Assessment of Agricultural Drought Vulnerability in the Guanzhong Plain,China

The Guanzhong Plain, as an important traditional agricultural area, is suffering from high frequency droughts and a trend towards more serious drought. In this paper, eight factors, precipitation, evapotranspiration, surface water availability, depth to groundwater, well yield capacity, slope, potential water storage of soil, and GDP from agriculture, are integrated into an index to represent drought vulnerability based on the overlay and index method. In this approach, according to the internal connections between factors, precipitation and evapotranspiration are integrated into the moisture index, and depth to groundwater and well yield capacity are integrated into groundwater availability. To improve the rationality and accuracy, normalization is employed to assign rating values, and the analytic hierarchy process is introduced into the weighting scheme. Two local drought monitoring datasets endorses the results of the model. The map removal sensitivity analysis indicates the vulnerability index has low sensitivity in removing each layer. The single-parameter sensitivity analysis indicates the major contribution to the vulnerability index is meteorology followed by groundwater availability and surface water availability. The vulnerability map shows the low vulnerability coincides roughly with irrigation districts on the terraces and floodplains. The northwest tableland generally has moderate vulnerability, due largely to inefficient groundwater withdrawal. The high vulnerability is concentrated at the peripheries of the plain, where agriculture is generally rain-fed without irrigation and groundwater support, and land is rugged with high slopes.     

Identifying Major Factors Controlling Groundwater Quality in Semiarid Area Using Advanced Statistical Techniques

There are many factors controlling groundwater pollution and vulnerability. However, the factors’ weights are still not reasonably investigated. In order to assess groundwater quality and the controlling factors in semiarid region, 178 groundwater samples were collected and analyzed for salinity and nitrate content. New statistical techniques of prediction profiler and hierarchical cluster combined with geographic information systems (GIS) were used to assess the groundwater quality based on three categorical controlling factors; landuse/ land cover (LULC), soil texture, and aquifer type. It is hypothesized these factors are controlling groundwater quality with various weights. Groundwater salinity across the study area varied from 327.0 to 9110.0 mg/L, while nitrate ranged from 0.2 mg/L to 339.6 mg/L. Both prediction profiler and cluster analyses provided excellent tools for quantifying the pollution magnitudes, weighing the controlling factors, and visualizing the pollution zones. Prediction profiler showed high capability to predict groundwater pollution (P?<?0.0001 and 0.0038 for salinity and nitrate, respectively) where LULC was the most effective factor, followed by aquifer type and soil texture class. According to desirability function analysis, maximum salinity and nitrate pollution was predicted to be associated with irrigated agriculture lands at shallow aquifers with silty clay loam soils. Hierarchical cluster analysis combined with GIS mapping was able to group the controlling factors into six vulnerability zones. The generated groundwater spatial pollution map allowed for potential pollution sources identification (e.g. fertilizer use, treated waste water, overdrafting). This paper also offers detailed mapping for decision makers to allow further ecosystem restoration and rehabilitation planning.     

Intrinsic Vulnerability Assessment for the Alluvial Aquifer in the Northern Part of Jordan Valley

The Northern Jordan Valley (NJV) is an important and significant water basin in Jordan where most of Jordan’s agricultural crops are produced. Knowing that the aquifer system is mainly composed of alluvial deposits, it is important to assess the potential of ground water for pollution. For this purpose intrinsic vulnerability was assessed using SINTACS model with the aid of geographic information system (GIS) techniques. The final results show that about 40% of the investigated area has been classified as high to very high vulnerable to groundwater pollution. These results were correlated with measured concentration of nitrate (NO₃^-1)_{3}^{-1}) at different locations. A high correlation was found between areas of high nitrate concentrations and those of high vulnerability category. To validate the model results, a sensitivity analysis has been carried out to assess the influence of each of SINTACS parameters on the obtained vulnerability values. It was found that the soil overburden attenuation capacity parameter (T) and the depth to the groundwater parameter (S) are the most sensitive parameters to SINTACS vulnerability model. The effective-weights analysis was also performed in this study to revise the weights in the computed vulnerability index. It was noticed that the effective weights for each parameter were sometimes varies from the theoretical weights assigned by the SINTACS method.     

A GIS-based DRASTIC Model for Assessing Aquifer Vulnerability in Kherran Plain, Khuzestan, Iran

The Kherran plain is located in the northeast of Ahwaz in Khuzestan Province, Iran. The state of groundwater pollution is a critical issue with increasing population and agricultural development in Iran. For this reason, vulnerability assessment is an important factor in any policy making decision in any part of country. Focusing on this issue, the article attempts to presents a groundwater vulnerability map for the Kherran plain. The map designed to show areas of highest potential for groundwater pollution based on hydro-geological condition and human impacts. Seven major hydro-geological factors (Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone and hydraulic Conductivity) were incorporated into DRASTIC model and geographical information system (GIS) was used to create a groundwater vulnerability map by overlaying the available hydro-geological data. The output map shows that the west and southwest of the aquifer are under medium vulnerability while small areas on northwest and east of the study area have no risk to pollution. Other parts of aquifer have low vulnerability. For testing of the vulnerability assessment, 27 groundwater samples were collected from the different vulnerability zones of the study area. The chemical analysis results show that the southwest and west parts of aquifer (moderate vulnerability zones) have higher nitrate concentration relative to the rest of aquifer, that are located in low vulnerability zone.     

天山北坡经济带东段浅层地下水固有脆弱性评价

基于改进的DRASTIC方法,选择地下水埋深、含水层净补给量、含水层岩性、土壤介质类型、地面坡度、浅层地下水水质、包气带介质类型、含水层渗透系数和潜水蒸发量9项评价指标,分别确定其评分体系和权重体系,并利用Arc Gis 10.2中的图层空间叠加分析功能,对天山北坡经济带东段地区的浅层地下水固有脆弱性进行评价。结果表明:脆弱性较高区和中等区占研究区总面积的80.17%,地下水整体脆弱性偏高,而导致研究区浅层地下水脆弱性偏高的主要因素为地下水埋深较小、含水层渗透性较强、浅层地下水水质差。     

尖点突变模型在地下水特殊脆弱性评价中的应用

根据长春城区半承压含水层的具体状况,用突变理论进行脆弱性评价。将含水层厚度等7个评价因子划分为两个综合因子,以这两个综合因子为控制变量建立地下水特殊脆弱性状态的尖点突变模型,分析了脆弱性的突变特征,对地下水特殊脆弱性进行评价,绘制评价图,为地下水资源的科学管理提供依据。     

基于复合权重-GIS的下辽河平原地下水脆弱性评价

在传统的DRASTIC模型基础上,结合下辽河平原的实际情况,从水质和水量两方面考虑,建立下辽河平原地下水脆弱性评价指标体系。通过层次分析法(AHP)与熵权法确定评价指标在满足主客观条件下的综合权重。结合GIS的地图计算功能对该地区的地下水脆弱性进行评价,同时用硝酸盐氮的质量浓度对评价结果进行了验证。评价结果表明下辽河平原50.39%的地区地下水脆弱性较高,并且相对于脆弱性低的地区有较高的硝酸盐氮浓度。     

云南曲靖盆地地下水脆弱性模糊评价

在DRASTIC指标的基础上,运用层次分析法构建了云南省曲靖盆地地下水脆弱性指标体系,并采用多级二层模糊评价方法进行脆弱性评价。结果表明:曲靖盆地地下水脆弱性分区为四级,西部基岩地下水和孔隙水脆弱性高,东部的孔隙水及少量岩溶水处于脆弱性中等。评价结果有利于地下水环境的保护。     

平原河网区地下水污染风险评价体系及其应用

针对平原河网地区特征,结合地下水污染影响因素及途径分析,建立了包含地下水本质脆弱性、地表水系和地下工程特殊脆弱性以及污染源荷载3个部分16个指标的地下水污染风险评价体系,并以上海市金山区为例进行案例解析。结果表明:金山区地下水脆弱性较高,中等脆弱以上级别面积达到449.80 km~2,占评价区面积的70.67%,主要受本质脆弱性和地表水系特殊脆弱性较高影响叠加而成;地下水污染源荷载评价"中"级别以下风险区面积达到555.44 km~2,面积占比达87.27%,其主要潜在污染源为化工类工业园区及加油站;金山区地下水污染风险整体处于较低级别状态,"中"以下级别风险区面积为553.38 km~2,"低"级别风险区面积为231.13 km~2,"高"级别风险区主要集中在金山南部,是该区域较高的地下水脆弱性、密集的工业区等多因素综合叠加的结果。     

Groundwater Quality Zonation Assessment using GIS, EOFs and Hierarchical Clustering

Three methods are utilized in this paper to assist in the groundwater clustering, in an arid region aquifer, into similar zones according to its quality. A multiple regression is first applied in order to assess the importance of the different chemical constituents in the amount of total dissolved salt, which shows the dominance of chlorine and sodium. A multivariate analysis based on empirical orthogonal functions and hierarchical clustering (EOFs) is applied to assist in water quality clustering in the studied aquifer. The clustering has produced five distinguished categories of groundwater quality, which agree well with World Health Organisation criteria and limits for water usage. Based on these categories, spatial distribution maps of groundwater quality are produced by Kriging and GIS software.     

基于WPI模型的重庆市水资源安全分析

为综合评价重庆市水资源安全情势,分析多重背景下水资源安全影响因素,以WPI模型构建水资源安全评价指标体系,该体系分为5个子系统资源(R)、途径(A)、效率(U)、能力(C)和环境(E)。采用加权函数法计算1997—2013年重庆市水资源安全综合评价指数和5个子系统得分值,并利用因子分析法进行对比分析;建立水资源安全因素判定模型,对子系统进行优等、中等、劣等因素划分。结果表明重庆市水资源安全值呈阶梯式上升,趋势系数为0.022 8 /a,水资源安全状况趋于好转,并且与因子分析对比结果基本一致;但各子系统时序变化差异较大,途径和能力子系统分值逐年上升,资源和环境子系统分值比早年有所下降,该阶段的效率子系统分值变化不大;因素评判结果显示,途径因素和能力因素随着时间推移而不断提高,从劣等因素变为优等因素,但资源和环境因素却逐渐演变为重庆市水资源安全的劣等因素,效率因素降为中等因素。未来重庆市水资源安全存在一定风险,需加强水资源管理和水环境改善,提高公民节水意识来加以防范。     

Evaluation of a GIS-Based Integrated Vulnerability Risk Assessment for the Mancha Oriental System (SE Spain)

It is widely recognized that groundwater-vulnerability maps are a useful tool for making decisions on designating pollution-vulnerable areas, in addition to being a requirement of European Directive 91/676/EEC. This study addressed the vulnerability of the Mancha Oriental System (MOS) to groundwater contamination with an integrated Generic and Agricultural DRASTIC model approach. In the MOS, groundwater is the sole water resource for a total population of about 275,000 inhabitants and for 1,000 km² of irrigated crops. DRASTIC vulnerability maps have been drawn up for two different years (1975 and 2002) in which the potentiometric surface has dropped dramatically (80 m in some areas) due to the considerable expansion of irrigated croplands. The quality of available resources has also deteriorated due to the agricultural practices and the discharge of wastewater effluents. Vulnerability maps are used to test the data on nitrate, sulphate, and chloride contents in groundwater in the Central and El Salobral-Los Llanos hydrogeologic domains of the MOS for 2002. Regardless of the method applied, the dramatic alteration in land use leads to a change in the DRASTIC index and vulnerability to groundwater contamination decreases for the study period. Vulnerability in the MOS increases in areas where the irrigation return flow is notable. The lack of a statistical correspondence between the DRASTIC index and the spatial distribution of nitrate, chloride, and sulphate contents and the distribution of the pollution load suggest that this method does not accurately assess the risk of the MOS to groundwater pollution.     

页岩气开采区地下水脆弱性评价模型

为了更准确评价页岩气开采过程中水力压裂和废水回注对地下水的影响,需要采用不同指标体系的模型对地下水脆弱性进行评价。通过分析页岩气开采过程中污染物的潜在运移途径,在DRASTIC模型的基础上分别建立了开采井区地下水脆弱性评价模型DIRTEV和回注井区地下水脆弱性评价模型DIRWOCT。根据相关资料对模型中各评价因子进行了分级及评分,运用模糊综合矩阵法确定了各因子权重,并利用单参数法对评价结果进行了敏感性分析。对四川某页岩气采区的评价结果表明,所建模型能较好地应用于页岩气开采区地下水脆弱性评价。     

Groundwater Protection and Management Strategy in Jordan

Groundwater resources are essential in Jordan that require careful planning and management in order to sustain human socio-economic development and various ecosystems. However these vital resources are under the threat of degradation by both mismanagement and over-exploitation that leads to contamination and decline of water levels. A new by-law, which specifically addresses pollution prevention and protection of water resources used for domestic purposes through appropriate land use restriction and zoning, is currently under preparation in Jordan. This law (i.e., Groundwater Management Policy) addresses the management of groundwater resources including development, protection, management, and reducing abstraction for each renewable aquifer to the sustainable rate (i.e., safe yield). Groundwater vulnerability mapping and delineation of groundwater protection zones were implemented in different areas in Jordan in cooperation between the German Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) company and Ministry of Water and Irrigation. This paper presents the status of groundwater resources in Jordan and their major issues. It attempts to discuss the groundwater vulnerability and protection strategy and the impacts of over-exploitation on the groundwater aquifers in an integrated water resources management perspective.     

A New Approach for Aquifer Vulnerability Assessment: the Case Study of Campania Plain

We are going to propose a new method for aquifer vulnerability assessment, named Susceptibility Index-Contamination Degree (SICODE). Starting from the assumption that soil chemistry impacts on infiltration water quality, geochemical tool such as the soil contamination degree index (CD) was combined with hydrogeological parameters in order to enhance previous well-known index (DRASTIC, Susceptibility Index). The study has been carried out at the Campania Plain (CP) aquifer, which mostly supplies the drinking water distribution system of Napoli (Southern Italy). The survey area extends from Mt. Vesuvius to the metropolitan area of Napoli and it can be considered an interesting field laboratory in order to test hydro-geochemical methods and models since both diffuse anthropogenic pollution and natural contamination sources (e.g. interaction processes between groundwater and rock) coexist. Three models have been compared. Our results have showed that DRASTIC is not the best model to be applied to urbanized environments since it does not account for the anthropogenic influence. Susceptibility Index (SI), which incorporates land use parameter, has showed a more detailed map of vulnerability degree and it better answers the local variability of human pressure. However, the proposed SICODE method completely meets the geochemical fingerprint of soil. Sensitivity analysis has revealed a high variability of the parameters due to the local heterogeneity of the analyzed system conditions. A comparison between the groundwater nitrates distribution and the predicted vulnerability has showed that. SICODE gave more accurate predictions than the other ones. This study has provided the evidence that combining hydrogeological and geochemical tools may enhance aquifer vulnerability assessment.

     

天津市平原区第Ⅰ含水岩组地下水脆弱性评价研究

地下水脆弱性分区评价是合理开发利用地下水资源、防止地下水污染的重要基础性工作。传统的DRASTIC方法对评价参数赋予固定的经验性权重,存在一定缺陷。采用熵权法与层次分析法相结合的方法,对权重确定方法加以改进,并以易受污染的天津市平原区第Ⅰ含水岩组地下水为研究对象开展实例研究。改进权重的DRASTIC方法突出了影响程度大、原始数据较分散的净补给量、地下水埋深和包气带类型三项评价参数的权重值,剔除了影响不大且各评价单元原始数据相差很小的坡度参数。结果表明,天津市平原区第Ⅰ含水岩组地下水较低脆弱性分区、中度偏低脆弱性分区、中度偏高脆弱性分区、较高脆弱性分区和高脆弱性分区的面积比例分别为1.3%、22.3%、42.6%、31.2%、2.6%,具体分布与实际情况吻合较好。改进权重的DRASTIC方法可同时兼顾指标数据的分布特点和权重的经验性取值,对开展地下水脆弱性评价具有参考价值。     

Risk Assessment of Groundwater and its Application. Part II: Using a Groundwater Risk Maps to Determine Control Levels of the Groundwater

With the rapid development of economy, demand of water resources is becoming larger and larger, and over-exploitation of groundwater is common in many areas. Due to over-exploitation of groundwater over many years, a number of potential adverse hydrogeological problems have raised. To reduce such adverse effects, it is necessary to carry out strict groundwater management in over-exploited areas. And to achieve the strictest management of groundwater, it is critical to determine control levels of groundwater including the blue line levels (proper levels) and red line levels (warning levels). According to the establishment of evaluation model of shallow and deep groundwater exploitation and utilization risks, it can be observed that the groundwater level index factor is included in the evaluation index system in different groundwater function zones. Therefore, there is a corresponding relationship between the risk grade and groundwater level of different underground aquifers. The risk grade of different groundwater function zones in Tianjin is divided into five grades, which contributes to the risk management of groundwater, avoiding the arising of a wide range of risk management measure. However, to determine the key groundwater level, the standard of five grades cannot meet the requirements. The risk grades need to be divided more subtly. Hence, in this paper, the risk grade was divided according to the standard of sixteen grades based on that of five grades in the first place. The higher the grade is, the greater the risk. And then the occurrence frequency of risk grade for each aquifer was counted in each administrative district or country. The corresponding water level of the risk grade, whose occurrence frequency was the highest, served as the base level. The water level of groundwater that would be exploited and utilized in the future cannot be below this base level. In consequence, this water level that served as the red line level was the minimum requirement in the planning years, while the corresponding water levels of other risk grades that were inferior to this risk grade can all be seen as red line levels. And the planning period the long-term corresponding groundwater level of the aquifers under mining-banned condition can be used as blue line control levels of the different planning years. Finally, according to the determinate range of red line level change amplitude in each district or country, as well as the ultimate restoration aim of groundwater levels (blue line levels), corresponding measures were taken step by step to achieve the overall rising of groundwater levels. The obtained determinate control levels can provide a scientific basis for dynamic management of groundwater.     

兴平地区渭河南岸潜水防污性评价

在干旱半干旱地区,地下水是主要供水水源之一.目前水体污染、水资源短缺、水生态失衡,导致干旱半干旱地区经济发展与水安全保障的矛盾日益尖锐.以兴平地区渭河南岸为例,利用DRASTIC方法,选取潜水埋深、净补给量、含水层介质类别、土壤介质类别、地形坡度、包气带介质类别以及渗透系数为防污性7项评价因子,构建了潜水防污性评价指标体系,对该地区的潜水防污性进行了分区评价,将兴平地区渭河南岸的潜水防污性分为防污性差和防污性较差两个等级,并绘制了潜水防污性评价分区图,为该地区工农业生产的发展和城市规划提供了科学的依据.     

土水比指标在天津沉降区地下水资源管理中的应用

天津地面沉降形势严峻,加强地下水资源管理是控制地面沉降的关键。理论和实践证明,可开采量和临界水位等地下水资源管理指标,其可操作性不强。为此,在综合分析沉降区内地下水开采量和地面沉降所引起的土方损失情况的基础上,提出了一种新的地下水资源管理指标——土水比。研究结果表明:土水比能够指示地面沉降相对于地下水开采的易发性以及沉降区内的地下水资源保障程度;将土水比作为沉降区地下水资源管理的指标,就可以确定出不同级别的沉降易发区域以及地下水资源的保障程度,了解开采条件下地下水资源的补给能力,从而可保证地下水开采不消耗地下水储存资源,有效监控和防治地面沉降。     

地下水脆弱性评价方法的探讨及实例

本文对当前地下水脆弱性评价的方法进行了评述。指出了目前应用最为广泛的DRASTIC法的局限之处，在充分考察中国平原盆地水文地质条件的前提下，提出了基于层次分析的DRUA评价方法。该方法是选取影响地下水脆弱性的地下水埋深等4个评价参数作为评价因子，应用层次分析法确定各因子的权重，结合GIS空间分析功能对地下水本质脆弱性进行评价。