Optimization of water-urban-agricultural-ecological land use pattern:A case study of Guanzhong Basin in the southern Loess Plateau of Shaanxi Province,China

Extensive land use will cause many environmental problems.It is an urgent task to improve land use efficiency and optimize land use patterns.In recent years,due to the flow decrease,the Guanzhong Basin in Shaanxi Province is confronted with the problem of insufficient water resources reserve.Based on the Coupled Ground-Water and Surface-Water Flow Model(GSFLOW),this paper evaluates the response of water resources in the basin to changes in land use patterns,optimizes the land use pattern,improves the ecological and economic benefits,and the efficiency of various spatial development,providing a reference for ecological protection and high-quality development of the Yellow River Basin.The research shows that the land use pattern in the Guanzhong Basin should be further optimized.Under the condition of considering ecological and economic development,the percentage change of the optimum area of farmland,forest,grassland,water area,and urban area compared with the current land use area ratio is+2.3,+2.4,-6.1,+0.2,and+1.6,respectively.The economic and ecological value of land increases by14.1%and 3.1%,respectively,and the number of water resources can increase by 2.5%.

Changes of groundwater flow field of Luanhe River Delta under the human activities and its impact on the ecological environment in the past 30 years

The Luanhe River Delta is located in the center of the Circum-Bohai Sea Economic Zone.It enjoys rapid economic and social development while suffering relatively water scarcity.The overexploitation of groundwater in the Luanhe River Delta in recent years has caused the continuous drop of groundwater level and serious environmental and geological problems.This study systematically analyzes the evolution characteristics of the population,economy,and groundwater exploitation in the Luanhe River Delta and summarizes the change patterns of the groundwater flow regime in different aquifers in the Luanhe River Delta according to previous water resource assessment data as well as the latest groundwater survey results.Through comparison of major source/sink terms and groundwater resources,the study reveals the impacts of human activities on the groundwater resources and ecological environment in the study area over the past 30 years from 1990 to 2020.The results are as follows.The average annual drop rate of shallow groundwater and the deep groundwater in the centers of depression cones is 0.4 m and 1.64 m,respectively in the Luanhe River Delta in the past 30 years.The depression cones of shallow and deep groundwater in the study area cover an area of 545.32 km^(2)and 548.79 km^(2),respectively,accounting for more than 10%of the total area of the Luanhe River Delta.Overexploitation of groundwater has further aggravated land subsidence.As a result,two large-scale subsidence centers have formed,with a maximum subsidence rate of up to 120 mm/a.The drop of groundwater level has induced some ecological problems in the Luanhe River Delta area,such as the zero flow and water quality deterioration of rivers and continuous shrinkage of natural wetlands and water.Meanwhile,the proportion of natural wetland area to the total wetland area has been decreased from 99%to 8%and the water area from 1776 km^(2)to 263 km^(2).These results will provide data for groundwater overexploitation control,land subsidence prevention,and ecological restoration in plains and provide services for water resources management and national land space planning.

An Ecologically Oriented Operation Strategy for a Multi-Reservoir System： A Case Study of the Middle and Lower Han River Basin, China

水库群的建设和调度改变了河流的自然流态,对河流生态系统造成了不利影响。本文提出了一种面向生态的水库群调度策略,将河流内不同生态功能所需的生态流量整合到水库群联合调度中,以实现生态流量需求和人类用水需求之间的均衡。该策略耦合了常规优化调度方案和一系列实时生态调度方案。在人类用水需求与生态流量需求冲突较小的时段,水库群调度在保障河流最小流量的前提下采用常规优化调度方案,最大限度地提高人类用水效益。在水库引发的水文改变对河流关键生态功能产生严重影响的时期,水库群调度采用实时生态调度方案,调整下泄流量,从而满足河流生态流量需求。该策略被应用于位于中国汉江中下游流域的一个大型水库群中。模拟调度结果表明,实时生态调度方案保证了河流关键生态功能的生态流量需求,其对人类用水效益的不利影响可通过常规优化调度方案得到部分补偿。本文提出的面向生态的水库群调度策略丰富了考虑生态流量需求的水库群联合调度的理论应用。

基于BHM-EcoFlow模型的汉江中下游河段水文-生态响应关系研究

河流水文-生态响应关系是确定生态流量阈值的科学基础。针对当前河流水文-生态响应关系研究中生态数据不足且生态建模难度大的问题,建立了基于贝叶斯层次分析法的BHM-EcoFlow(Bayesian hierarchical modelling-ecological flow)模型,该模型将河流不同河段及同一河段不同站点间的先验知识与实测数据相结合,可有效利用短系列数据,实现河流水文-生态响应关系的模拟。采用汉江中下游干流2011年的水文、生态数据,模拟了浮游植物细胞密度与流量、混合层温度间的关系,计算了不同流量条件下各河段的浮游植物密度。结果表明:BHM-EcoFlow模型提高了短系列数据的可用性,对汉江中下游干流的水文-生态响应关系具有良好的识别能力,为确定生态流量提供了科学依据。

Inducing Flow Velocities to Manage Fish Reproduction in Regulated Rivers

Conservation of endangered or economic fish and control of invasive fish is a great challenge of hydraulic engineering worldwide.Flow velocity has been recognized to affect the spawning of fishes delivering drifting eggs in rivers.However,solid scientific supports and associated mechanisms to establish quantitative relations between flow velocity and fish reproduction,taking into account spawning,fertilizing,hatching,as well as surviving,are lacking.In this paper,we quantified the relationship between flow velocity and reproduction of Chinese carps through both lab and field experiments.The results showed that a minimum velocity was required to trigger Hypophthalmichthys molitrix(H.molitrix)releasing eggs,and a velocity range was preferred to sustain spawning activity.However,the embryo incubation and larvae development of H.molitrix were found to be inhibited with the increase in flow velocity.Considering the requirements of spawning and hatching,as well as larvae surviving,an optimized flow velocity processes was identified for the reproduction of H.molitrix in rivers.These findings were of great significance to the adaptive operation of reservoirs to create reasonable and precise ecological flows for managing fish reproduction,as shown by the promising results in the engineering application to the Three Gorges Reservoir.

基于River 2D模型的黄河花园口河段生态流量研究

针对目前生态流量研究方法难以充分考虑鱼类栖息地等生境因素的问题,以黄河花园口鲤鱼核心保护区为研究区域,选取黄河鲤鱼为研究物种,基于耦合水动力学模型和栖息地模型的River 2D模型确定黄河鲤鱼的生态流量,将水深和流速作为鱼类生存保护的限定性因子,采用栖息地模型模拟不同流量下对应的黄河鲤鱼的适宜栖息地面积。计算结果表明:花园口河段鲤鱼产卵期的最小生态流量为230 m^(3)/s,生长期的最小生态流量为430 m^(3)/s,越冬期的最小生态流量为150 m^(3)/s。计算结果可以为花园口核心鱼类保护区的鱼类保护以及黄河小浪底水库的生态调度提供参考。

Effects of Mountain Rivers Cascade Hydropower Stations on Water Ecosystems

China is rich in hydropower resources,and mountain rivers have abundant water resources and huge development potential,which have a profound impact on the pattern of water resources allocation in China.As the main way of water resources and hydropower development,the construction of cascade hydropower stations,while meeting the requirements of water resources utilization for social development,has also brought adverse effects on river ecosystems.Therefore,the impact of the construction of cascade hydropower stations on mountainous river ecosystems,where the minimum ecological flow of rivers must be ensured and reviewed.In addition,this paper proposed the deficiencies and outlooks for cascade hydropower stations based on previous research results.

面向生态环境复苏的生态流量优化计算研究

当前多数中小河流的水环境状况不容乐观,亟需开展河道的生态环境复苏工作,在河流生态流量确定过程中也存在计算方法不易推广和生态因子难以量化的问题。面向河道生境最大程度改善的河流生态复苏通常以水量保障和水环境改善为基础,并且也是对基于自然解决方案(NbS)中自然化修复理念的有效落实。为满足北方缺水河流的生态水量要求,该研究选取指示物种,借助二维水动力栖息地模拟模型和Penman-Monteith公式,开展恢复河流功能自然化、实现河流径流自然过程的研究。首先以恢复河流自然状态为目标,并以龙河作为典型河流在时空尺度开展指示物种-生态流量计算,得出相应生态流量及年最小生态需水量。然后以生态幅范围广且易于捕获的麦穗鱼为指示物种,开展产卵期(4-6月)、幼鱼期(7-11月)和成长期(12-3月)最适生态流量确定,3个时段对应的流量分别为3.22、4.30和10.81 m^(3)/s,典型河段芦苇的最小年生态需水量为1.51万m^(3)。计算结果均能满足陆域和水体指示物种的生理需水要求。以NbS为基础的生态流量计算方法适用范围广、结果代表性强,可用于流量小、流速低的北方中小河流的生态流量计算,利于实现河湖生态环境复苏。

黄河内蒙古河段水文情势变化及生态效应初探

选择月均流量、日均流量变幅、极端流量和脉冲延时4个水文情势指标,采用IHA-RVA(水文情势变化指标-变化范围法)分析黄河干流内蒙古河段水文情势的时空变化特征,辨析黄河鱼类生态习性与径流组分的响应关系,探讨内蒙古河段流量过程、极端流量变化的生态效应。黄河干流上游河段水利工程运行后,内蒙古河段的水文情势明显改变,进而改变该河段的生态水文联系过程。黄河内蒙古河段枯水期月均流量增加(1、2月份月均流量增幅超过70%)、最小日均流量增加(石嘴山断面最小日流量增幅超过50%),保障了河道流水栖息生境,有利于鱼类越冬。该河段日均流量变幅降低,有利于粘性卵孵化。但是内蒙古河段汛期月均流量减小(7-10月份月均流量降幅接近50%),大、小洪水持续时间缩短,不利于扩展横向栖息地;最大流量出现时间在上游河段延迟超过2个月、在中下游河段提前约1个月,洪水脉冲刺激时间紊乱可能影响鱼类繁殖行为。研究可为黄河内蒙古河段鱼类栖息地保护以及上游水库生态调度提供技术支持。

确定生态流量的准则与方法

基于反映河流生态系统自然属性的生态水文季节概念,构建了多参数生态流量体系并分析了其内涵;提出了生态水文危机管理模式下的生态流量确定准则,以临界水文条件定义生态流量,形成“生态标准河流”;研发了具有明确物理意义、规范、客观的分季节生态流量计算方法,并以黄河流域、松辽流域为典型案例进行了分析说明;确定了我国非季节性河流的生态流量管控指标,提出生态流量与河流安全管理建议。

长江流域河湖生态流量监督管理标准体系研究

为适应生态文明建设、落实《长江保护法》关于生态流量管控的规定,亟需建立长江流域河湖生态流量监督管理标准体系。在阐述河湖生态流量监督管理标准体系建设必要性和相关标准发展现状的基础上,从生态流量管控目标的确定、生态流量泄放设施的实施、生态流量监测监控的建设、生态流量保障程度的评估、生态流量调度调控的应对等方面出发,探讨了河湖生态流量监督管理标准体系建设,使长江流域河湖生态流量监督管理都有统一可遵循的准则,切实保障河湖生态流量。研究成果对保护和改善长江流域生态环境具有重要意义。

小浪底水库运行下花园口河段黄河鲤生态流量研究

【目的】大坝和水库等水利工程的修建在带来防洪减灾效益的同时,也给所在区域的水生生物栖息繁衍带来了一定影响,诊断关键水生生物的生态流量对大坝下游的生态环境修复工作具有重要意义。【方法】以黄河下游花园口河段为例,探讨了小浪底水库运行下不同流量情景下的黄河鲤栖息地质量情况,并由此推求黄河鲤的生态流量。基于栖息地模拟法,通过构建耦合栖息地适宜度模型的二维水动力模型,分析了黄河鲤鱼苗期、亲鱼期的栖息地适宜度指数空间分布,分别建立了黄河鲤两个生命阶段流量与栖息地加权可用面积关系曲线。【结果】结果表明:随着模拟流量的增大,黄河鲤不同生命阶段的栖息地适宜度指数空间分布及栖息地加权可用面积呈现先增加,达到峰值后逐渐减小的变化规律。【结论】黄河下游花园口河段的最小生态流量为1 150 m~3/s,适宜生态流量为1 450 m~3/s,最适宜生态流量为3 000 m~3/s,研究成果加深了对大流量情景下黄河鲤栖息地质量的认识,对黄河下游生态保护与修复具有重要意义。

Development of a groundwater flow and reactive solute transport model in the Yongding River alluvial fan,China

The Yongding River in the western suburbs of Beijing has been recharged with reclaimed water since 2010 for the purpose of ecological restoration.Where the reclaimed water is not well treated,it poses a danger to the aquifer underneath the river.To provide a reliable tool which could be used in future research to quantify the influence of reclaimed water in the Yongding River on the local groundwater environment,a transient groundwater flow and reactive solute transport model was developed using FEFLOW^TM in the middle-upper part of the Yongding River Alluvium Fan.The numerical model was calibrated against the observed groundwater levels and the concentrations of typical solutes from June 2009 to May 2010 and validated from June 2010 to December 2010.The average RMSE and R2 of groundwater level at four observation wells are 0.48 m and 0.61,respectively.The reasonable agreement between observed and simulated results demonstrates that the developed model is reliable and capable of predicting the behavior of groundwater flow and typical contaminant transport with reactions.Water budget analysis indicates that the water storage in this aquifer had decreased by 43.76×10^6m^3 distributions of typical solutes suggest that the middle and southern parts of the unconfined aquifer have been polluted by previous discharge of industrial and domestic sewage.The results underscore the necessity of predicting the groundwater response to reclaimed water being discharged into the Yongding River.The study established a coupled groundwater flow and reactive solute transport model in the middle-upper part of the Yongding River Alluvium Fan,one of the drinking water supply sites in Beijing city.The model would be used for risk assessment when reclaimed water was recharged into Yongding River.

汉江中下游藻华暴发特征及生态流量阈值

基于2015~2019年汉江中下游水文,水环境和水生态数据,采用主成分分析与冗余分析识别了河流藻华暴发防控的关键因子,拟合得到其调控阈值,然后,使用断面通量法和流速抑制法推求了抑制河流藻类水华暴发的生态流量.结果表明:汉江中下游藻类水华主要发生在枯水期,枯水期藻类优势种群为硅藻,小环藻为优势种,丰水期绿藻门和硅藻门是优势种群,小球藻为优势种.流速是影响汉江藻类生长的主控因子,当流速超过0.462m/s时,流速继续增大将抑制藻类生长.汉江中下游枯水期控制藻类水华的生态流量:沙洋断面流量为890m^(3)/s,潜江断面流量为918m^(3)/s,仙桃断面流量为953m^(3)/s,汉川断面流量为1075m^(3)/s.

不同生态流量需求下雅砻江中下游梯级电站联合优化调度

为协同雅砻江干流水力发电与河道生态流量需求,以中下游7座电站为研究对象,进行不同生态流量需求下雅砻江中下游梯级电站联合优化调度。基于改进型可变月径流法,计算了雅砻江主要生态控制断面最小、适宜及最佳生态流量过程;构建了以梯级发电量最大化为目标的雅砻江中下游梯级电站联合优化调度模型,并用遗传算法对其求解。结果表明:(1)随河道生态流量需求的提高,梯级电站发电效益和水资源利用效率均下降,其中锦屏二级电站发电量下降最为显著;(2)梯级电站保障发电效益正常发挥的同时,实施联合优化调度,其下游河道能维持更高层次的生态流量,一定程度缓解了流域水能开发利用与河道生态保护间的关系。

基于水情变化的河流生态流量阈值及多时间尺度保障率计算

为加强河流生态流量阈值及保障率计算对天然水文情势变化的适应性,提出了基于水文集合分位数的生态流量计算方法。根据河流长序列实测径流数据,在年际和年内划分不同水文情景,基于生态流量水文集合的中位数和下四分位数确定年内汛期、非汛期生态流量阈值下限,以丰、平水年组的计算结果分别作为平、枯水年组的生态流量理想值,结合生态流量中长期和短期保障率,计算分析河流在不同时间尺度下的生态流量保障程度。抚河下游应用结果表明:综合水情变化的生态流量阈值和多时间尺度保障率分析方法能够更好地适应天然河流年际和年内水情变化,更准确识别河流水文健康状况;丰、平、枯水年组抚河下游年均生态流量阈值下限分别为156.49、90.43、29.54 m 3/s;不同时间尺度下抚河下游生态流量的保障程度均较低,中长期保障率大于短期保障率,中长期和短期保障率分别为63.64%~93.11%、42.50%~91.85%。

基于水文-水力-生境分析的河道基本生态流量计算方法

针对现有河道基本生态流量计算方法无法兼顾结果准确和流程简约的问题,提出了一种综合水文频率、水力条件及生境需求的基本生态流量计算方法。选取流域控制断面进行径流还原,根据河道天然来水特性和水生生物需水特性划分水期,进行分期水文排频;利用水力学方法计算断面流量与平均水深和平均流速之间的关系;根据生态水深和生态流速等生境指标需求,综合分析得到不同水期下的河道基本生态流量。将该方法应用于浙江始丰溪流域基本生态流量计算,并将计算结果与Tennant法结果进行对比分析,结果表明:沙段水文站控制断面产卵育幼期的基本生态流量为16.0 m^(3)/s,一般用水期的基本生态流量为4.4 m^(3)/s,计算结果落在Tennant法的计算区间值中;本文提出的方法计算结果合理,可针对不同水期给出更为精准的基本生态流量。

基于水文学法的生态流量适宜性评价研究

水资源开发利用改变了河流天然水文情势,影响了河流生态环境,提供适宜的生态流量对保障河流系统健康具有重要意义。考虑径流非一致性及数据冗余,运用M-K检验法、累积距平法、PCA-IHA指标体系等能更准确地判断河流水文情势的改变程度;基于生态流量计算的水文学法,建立了完整的生态流量适宜性评价体系,提出了阈值区间保证率、偏差指数、达标率等3个评价指标,并综合成适宜性指数这一综合指标,在赣江干流进行应用。结果表明:①赣江干流1960~2015年的水文情势改变度较低,变异点为1991年;②各水文学法在所提出的评价指标中各有优劣,且适宜性指数差异较大,说明该评价体系可以较好地筛选出对研究区域适用的计算方法,其中赣江干流最适宜的为逐月频率法,适宜性指数为0.8。研究成果可为完善生态流量适宜性评价体系提供科学参考。

大渡河干流已建水电站生态基流目标值复核分析

以大渡河干流已建水利水电工程为研究对象开展回顾性评价,为推动后续生态基流研究和水资源管理提供参考。研究采用多种水文学方法,包括Tennant法、Texas法、Q90法、多年最小月平均流量法和NGPRP法,计算大渡河干流已建梯级水电站的生态基流目标值。根据计算结果中各控制断面的最小值、最大值和平均值,建立生态基流目标值的参考区间,分别对应底线、优和良好的标准线,并对大渡河干流已建梯级水电站生态基流目标进行了回顾性评价。结果表明,大多数断面的现行生态基流目标值均在最大和最小参考值区间范围,设置基本合理。针对不同历史条件下或不同行业领域中存在的生态基流相关概念内涵和适用边界条件的不一致问题,以及拦河工程生态基流调度的实际问题,研究提出生态基流目标体系的双指标控制法,并提出了大渡河干流已建梯级水电站生态基流目标建议值,建议双江口、猴子岩、深溪沟、龚嘴、铜街子水电站的生态基流目标采用日均和瞬时双控值,分别设为121/52、160/78、327/188、366/149和366/236 m^(3)/s,而沙湾和安谷水电站均设为366 m^(3)/s。

曹娥江适宜生态流量计算和评价研究

保障河流生态流量对维持河流生态健康状态具有重要意义。通过对曹娥江流域东沙埠和黄泥桥两个控制断面1961—2017年还原径流量资料进行可靠性、代表性和一致性检验,表明还原径流量可视为天然径流量。选取Tennant法、Qp法、频率曲线法、年内展布法、月流量变动法共5种水文学方法分别计算两个控制断面各月适宜生态流量。以准确率、满足率和适宜度为指标综合评价了不同方法在曹娥江流域研究区的适用性,最终推荐月流量变动法作为适宜生态流量的计算方法,最小值分别为14.83 m^(3)/s和2.44 m^(3)/s,最大值分别为46.61 m^(3)/s和6.74 m^(3)/s。该研究为流域水库生态调度提供参考。