Spatio-temporal variability of terrestrial water storage in the Yangtze River Basin: Response to climate changes

The Yangtze River Basin(YRB)is an important region for China's economic development.However,it has a complex terrain layout,most of which is affected by monsoon weather,and the geographical and temporal distribution of water resources is severely unbalanced.Therefore,the detailed analysis of spatio-temporal water mass changes is helpful to the development and rational utilization of water resources in the YRB.In this study,the variation of terrestrial water storage(TWS)is monitored by Gravity Recovery and Climate Experiment(GRACE)satellite gravity.We find that the University of Texas Center for Space Research(CSR)solution shows a notable difference with the Jet Propulsion Laboratory(JPL)in space,but the general trend is consistent in time series.Then the GRACE inferred water mass variation reveals that the YRB has experienced several drought and flood events over the past two decades.Global Land Data Assimilation System(GLDAS)results are similar to GRACE.Furthermore,the overall precipitation trend tends to be stable in space,but it is greatly influenced by the strong El Nino-~Southern Oscillation(ENSO),which is the response to global climate change.The upper YRB is less affected by ENSO and shows a more stable water storage signal with respect to the lower YRB.

The Relationship between Water Resources Use Efficiency and Scientific and Technological Innovation Level: Case Study of Yangtze River Basin in China

The Yangtze River Basin’s water resource utilization efficiency(WUE)and scientific and technological innovation level(STI)are closely connected,and the comprehension of these relationships will help to improve WUE and promote local economic growth and conservation of water.This study uses 19 provinces and regions along the Yangtze River’s mainstream from 2009 to 2019 as its research objects and uses a Vector Auto Regression(VAR)model to quantitatively evaluate the spatiotemporal evolution of the coupling coordination degree(CCD)between the two subsystems of WUE and STI.The findings show that:(1)Both the WUE and STI in the Yangtze River Basin showed an upward trend during the study period,but the STI effectively lagged behind the WUE;(2)The CCD of the two subsystems generally showed an upward trend,and the CCD of each province was improved to varying degrees,but the majority of regions did not develop a high-quality coordination stage;(3)The CCD of the two systems displayed apparent positive spatial autocorrelation in the spatial correlation pattern,and there were only two types:high-high(H-H)urbanization areas and low-low(L-L)urbanization areas;(4)The STI showed no obvious response to the impact of the WUE,while the WUE responded greatly to the STI,and both of them were highly dependent on themselves.Optimizing their interaction mechanisms should be the primary focus of high-quality development in the basin of the Yangtze River in the future.These results give the government an empirical basis to enhance the WUE and promote regional sustainable development.

Variations of Terrestrial Water Storage in the Yangtze River Basin under Climate Change Scenarios

In this study, the water balance-based Precipitation-Evapotranspiration-Runoff (PER) method combined with the land surface model Variable Infiltration Capacity (VIC) was used to estimate the spatiotemporal variations of terrestrial water storage (TWS) for two periods, 1982-2005 (baseline) and 2071-2100, under future climate scenarios A2 and B2 in the Yangtze River basin. The results show that the estimated TWS during the baseline period and under the two future climate scenarios have similar seasonal amplitudes of 60-70 mm. The higher values of TWS appear in June during the baseline period and under the B2 scenario, whereas the TWS under A2 shows two peaks in response to the related precipitation pattern. It also shows that the TWS is recharged from February to June during the baseline period, but it is replenished from March to June under the A2 and B2 scenarios. An analysis of the standard derivation of seasonal and interannual TWS time series under the three scenarios demonstrates that the seasonal TWS of the southeastern part of the Yangtze River basin varies remarkably and that the southeastern and central parts of the basin have higher variations in interannual TWS. With respect to the first mode of the Empirical Orthogonal Function (EOF), the inverse-phase change in seasonal TWS mainly appears across the Guizhou-Sichuan-Shaanxi belt, and the entire basin generally represents a synchronous change in interannual TWS. As a whole, the TWS under A2 presents a larger seasonal variation whereas that under B2 displays a greater interannual variation. These results imply that climate change could trigger severe disasters in the southeastern and central parts of the basin.

Runoff variations in the Yangtze River Basin and sub-basins based on GRACE, hydrological models, and in-situ data

Water budget closure is a method used to study the balance of basin water storage and the dynamics of relevant hydrological components(e.g.,precipitation,evapotranspiration,and runoff).When water budget closure is connected with terrestrial water storage change(TWSC)estimated from Gravity Recovery and Climate Experiment(GRACE)data,variations in basin runoff can be understood comprehensively.In this study,total runoff variations in the Yangtze River Basin(YRB)and its sub-basins are examined in detail based on the water budget closure equation.We compare and combine mainstream precipitation and evapotranspiration models to determine the best estimate of precipitation minus evapotranspiration.In addition,we consider human water consumption,which has been neglected in earlier studies,and discuss its impact.To evaluate the effectiveness and accuracy of the combined hydrological models in estimating subsurface runoff,we collect discharge variations derived from in situ observations in the YRB and its sub-basins and compare these data with the models’final estimated runoff variations.The estimated runoff variations suggest that runoff over the YRB has been increasing,especially in the lower sub-basins and in the post-monsoon season,and is accompanied by apparent terrestrial water loss.

Maintaining healthy rivers and lakes through water diversion from Yangtze River to Taihu Lake in Taihu Basin

On the basis of the Taihu water resources assessment, an analysis of the importance and rationality of the water diversion from the Yangtz,e River to Taihu Lake in solving the water problem and establishing a harmonious eco-environment in the Taihu Basin is performed. The water quantity and water quality conjunctive dispatching ＇decisi＂ofi-makifig support system, which ensures flood control, water supply and eco-aimed dispatching, is built by combining the water diversion with flood control dispatching and strengthening water resources monitoring and forecasting. With the practice and effect assessment, measures such as setting the -integrated basin management format, further developing water diversion and improving the hydraulic engineering projects system and water monitoring system are proposed in order to maintain healthy rivers and guarantee the development of the economy and society in the Taihu Basin.

Engineering Strategies on Flood Control in Middle Reach of Yangtze River, China

Flood disaster has been a serious hidden danger since the ancient time. The essential cause for the fact that floods have not been eliminated for hundreds of years is that time honored strategies do not suit the cases of flood prevention. In the view of geological environmental analyses of flood formation and from the synthesis of experiences gained in flood control in the past hundreds of years, sluggish draining of flood, silt sedimentation in channel and building levee blindly constitute the main cause of intractable flood for a long time in the middle reach of the Yangtze River. Draining away silt and water is the only way to stamping out flood disaster. Opening up artificial waterways for flood diversion, draining away the silt of channel into the polders, and storing the flood water are important engineering measures for the flood control and damage reduction.

A holistic approach to creating a new yangtze river basin protection legislation

The protection of the Yangtze River Basin is a top priority in China,and the National People's Congress(NPC)Standing Committee has started to draft a new protection legislation specifically for the Yangtze River Basin.The Basin forms the epicenter of environmental,social,and economic life.Any efforts to protect the Basin must accommodate several competing interests from a multiplicity of interested parties and stakeholders such as local governments,villages,and business enterprises.Current relevant institutions and organizations are unable to sufficiently ensure environmental protection and green development in the Basin.The NPC Standing Committee must thus adopt a more holistic approach when creating new protection legislations aimed at the Yangtze River Basin.

Extreme characteristics and causes of the drought event in the whole Yangtze River Basin in the midsummer of 2022

Due to their huge socio-economic impacts and complex formation causes,extreme and continuous drought events have become the focus and nodus of research in recent years.In the midsummer(July-August)of 2022,a severe drought event occurred in the whole Yangtze River Basin(YRB),China.During that period,the precipitation in the upper,middle and lower reaches of the YRB dropped over 40%less than the 1961-2021 climatic mean,which had never happened previously.Furthermore,the temperature was the highest during 1961-2022.The record-breaking magnitude of less rainfall and high temperature directly led to the continuous development of this extreme drought event.An atmospheric moisture budget analysis revealed that the YRB midsummer rainfall anomaly was dominated by the anomalous powerful vertical moisture advection,which was derived from the strongest descending motion over the whole YRB in the 2022 midsummer during 1981-2022.The western Pacific subtropical high(WPSH)during the midsummer remained stronger,more westward and lasted longer than the climatic mean.As a result,the whole YRB was controlled by a positive geopotential height centre.Further evidence revealed that the anomalous subtropical zonal flow played a crucial role in inducing the extreme descent over the YRB.Moreover,the anomalous upper-tropospheric easterly flow over the YRB in 2022 is the strongest during 1981-2022,modulating the generation of the unprecedented descent anomaly over the YRB.The likelihood that an integrated connection of severe drought in East Asia and flood in West Asia and northwestern South Asia would increase when the extremely strong easterly anomalies in the upper troposphere emerged and induced descending adiabatic flow on the eastern sides of the Tibetan Plateau.The results of this study can provide scientific insights into the predictability of extreme drought events and provide ways to improve predictions.

Seasonal water storage change of the Yangtze River basin detected by GRACE

US-Germany co-sponsered satellite gravimetry mission GRACE (Gravity Recovery And Climate Experiment), launched in March 2002, has been producing monthly time series of Earth gravity models up to degree and order of 120. The GRACE mission consists of two identical satellites flying on an almost polar orbit with an altitude of about 300-500 km and satelite-to-satellite ranging of about 220 km. Thanks to the payloads of space-borne GPS receivers, accelerometers and high-precision K-band satelite-to-satellite ranging mesurements, GRACE gravity models are expected to achieve more than one order of magnitude of improvement over previous models at spatial scales of a few hundred kilometers or larger. Recovery of surface mass re-distribution based on GRACE’s time-varying gravity models is applied to studies in solid Earth geophysics, oceanography, climatology and geodesy. At secular time scales, GRACE is expected to provide valuable information on global ice changes, whose variations have profound influences on global climate, and in particular, on sea level changes. At seasonal time scales, GRACE is expected to reveal surface water changes with an ac- curacy of less than 1 cm, or ocean bottom pressure changes with an accuracy of less than 1 mbar (1 mbar =102 Pa). These surface mass redistribution measurements would impove our understanding of the global and regional mass and energy cycles that are critical to human life. Using 15 GRACE monthly gravity models covering the period from April 2002 to December 2003, this study compares seasonal water storage changes recovered from GRACE data and hydrology models at global and regional scales, with particular focus on the Yangtze River basin of China. Annual amplitude of 3.4 cm of equivalent water height change is found for the Yangtze River basin with maximum in Spring and Autumn, agreeing with two state-of-the-art hydrology models. The differences between GRACE re- sults and model predictions are less than 1-2 cm. We conclude that satellite gravimetry has huge potentials in monitering water storage changes in large river basins such as Yangtze.

Water storage variations of the Yangtze,Yellow,and Zhujiang river basins derived from the DEOS Mass Transport (DMT-1) model

In general,China is short of water resources and some regions even experience a shortage of daily water supply.This could threaten the stability and economic development of the nation.A study on the water storage variations is especially important for the water management and storage prediction in three largest river basins of China,namely,Yangtze,Yellow,and Zhujiang,where the most dense population and leading economic regions are located.The satellite gravity mission GRACE(Gravity Recovery and Climate Experiment) provides an opportunity to macroscopically identify water(or mass) variations in the Earth's system with a spatial resolution of 300-400 km and a temporal resolution of about one month.We use the first release of the DEOS(Delft Institute of Earth Observation and Space Systems) Mass Transport(DMT-1) model based on GRACE data to analyze water storage changes in the three river basins.The DMT-1 model consists of monthly solutions,which are computed using an innovative methodology.The methodology includes,in particular,the application of a statistically optimal Wiener-type filter based on full variance-covariance matrices of noise and signal.This results in particularly sharp mass variation maps.Taking one monthly solution as an example,we compare the results derived from the DMT-1 model with ones produced with the standard post-processing scheme based on a combination of the de-striping and Gaussian filtering.The comparison shows that the DMT-1 model outperforms the other models and is suitable for the analysis of the mass changes in river basins.A subset of the DMT-1 solutions in the interval between February 2003 and May 2008 is used to estimate the secular trends and seasonal variations for the three river basins.The estimated trends show that the water storage of the Yellow River basin does not have significant changes,while the Zhujiang and Yangtze river basins have a large and statistically significant water storage increase.The estimation of seasonal variations demonstrates that the water storage variations in Yangtze and Zhujiang river basins are almost in the same phase.The amplitude of variations in the Zhujiang River basin is larger than that in Yangtze.No clear annual variations are observed in the Yellow River basin.The observed water storage variations generally coincide with the observations and conclusions presented in the hydrological reports of the Chinese Ministry of Water Resources.

长江水资源调配推演器构建与推演分析

长江水资源调配推演器(CJGWAS)由中国长江三峡集团有限公司、中国水利水电科学研究院联合研发,实现长江流域水库工程“点”、河流及调水工程“线”、地市单元“面”、流域综合“体”的“点—线—面—体”一体化水资源科学模拟与开发利用分析。推演器融合水文模型、配置模型、水库调配模型、需水预测等算法,可对长江流域历史、现状进行复盘,并对未来状况进行推演。研究成果可为长江流域水网规划、重大引调水工程评估、断面生态流量及发电冲击预判等提供支撑。

新时期长江流域水资源保护规划及管理工作的思考

组织编制并实施水资源保护规划是国家赋予水行政主管部门的法定职责,也是水利部门履行水资源管理和生态环境保护责任的重要工作。长江流域水资源保护规划经历了从起步、探索、实践与发展到形成完善体系的过程,推进了流域水资源保护与管理科学有序发展。随着国家机构改革部门职能调整和《中华人民共和国长江保护法》出台,为更好地推进和落实新时期长江流域水资源保护规划和管理工作,系统梳理长江流域水资源保护规划发展历程与成效,分析当前流域水资源保护面临的形势与挑战,厘清流域水资源保护工作定位和思路,并据此提出新时期流域水资源保护规划及管理的工作建议,对凝聚流域水资源保护规划共识、建立流域水资源保护规划体系、推进水资源保护高质量发展、助力实现治江现代化具有重要的指导意义。

长江流域建立水资源刚性约束制度的关键问题与对策研究

南方丰水地区建立水资源刚性约束制度,是为了更好地促进生态环境高水平保护和经济社会高质量发展。基于长江流域水资源开发利用、管理现状及特点,分析了长江流域建立水资源刚性约束制度需重点研究的关键问题,并从水资源和水环境承载能力、用水定额标准、计量监测、水资源规划论证、监管考核和市场机制等方面,提出长江流域建立水资源刚性约束制度的对策建议。

Spatio-temporal variation of net anthropogenic nitrogen inputs in the upper Yangtze River basin from 1990 to 2012

The net anthropogenic nitrogen input(NANI) is an important nutrient source that causes eutrophication in water bodies. Understanding the spatio-temporal variation of NANI is important for regional environment assessment and management.This paper calculated NANI in the upper Yangtze River basin(YRB), upstream of the Three Gorges Dam(TGD), from1990 to 2012, and analyzed its spatio-temporal characteristics. Over the past 23 years of the study, the average annual NANI increased from 3200 kg N km^(-2) to 4931 kg N km^(-2). The major components were fertilizer N application, atmospheric N deposition,and net food and feed N import. In the northwest high mountainous region with a sparse population, the main component was atmospheric N deposition. Fertilizer N application and net food and feed N import were concentrated in the Chengdu Plain because of the high population density and large areas of farmland. This research found that NANI increased with rapid urbanization and increasing population. The Pearson correlation results illustrated that the spatial distributions of NANI and its major components were affected by land cover/use, agricultural GDP and total population. Increasing NANI has been the major cause of the degrading stream water quality over the past 20 years and is becoming a major threat to the water quality of the TGD reservoir.

Comparative study of carbonic anhydrase activity in waters among different geological eco-environments of Yangtze River basin and its ecological significance

This study provides the presence of carbonic anhydrase（CA） activity in waters of the Yangtze River basin, China, as well as the correlation of CA activity with HCO-3 concentration and CO2 sink flux. Different degrees of CA activity could be detected in almost all of the water samples from different geological eco-environments in all four seasons. The CA activity of water samples from karst areas was significantly higher than from non-karst areas（PP3-concentration（r = 0.672, P2 sink flux（r = 0.602, P = 0.076） in karst areas. This suggests that CA in waters might have a promoting effect on carbon sinks for atmospheric CO2 in karst river basins. In conditions of similar geological type, higher CA activity was generally detected in water samples taken from areas that exhibited better eco-environments, implying that the CA activity index of waters could be used as an indicator for monitoring ecological environments and protection of river basins. These findings suggest that the role of CA in waters in the karst carbon sink potential of river basins is worthy of further in-depth studies.

长江流域水源涵养服务价值及其空间转移评估

水源涵养服务价值在不同区域之间的转移是流域上下游之间进行横向生态补偿需要考虑的关键内容。然而,水源涵养服务价值的转移依赖于流域的水文循环路径和河流的水量输送。现有的生态系统服务价值转移量评估方法缺乏对水源涵养服务转移中水文特征的描述,评估结果的合理性有待加强。针对此问题,从转移方向和转移路径2个方面改进断裂点-场强模型,通过引入河流方向系数判断流域上下游以及干支流地区之间的水力联系,在水源涵养服务转移评估中考虑河流的水文特征,并在长江流域应用,提高评估结果的合理性与可用性。结果表明,2020年长江流域水源涵养量为11 538.45亿m3,水源涵养服务的价值量为11 953.83亿元。相比现有模型的评估结果,研究改进的断裂点-场强模型突出了水源涵养服务价值从流域上游向下游转移的特征、增加了转移强度和范围。长江流域水源涵养服务价值的转出量由大到小依次为:四川>江西>湖南>贵州>湖北>安徽>重庆>云南>浙江>青海>陕西>广西>西藏>河南;各省份水源涵养服务价值的转入量由大到小依次为:云南>安徽>湖北>重庆>江苏>湖南>四川>上海>西藏。

长江流域发展水利新质生产力路径探析

结合新阶段长江治理保护的基本特征和面临的挑战,分析新阶段流域高水平保护、高水平安全和高质量发展对科技创新的迫切需求,探讨推动发展水利新质生产力的重要任务,提出通过科技创新催生生态水利、智慧流域、绿色经济带、美丽长江建设等新产业的可行路径。

长江流域重要饮用水水源地保护长效机制

指导重要饮用水水源地保护是《中华人民共和国水法》《中华人民共和国长江保护法》和“三定”规定赋予水行政主管部门的法定职责,也是维系流域供水安全保障的底线。通过对长江流域重要饮用水水源地保护管理现状的回顾分析,针对保护管理中存在的水源地名录准入退出机制不健全、安全评估制度不完善、资金投入保障机制不足等问题,提出了完善水源地安全保障规划体系、规范水源地名录管理机制、强化水源地安全评估和保护、严格水源地保护考核等长效机制构建思路和后续工作建议。研究成果对于落实《中华人民共和国水法》《中华人民共和国长江保护法》饮用水水源地保护要求、贯彻长江经济带绿色发展和长江大保护建设的要求、推动长江流域重要饮用水水源地保护长效机制建设具有重要意义。

长江流域冬油菜需水量及水分盈亏特征分析

基于长江流域冬油菜优势产区11个省、2个直辖市共计129个城市近20年的逐日气象数据,采用经验公式、FAO推荐的改进HS数据模型和作物系数分别计算各城市冬油菜全生育期及各生育阶段有效降水量及需水量,并对水分盈亏指数及多年旱涝灾害发生频率进行分析。结果表明,长江流域冬油菜在各生育阶段有效降水量均呈由东南向西北递减的带状分布特征,其中鄱阳、洞庭两湖平原及杭嘉湖平原有效降水量充沛,长江中下游干流南北沿岸地区有效降水量适中,秦岭—淮河一线、四川盆地及云贵高原有效降水量偏少;各生育阶段的需水量呈现西南高、东南中、西北低的分布特征,其中云南省需水量最高,长江中下游平原需水量适中,秦岭—淮河一线、四川盆地、贵州省需水量最低;多年水分盈亏空间分布特征表现为长江中下游干流南北沿岸地区水分供应适中,秦岭—淮河一线、四川盆地、云贵高原水分供应不足;水分盈亏年代演变特征表现为苗期长江上游旱灾多发、涝灾偶发,中下游涝灾多发、旱灾偶发,其他生育阶段长江上游旱灾频发,中下游旱灾多发、涝灾偶发的特征。为有效保障长江流域冬油菜各生育阶段的适当水分供应,在苗期阶段,长江上游地区应注意适量灌溉、中下游地区应注意及时排涝;其他生育阶段,长江上游地区应注意充分灌溉,中下游干流北岸城市应注意适时灌溉,中下游干流南岸城市应注意适时排涝,以促进长江流域冬油菜高产稳产,保障国内油菜籽原料稳定供应。

流域水网环境异质性及驱动力分析

【目的】水网结构和类型的产生与多种环境因素相关,对流域水网的环境异质性及驱动力方面的分析,是调整水系结构、合理恢复和保护水网的重要基础工作。【方法】以长江流域、黄河流域、淮河流域和海河流域为研究对象,基于典型水网类型,系统分析对比四大流域的环境异质性。进一步采用Pearson相关性分析、冗余分析、地理探测器分析方法,定量梳理各因子对于水网结构和类型的解释度。【结果】结果表明:网状和混合状水网流域内,坡度为0.0°~5.0°的比例大于55.05%,地形起伏度为0~70 m的比例大于67.98%,土地利用类型多为耕地和人造地表。矩形状、平行状、树枝状和扇状水网流域内,坡度为5.0°~35.0°的比例大于62.42%,地形起伏度为70~500 m的比例大于49.63%,土地利用类型多为耕地、林地和草地。土壤侵蚀强度、降水量、湿润指数、气温和水利设施数量也在不同水网类型中表现出异质性。气候因子与河流弯曲度显著正相关,地形因子、开发程度与水网的密度和流向最大频率均显著负相关。所选因子对四大流域水网结构特征的总解释率达53.47%。【结论】水网结构和类型受到多种因素的综合影响。坡度和湿润指数对水网结构有较大影响,解释率分别为21.40%和16.50%。降水量对水网类型的解释度最高,为16.61%。开发程度和气候因子的交互作用对水网类型的形成有重要影响,解释度接近50%。