Risk assessment of water security in Haihe River Basin during drought periods based on D-S evidence theory

The weights of the drought risk index （DRI）, which linearly combines the reliability, resiliency, and vulnerability, are difficult to obtain due to complexities in water security during drought periods. Therefore, drought entropy was used to determine the weights of the three critical indices. Conventional simulation results regarding the risk load of water security during drought periods were often regarded as precise. However, neither the simulation process nor the DRI gives any consideration to uncertainties in drought events. Therefore, the Dempster-Shafer （D-S） evidence theory and the evidential reasoning algorithm were introduced, and the DRI values were calculated with consideration of uncertainties of the three indices. The drought entropy and evidential reasoning algorithm were used in a case study of the Haihe River Basin to assess water security risks during drought periods. The results of the new DRI values in two scenarios were compared and analyzed. It is shown that the values of the DRI in the D-S evidence algorithm increase slightly from the original results of Zhang et al. （2005）, and the results of risk assessment of water security during drought periods are reasonable according to the situation in the study area. This study can serve as a reference for further practical application and planning in the Haihe River Basin, and other relevant or similar studies.

PROGRESS IN RESEARCH ON RIVER WATER CHEMISTRY IN CHINA

River water resource is the most important component of water resources in China. This paper reviews the progress in the research on river water chemistry in China. It includes three parts: 1) the development of river water quality monitoring in China (at present, there exist three water quality monitoring networks in China: near 3000 water quality monitoring stations under the Ministry of Water Resources, several thousands water quality monitoring sites under the State Environmental Protection Administration and four sites under the China’s GEMS/Water Program); 2) progress in the research on chemical characteristics of river water chemistry in China and their geographical roles on natio wide and region wide scales; and 3) progress in the research on river quality changes in the last 40 years (the long term monitoring data reveals that the water quality of the Changjiang River has acidification trend, the Songhuajiang River had alkalization trend, and the Huanghe River has concentration trend in the last 4 decades).

Climate Change and its Impact on Water Resources in the Huai River Basin

Rainfall and air temperature data from six meteorological stations above the Bengbu Sluice and hydrological and water resources evaluation data from the Bengbu Hydrological Station in the Huai River Basin from 1961 to 2008 are used to analyze the impact of changes in climatic factors on the amount of water resources in the Basin. There was a general trend of rise in its average annual air temperature, with the highest increase of 0.289℃/10a recorded at Bengbu in Anhui Province. Rising rainfall was mainly observed in the western part of the study area, while rainfall actually declined in the eastern part, i.e. the middle reaches of the Huai River. The Average rainfall in the study area was in a vaguely declining trend. In other words, the rainfall in the Basin is still much affected by natural fluctuations. On the whole, there was a trend of gradual decrease in the quantity of the Basin＇s water resources for the period under study. Water resources quantity is found to fall with decreasing rainfall and rising air temperature. Regression analysis is used to establish a mathematical model between water resources quantity and climatic factors （i.e. air temperature and rainfall） in order to explore the impact of climate change on water resources in the Basin. Moreover, various scenarios are set to quantitatively analyze the response of water resources to climate change. Sensitivity analysis shows that changes in rainfall have a much bigger impact on its water resources quantity than changes in its air temperature.

Studies on the Evolutionary Laws and Maintaining Mechanism of Renewability of the Yellow River's Water Resources

The Yellow River has a vast catchment area and historically it is the mother river of the Chinese nation. Now it serves as one of the main theatres for the on-going national campaign to develop China's western hinterland.……

Changes in sediment discharge in a sediment-rich region of the Yellow River from 1955 to 2010: implications for further soil erosion control

The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus（SDM） in the study area decreased from 7,767.4 t/（km^2·a） in 1951–1969 to 980.5 t/（km^2·a） in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/（km^2·a） is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/（km^2·a）.

The Instream Ecological Water Flow Research at the Lower Reach of Guanting Reservoir on Yongdinghe River,Beijing

作为北京市母亲河的永定河自上个世纪80年代以来三家店以下一直处于断流,河床裸露、河道两岸土地沙化严重,是北京春季沙尘天气的主要沙源之一,由于地下水超采严重,加之无水补给地下水,使得北京西部地区第四纪地下水已经基本枯竭,永定河的生态系统已经受到严重破坏。要想恢复或治理受损的河道生态环境,作为生态系统中最活跃最重要的水分多少要先算清楚。本文采用湿周法计算了永定河官厅水库下游三个控制断面（官厅水库（坝下）、雁翅、卢沟桥）的河道内生态需水流量,计算结果为:官厅水库（坝下）站的河道内流量为3.7m3 s-1。（平水年P=50%,1978年）,占年平均流量的20.7%,雁翅站的河道内流量为4.1m3 s-1（平水年P=50%,1981年）,占年平均流量的20.1%,卢沟桥站的河道内流量为1.3m3 s-1（平水年P=50%,1978年）,占年平均流量的22.1%。若能按照计算的流量来补充河道水量,即可使永定河恢复其基本的生态功能,按照Tennant法的标准,基本能使当地的河道生态系统处于较为良好的状态。

基于STAR气候模型的张家口市永定河流域气候变化及对水文水资源系统的影响

为了分析张家口市永定河流域气候变化情况及对水文水资源系统的影响,基于STAR模型,对实测气候数据时间序列系列进行重组,并利用模糊优选神经网络模型,对站点未来情景下的天然年径流量变化进行预测。结果表明,2009-2035年均日最高气温在高升温、中升温、低升温情况下,升温幅度分别为1.85℃、1.27℃、0.73℃;气温升高,径流量有所减少,并且能够通过模糊优选神经网络模型模拟径流变化情况。

数字孪生永定河建设实践

数字孪生永定河建设是流域治理管理现代化的主要标志。围绕永定河生态修复与治理,构建数字孪生永定河,建设水利感知、数据底板、模型平台、知识平台、业务应用等内容,相关成果应用于永定河全年全线有水的生态水量调度与海河“23·7”流域性特大洪水的防洪调度,取得了初步成效。建议下一步从完善数据底板、完善防洪模型、提升防洪“四预”能力、提升水资源调度“四预”能力等方面加强数字孪生永定河建设,助力流域治理管理现代化。

永定河流域水文演变与多水源联合优化调度

水资源是保护修复永定河生态环境功能、维护河流生命健康的控制性因素。永定河流域水资源极为紧缺,且地表水资源量呈显著衰减态势。为实现紧缺严苛的水资源条件下永定河生态水量的有效保障,系统解析了流域水文演变特征,核算了分河段基本生态水量和多水源生态补水潜力,建立了耦合水资源供用耗排过程和水工程群联合运用的多水源优化调度模型,提出了常规和极端情况下的多水源生态水量调度方案和基于降水年型研判的调度方案运用方式。研究成果为有效保障永定河生态水量、提升应对变化环境的韧性提供了关键方法和模型,为华北地区其他河流生态保护修复和综合治理提供技术参考。

永定河流域生态补水绩效分析及生态调度方案评估

为分析生态补水对河道内生态需水量的满足程度,以永定河流域三家店以上流域为研究区域,利用流量历时曲线法计算了不同需求条件下的河道内生态需水量,明确了现状水文条件下的河道生态缺水程度,评估了2019年和2020年生态补水过程中河道主要断面收水率及沿途损耗的空间分布规律,定量评估了生态补水对官厅水库入库流量的贡献,构建了生态水量调度模拟模型,通过对不同生态补水情景河道生态水量调度过程模拟分析,推荐了合理的生态补水调度方案.结果表明:现状永定河山区主要控制断面生态水量处于较为严重的亏缺状态,尤其是山区总控制站三家店缺水率达97%,沿途输水损耗率变化范围为(0.94%~5.38%)/10 km,且呈现上游至下游河段依次减少的规律,收水率与上游补水量呈正相关关系,构建的生态水量调度模型在两个断面率定期和验证期纳什效率系数为0.67~0.96,能够反映永定河河道生态补水过程的水流运动.根据不同情景河道生态水量调度过程模拟结果,为达到低生态流量需求目标,可采用生态补水情景方案4;为达到高生态流量需求目标,可采用生态补水情景方案5.研究成果对认识跨流域调水影响下中国北方季节性河道的生态流量恢复过程具有重要的科学意义,可为面向生态水量恢复目标的永定河跨流域调水与流域内生态补水方案制定等提供科技支撑.

Water quality characteristics and assessment of Yongding New River by improved comprehensive water quality identification index based on game theory

The Yongding New River is essential for the water supplies of Tianjin.To date,there is no comprehensive report that assesses the year-round water quality of the Yongding New River Main stream.Moreover,little attention has been given to determining a combined weight for improving the traditional comprehensive water quality identification index(ICWQII)by the game theory.Seven water quality parameters were investigated monthly along the main stream of the Yongding New River from May 2018 to April 2019.Organic contaminants and nitrogen pollution were mainly caused by point sources pollution,and the total phosphorus mainly by non-point source pollution.Dramatic spatio-temporal variations of water quality parameters were jointly caused by different pollutant sources and hydrometeorological factors.In terms of this study,an improved comprehensive water quality identification index(ICWQII)based on entropy weight or variation coefficient and traditional CWQII underestimated the water qualities,and an ICWQII based on the superstandard multiple method overvalued the assessments.By contrast,water qualities assessments done with an ICWQII based on the game theory matched perfectly with the practical situation.The ICWQII based on game theory proposed in this study takes into account not only the degree of disorder and variation of water quality data,but also the influence of standard-exceeded pollution indicators,whose results are relatively reasonable.All findings and the ICWQII based on game theory can provide scientific support for decisions related to the water environment management of the Yongding New River and other waters.

Distribution of fluoride in surface water and a health risk assessment in the upper reaches of the Yongding River

The excessive exposure to high concentrations of fluoride in drinking water can lead to a serious disease called fluorosis.The upstream region of the Yongding River is an ecological protection area for Beijing.Some studies have reported that there is a high concentration of fluoride in the groundwater in this area.However,there are few data on the distribution of fluoride in surface water and health risk assessments in this area.In this study,the fluoride concentrations were determined by using the spectrophotometric method using data from 2013 to 2017 from 9 surface water quality monitoring stations in the upper reaches of the Yongding River.The health risks of fluoride were assessed using the approach developed by the United States Environmental Protection Agency(US EPA).The results indicated that the fluoride content in the drinking water ranged from 0.30 to 1.50 mg L 1,with an average of 0.86 mg L"1.In total,22.7%of the analyzed samples exceeded the Chinese limit of 1.0 mg L"1 for fluoride,and 5.5%of samples had less than the permissible limit of 0.5 mg L"1.Higher fluoride concentrations and fluorosis hotspots were found to be predominately located downstream of the Yanghe River close to the Guanting Reservoir,where 71.4%of samples exceeded the limit of 1.0 mg/L'1.The spatial distribution of high fluoride concentrations was found to be primarily determined by industry.The hazard quotient(HQ)index for children,teenagers and adults indicated that 19.6%,15.6%,and 5.1%of the samples in the upper reaches of the Yongding River,respectively,posed health hazards to the associated groups.Furthermore,the HQ index more than 1 for children,teenagers and adults had values of 64.3%,56.1%,and 19.4%,respectively,in samples from the downstream region of the Yanghe River.Therefore,there are potential risks of dental and skeletal fluorosis in the upper river reaches of the Yongding River.It is imperative to take measures to reduce the fluoride pollution in surface water and control fluorosis.Action should be taken to improve the disposal of industrial waste.

河流分类分级分段及河流形态学研究进展

河流分类、河流分级及干流河道分段合称为河流三分(分类·分级·分段);基于河流三要素(流域-水系-干流河道)和河流三分-河流形态学-河流学体系,开展了河流三分理论研究及实践应用、河流形态学再构建以及河流形态定性特性与定量因子指标辨识。主要成果结论包括:①优化了独立与非独立河流分类、河流分级Horton法改进、河流5区分段等方法,完善了河流界定拓展、河流平等与分级、干流河道“层次分段”等新理论,总结了世界大江大河及长江河流三分实践应用;②河流形态学研究河流现状及恒常形态,包括以河流三分为基石的河流三要素特性研究和以干流河道平面-剖面-断面形态为核心的河谷-河床-河道形态研究;③定性辨识了河流形态15项殊相特性与共相原则(包括复合流域水系、复杂干流河道等形态特性,干流河道优先、河流湖泊统一、干流河道唯一、侵蚀基面统一等新增原则);④定量辨识了河流形态4类因子指标,双指标3种相关关系(并行-从属-或然)与3类组合模式(物理-化学-生物)以及三因子4类及9种相关模式(均衡线型-瓶颈线型-三角形-金字塔-均分圆-同心圆-同切圆-交叉圆-三角圆)。倡导“河流学-长江学-水科学”学科范式,积极践行“治河·治江·治水”理念。

基于动态损失的水动力学模型在永定河生态补水过程中的应用

为精准模拟一维水动力学过程,基于明渠非恒定流的水动力模型,提出耦合改进考斯加科夫(Kostiakov)公式,考虑实际河道渗漏损失动态变化。在同一时间步长上,将水动力模型计算流量作为损失模型流量边界条件,通过损失经验参数a和b计算得出此时间步长河道损失量,对水动力河道损失参数进行实时修正。以永定河流域2022-2024年4场实测补水数据对模型精度进行检验,分析海河“23·7”流域性特大洪水(简称“23·7”洪水)前后永定河河道生态变化特点。结果表明:该模型在永定河流域具有良好适用性,相对误差的绝对值最小为0.004,最大为0.218;“23·7”洪水对永定河河道冲刷作用明显,河道形状发生明显改变,河道糙率与河道下渗损失较洪水冲刷前均减小,永定河下游流域较洪水冲刷前以小流量补水即可实现全流域通水,可为永定河下游生态调水提供参考。

永定河门头沟段河道生态需水特征研究

为提高永定河门头沟段的整体生态健康状况,保障河道生态需水量,应对气候变化和人类活动对河流生态系统的影响,研究分析了该区的水文气象要素演变特征及河道生态需水的时间序列动态。根据永定河门头沟段的生态保护目标,采用环境功能设定法整合计算了包括生态基流、水生生物需水、输沙需水、自净需水和水面蒸发需水5项河道生态需水量。并通过定量分析气候变化和人类活动对径流的影响来确定河道生态需水的影响因素。结果显示,1980—2020年研究区域年平均气温呈显著上升趋势,年降水量有所增加但并不显著;1980—2020年区域河道生态需水量呈显著减少趋势,其中水生生物需水量最大。人类活动是影响区域生态需水量的最主要因素,其通过影响径流量进而影响河道生态需水量。研究结果可为未来永定河门头沟段的水量调配、水资源管理、河道生态需水量预测提供理论参考。

基于S-P概化模型的滁河干流六合段纳污能力分析

根据滁河干流六合段各水功能区水环境现状和水质目标的要求,利用一维S-P水质概化模型,在一定的设计水文条件、水质背景、排污口位置及排污方式的条件下,以化学需氧量(COD)和总氮(TN)作为主控因子进行了该江段纳污能力的计算。在90%设计保证率下COD和TN的总纳污能力分别为7333t/a和289t/a;该河段COD和TN实际纳污量分别为11676t/a和1647t/a;各水功能区中,COD和TN入河量较多的是工业用水区和龙池保留区,其实际纳污量分别为4274t/a和691t/a;污染物消减率最大的功能区为工业用水区,COD和TN消减率分别为68.6%和91.3%,说明工业用水区是该河段水环境治理的重点区域。

基于T-S模糊神经网络的颍河水质时空变化特征分析

基于T-S模糊神经网络分析颍河(河南段)2007-2010年5个监测断面的水质指标监测数据,克服了过去仅用各级评价标准作为训练样本,导致训练样本数过少和不能构建检测样本的缺点,对实测数据仿真有很好的效果。应用主成分分析法,选出溶解氧、高锰酸盐指数、生化需氧量、氨氮、化学需氧量、总磷、六价铬、阴离子表面活性剂8项对水质具有重要影响的指标,建立适用于颍河的T-S模糊神经网络水质评价模型,对颍河水质时空变化特征进行分析。结果显示:颍河水质在近几年呈改善趋势;白沙水库断面水质最优,且稳定;周口康店断面水质较差,西华址坊在2007年第2季度水质恶化严重;沈丘纸店断面水质逐渐改善。表明了T-S模糊神经网络对水质时空变化特征分析的效果显著,也反映了颍河水质状况,为颍河水质监测、管理与控制提供依据。

北京香山历史水系的开发与利用

北京香山在历史上就是著名的风景名胜,地下水资源丰富,拥有众多泉眼。随着香山地区的营建,香山水系也得到开发与利用,至清代达到鼎盛,水系不仅因借山势在静宜园中形成了泉、池、溪、瀑等多种形式的水景,而且其利用远及静明园等“三山五园”,甚至通州。通过对历史文献、样式雷图档、测绘图进行研究,结合田野调查等方法,梳理香山水景的类型与分布,分析香山地形的高差变化与水景之间的关系,总结历史上对于香山水系的开发与利用,并提出传承保护香山水系的建议。

STREETER-PHELPS模型的缺陷及其改进研究

Streeter-Phelps模型应用于重污染河流时,因起始BOD浓度大,得出负值的氧浓度,而导致S-P模型失效。本研究比较了BOD浓度L、氧亏值D与自净系数f的关系,定义λ=fD/L为复氧判别数。λ单调递增,λ=1对应河流的复氧起点,λ<1或λ>1说明河流中的溶解氧呈下降或上升态势。通过将河流划分为三个区段,完成了BOD衰减及DO复氧过程的求解,这一改进可以有效地弥补S-P模型的缺陷。

北京市永定河流域水工程调度实践与思考——以海河“23·7”流域性特大洪水应对为例

2023年7—8月,受2305号台风“杜苏芮”北上和西北太平洋副热带高压异常偏北影响,海河流域发生“23·7”流域性特大洪水。北京市永定河段首次启用大宁水库、滞洪水库分蓄洪水。围绕本次北京市永定河流域水工程调度实践,简述洪水预报与调度策略,梳理斋堂水库、三家店拦河闸、卢沟桥枢纽调度过程,总结实施预报调度、精细调度、流域统一调度等经验,从精准预报调度技术、突发状况应急处置、智能化调度能力提升等方面提出对策建议。