that the improved SAA can improve the optimal configuration by more than 50% and up to 96%, indicating that the improved algorithm has a more stable optimization planning function for the optimization of objectives and can often get a more perfect route. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although some methods have identified the physical urban area to a certain extent, the driving factors for the identification threshold have not been studied deeply. In this paper, vector building data and road intersection data are used for comparative validation based on the urban expansion curve method to identify the physical urban area using the meso-city scale. The geographical detector technique is used to detect how and to what extent the urban spatial structure factors, geographical environment factors and social economic factors affect the optimal distance threshold of 22 administrative districts in the Chongqing municipality. The results based on the vector buildings are more precise and show the characteristics of the physical urban area of core-periphery distribution and the distribution along the water corridor. From the results of quantitative attribution, it was found that the road network density, building density, urbanization rate and urban population density, and their interaction with regional GDP, play a critical role in the optimal distance threshold, with the index value of influence degree ≥0.79. Under the influence of different factors, the optimal distance thresholds of 22 administrative districts show adaptive characteristics. Looking forward to the future, this study provides ideas for further research on the morphological characteristics and distribution laws of multi-spatial scale cities. [ABSTRACT FROM AUTHOR]

Global warming has changed the thermal and dynamic environment of climate effects, further exacerbating the uneven distribution of water in China within the year, and the threat of drought will continue to intensify. Flood control and drought resistance are equally important at present. How to reasonably utilize the flood control capacity of reservoirs and raise the flood control level is the key to alleviating the supply-demand contradiction of water resources in China. In the face of new situations, combining the existing operation regulations of the Three Gorges Reservoir and long series of historical runoff data, this paper takes the Three Gorges Reservoir as the object and formulates different flood control level schemes to analyze the benefits and risks of raising the flood control level of the Three Gorges Reservoir. The results indicate that relying on the current forecast level and the joint operation of upstream reservoirs, the flood control risk of the Three Gorges Reservoir flood control level rising to 155-157 m is controllable. It will not lower the flood control standards of Jingjiang and increase the risk of backwater flooding in the reservoir area. When the flood control level of the Three Gorges is raised to 153 m, the average annual power genertion reached its maximum value of 102.9 billion kWh, an increase of 16.7% compared to the initial design value. Consistent with years of statistical law, the Three Gorges Reservoir reaches its maximum power generation capacity in both wet and normal years when the flood control level increases to 153 m. Higher flood control level in dry years, resulting in better power generation efficiency. The flood control benefits are negatively correlated with the flood control level, but the average annual flood detention volume of different schemes varies by 1.5 billion m3. It has changed little. The benefits of water resources are positively correlated with the flood control level. The starting water level of the Three Gorges Reservoir increases synchronously with the rise in the flood control level. When the flood control level rises to 147 m, the full storage rate of the Three Gorges Reservoir can reach 100% by the end of October. For every 1m increase in flood control level, the average annual outflow of water during the storage period can increase by about 500 million m3. Relying on the current forecast level and the joint operation of upstream reservoirs, the flood control risk of the Three Gorges Reservoir s flood control water level rising to 155- 157 m is controllable. Considering both benefits and risks, the flood control level of the Three Gorges Reservoir can be raised to 153 m at present. [ABSTRACT FROM AUTHOR]

The original intention of virtual water trade (VWT) is to help water-scarce areas adjust the crop trade structure to alleviate the water shortage problem. However, China's existing virtual water trade (VWT) must effectively alleviate the problem. This paper's structural features and stability of the VWT network (VWTN) in China's major crop trade between 2000 and 2017 were characterized using complex network theory. The results in terms of time scale showed that the total content of VW in China's major crops increased by ~23.6% for 18 years. Trade relations among most regions remained stable, whereas a few areas changed: Jilin, Henan, and Heilongjiang played essential roles in the output network, and so did Guangdong, Shanghai, and Fujian in the input network. Attributed to policy adjustment, Henan and Jilin became more prominent in the output network with the gradual decline of Jiangsu's position. Regarding spatial scale, the cumulative distribution of degrees consistent with the power–law relationship showed high variability and vulnerability of China's VWTN, especially when nodes were weighted. Since areas with more VWT partners/content provided connectivity to those with fewer partners/content, it is worthwhile to focus on developing protection policies for critical areas. The virtual water trade from North China (water-poor) to South China (water-rich) is contrary to the distribution of water resources. A similar situation showed in a global world that the long-term supply relationship would aggravate the water resources shortage and food security. Furthermore, we suggest combining network theory and VWT to lay the foundation for the invulnerability research of VWTN and the optimal regulation of crops. [ABSTRACT FROM AUTHOR]

Due to the uneven distribution of water resources, there are many water diversion projects around the world, such as the South-to-North Water Diversion Project in China, especially in some plain areas. To transfer water from low to high areas, large low-head pumps have been widely used. The transition process of the pumping station is mainly caused by the sudden change in the flow velocity and pressure of the fluid in the pipeline of the pumping station system caused by the start-up and shutdown processes. The previous research has mainly been based on the one-dimensional characteristic line method. However, due to the characteristics of the low-lift pumping station, the flow passage is short and irregular, and the calculation results often cannot guarantee the accuracy of the calculation. In addition to some faults in the actual operation process, in some pumping stations, accidents or operation-scheduling faults are caused by transient processes, such as a high degree of water hammer, the inability to initiate backward flow, the shutdown load rejection runaway exceeding the standard, and decreased hydraulic efficiency. To avoid transition process failures in the newly designed pumping stations and the modified pumping stations, it is necessary to carry out a research review of the three-dimensional transition process of large low-lift pumps. Especially with the development of computing technology, CFD numerical simulation technology has become the main research method for analyzing the pump transition process. The research on the transition process is mainly based on the combination of numerical simulations and experiments. The reliability of a numerical simulation is verified by an experiment. A numerical simulation can measure some parameters that cannot be measured by an experiment. Dynamic mesh technology has become the main technical means for using CFD numerical simulation to study the three-dimensional transition process, and the secondary development of computing software has become the main trend of future development. This paper analyzes and summarizes the research status of the start–stop transition process of large low-lift pump stations and provides a reference for the protection of the start–stop transition process of pump stations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conflict in cost sharing is normal in complex water distribution system projects, such as the inter-basin water diversion project (IWDP). China's South to North Water Diversion Project (SNWDP) is the largest IWDP in the world, with a complex relationship between upstream and downstream users of the water supply. Therefore, it is necessary to propose an applicable and unsophisticated cost-sharing method to deal with the complex relationship between upstream and downstream users. This paper proposes an improved cost-sharing method based on the continuity equation of water quantity and the balance equation of the project cost between upstream and downstream users. The fairness of sharing the joint cost between parties involved in the eastern route of SNWDP (ER-SNWDP) obtained using the proposed improved cost-sharing method is investigated by comparing its results with the existing cost-sharing method. The results demonstrate that the proposed method can overcome the non-convergence issue of the existing sharing formula and reduce the differences between upstream and downstream users' sharing costs. The improved method provides a cost-sharing strategy that is more easily accepted by both the upstream and downstream users than the existing estimation approach. Therefore, the proposed pricing approach can provide technical guidance for decision makers in the effective operation of large-scale IWDPs in areas with quasi water markets. [ABSTRACT FROM AUTHOR]

The reservoir water level fluctuation zone (WLFZ) is a new and fragile ecosystem that is gaining attention with the construction of large and medium-sized hydropower plants. Compared to the natural riparian zone, it has a greater drop in water level, longer inundation time, more intense impact from alternating wet and dry conditions, and a wider impact on ecological security. The Jinsha River basin is located in the upper reaches of the Yangtze River in China, and several world-class large-scale hydropower projects with dam heights over 100 m have been built, forming a large area of reservoir WLFZ, however, due to the short time since their construction, there are few related studies. In this paper, fixed sample plots were set up in the typical WLFZs of each large reservoir in the Jinsha River basin. In response to the problem of the precipitous terrain and poor accessibility of the Jinsha River basin, a combination of small UAV surveys and field research in July 2020 was used to draw vegetation cover maps and extract topographic data for each site, and quantitatively analyse the community composition, dominant species types, area, coverage, spatial distribution patterns and environmental factors of tolerant vegetation using spatial superposition analysis, neural network models, landscape pattern indices and typical correlation analysis. The results showed that the original drought-tolerant vegetation in the arid river valley WLFZ has evolved into amphibious herbaceous vegetation, with trees and shrubs disappearing and species composition tending to be simpler. 44 species of plants, mainly in the Asteraceae and Gramineae families, were extant, 61% of which were also reported in the Three Gorges Reservoir WLFZ. The water level variation showed convergence in the natural screening process of suitable species in the WLFZ. Moreover, even in the dry valley WLFZs, flood stress showed a more significant filtering effect on vegetation species than drought stress. The vegetation in the WLFZ showed an obvious band-like aggregated distribution along the water level elevation gradient, and the vegetation coverage along the flooding gradient is as follows: upper part of the WLFZ >> middle part > lower part, and mainly concentrated in the gentle area with slope less than 35°. Flooding stress, drought stress and soil substrate deficiency were the main limiting factors for vegetation recovery in the WLFZ. The vegetation restoration of the WLFZ should be adapted to local conditions, and the dominant role of native species should be emphasized. At the early stage of the restoration of the WLFZ, native species should be selected for artificial planting to accelerate the formation of vegetation cover, and gradually advance downwards along the gradient of water level elevation, while for areas of the WLFZ with slopes greater than 35° and large topographic relief, biological engineering measures should be used to help plant establishment, and after a certain stable cover has been formed, natural restoration should be the main focus. [ABSTRACT FROM AUTHOR]

Objective Agricultural production in most regions in northern China relies on irrigation. Understanding spatiotemporal variation of the demand of different crops for water is critical to improving agricultural management. Taking the northwest Shandong province as an example, this paper studies the change in its demand for irrigation. Method We took winter wheat as the model plant, and calculated its water demand based on the Penman-Monteith formula. Spatiotemporal variation in the water demand was analyzed using the Mann-Kendall mutation test, the inverse distance weighting and the interpolation method. The factors that affect the water demand was calculated using the Pearson correlation analysis method. Result Annual average irrigation water demand of the winter wheat is 339 mm, but has been increasing. Spatially, distribution of irrigation water demand is ring-shaped across the studied region, with the shape of the rings varying with growth season. The relative humidity and sunshine duration are the factors that affect the irrigation water most, with the former negatively correlated while the latter positively correlated with the irrigation water demand, both at significant level. Conclusion The irrigation water demand of winter wheat in northwest Shandong province has been increasing. Spatially, it increases from the northeast to the southwest. Precipitation cannot meet the demand of the wheat during its seeding, returning green and elongation stages. Topping up the soil water by irrigation is hence required. [ABSTRACT FROM AUTHOR]

In this paper, we attempt to clarify the relationships between oilfield water and hydrocarbon distribution of the Triassic Baikouquan Formation, in the slope zone of Mahu depression, Junggar Basin, NW China, based on oilfield water mineralization degrees, diagenesis analysis, formation pressure coefficients, burial history, and thermal evolution processes. The results show that the study area can be divided into four zones according to the mineralization degrees, that is, (1) zone I: NaHCO3 + Na2SO4 type water with residual intergranular pores, porosity usually higher than 10%. The strata of zone I are generally buried shallow and influenced by leaching from atmospheric precipitation. This area contains normal edge and bottom water and has normal formation pressure coefficients (average 1.12); (2) zone II: CaCl2 type water with mainly compaction diagenesis, porosity usually less than 7% and high formation pressure coefficients (average 1.41); (3) zone III: NaHCO3 + CaCl2 type oilfield water with mainly feldspar dissolution diagenesis, porosity usually greater than 9% and high formation pressure coefficients (average 1.53); and (4) zone IV: CaCl2 type water, mainly compacted diagenesis with a few intergranular and feldspar dissolved pores, and high formation pressure coefficients (average 1.58). The mineralization degrees of the oilfield water in zone II, III, and IV are relatively high. The appearance of NaHCO3 type water in the deeply buried areas is usually related to oil and gas charging. Therefore, within the strata, deeply-buried areas (e.g., zone III), where NaHCO3 type water has been developed, are favorable targets for oil and gas exploration. [ABSTRACT FROM AUTHOR]

The dynamic response of groundwater level is examined in traverse and lengthways directions. Take the Yinsu section for an example, we have simulated groundwater levels before and after water-conveyance every time and calculated the incidence of groundwater on the both sides of the river. It is noted that the effect keeps growing with the water-delivery times increasing, from 570 m after the first times to 3,334 m after the eighth times. In addition, this paper involves the temporal response of the natural vegetation to water conveyance, vegetation coverage, planted-species number, dominant position and species diversity from 2002 to 2006. The findings indicate that the positive influence of ecological water conveyance project (EWCP) on the ecosystem in the Lower Tarim River is a long-term process. In this paper, we try to calculate water required for recovery of damaged ecosystem by using data available. This project is likely the base of research on water demand and the reference of measures for research on ecological water conveyance effect. [ABSTRACT FROM AUTHOR]

It is difficult to detect bridges in synthetic aperture radar (SAR) images due to the inherent speckle noise of SAR images, the interference generated by strong coastal scatterers, and the diversity of bridge and coastal terrain morphologies. In this paper, we present a two-step bridge detection method for polarimetric SAR imagery, in which the probability graph model of a Markov tree is used to build the water network, and bridges are detected by traversing the graph of the water network to determine all adjacent water branch pairs. In the step of the water network construction, candidate water branches are first extracted by using a region-based level set segmentation method. The water network is then built globally as a tree by connecting the extracted water branches based on the probabilistic graph model of a Markov tree, in which a node denotes a single branch and an edge denotes the connection of two adjacent branches. In the step of the bridge detection, all adjacent water branch pairs related to bridges are searched by traversing the constructed tree. Each bridge is finally detected by merging the two contours of the corresponding branch pair. Three polarimetric SAR data acquired by RADARSAT-2 covering Singapore and Lingshui, China, and by TerraSAR-X covering Singapore, are used for testing. The experimental results show that the detection rate, the false alarm rate, and the intersection over union (IoU) between the recognized bridge body and the ground truth are all improved by using the proposed method, compared to the method that constructs a water network based on water branches merging by contour distance. [ABSTRACT FROM AUTHOR]

Due to the large volume of sewage in China, the efficiency of water consumption evaluated by the traditional model may be inaccurate. This paper evaluates the water consumption efficiency more scientifically. First, this paper uses the CCR model to evaluate the resource efficiency and environmental efficiency separately. The latter is generally lower than the former, which means the issue of water pollution is more serious than the problem of water resource consumption. Then, the water consumption efficiency is integrally evaluated by an eco-inefficiency model which focuses on undesirable outputs. The results are in good agreement with the results of the CCR model: (1) Only Beijing, Tianjin, and Shanghai are eco-efficient in terms of water consumption, water consumption efficiency in the southeastern coastal areas is higher than in the Midwest, and the overall water environment is bad; (2) China needs to focus on reducing industrial wastewater; (3) the output of water consumption has a lot of room for improvement; and (4) the output improvement schemes of all provinces have some similarities and are related to many features. So, this paper has made a clustering analysis of the improvement schemes and given detailed suggestions for improving the eco-efficiency of water consumption in China according to the clustering result. [ABSTRACT FROM AUTHOR]

Hydropower, an excellent power source for peak shaving, can respond quickly to load changes, which helps to overcome the anti-peak characteristics of wind and solar power. However, complementary operation with wind and solar power changes the operating boundaries of hydropower stations, making the original operating rules no longer applicable. Considering daily peak-shaving demands, this paper proposes a methodology to develop operating rules for a hydro–wind–solar hybrid system (HWSHS). First, a multi-objective and multi-timescale operation model is developed to ensure energy generation and peak-shaving performance simultaneously. Second, the feasible and reasonable region of available energy-based operating rules is analyzed, and three rule forms are employed to explore the optimal operating rules. Last, NSGA-II is utilized to optimize the rule parameters. A decoupling method is proposed to handle the shape constraints of operating rules, and the multi-timescale simulation method for a HWSHS is developed as the fitness function. In the simulation method, a load reconstruction-based load shedding (LRLS) method is introduced to determine the hourly output of each hydropower station. A forebay elevation check method is performed to obtain the hourly forebay elevation and correct the hourly output. The Beipan HWSHS in Guizhou Province, China, is selected as a case study, and the optimal operating rules are determined. The results also show that (1) the standard operating rules with hedging and packing increase peak-shaving performance by an average of 4.31% and 2.03% compared to the standard operating rules and linear operating rules, respectively; (2) the peak-shaving performance can be significantly increased (6.70%) with a slight decrease (0.37%) in the energy generation through changing the seasonal distribution of water and energy of the cascade hydropower stations; (3) the LRLS method, which makes the interday energy distribution more uniform, increases the peak-shaving performance by an average of 9.17% compared to the traditional load shedding method; (4) the energy generation and peak-shaving performance of the HWSHS are affected by the transmission capacity, and it is necessary to increase the transmission capacity by 25% to 35% of the installed capacity of wind and solar power stations. • A methodology is proposed to develop operating rules considering peak-shaving demands. • A multi-objective and multi-timescale operation model is developed. • The feasible and reasonable region of available energy-based operating rules is analyzed. • A multi-timescale simulation method is designed to simulate the operation of a HWSHS. • The methodology significantly improves the peak-shaving performance. [ABSTRACT FROM AUTHOR]

• Dam regulation disturbances influence distribution of planktonic organisms. • Ecological environment status of the upstream was better than middle and downstream. • The negative impact of human interference on the ecological health of the Shaying River is greater than the positive. In multi-dam river systems, human disturbances can significantly disrupt river connectivity, fragment habitats, and harm aquatic ecosystems. Aiming at the comprehensive assessment of the spatial distribution of water ecological health, as well as the investigation of the impacts of human activities on river health, Shaying River in China between 2011 and 2015 was taken as a case study. Data on water environment, ecology, and habitat quality were collected by field investigations and then investigated by correlation analysis and principal component analysis. The SMI-P method was adopted to estimate the water ecological health condition. It was found that oxygen-consuming organic pollutants and nutrient salts were predominantly concentrated in the midstream and downstream sections, leading to severe pollution and degraded aquatic biodiversity. All monitored river sections were classified as the sub-healthy state or worse, while the Huaidian section exhibited the poorest conditions, with 100% of ratings falling into medium and sub-morbid categories. It was concluded that dam regulation, tributary water quality, and seasonal drivers like fertilizer use and river flow discharge, were the primary factors affecting the spatial variability of river ecological health. Furthermore, this paper has proposed a well-suited framework for the assessment of the water ecological health of dam-controlled rivers. This framework can be widely applied to similar river systems, providing valuable insights for effective management and conservation efforts. [ABSTRACT FROM AUTHOR]

Northeast China, rich in natural resources and diverse biodiversity, boasts a unique habitat for threatened bird species due to its remote location and perennial cold climate. An analysis assessed the adaptability of these species using data on their geographic distribution and functional traits collected through database queries. The results revealed that threatened bird species share similar functional traits and a stronger phylogenetic signal (Blomberg mean K = 0.39) compared to common species. The Biomod2 model analyzed potentially suitable ranges and environmental drivers under current and future climate scenarios, showing a pattern of larger suitable areas in southern regions and smaller suitable areas in the north. The most critically threatened species faced greater geographical constraints (0.989), with mean annual temperature being a key influence. Altitude and water system distribution were also key factors impacting the distribution of other threatened bird species. Simulated projections under different climate scenarios (RCP 45 and 85) indicated varying degrees of expansion in the suitable range for these species. This research sheds light on the functional traits and distribution of threatened bird species in Northeast China, providing a scientific foundation for future conservation and management efforts. [ABSTRACT FROM AUTHOR]

The root distribution and water uptake of irrigated vines (Vitis vinifera L.) in arid oasis areas remain poorly understood, particularly in terms of the variations in water uptake resulting from plant type and growing period. In this study, excavation and soil coring were employed to investigate the root distribution of vines. Meanwhile, the water uptake dynamics of irrigated vines in an arid oasis area were developed using stable isotopes of hydrogen and oxygen in water bodies (δD and δ18O) and in crops and soil water, coupled with a direct inference approach and a linear mixed model (IsoSource). The soil layers were divided into nine layers via hierarchical cluster analysis. The results indicated that the vertical distributions of the total and fine roots of grapevines were mainly in the range of 40–160 cm, accounting for 93.1% (91.2%) and 92.5% (90.0%) of the total root (200 cm) distribution during May and October, respectively. In the horizontal direction, both the total root and fine root systems were mainly distributed within 0–100 cm from the trunk and contributed 81.2% and 79.8% of the total root distribution, respectively. Meanwhile, both the total root weight (length) density and fine root weight (length) density decreased gradually with increasing radial distance from the trunk in the 0–80 cm range. The main water uptake of vines was at 0–40 cm in June, 20–80 cm in July, and 40–100 cm in August. These findings suggest that the main depth of root water uptake increases during the whole growth stage for grapevines in arid oasis ecosystems. This information will help growers to improve irrigation efficiency and provide a data analysis of water conservation in an arid oasis area during water stress. [ABSTRACT FROM AUTHOR]

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Climate varies along geographic gradients, causing spatial variations in the effects of energy and water on species richness and the explanatory power of different climatic factors. Species of the Quercus genus are important tree species in China with high ecological and socioeconomic value. To detect whether the effects of energy and water on species richness change along climatic gradients, this study built geographically weighted regression models based on species richness and climatic data. Variation partition analysis and hierarchical partitioning analysis were used to further explore the main climatic factors shaping the richness distribution pattern of Quercus in China. The results showed that Quercus species were mainly distributed in mountainous areas of southwestern China. Both energy and water were associated with species richness, with global slopes of 0.17 and 0.14, respectively. The effects of energy and water on species richness gradually increased as energy and water in the environment decreased. The interaction between energy and water altered the effect of energy, and in arid regions, the effects of energy and water were relatively stronger. Moreover, energy explained more variation in species richness in both the entire study area (11.5%) and different climate regions (up to 19.4%). The min temperature of coldest month was the main climatic variable forming the richness distribution pattern of Quercus in China. In conclusion, cold and drought are the critical climatic factors limiting the species richness of Quercus, and climate warming will have a greater impact in arid regions. These findings are important for understanding the biogeographic characteristics of Quercus and conserving biodiversity in China. [ABSTRACT FROM AUTHOR]

The uneven spatial and temporal distribution of water resources has consistently been one of the most significant limiting factors for social development in many regions. Furthermore, with the intensification of climate change, this inequality is progressively widening, posing a critical challenge to the sustainable development of human societies. The construction of large-scale water projects has become one of the crucial means to address the contradictions between water supply and demand. Thus, evaluating the functional aspects of water source network structures and systematically planning the layout of engineering measures in a scientifically reasonable manner are pressing issues that require urgent attention in current research efforts. Addressing this, our study takes the Erhai Lake basin and the surrounding areas in southwest China as the study area and combines landscape ecology and network analysis theory methods to propose a water supply network analysis method that takes into account both structure and node characteristics. Based on this methodology, we analyze the connectivity characteristics of water supply networks in the Erhai region under current (2020) and future (2035) planning scenarios. The results show that there were 215 nodes and 216 links in the water supply network of the Erhai Lake basin in 2020; with the implementation of a series of water conservancy projects, the planned 2035 water supply network will increase by 122 nodes and 163 links, and the connectivity of the regional water network will be significantly improved. Also, we identify some key nodes in the network, and the results show that the water supply network in 2035 will have obvious decentralization characteristics compared with that in 2020. And, based on the network degradation analysis, we find that with the implementation of engineering measures, the resilience of the water supply network will be significantly strengthened by 2035, with stronger risk tolerance. This study extends the quantitative representation of water source network characteristics, which can provide a useful reference for water network structure planning and optimization. [ABSTRACT FROM AUTHOR]

The distribution focuses of water resources, socio-economic development and environmental maintenance are usually mismatched, leading a gap between regional resources and the environment, as well as the disharmony of development. Water resource spatial equilibrium (WRSE) is an important yardstick for guiding regional water resource planning and sustainable utilization. However, research on the spatiotemporal heterogeneity and driving factors of WRSE is extremely lacking, and few existing studies have considered drought and flood disasters as the important reflection of WRSE. Therefore, this paper proposes a systematic integrated model for WRSE including regional evaluation, spatiotemporal heterogeneity and geodetector analysis functions, and constructs the evaluation index system considering droughts and floods. First, the performance of WRSE is quantified using the general deprivation index (GDI) innovatively. Then, combined with the Moran's I , the spatial patterns and regional differences of WRSE are analyzed. Last, the geographical detector models are employed to perform driving analysis of WRSE. The effectiveness of the model is verified in China. Results show that (1) from 2009 to 2021, the national average of WRSEI exhibits a declining trend from 0.879 in 2009 to 0.789 in 2021. (2) The areas with high WRSEI values are mainly distributed in the western provinces, whereas the eastern region has a higher percentage of imbalanced provinces. (3) Water resources per capita, added value of tertiary industry, urbanization rate and GDP per capita are key driving factors of China' WRSE. The study provides a novel insight for WRSE improvement and is greatly helpful for developing differentiated management measures to optimize resource allocation. • A systematically integrated model for water resource spatial equilibrium (WRSE) was established. • First applying the general deprivation index method to analyze WRSE. • The evaluation index system was enriched by adding drought and flood factors. • Differentiated measures can improve the equity of water resources development and utilization process. [ABSTRACT FROM AUTHOR]

Considering the importance of soil moisture in hydrological processes, it is crucial to understand the water distribution and time stability of different aerial shrub soils. There are few studies on the soil moisture of aerial vegetation in the northeastern margin of the Tengger Desert. Based on long-term monitoring data from the aerial seeding area in the northeastern margin of the Tengger Desert, the distribution characteristics of soil moisture and the temporal stability of soil moisture were studied. From June to October 2022, the soil moisture monitoring instrument WatchDog was used to monitor the long-term soil moisture changes (0–200 cm) in the four aerial afforestation plots of Hedysarum scoparium, mixed forest land (Hedysarum scoparium dominant species), mixed forest land (Calligonum mongolicum dominant species), and Calligonum mongolicum. The Spearman rank correlation coefficient was used to study the temporal stability of soil moisture in the four plots. Rainfall data were collected through small weather stations. The results show that the average soil water storage of four kinds of aerial shrub land in the study area was the highest in August, and the average soil water storage of different forest lands was different. The soil water content of the surface layer (0–30 cm) fluctuated the most in different months. The variation in soil water content in the shallow layer (30–100 cm) was smaller than that in the surface layer. The fluctuation of soil water content in the middle layer (100–150 cm) and deep layer (150–200 cm) was relatively stable. There was no strong variability in soil moisture content, and the temporal variation coefficient of surface soil moisture was the highest (31.44–39.8%), which showed moderate variability. The temporal variation coefficient of soil moisture in the shallow, middle and deep layers of all kinds of plots was significantly reduced, and the soil moisture stability of different aerial shrub land was the same. Spearman rank correlation analysis showed that the spatial pattern of soil water content in the surface layer (0–30 cm) and deep layer (150–200 cm) was more stable over time, that is, the temporal stability of soil water content was higher, and the temporal stability of soil water content in the middle and shallow layers of different types of shrub land was different. The research results help us to understand the soil hydrological process in the aerial seeding afforestation area in the northeastern margin of Tengger Desert, rationally arrange soil moisture monitoring points, efficiently manage and utilize water resources in the aerial seeding area, and provide a theoretical basis for local vegetation restoration and the optimization of the ecological environment. [ABSTRACT FROM AUTHOR]

• A method was proposed by coupling the ERI and the CLUE-S model. • Three different scenarios designed to explore ERI of LUCC in 2027. • Spatiotemporal characteristics of ERI were predicted under different scenarios. The Jinghe County of the Ebinur Lake Basin was chosen as the study area. Based on Landsat TM / OLI images obtained in 2007 and 2017, this paper attempts to use CLUE-S model to predict LUCC under three different scenarios (Natural Development scenario, Farmland Protection scenario, Water Resources Protection scenarios) in 2027. Landscape indices and ecological risk index were calculated and spatially interpolated for the whole region, and the results of ecological risk could be divided into five different zones: extremely low, low, moderate, high and extremely high. They were carried out for assessing the spatial–temporal changes in ecological risk for each landscape pattern. The results show that: (1) Among the three scenarios designed in this paper, the spatial distribution of LUCC in the Water Resource Protection scenario has the most obvious changes, followed by the Farmland Protection scenario and the Natural Development scenario becomes the third. In the water resources protection scenario, the scale of the desert decreases, but the forest and grass part increases, which is conducive to ecological improvement. (2) the distribution area of high ecological risk areas was the largest of three different scenarios, especially the farmland protection scenario. The area of low-risk level is the largest under the water conservation scenario. The ecological risk of LUCC under the water resources protection scenario is lower, which is better for ecological environment. (3) Water bodies mainly concentrate upon low ecological risk degree, accounting for approximately 62.8%, 82.2%, and 73.1% of low ecological risk; Farmland mainly lies in the low-risk areas, accounting for 59.1%, 63.5% and 68.8% of the lower ecological risk levels; In 2027, the unused land and other land types are the main land types of the higher ecological risk areas under three different scenarios, whose proportions are 67.40%, 68.24% and 65.90%, respectively. [ABSTRACT FROM AUTHOR]

Water vapor plays a key role in the global hydrologic cycle and in climatic change. However, the distribution and variability of water vapor in the troposphere are not understood well—in particular, in China with the complex Tibetan Plateau and the influence of the Asian and Pacific monsoons. In this paper, continuous global positioning system (GPS) observations for 2004–07 in China are used to produce precipitable water vapor (PWV) measurements; these measurements constitute the first investigation of PWV distribution and variability over China. It has been found that the stronger water vapor values are in southeastern China and the lower water vapor values are in northwestern China. These distributions are mainly affected by the latitude, topographical features, the season, and the monsoon. Water vapor variations over China are mainly dominated by seasonal variations. The strong seasonal cycles are in summer with maximum water vapor and in winter with minimum water vapor. The PWV in southeastern China has an annual amplitude of about 15 mm, much larger than in northwestern China at about 4 mm, and meanwhile the time of peak water vapor content is one month earlier than in other regions, probably because of the known rainy season (mei-yu). In addition, significant diurnal variations of water vapor are found over all GPS stations, with a mean amplitude of about 0.7 mm, and the peak value occurs around noon or midnight, depending on geographic location and topographical features. The semidiurnal cycle is weaker, with a mean amplitude of about 0.3 mm, and the first peak PWV value appears around noon. [ABSTRACT FROM AUTHOR]

The characteristics and sources of the hydrochemical composition of natural water are mainly influenced and limited at the basin scale by what factors, this has become a focal issue of environmental change in the middle latitude areas and even globally. In this study, three large drainage systems (Junggar, Yili, and Erlqis) in the north of the Tianshan Mountains were selected to study the hydrochemistry of different river basins and understand the relevant causes and attributions of different water bodies in arid environments in the Central Asian Orogenic Belt (CAOB). Natural water samples from the three drainage systems and their hydrochemical data, combined with literature data of the north and south Tianshan Mountains and surrounding areas, were systematically collected and comprehensively compared with other higher, middle, and low latitude watersheds with different climate conditions. The results show that the total dissolved solid concentrations in the CAOB drainage systems are generally higher than those of rivers in Chinese monsoon and humid regions, and also higher than the world average level. The relative concentrations of different ions are similar to those of rivers in the monsoon region of eastern China and most rivers in the world dominated by carbonate weathering. The ionic compositions of surface water bodies from different sub-basins in the study area are distributed near the Ca apex in the piper diagram, while those of phreatic and confined groundwater samples tend to the Na apex. The compositional differences in the anions are not like those in the cations, rarely distinguishable for these different water types. In a sub-drainage basin scale from I to VIII sub-basins in the study area, major ion concentrations and distributions in these basins are evidently heterogeneous. Almost all the cation and anion concentrations span > 1 order of magnitude, especially sodium and chlorine; however, the calcium and alkalinity concentrations and distributions are relatively homogeneous for some basins in the Junggar and Yili drainage systems. The relative homogeneity between anions and the relative heterogeneity between cations can be recognized in the ion chemistry of natural water samples between different types, indicating that the composition and distribution of cations in water is more conducive than those of anions to identifying the differences and commonalities between different regions. Atmospheric precipitation plays a key role on the hydrogeochemical process in the north of the Tianshan Mountains, and the elevation differentiation of chemical weathering and ion concentrations are closely related to it. The positive correlation between total solute flux and runoff cannot be explained by the dilution effect, indicating that hydroclimatic factors such as runoff and aridity have a strong effect in limiting the hydrochemistry of natural water bodies in the study area. [ABSTRACT FROM AUTHOR]

To investigate the research hotspots and development trends of subsurface drip irrigation (SDI) over the past 20 years, this study analyzed relevant literature from the Web of Science Core Collection spanning from 2002 to 2022. The data were visualized using CiteSpace, showcasing the publication volume trends, countries, keywords, cited references, authors, and affiliated institutions. Based on 1079 articles, the annual publication volume showed an overall upward trend. The United States had the most extensive research coverage and highest publication volume, whereas China had the fastest growing publication rate in recent years. However, relatively little cooperation occurred among research teams and institutions. Over time, research topics became increasingly diverse, with water conservation and yield increases being the primary research objectives. In addition to improving irrigation and fertilizer use efficiency, SDI has also been applied in research on the safe utilization of unconventional water resources (wastewater and salt water) and the optimization of soil conditions. Among these, aerated irrigation technology—aimed at improving root growth in the rhizosphere—may become a new branch of SDI research. Currently, the main research focus in the field of SDI is the diffusion and distribution of water in the crop root zone, for which Hydrus model simulation is a particularly important method. [ABSTRACT FROM AUTHOR]

Surface water is extensively used for irrigation and industrial purposes in the Wei River Plain. However, the surface water shows different characteristics in the southern and northern zones of the Wei River Plain. This study aims to investigate the differences in surface water quality between the southern and northern zones of the Wei River Plain and their influencing factors. To ascertain the hydrochemistry and its governing factors, graphical methods, ion plots, and multivariate statistical analyses were employed. The quality of the irrigation water was assessed using various irrigation water quality indices. In addition, water foaming, corrosion, scaling, and incrustation risks were determined to evaluate water quality for industrial uses. The spatial distribution of water quality was done using GIS models. This research revealed that the concentrations of EC, TH, TDS, HCO3−, Na+, Mg2+, SO42− and Cl− on the north side of the plain were twice as high as those on the south side. On both sides of the Wei River Plain, water‒rock interactions, ion exchange, and considerable evaporation were observed. Gypsum, halite, calcite, and dolomite all dissolve to produce significant anions and cations in the water, according to ion correlation analysis. However, additional sources of contaminants led to higher concentrations in the surface water on the north side than on the south side. Surface water in the south of the Wei River Plain has superior quality to that in the north, according to the overall findings of irrigation water and industrial water quality assessments. The findings of this study will boost better water resource management policies for the plain. [ABSTRACT FROM AUTHOR]

Drought is a damaging and costly natural disaster that will become more serious in the context of global climate change in the future. Constructing a reliable drought risk assessment model and presenting its spatial pattern could be significant for agricultural production. However, agricultural drought risk mapping scientifically still needs more effort. Considering the whole process of drought occurrence, this study developed a comprehensive agricultural drought risk assessment model that involved all risk components (exposure, hazard, vulnerability and mitigation capacity) and their associated criteria using geospatial techniques and fuzzy logic. The comprehensive model was applied in Songnen Plain to justify its applicability. ROC and AUC techniques were applied to evaluate its efficiency, and the prediction rate was 88.6%. The similar spatial distribution of water resources further verified the model's reliability. The southwestern Songnen Plain is a very-high-risk (14.44%) region, determined by a high vulnerability, very high hazardousness and very low mitigation capacity, and is the region that should be paid the most attention to; the central part is a cross-risk region of high risk (24.68%) and moderate risk (27.28%) with a serious disturbance of human agricultural activities; the northeastern part is a dry grain production base with a relatively optimal agricultural production condition of very low risk (22.12%) and low risk (11.48%). Different drought mitigation strategies should be adopted in different regions due to different drought causes. The findings suggest that the proposed model is highly effective in mapping comprehensive drought risk for formulating strong drought mitigation strategies and could be used in other drought-prone areas. [ABSTRACT FROM AUTHOR]

The management of crop production in a sandy soil "culture" is difficult, mainly due to its low soil-water-holding capacity, organic matter and poor fertilizer efficiency. Options to increase soil water and nutrient retention for these soils include the addition of surface mulch covers, amendment with biochar and the use of layers of a mixture of charcoal and compost material. Our objective was to measure the distribution of water and nutrients for layers of control 1 (CK1), control 2 (CK2) and compost material of different thicknesses (0.02, 0.05 and 0.10 m) buried 0.01 m from the surface in a column (0.2 m radius, 0.5 m height) filled with sand. The experiment was conducted in a greenhouse located at the Agricultural Science Training Base of Ningxia University, China. There were three replicates per treatment and one soil column per replicate. The soil columns were watered with 2 L via a surface drip emitter and 45 days later, soil samples were obtained in 0.01 m increments across the diameter and depth of 0.4 m, with a total of 12 samples per column. In each sample, we measured soil water, pH, electrical conductivity, ammonium and nitrate nitrogen and available P and K. The results showed that the distribution of water content and nutrient contents were centered on the dripper and diffused to its surroundings. Notably, the horizontal diffusion distance was smaller than that of the vertical direction. In the vertical direction, compared with control 1, adding compost changed the spatial distribution of WC and nutrients and had a greater impact on available potassium (AK) than on inorganic nitrogen (IN) and available phosphorus (AP). Compared with control 1, the composting treatment decreased the content of water in the 0–10 cm surface soil, reduced the electrical conductivity (EC) and nitrate nitrogen (NO3-N), C5 and C10 increased the available potassium. Moreover, composting treatments increased the electrical conductivity, available phosphorus, available potassium and nitrate nitrogen of the 10–30 cm substrate by 61–384%, 10–240%, 11–45% and 133–929%, respectively, when compared with control 1.The nutrients increased as the thickness of the compost interlayer increased. A principal component analysis (PCA) of the C5 and C10 treatments significantly distinguished them from control 1. A linear regression fitting analysis showed that the inorganic nitrogen, available potassium and total nutrients positively correlated with the water content and electrical conductivity of the sand. The 5 cm and 10 cm composting interlayers had a high water content and ability to conserve fertilizer for sand culture, but C10 caused an excessive accumulation of nutrients. Thus, it was concluded that a composting interlayer that was less than 5 cm reduced the base fertilizer input by 24–84%. All these results suggest that applying a composting interlayer of 5 cm could retain more suitable root zone water and fertilizer for the next crop season and provide technological support to reduce fertilizer inputs. [ABSTRACT FROM AUTHOR]

The long-term characteristics of four hydrometeor species (cloud water, cloud ice, rain, and snow) in precipitating clouds over eastern China (divided into South China, Jianghuai, and North China) and their relationships with surface rainfall are first investigated using the fifth major global reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ERA5) hourly dataset from May to August during 1979–2020. The results show that the cloud water path decreases significantly from south to north as a result of the large-scale circulation and water vapor distribution, with the maximum value of 180 g m−2 in South China and only one-half of that value in North China. The slope in linear relationship between rainwater path and precipitation intensity is at the maximum (5.68 h−1) in South China, implying the highest conversion rate from rainwater to precipitation in this region. When the precipitation rate exceeds 15 mm h−1, the ice-phase hydrometeor contents in South China become the largest among the three regions, indicating that the cold-rain process is crucial to heavy rainfall. The moisture-related processes play a dominant role in the precipitation intensity. Although the contribution of hydrometeor advection to precipitation is generally between −5% and 5%, we found that it can jointly modulate the location of heavy rainfall. In addition, the peaks of cloud water path commonly appear 2–3 h ahead of precipitation, whereas the peaks of ice-phase particles occur 2 and 1 h behind the afternoon precipitation onset in South China and Jianghuai, respectively, which is mainly attributed to the different upward velocity and water vapor convergence in the mid–upper troposphere. Significance Statement: Reanalysis data and satellite retrievals have been widely used in investigating cloud water and cloud ice in nonprecipitating clouds. However, studies on long-term characteristics of precipitating hydrometeors in precipitating clouds, which are directly connected and crucial to surface rainfall, are still very limited to date because of limitations in observations of precipitating clouds. In this study, the latest ERA5 reanalysis hourly dataset is first used to quantitatively explore the climatological characteristics of four hydrometeors (cloud water, cloud ice, rain, and snow) in precipitating clouds as well as their relationships with precipitation intensity over eastern China from 1979 to 2020. The results advance our understanding of precipitation mechanisms from the perspective of hydrometeor climatology. [ABSTRACT FROM AUTHOR]

Yue, Y.L.; Qing, S.; Diao, R.X., and Hao, Y.L., 2020. Remote sensing of suspended particulate matter in optically complex estuarine and inland waters based on optical classification. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 303-317. Coconut Creek (Florida), ISSN 0749-0208. Accurate suspended particulate matter (SPM) concentration retrieval across complex estuarine to inland waters from ocean color remote sensing reflectance (Rrs(λ)) faces challenges. In this paper, an optical classification-based SPM retrieval algorithm in optically complex estuarine and inland waters was proposed and tested in the Yellow River Estuary and Daihai Lake, China. Firstly, the in situ measured Rrs(λ) (n = 204) were classified into two optical water types with the method defined by Matsushita et al. (2015). Secondly, we designed several mathematical models and selected the optimal algorithm according to the goodness of fit. Optimal algorithms were developed for each water type to achieve accurate SPM retrieval. Through the construction of the optimal retrieval algorithm in each water type, the uncertainty of SPM retrievals has been reduced from 95 % to about 39 % compared with the algorithm without optical classification. The retrieval algorithm based on optical water classification was further applied to the Sentinel-2 MSI L2A data over the study area and produced reliable SPM maps. Independent validation with the in situ-satellite match-ups further demonstrates the algorithm's validity (uncertainty of about 47 %). In contrast, applications of other SPM retrieval algorithms resulted in less reliable SPM results with either unsatisfactory retrieval accuracy in class1 (the lowest value of r can reach 0.02). The optical classification, together with the optimal retrieval algorithm for each optical type, is proved to be a feasible way for SPM retrieval in high accuracy over optically complex waters. [ABSTRACT FROM AUTHOR]

In this paper, an inexact two-stage stochastic programming model was developed for supporting regional water resource allocation management under uncertainties. The proposed model is an integrated framework of interval parameter programming and two-stage stochastic programming, which can tackle uncertain parameters expressed as interval values with probability distribution information. The proposed model was successfully applied to a typical heavy industrial city suffering water shortage in the east of China, Tianjin. The uncertainties of future water demand were taken into account through generating a set of representative scenarios. The results indicated that different scenarios would affect the water distribution patterns, water shortages, total benefits and system cost. The results revealed that the transferred water from Luan River and Changjiang River would still be the main water resource for each water user. Besides, nearly all water demand in planning horizon would be guaranteed through the reasonable dispatch except under high demand level scenario, in which a small proportion of water requirement in agricultural, municipal and environmental sectors would not be satisfied. The developed method could be used by environmental managers to identify the optimal water supply plan from multiple sources to different end-user sectors under system uncertainties. [ABSTRACT FROM AUTHOR]

In this paper, a stochastic multi-objective chance-constrained programming model (SMOCCP) was developed for tackling the water supply management problem. Two objectives were included in this model, which are the minimization of leakage loss amounts and total system cost, respectively. The traditional SCCP model required the random variables to be expressed in the normal distributions, although their statistical characteristics were suitably reflected by other forms. The SMOCCP model allows the random variables to be expressed in log-normal distributions, rather than general normal form. Possible solution deviation caused by irrational parameter assumption was avoided and the feasibility and accuracy of generated solutions were ensured. The water supply system in the Xiaoqing River watershed was used as a study case for demonstration. Under the context of various weight combinations and probabilistic levels, many types of solutions are obtained, which are expressed as a series of transferred amounts from water sources to treated plants, from treated plants to reservoirs, as well as from reservoirs to tributaries. It is concluded that the SMOCCP model could reflect the sketch of the studied region and generate desired water supply schemes under complex uncertainties. The successful application of the proposed model is expected to be a good example for water resource management in other watersheds. [ABSTRACT FROM AUTHOR]

Energy, water and carbon are inextricably linked. The limited endowments, uneven temporal and spatial distribution of energy and water resources pose great challenges to China’s sustainable development. In this paper, a bottom-up model (China TIMES model) is developed to integrate China’s energy system with water resources, to project water demand in power sector and to assess the impacts of China’s Intended Nationally Determined Contributions (INDC) and water constraints on power generation portfolio out to the year 2050. The modelling results show that: (1) under reference scenario, electricity generation will increase from 4518 TW h in 2010 to 13,270 TW h in 2050, with CO 2 emission from 3.1 Gt to 6.1 Gt and water withdrawal from 59 Gm 3 to 104 Gm 3 ; (2) CO 2 mitigation target can help reduce water withdrawal in power sector by promoting the expansion of renewable technologies; (3) by affecting the cooling mixture, water cost has significant impact on water withdrawal in power sector; (4) when both CO 2 and water constraints are considered, renewable technologies will be more prevalent. [ABSTRACT FROM AUTHOR]

The Yellow River has long been known for having low water and abundant sediment. The amount of sediment transported in the upper and middle reaches of the Yellow River (UMRYR) has changed significantly in recent years, resulting in an obvious imbalance in the spatiotemporal distribution of the water resources in the Yellow River Basin (YRB). The changes in the sediment transport in the Yellow River significantly affect ecological security and socioeconomic development in the YRB. In this study, the Google Earth Engine (GEE) platform was used to obtain the potential driving factors influencing the five main gauge stations in the UMRYR: vegetation, soil moisture, population, precipitation, land types, etc. The data on the annual sediment transport (AST) were from the River Sediment Bulletin of China (2001~2020). Linear regression and the Mann–Kendall test were used to study the temporal variation in the AST. The first-order difference was determined from the original data to remove the autocorrelation, and it met the requirement of sample independence. The factors without collinearity were used for the driving force analysis using linear regression (linear model) and random forest regression (nonlinear model). We used the selected driving factors to establish the linear regression, the random forest model for predicting the AST, and cross-validation for verifying the prediction accuracy. Furthermore, the prediction outcomes were compared with the simplest ARIMA time-series model (control model). Our findings showed that the changing trend and the mutation of the AST were different in the UMRYR during the past 20 years. However, after the first-order difference of the AST, the amount of interannual variation in the annual sediment transport (ΔAST) was almost unchanged in the UMRYR. The five driving factors were chosen to establish the prediction models of linear regression and random forest regression, respectively. Compared with the control model, ARIMA, the prediction accuracy of the random forest model was the highest. [ABSTRACT FROM AUTHOR]

Clarifying the interrelationship between climate and land use/land cover (LULC) changes on water yield in mountainous areas is very urgent due to the dramatic decrease in the water availability of mountainous areas. In this study, the InVEST model was used to calculate the water yield of the mountainous area in Beijing–Tianjin–Hebei region (BTH) from 1980 to 2020, and six scenarios were designed to identify the contribution rates of climate and LULC change on the water yield. The results showed that, in 1980–2020, the water yield in the mountainous area of BTH was the largest in 1990, at 377.95 mm and the smallest in 1980, at 150.49 mm. After 2000, the interannual water yield showed a slightly increasing trend, which was significantly lower than the water yield in 1990, the values ranging from 217.01 mm to 324.65 mm. During the study period, the spatial distribution of the water yield was similar over the years, with high values in the south-central Taihang Mountain (THM) and the northeastern Yanshan Mountain (YSM). The THM was the main water yield area of the mountainous area in BTH. The annual water yield of farmland was the highest, followed by forest land and grassland, while the proportion of volumetric water yield was the largest in forest land with an increasing trend from 1980 to 2020 and the grassland showed a decreasing trend, while that of farmland increased first from 1980 to 2000 and decreased from 2000 to 2020. Climate is the key factor controlling the water yield of the mountainous area in BTH from 1980–2000, 2000 to 2020, and 1980 to 2020. In the period of 2000–2020, the effect of LULC on the water yield is negative, while the effect is positive in 1980–2000 and 1980–2020. The contribution rate of climate to the water yield increases in the THM, Bashang region (BSR) and YSM from the period 1980–2000 to 2000–2020, while that of LULC in those three regions changes from a positive impact in 1980–2000 to a negative impact in 2000–2020, and the contribution rate is also greatly reduced. In the long term, land revegetation will gradually benefit the water yield in the mountainous areas of BTH, including the THM, BSR, and YSM. These results can provide an important scientific and technological reference for the ecological management and protection of water source sites, as well as the planning and utilization of water resources in mountainous areas of BTH. [ABSTRACT FROM AUTHOR]

Water scarcity has become a global severe challenge over the past few decades. Quantifying the impact of climate variability and land use on water resource availability is crucial for integrated water resource management. Many studies have focused on blue water but ignored green water which is important in the terrestrial ecosystem, especially on different temporal scales. In this study, we selected the Shanmei Reservoir, the most import drinking water resource for a rapidly development city of Southeast China, as a case for analysis of these impacts for the entire basin. We adopted the Soil and Water Assessment Tool (SWAT) to investigate the spatial and temporal distributions of blue water (BW), green water flow (GWF) and green water storage (GWS) in the Shanmei Reservoir Basin (SRB). The results of the blue and green water components (BW and GW) revealed that SRB is dominated by BW, accounting for 52.6% of the total water resources, while GW accounted for 47.4%. There was an insignificant upward trend of BW and a significant upward trend of GWF, with a tendency rate of 1.125 mm a−1. Precipitation was the key factor affecting BW on annual and monthly scales. The GWF was more sensitive to temperature at both the annual and monthly scales. The GWS was significantly correlated with precipitation at the monthly scale, while insignificant correlation occurred at the annual scale. The spatial distribution of BW was largely dominated by precipitation, and land-use types led to the differentiation of GW. It indicates that the BW of paddy fields is greater than that of forests, while the GWS of forests is greater than that of orchards and rainfed croplands. [ABSTRACT FROM AUTHOR]

Silty soil is common in the seabed of eastern coastal areas of China. The behaviors of the silty soil and a bucket foundation installed within it need more study. In this work, model tests of a bucket foundation in silty soil were performed. The development of the excess pore water pressures in the different positions around the bucket was measured. Different loading conditions, with a change in the horizontal cyclic load amplitude ratio, horizontal cyclic frequency, and vertical load ratio, were considered. The effects of the pore water pressure on the shear strength of the soil around the bucket and the horizontal bearing capacity of the bucket foundation were investigated. The results show that the normalized pore water pressures close to the bucket wall at depths between 0.1 L and 0.3 L exhibit distinct change under the cyclic load. Consistent with the distribution of the pore water pressure, the degradation of the undrained shear strength is more obvious with a greater load amplitude ratio, a greater load frequency, and a smaller vertical load. The degradation rate of the static horizontal ultimate bearing capacity is in a range of 1.57% to 14.90%, under different loading conditions. [ABSTRACT FROM AUTHOR]

Water cycles exist in all processes of water resources utilization, including water-saving irrigation. Due to the complex water cycle process of irrigation, the ecological effects and safety of large-scale water-saving irrigation have received increasing attention. This paper analyzed both the positive and negative ecological effects of water-saving irrigation and the scale effects from the plant-scale to the watershed-scale. Based on the Vensim and GMS (Groundwater Modeling System) models, a quantitative evaluation method of ecological safety of large-scale water-saving irrigation was proposed. The case study in Changma Irrigation District in the arid inland river basin of Northwest China showed that the ecological safety of large-scale water-saving irrigation was sensitive to the combination of water source condition, water distribution technology and water-saving irrigation technology in field. In terms of the positive effects, large-scale water-saving irrigation can reduce the percolation loss of irrigation water, increase the environment water flow for the downstream, and slow down the salinity accumulation. As for the negative effects, large-scale water-saving irrigation could reduce the groundwater recharge, decrease the environment water supply in local farmland, and cut down the soil salinity leakage. The research results have positive significance for guiding the sustainable development of water-saving irrigation and conservation of ecosystem in an arid inland river basin. [ABSTRACT FROM AUTHOR]