海河流域地下水资源保护

地下水资源在海河流域至关重要的资源。海河平原的浅层和深层含水层大面积处于严重超采状态。地下水资源的的过量开采造成了严重环境问题。为了保护地下水资源，评价了可行的技术。利用洪水和废水进行人工回灌已进行了试验。在很多地区可以应用地表回灌系统，城市地区实施深层含水层的回灌。更好地策略是减少地下水的抽取量，特别是为了减缓地面沉降和海水入侵。应该联合运用减少地下水抽水量和人工回灌，以解决地下水位持续下降和含水层恢复的问题。     

吉林省西部潜水资源与生态环境风险分析

吉林省西部是我国主要粮食产区,但区内农业水利规划管理同时面临潜水资源与生态环境双重风险。近20年来,区内曾尝试多种水资源利用模式,但缺少不同模式应用效果的定量化对比。文章建立了不同水资源利用模式,对比分析各模式的水资源与次生盐碱化风险。以洮儿河流域为例,采用循环神经网络预测2019—2023年该地区大气降水和地表水对地下水补给量;通过随机数值模拟预测现状开采、连续干旱、无序开采、地下水库建设、节水灌溉、旱田改水田6种情形下,区内潜水水位空间分布特征。以防止次生盐碱化为目标,定义水位埋深上限为1 m;以含水介质厚度为参考,定义水位埋深下限为12 m。遴选适合吉林省西部地区地下水资源可持续利用模式。结果显示:无序开采是导致区内水资源枯竭的主要诱因;地下水库建设和旱改水工程有助于潜水资源维护,但长期运行可加剧生态环境风险。节水灌溉（净采强度为2.0×108～3.0×108 m3/a）是降低区内水资源风险和生态环境风险的最佳方式。文章采用的神经网络—随机模拟分析方法成功预测了地下水位变化驱动因子和地下水位中长期变化趋势,为我国干旱半干旱地区潜水资源利用方案制定提供了新方法。     

Land subsidence caused by groundwater exploitation in Suzhou City,China

Suzhou City, located at the lower reaches of the Yangtze River in southeastern Jiangsu Province, is one of the few cities in China which suffer from severe ground settlement. A research project was carried out to investigate this problem. Geological and hydrogeological studies show that there is a multi-layered aquifer system with three distinct, soft mud layers of marine and lagoonal origins. An examination of historical records of groundwater extraction, water levels, and ground settlement shows that the ground subsidence is associated with the continuously increasing groundwater extraction in the deep, confined aquifer. It is believed that the consolidation of the soft mud layers, especially the third layer which is thick and close to the main pumped aquifer, contributes to the ground settlement. A three-dimensional finite difference numerical model representing the multi-layered aquifer system was developed to study the ground settlement in response to groundwater extraction. By calibrating the model with both the measured groundwater level and ground settlement, the aquifer parameters were estimated. The model outputs fit reasonably well with the observed results, which indicates that the numerical model can reproduce the dynamic processes of both groundwater flow and soil consolidation. The hydraulic conductivity of the third mud layer near the center of the ground settlement has been reduced by over 30% in the last 14 years. The gradual deterioration in the hydraulic conductivity of the mud may have significant adverse effect on the sustainable groundwater resource of the deep confined aquifer, since the recharge from the shallow aquifers through the mud layer is the only source of water to the deep aquifer. An analysis of the spatial distributions of groundwater drawdown and ground settlement shows that the area with maximum drawdown is not necessarily the area with maximum ground settlement due to the occurrence of the soft mud layer. A simple reallocation in pumping rates on the basis of the spatial distribution of the thick mud layer could significantly reduce the ground settlement. Electronic Publication     

中国地下水资源演变趋势及影响因素分析

中国地下水资源发生了显著变化,全面摸清地下水资源演变趋势及其影响因素是治理和管理地下水资源的基础。基于全国水资源调查评价、中国水资源公报等资料,对中国60余年来地下水资源的演变规律与影响因素进行了系统分析。结果表明：全国地下水资源量总体稳定,但区域演变趋势差异明显,海河区、辽河区、黄河区呈明显衰减态势;地下水补给结构发生重大变化,由自然补给演变为自然与人工补给并存的模式;地下水排泄结构发生巨大变异,由天然排泄逐渐演变为以人工排泄为主。海河区、松花江区、黄河区、西北诸河区等区域地下水补给排泄关系严重失衡,超采问题突出;降水变化、下垫面条件改变、人类活动干扰是地下水资源变化的主要原因。     

中国地下水资源演变趋势及影响因素分析

中国地下水资源发生了显著变化,全面摸清地下水资源演变趋势及其影响因素是治理和管理地下水资源的基础。基于全国水资源调查评价、中国水资源公报等资料,对中国60余年来地下水资源的演变规律与影响因素进行了系统分析。结果表明:全国地下水资源量总体稳定,但区域演变趋势差异明显,海河区、辽河区、黄河区呈明显衰减态势;地下水补给结构发生重大变化,由自然补给演变为自然与人工补给并存的模式;地下水排泄结构发生巨大变异,由天然排泄逐渐演变为以人工排泄为主。海河区、松花江区、黄河区、西北诸河区等区域地下水补给排泄关系严重失衡,超采问题突出;降水变化、下垫面条件改变、人类活动干扰是地下水资源变化的主要原因。     

滩小关水源地地下水计算与评价

滩小关水源地位于伊洛河口以东的黄河漫滩区,西、北、东分别与伊洛河和黄河相邻,属傍河型水源地。对埋深60 m以浅的地下水进行了计算与评价。计算方法主要采用水量均衡法、数值法评价地下水允许开采量,对浅层地下水资源保证程度进行了评价。两种方法的计算结果差别较小,结果可靠。开采量中大部分来自黄河、伊洛河的侧渗补给和洪水入渗补给,开采条件下河流入渗补给量仅占黄河最小流量的1 453分之一。因此,该水源地的允许开采量是完全可靠的。     

云应盆地东北部含水层结构特征及地下水转化模式

云应盆地东北部属鄂北贫水地区,赋存于古近系—第四系含水层中的地下水是当地生产、生活用水的主要来源,亟需查明含水层的结构、含水层间地下水的转化关系等基本条件,为研究区内合理开发利用地下水提供依据。本研究通过野外水文地质调查、水文地质钻探工作,将研究区划分为单层含水层与双层含水层结构两个亚区（6个小区）。并通过地下水水位动态长期监测,获取了区内不同含水层的水位动态变化特征,分析各含水层之间的水力联系,建立了区域地下水转化的概念模式,即:研究区地下水以接受山前降雨入渗及风化裂隙水侧向径流补给为主,主要以水平径流的形式经古近系孔隙-裂隙含水层及第四系孔隙承压含水层往澴水方向运移,而后进入第四系孔隙潜水含水层。地下水和地表水在不同季节补排模式不同,雨季地表水（澴水）补给地下水,旱季地下水向地表水（澴水）排泄。古近系孔隙-裂隙水与上覆第四系孔隙水联系密切互为补给,共同构成具有统一水力联系的垂向多层结构的含水系统。独特的含水层结构决定了区内地下水接受降水补给的条件较差,地下水可开采资源量总体较贫乏,建议重点利用区域地表水资源,适度开发地下水资源,推进农业节水灌溉工程,实现水资源可持续利用。     

Influences of groundwater extraction on flow dynamics and arsenic levels in the western Hetao Basin,Inner Mongolia,China

Data on spatiotemporal variations in groundwater levels are crucial for understanding arsenic (As) behavior and dynamics in groundwater systems. Little is known about the influences of groundwater extraction on the transport and mobilization of As in the Hetao Basin, Inner Mongolia (China), so groundwater levels were recorded in five monitoring wells from 2011 to 2016 and in 57 irrigation wells and two multilevel wells in 2016. Results showed that groundwater level in the groundwater irrigation area had two troughs each year, induced by extensive groundwater extraction, while groundwater levels in the river-diverted (Yellow River) water irrigation area had two peaks each year, resulting from surface-water irrigation. From 2011 to 2016, groundwater levels in the groundwater irrigation area presented a decreasing trend due to the overextraction. Groundwater samples were taken for geochemical analysis each year in July from 2011 to 2016. Increasing trends were observed in groundwater total dissolved solids (TDS) and As. Owing to the reverse groundwater flow direction, the Shahai Lake acts as a new groundwater recharge source. Lake water had flushed the near-surface sediments, which contain abundant soluble components, and increased groundwater salinity. In addition, groundwater extraction induced strong downward hydraulic gradients, which led to leakage recharge from shallow high-TDS groundwater to the deep semiconfined aquifer. The most plausible explanation for similar variations among As, Fe(II) and total organic carbon (TOC) concentrations is the expected dissimilatory reduction of Fe(III) oxyhydroxides.     

地下水对气候变化的敏感性研究进展

地下水是人类生活、生产、生态用水的重要水源。地下水含水层的补给及其开发利用是水资源可持续开发利用与管理的重要组成部分。浅层地下水的补给主要受制于气候变异与变化。气候变化影响研究从地表水扩展至地下水不仅有利于正确地评估可利用的淡水资源,而且对于改进气候模型,更完整的描写水文循环有重要的科学意义。自21世纪以来,欧美等国开始研究不同时空尺度的地下水补给的定量估算方法,并在气候变化对水资源影响的研究中,考虑了气候变化与人类活动对地下水补给的影响。目前在我国,无论对地下水观测资料的诊断分析,或对地下水补给模型的研制都尚属空白或起步阶段。本文对当前国际上研究地下水补给以及地下水对气候变化敏感性的研究现状予以综述,目的是为了推动我国关于气候变化对水资源影响的深入研究。     

淄博孝妇河源区地下水资源的开发利用研究

在分析淄博市孝妇河流域源头的南神头－窑广地下水富水区水文地质条件的基础上，应用数值模拟方法建立了该区的地下水流模型，并根据当地的资源需求建立了地下水动态预测模型，研究了可能通过该区出流边界补给下游地区地下水的侧向排泄量。应用系统工程学和运筹学理论，以“开采费用最小”为目标函数，以研究区的需水量及开采井的供水作为约束条件，建立了该区的地下水最优控制模型。通过优化地下水开采布局对出流边界的流量进行了研究，既为富水区的地下水资源利用确定开采方案，又科学地评价地富水区北部边界对下游地区的地下水侧向补给量。     

A study on groundwater recharge in the Anyanghe River alluvial fan,North China Plain,based on hydrochemistry,stable isotopes and tritium

Studies on groundwater recharge are essential for sustainable exploitation of groundwater resources, especially in areas of extensive groundwater exploitation such as the Anyanghe River alluvial fan (ARAF) in the North China Plain (NCP). However, the recharge sources and processes and the contribution of each recharge flow component remain unclear. This study used hydrochemistry, stable isotopes, and tritium to investigate sources and underlying processes of groundwater recharge, along with the steady flow Mixing Cell Model (MCMsf) to quantify the proportion of each source flow for the shallow confined groundwater system in the medial fan. The results showed that groundwater mainly originates from precipitation occurring on the eastern Taihang Mountain area with average elevation estimated at 700–1,000 m above sea level during the East Asia summer monsoon period since 1952. Recharge mechanisms are: (1) river water seepage for the unconfined aquifers of the proximal and medial fan; (2) lateral flow for the confined aquifers of the medial and distal fan; and (3) precipitation infiltration for the phreatic water system. The MCMsf simulation showed that the shallow confined groundwater system in the central zone of the medial fan mainly recharged by the lateral flow from the proximal fan, a constant and considerable recharge flow from the southwestern and southern hills, and river water seepage in the medial fan; the lateral recharge flow from the Zhanghe alluvial aquifer was insignificant by comparison. The results of this study can act as a valuable reference for sustainable groundwater management in the ARAF.

     

Numerical modeling the role of rubber dams on groundwater recharge and phreatic evaporation loss in riparian zones

Rubber dams have been widely built for their advantages in increase of flooding resources utilization in the north arid and semiarid plain regions of China. Rise in river water stage by the dams, particularly during the drought periods, increases lateral seepage of river water into groundwater, and thus groundwater table and phreatic evaporation loss in the riparian zones. In this study, a riparian area of the Baihe River in Nanyang of Henan Province, China was selected for investigation of influences of the river dams on the groundwater recharge and evaporation loss. A hydraulic model, HEC-RAS, was used for simulation of the river stage variations along the Baihe River, and a numerical groundwater model, MODFLOW, was applied for simulation of groundwater dynamics and estimation of river flow seepage into aquifer and evaporation loss. The results show that the dams increase river stages of 2–3 m during January 2000–December 2002. The increase in the captured groundwater recharge was 7.15–34.06 million m³/a and the increased phreatic evaporation loss occupies 10% of the increased recharge when four rubber dams were built.     

Assessment of groundwater recharge and water fluxes of the Guarani Aquifer System, Brazil

The groundwater recharge and water fluxes of the Guarani Aquifer System in the state of Sao Paulo in Brazil were assessed through a numeric model. The study area (6,748 km²) comprises Jacaré-Guaçú and Jacaré-Pepira River watersheds, tributaries of the Tietê River in the central region of the state. GIS based tools were used in the storage, processing and analysis of data. Main hydrologic phenomena were selected, leading to a groundwater conceptual model, taking into account the significant outcrops occurring in the study area. Six recharge zones were related to the geologic formation and structures of the semi-confined and phreatic aquifer. The model was calibrated against the baseflows and static water levels of the wells. The results emphasize the strong interaction of groundwater flows between watersheds and the groundwater inflow into the rivers. It has been concluded that lateral groundwater exchanges between basins, the deep discharges to the regional system, and well exploitation were not significant aquifer outflows when compared to the aquifer recharge. The results have shown that the inflows from the river into the aquifer are significant and have the utmost importance since the aquifer is potentially more vulnerable in these places.     

大清河流域平原区地下水人工补给潜力与补给方式分析

为了有效提升大清河流域平原区地下水水位,亟需在此区域开展地下水人工补给工程,并确定合理的建设位置及有效的补给方式。首先基于研究区可利用补给水源、地下水位、地表高程、地表坡度及与河道距离5个指标的分布特征,构建地下水补给潜力评价体系,采用ArcGIS空间分析功能对研究区进行了地下水人工补给潜力区划;然后在此评价体系基础上,在典型人工补给高潜力区进一步开展系列野外现场试验,探讨适宜可行的地下水人工补给方式。结果表明：研究区西北部及南部河道附近区域开展人工补给工程潜力较高,而中部、北部及西南部远离河道的区域潜力较低。高潜力区——白沟引河地段包气带及含水层渗透性良好,整体渗透系数均在5 m/d左右或更高,适宜地表补给,但河床渗透性较差,渗透系数基本在0.01~0.09 m/d间,若通过河道补给需配合清淤等措施。其中,在上游及中游沿岸适宜将河道水通过生态水渠引至修建的地表入渗池或借助天然渗坑内入渗补给,在中下游沿岸区域适宜将补给水进行严格的水处理后采用井灌方式补给,在白沟引河中下游河道适宜修建拦水坝,利用河道进行入渗补给。     

Numerical groundwater-flow modeling to evaluate potential effects of pumping and recharge: implications for sustainable groundwater management in the Mahanadi delta region,India

Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997–2006, followed by validation (2007–2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.     

Pollution vulnerability of the Quaternary aquifer near Cairo, Egypt, as indicated by isotopes and hydrochemistry

The present study was conducted to delineate the pollution vulnerability of the Quaternary aquifer in two areas, Imbaba and Shobra El-Khima, near Cairo, Egypt. Environmental isotopes combined with hydrochemistry were used for this purpose. The groundwater in the Imbaba area (average total dissolved solids about 900 mg/L; sodium/chloride, sulfate, and bicarbonate water types) is more mineralized than groundwater in the Shobra El-Khima area (average total dissolved solids 500 mg/L; calcium and sodium/bicarbonate water type). A high nitrate content and significant mineralization in the groundwater are probably due to contamination of recharge to the aquifer by irrigation drainage, deteriorated sewage networks, and septic tanks. The deuterium and oxygen-18 compositions of the groundwater are depleted compared to Nile River water, which is the main source of aquifer recharge. This less isotopically enriched water probably represents older Nile water recharge that flooded the region before construction of the Aswan High Dam in 1963, or it is a mixture of a young water and originally deposited paleowater that was in deeper horizons at a time of cooler and more humid climate. Intensive pumping has moved the paleowater higher in the aquifer. Groundwater in the Shobra El-Khima area has higher residence time, based on the tritium concentration, than groundwater in the Imbaba area. The percentage of the isotopically depleted water equals 75% in the Shobra El-Khima and 35% in Imbaba, and the thickness of the clay cap above the aquifer is 38 m in Shobra El-Khima and 20 m in Imbaba. These factors are indicative of the rate of recharge to the aquifer and were used to evaluate the pollution vulnerability in the two areas. Electronic Publication     

伊犁河支流大西沟河水与地下水转化关系研究

开展河流和地下水转换关系研究对于区域水资源合理开发利用具有重要意义。文章以大西沟河水与地下水转换关系为目标,在分析地下水动力场的基础上,通过水化学类型、溶解性总固体(TDS)、氯离子（Cl-）等水化学以及环境同位素18O、D、T等指标作为示踪剂,分析大西沟河和地下水的转换关系和转化强度。结果表明:研究区河流和地下水化学类型主要为HCO3—Ca,水化学类型空间分布特征相似;TDS和Cl-浓度表现为先增加后下降,但地下水的变化幅度大于河水。通过对大西沟河水和地下水中的水化学和环境同位素指标对比分析,发现研究区河流与地下水之间补给排泄关系具有明显的分段性;从河流出山口到下游地区,河水和地下水之间发生了三次转化关系:在山前倾斜砾质平原区以河水入渗补给地下水为主,补给量占该段潜水径流量的56%;到了细土平原区出现地下水补给河水地段,补给源为承压水越流补给潜水后的混合水体,潜水和承压水补给比例占该段河水径流量的20.4%与58.4%;风成沙漠区河水沿途渗漏补给地下水直至河流断流。本次研究结果为建立研究区水循环演化模式和水资源合理开发利用提供了理论和技术支持。     

黑河中游盆地南部山区地下水对平原区侧向径流补给量的估算

山区地下水对平原区的侧向径流补给量是一个长期争议且悬而未决的难题,这个量在西北内陆干旱盆地,被估算得或很小或很大。在总结前人研究的基础上,采用地质水文地质调查、物探、钻探、抽水试验、地下水动态观测、水化学测试、盆地地下水水位统测和综合研究等技术方法,查明了黑河中游盆地南部山盆交接带的地质构造接触关系、地层岩性接触关系及梨园河口白垩系风化壳含水层结构和水文地质参数。通过山区不同流域等级的地表水与地下水转化关系分析,将山区地下水对平原区侧向径流补给带划分为大中型河流河谷补给段和小微型河流或冲沟群流域构成的浅山带补给段。河谷补给段勘探资料较为丰富,多用达西断面流方法计算;针对浅山带补给段极为缺乏勘探资料的实际,以梨园河口断面径流量为参照,构建了浅山带岩性、汇水区面积、降水量等3 个变量的山区地下水对平原区侧向径流补给量的估算方法。估算出黑河中游盆地南部山区浅山带地下水对平原的侧向径流补给量为0.40×108 m3/a,河谷段基岩侧向补给量为0.07×108 m3/a;推算出河谷段第四系地下水补给量为0.30×108 m3/a;3 项补给量之和为0.77×108 m3/a,占盆地地下水资源量的3.0%。该研究为西北内陆干旱盆地山区地下水对平原区侧向径流补给量的估算提供了一个可供借鉴的实例。     

Determination of water balance equation components in irrigated agricultural watersheds using SWAT and MODFLOW models : A case study of Samalqan plain in Iran

Increasing water demands,especially in arid and semi-arid regions,continuously exacerbate groundwater as the only reliable water resources in these regions.Samalqan watershed,Iran,is a groundwater-based irrigation watershed,so that increased aquifer extraction,has caused serious groundwater depletion.So that the catchment consists of surface water,the management of these resources is essential in order to increase the groundwater recharge.Due to the existence of rivers,the low thickness of the alluvial sediments,groundwater level fluctuations and high uncertainty in the calculation of hydrodynamic coefficients in the watershed,the SWAT and MODFLOW models were used to assess the impact of irrigation return flow on groundwater recharge and the hydrological components of the basin.For this purpose,the irrigation operation tool in the SWAT model was utilized to determine the fixed amounts and time of irrigation for each HRU(Hydrological Response Unit)on the specified day.Since the study area has pressing challenges related to water deficit and sparsely gauged,therefore,this investigation looks actual for regional scale analysis.Model evaluation criteria,RMSE and NRMSE for the simulated groundwater level were 1.8 m and 1.1%respectively.Also,the simulation of surface water flow at the basin outlet,provided satisfactory prediction(R²=0.92,NSE=0.85).Results showed that,the irrigation has affected the surface and groundwater interactions in the watershed,where agriculture heavily depends on irrigation.Annually 11.64 Mm3 water entered to the aquifer by surface recharge(precipitation,irrigation),transmission loss from river and recharge wells 5.8 Mm3 and ground water boundary flow(annually 20.5 Mm³).Water output in the watershed included ground water extraction and groundwater return flow(annually 46.4 Mm³)and ground water boundary flow(annually 0.68 Mm³).Overally,the groundwater storage has decreased by 9.14 Mm3 annually in Samalqan aquifer.This method can be applied to simulate the effects of surface water fluxes to groundwater recharge and river-aquifer interaction for areas with stressed aquifers where interaction between surface and groundwater cannot be easily assessed.     

Evaluation of climate change effects in a coastal aquifer in Morocco using a density-dependent numerical model

A density-dependent numerical groundwater model was applied to study the climate change impact in a shallow aquifer in the Mediterranean coast of Morocco, the Saïdia aquifer. The stresses imposed to the model were derived from the IPCC emission scenarios and included recharge variation and sea level rise. The main effect of the climate change in the Saïdia aquifer will be a decrease in renewable resources, which in the worst-case scenario may decrease to 50–60% of present-day values, due to the decline in recharge and to a reduced inflow from the adjacent Triffa aquifer. The water quality will be affected mostly in the area immediately adjacent to the seashore, where salinity may increase up to 30 g/l. Localised areas may see a decrease in salinity due to the induced freshwater recharge from Oued Moulouya River and diminished inflow from high-salinity springs.