河渠水位曲线回水影响半无限含水层河渠附近地下水非稳定流计算

本文探讨河渠水位呈曲线变化时,河渠附近地下水非稳定运动问题。抛开经典河渠附近地下水非稳定渗流理论之瞬时回水的假设条件,重新推导河渠影响半无限潜水含水层地下水非稳定流计算公式。应用数值逼近的理论、逼近河渠水位变化规律。给出河渠水位以任意次多项式规律变化的一系列地下水非稳定流计算公式。从理论上证明了瞬时回水假设的根本矛盾,并用一实际例子对比计算加以验证。指出了抛弃瞬时回水的假设条件,重新建立一套全新的河渠附近地下水非稳定流理论的必要性。     

江坪河水库库首右岸梅坪─曲溪河间地块岩溶发育特征与渗漏可能性分析

江坪河水库坝址地段具有在高坝的地形、地貌与地质条件．但是，库首右岸发育出圩一曲溪河间地块，其上广布岩溶强烈发育的寒武系一奥陶系戳欧盐岩．岩溶渗漏问是该坝址方案能否成立的关键．本文研究了河间地块上岩溶及岩溶地下水系统发育规律，运用物探手段，综合地质及水文资料，探讨了河间地块上地下水位分布特点，认为该河间地块上存在地下水位高于正常富水位的地下分水岭，不存在岩溶渗漏问题．     

江坪河水库库首右岸梅坪—曲溪河间地块岩溶发育特征与渗漏可…

江坪河水库坝址地段具有建高坝的地形、地貌与地质条件，但是，库首右岸发育梅坪－曲溪河间地块，其上广布岩溶强烈发育的寒武系－奥陶系碳酸盐岩，岩深渗漏问题是该坝址方案能否成立的关键，本文研究了河间地块上岩溶及岩溶地下水系统发育规律，运用物深手段，综合地质及水文资料，探讨了河间地块上地下水位分布特点，认为该河间地块上存在地下水位高于正常蓄水位的地下分水岭，不存在岩溶渗漏问题。     

消除气压效应估算黄土潜水的蒸发蒸腾强度

潜水蒸发蒸腾（ET_g）是干旱半干旱地区浅埋深地下水最主要的排泄方式,也是地下水系统中重要的均衡项。如果存在气压效应,用于估算地下水蒸发蒸腾强度的传统水位波动法则不适用。以黄土潜水为例,提出了一种基于水位变化和大气压变化规律的水位图方法,用于消除气压效应以获取潜水蒸发蒸腾强度。研究表明,大气压变化通常在午夜前,一般为22:00—24:00,会出现一个峰值,该时间段气压效应可以忽略,而且潜水蒸发蒸腾强度最小,此时潜水位的变化速率相当于净补给速率;在获取潜水净补给强度后,选择第二个时间段,0:00—4:00,此时潜水蒸发蒸腾强度最小,且气压一般处于连续下降阶段,可以用来估算气压效应系数。在此基础上,可利用水位均衡和水位波动法方便地估算潜水蒸发蒸腾强度。该方法数据获取容易,估算结果也较为准确。     

初析鄂尔多斯高原浅循环地下水水位动态

地下水水位变化是地下水系统对外界激励（包括气象、水文、人类工程活动、固体潮和地球内部构造应力等）的一种响应,外界对地下水系统任何微弱的＂扰动＂,均会导致地下水水位的变化,只是由于地下水水位对不同激励的＂敏感性＂不同,所表现出来的水位动态变化特征也不同。最明显的水位变化,是受控于地下水的补给和排泄条件。本文在对鄂尔多斯高...     

下辽河平原地下水多年动态变化特征分析

地下水水位动态变化,实际上是含水层中地下水资源量变化的一种反映,地下水水位的升降,直接反映了地下水补给与消耗量的变化.依据多年地下水水位监测数据,总结分析了下辽河平原1996~2005年间孔隙潜水的变化特征及趋势.揭示了孔隙潜水或孔隙承压水在多年升降变化过程中水位动态主要随降水量的变化而变化.此外,地下水开采规模、局部开采布局的调整等措施,也是影响其变化特征的主要因素.     

河北省滦县李家屿灰场2#副坝区灰水运动的水文地质评价

韩家哨村位于河北滦县李家屿灰场北部谷地,地势低于灰场,距离约800m。灰场运行期间,该区地下水出现水位升高及水质变差等问题。本文从水文地质条件角度,详细研究灰水的运移途径及其对该区地下水的影响。韩家哨村区域地下水系统分为上层滞水和孔隙一裂隙（溶隙）潜水含水层系统。潜水含水层系统水力传导系数为172．6～203．4m^2／d。地下水补给主要来源于韩家哨村以南坝后地形较高区域及灰水。灰水渗漏优势区韩家哨村南部宽约200m的带状区域。灰场堆灰形成新的地下水分水岭致使灰水在20副坝坝前垂直下渗进入风化带,沿白云岩裂隙（溶隙）补给潜水含水层,并向韩家哨村区域流动补给孔隙含水层,改变后的潜水部分通过民井向外排泄。     

黄泛平原区（1∶25万济南幅）浅层孔隙水多年动态变化特征

分析济南幅黄泛平原区浅层孔隙水的补给来源、地下水流场形态变化、地下水排泄途径及水化学多年变化特征,并结合区内浅层地下水开采强度资料综合研究认为,引起济南幅黄泛平原区浅层孔隙水动力场变化的主要原因是地下水开采量的变化与天然补给源的减少。研究表明,局部水位下降甚至产生超采漏斗主要是由于地下水长期过量开采引起的,并对区域地下水流场形态影响较大,区内已形成地下水分水岭。     

三元连通试验在岩溶渗漏研究中的应用

本文应用Cr、Mo、Cu三种化学元素对江坪河水电站河间河湾地块进行了三元连通试验,查明了长度分别为5 250m、7 200m、2 200m的3条岩溶管道的空间分布,为分析河间河湾地块中的地下水流向、地下水分水岭空间分布,同时为后期的勘探布设和渗漏条件分析提供了科学依据。     

基于同位素与水化学分析法的地下水补径排研究——以苏锡常地区浅层地下水为例

在分析研究区浅层地下水空间分布特征的基础上,采用同位素与化学分析相结合的方法研究苏锡常浅层地下水的补径排条件。利用氢氧同位素的分析结果,建立潜水与微承压水的δD-δ18O关系曲线,分析潜水含水层与河流、湖泊等地表水体关系以及微承水的蒸发程度;利用放射性同位素氚与14C研究微承水与现代水的补给关系;利用常规的水化学分析方法研究浅层地下水补给源的变化问题。结合研究区地下水水位、地层岩性、地形、地貌等多方面因素综合分析了浅层地下水的补径排条件,从而指导苏锡常地区浅层地下水合理开发利用。     

Artificial recharge of groundwater: hydrogeology and engineering

Artificial recharge of groundwater is achieved by putting surface water in basins, furrows, ditches, or other facilities where it infiltrates into the soil and moves downward to recharge aquifers. Artificial recharge is increasingly used for short- or long-term underground storage, where it has several advantages over surface storage, and in water reuse. Artificial recharge requires permeable surface soils. Where these are not available, trenches or shafts in the unsaturated zone can be used, or water can be directly injected into aquifers through wells. To design a system for artificial recharge of groundwater, infiltration rates of the soil must be determined and the unsaturated zone between land surface and the aquifer must be checked for adequate permeability and absence of polluted areas. The aquifer should be sufficiently transmissive to avoid excessive buildup of groundwater mounds. Knowledge of these conditions requires field investigations and, if no fatal flaws are detected, test basins to predict system performance. Water-quality issues must be evaluated, especially with respect to formation of clogging layers on basin bottoms or other infiltration surfaces, and to geochemical reactions in the aquifer. Clogging layers are managed by desilting or other pretreatment of the water, and by remedial techniques in the infiltration system, such as drying, scraping, disking, ripping, or other tillage. Recharge wells should be pumped periodically to backwash clogging layers. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s10040-001-0182-4. Electronic Publication     

Interactions of diffuse and focused allogenic recharge in an eogenetic karst aquifer (Florida, USA)

The karstic upper Floridan aquifer in north-central Florida (USA) is recharged by both diffuse and allogenic recharge. To understand how recharged water moves within the aquifer, water levels and specific conductivities were monitored and slug tests were conducted in wells installed in the aquifer surrounding the Santa Fe River Sink and Rise. Results indicate that diffuse recharge does not mix rapidly within the aquifer but instead flows horizontally. Stratification may be aided by the high matrix porosity of the eogenetic karst aquifer. Purging wells for sample collection perturbed conductivity for several days, reflecting mixing of the stratified water and rendering collection of representative samples difficult. Interpretive numerical simulations suggest that diffuse recharge impacts the intrusion of allogenic water from the conduit by increasing hydraulic head in the surrounding aquifer and thereby reducing influx to the aquifer from the conduit. In turn, the increase of head within the conduits affects flow paths of diffuse recharge by moving newly recharged water vertically as the water table rises and falls. This movement may result in a broad vertical zone of dissolution at the water table above the conduit system, with thinner and more focused water-table dissolution at greater distance from the conduit.     

Flash flood mitigation as a positive consequence of anthropogenic forcing on the groundwater resource in a karst catchment

The Mediterranean coastal region is prone to high-intensity rainfall events that are frequently associated with devastating flash floods. This paper discusses the role of a karst aquifer system in the flash floods of a Mediterranean river, the Lez river. Most of the Lez river watershed is located on karst terrains where interactions between surface water and groundwater take place. During extreme rainfall events, the presence of fractures and well-developed karst features in carbonate terrains enhances the infiltration processes and involves the concentration of the recharge into highly organized and permeable flow paths. The groundwater, therefore, quickly moves towards the natural outlets of the karst system. The influence of the Lez karst aquifer system on the associated river floods dynamics is analysed while considering the spatially distributed rainfall, as well as the time series of the groundwater level within the aquifer and of the Lez river discharge measured at various gauging stations. Special attention is given to the relative importance of the surface and underground processes involved in flash flood genesis. It is shown that the karst groundwater contributes to flash floods under certain conditions, while high-rate pumping within the karst aquifer, which generates significant drawdown, may mitigate flash floods under other conditions.     

Control of sea-water intrusion by salt-water pumping: Coast of Oman

A shallow alluvial coastal aquifer in the Batinah area of Oman, with sea-water intrusion that extends several kilometres inland, has been studied experimentally, analytically and numerically. The water table is proved to have a trough caused by intensive pumping from a fresh groundwater zone and evaporation from the saline phreatic surface. Resistivity traverses perpendicular to the shoreline indicated no fresh groundwater recharge into the sea. Using an analytical Dupuit-Forchheimer model, developed for the plain part of the catchment, explicit expressions for the water table, sharp interface location and stored volume of fresh water are obtained. It is shown that by the pumping of salt water from the intruded part of the aquifer, this intrusion can be mitigated. Different catchment sizes, intensities of fresh groundwater pumping, evaporation rates, water densities, sea level, incident fresh water level in the mountains and hydraulic conductivity are considered. SUTRA code is applied to a hypothetical case of a leaky aquifer with line sinks modeling fresh water withdrawal and evaporation. The numerical code also shows that pumping of saline water can pull the dispersion zone back to the shoreline.     

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.     

Remote sensing and GIS for artificial recharge study, runoff estimation and planning in Ayyar basin, Tamil Nadu, India

This paper focuses on artificial groundwater recharge study in Ayyar basin, Tamil Nadu, India. The basin is covered by hard crystalline rock and overall has poor groundwater conditions. Hence, an artificial recharge study was carried out in this region through a project sponsored by Tamil Nadu State Council for Science and Technology. The Indian Remote Sensing satellite 1A Linear Imaging Self Scanning Sensor II (IRS 1A LISS II) satellite imagery, aerial photographs and geophysical resistivity data were used to prioritize suitable sites for artificial recharge and to estimate the volume of aquifer dimension available to recharge. The runoff water available for artificial recharge in the basin is estimated through Soil Conservation Service curve number method. The land use/land cover, hydrological soil group and storm rainfall data in different watershed areas were used to calculate the runoff in the watersheds. The weighted curve number for each watershed is obtained through spatial intersection of land use/land cover and hydrological soil group through GeoMedia 3.0 Professional GIS software. Artificial recharge planning was derived on the basis of availability of runoff, aquifer dimension, priority areas and water table conditions in different watersheds in the basin.     

New system for the assessment of annual groundwater recharge from rainfall in the United Arab Emirates

In this study, the first groundwater recharge map for United Arab Emirates (UAE) was developed using the recharge potential and water table fluctuation methods. Recharge potential estimates were made using information about infiltration rate, soil type, ground slope, geological and hydrogeological factors, and the availability of rainfall harvesting infrastructure and were validated by measurements of water table rise in alluvial aquifers in wadis. Based on this information, the total recharge in the UAE is estimated to be about 133 million cubic meters per year (MCM/year). Annual recharge rates are calculated to vary between 1 and 28% of precipitation in the different regions of UAE depending on several natural and manmade parameters including, among others, recharge enhancing infrastructure. Estimates from the two methods are 98% in agreement; which suggests that the recharge potential method is suitable for estimating aquifer’s recharge in UAE and arid regions. The water table fluctuation method was found to be more suitable for assessing recharge through gravel plains and wadis in mountainous areas.     

Artificial groundwater recharge to a semi-arid basin: case study of Mujib aquifer,Jordan

Mujib watershed is an important groundwater basin which is considered a major source for drinking and irrigation water in Jordan. Increased dependence on groundwater needs improved aquifer management with respect to understanding deeply recharge and discharge issues, planning rates withdrawal, and facing water quality problems arising from industrial and agricultural contamination. The efficient management of this source depends on reliable estimates of the recharge to groundwater and is needed in order to protect Mujib basin from depletion. Artificial groundwater recharge was investigated in this study as one of the important options to face water scarcity and to improve groundwater storage in the aquifer. A groundwater model based on the MODFLOW program, calibrated under both steady- and unsteady-state conditions, was used to investigate different groundwater management scenarios that aim at protecting the Mujib basin. The scenarios include variations of abstraction levels combined with different artificial groundwater recharge quantities. The possibilities of artificial groundwater recharge from existing and proposed dams as well as reclaimed municipal wastewater were investigated. Artificial recharge options considered in this study are mainly through injecting water directly to the aquifer and through infiltration from reservoir. Three scenarios were performed to predict the aquifer system response under different artificial recharge options (low, moderate, and high) which then compared with no action (recharge) scenario. The best scenario that provides a good recovery for the groundwater table and that can be feasible is founded to be by reducing current abstraction rates by 20% and implementing the moderate artificial recharge rates of 26 million(M)m³/year. The model constructed in this study helps decision makers and planners in selecting optimum management schemes suitable for such arid and semi-arid regions.     

Groundwater geochemistry of a small reservoir catchment in Central Tunisia

Due to the scarcity of water resources in semiarid sedimentary basins, hill reservoirs are often constructed to recharge groundwater and limit runoff induced water loss. The impact of such reservoirs on groundwater chemistry is investigated in the aquifers of the El Gouazine watershed, Central Tunisia. Three groundwater types are recognised, Ca–HCO₃, Na–Cl and Ca–SO₄. The strong similarity between host rock and groundwater chemistries indicates significant rock–water interaction. A flowpath, along which the chemical composition of the groundwater evolves, can be identified using the contrast in stable isotope signature between upstream and downstream groundwater. Shallow upstream groundwater is recharged by the infiltration of rainwater with the rate of recharge strongly linked to the permeability of the host lithology. Calcium and HCO₃ are supplied to an alluvial aquifer from a more rapidly recharged limestone aquifer with the concentration of Ca and HCO₃ ions decreasing by dilution. The alluvial aquifer is also enriched in Ca and SO₄ during the downstream flow of groundwater through gypsiferous materials. There is evidence of mixing between meteoric groundwater and evaporated reservoir water. Below the reservoir and partly responsible for reservoir leakage is a sandy aquifer, formed by weathering and erosion of a sandstone host which also supplies water to the alluvial aquifer.