首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
The demand for water is rapidly increasing in Egypt, because of high population and agriculture production growth rate, which makes research of water resources necessary. The regional multi-aquifer system of the Miocene–Pleistocene age is discharged in Wadi El Natrun area. Intensive aquifer overexploitation and agricultural development in the area are related to groundwater quality deterioration. Hydrochemical and hydrogeological data was evaluated to determine the groundwater origin and quality in the south-eastern part of wadi, which appears to be more significant for water supply owing to lower groundwater salinity. The dominance of the high mineralised Cl groundwater type was found; however, also less mineralised SO4 and HCO3 types were identified there. Based on the ion relations, halite and gypsum dissolution and ion exchange are the most important hydrochemical processes forming the groundwater chemical composition. The Cl dominated groundwater matches the discharge part of the regional hydrogeological system. Contrary, the presence of HCO3 and SO4 hydrochemical types corresponds to the infiltration and transferring parts of the hydrogeological system indicating the presence of zones conducting low mineralised groundwater. The discharge area of the over-pumped aquifer in Wadi El-Natrun lies 23 m beneath the sea level with the shoreline being at the distance of 100 km, thus there is a real risk of seawater intrusion. Using the hydrochemical facies evolution diagram, four samples in the centre of the discharge area indicate advanced seawater intrusion. The zones of the highest demand for groundwater quality protection were indicated based on a spatial pattern of hydrogeochemical composition.  相似文献   

2.
Coastal aquifer of northern Sfax (Tunisia) suffers from the high risk to seawater intrusion and the water quality degradation due to the overexploitation. Hence, assessing the study area vulnerability to pollution is highly crucial so as to protect the groundwater resources. The assessment has been performed by applying the GALDIT method using Geographic Information System (GIS) software and multi-criteria evaluation techniques, and the sensitivity analysis approach to evaluate the effect of each GALDIT parameter on the vulnerability assessment. The GALDIT vulnerability map classifies the study area into three vulnerability classes: low vulnerability (30–50), moderate vulnerability (50–70), and high vulnerability (70–90), which represent 5, 30, and 65 % of the study area, respectively. The map illustrates that the coastal zones of the aquifer are the most threatened areas. The sensitivity analysis results show that the aquifer hydraulic conductivity (A) and the thickness of the aquifer (T) represent the determining factors in the modified vulnerability model. The real weight was used to elaborate the modified GALDIT model which was correlated with resistivity values for validation. This study could serve as a scientific basis for sustainable land planning and groundwater management in the study area.  相似文献   

3.
The present work attempts to interpret the groundwater vulnerability of the Melaka State in peninsular Malaysia. The state of groundwater pollution in Melaka is a critical issue particularly in respect of the increasing population, and tourism industry as well as the agricultural, industrial and commercial development. Focusing on this issue, the study illustrates the groundwater vulnerability map for the Melaka State using the DRASTIC model together with remote sensing and geographic information system (GIS). The data which correspond to the seven parameters of the model were collected and converted into thematic maps by GIS. Seven thematic maps defining the depth to water level, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity were generated to develop the DRASTIC map. In addition, this map was integrated with a land use map for generating the risk map to assess the effect of land use activities on the groundwater vulnerability. Three types of vulnerability zones were assigned for both DRASTIC map and risk map, namely, high, moderate and low. The DRASTIC map illustrates that an area of 11.02 % is low vulnerability, 61.53 % moderate vulnerability and 23.45 % high vulnerability, whereas the risk map indicates that 14.40 % of the area is low vulnerability, 47.34 % moderate vulnerability and 38.26 % high vulnerability in the study area. The most vulnerability area exists around Melaka, Jasin and Alor Gajah cities of the Melaka State.  相似文献   

4.
广东硇洲岛地下水化学演化及成因机理   总被引：4，自引：0，他引：4  
地下水一直是广东硇洲岛唯一的水资源,但近年来许多地区地下水咸化趋势加剧,严峻威胁着岛上居民的用水安全,研究地下水化学演化及成因机理,对预防和减缓水质变咸意义重大。本文结合区域水文地质条件、地形地貌条件及水化学资料分析了整个岛屿地下水水质状况,在此基础上采用Piper三线图研究了水化学特征,并利用PHREEQC软件对水文地球化学演化规律进行模拟研究,结果表明:(1)海水入侵是造成地下水咸化的主要原因,咸化对水质的影响主要表现为Cl-的增加,Ca2+在区分该地区不同水体时反应灵敏,是良好的识别指标之一;(2)海水入侵的过程中,过渡带前缘不存在经受长期古海水演化而成的卤水与地下淡水的混合作用,地下水中Mg2+、Ca2+与Na+之间存在着强烈的离子交换,石膏、白云石及方解石处于不饱和状态;(3)浅层地下水与深层地下水之间无明显的水力联系,属于相对独立的地下水流系统。在全球变暖,海平面上升的总趋势下,海岛地下水开发必须合理规划、严格管理,以防引发大规模海水入侵灾害的发生。  相似文献   

5.
Seawater intrusion is a major threat to the rapidly depleting groundwater resources in the coastal areas of India. Groundwater-based irrigation, significant industrial development and rapid urbanization are some of the key contributors exacerbating the stress on groundwater resources. Vulnerability to seawater intrusion in the Ramanathapuram district of Eastern India is assessed here utilizing the GALDIT method, for a period of 10 years (2001–2010). Results revealed a drastic increase in percent area coverage under moderate vulnerability, from 19.5 to 53.88 %, between the years 2001 and 2010. On the contrary, areas classified as highly vulnerable underwent minor changes over the span of the study. Vulnerability of the study area was also analyzed for the year 2050 considering an average global mean sea level rise of 3.1 mm/year. Results from the analysis for the year 2050 showed that, almost, the entire study area (~97 %) was classified under moderate vulnerability. As a remedial measure to this imminent threat, favorable zones for artificial recharge were delineated on the basis of overlay analysis with weightage values for important controlling factors. Subsequently, the quantity of artificial recharge required to inhibit the intrusion of seawater, at specified favorable zones were estimated to be 674.87, 599.18 and 1,450.66 m3/year.  相似文献   

6.
The study area is a part of central Ganga Plain which lies within the interfluve of Hindon and Yamuna rivers and covers an area of approximately 1,345 km2. Hydrogeologically, Quaternary alluvium hosts the major aquifers. A fence diagram reveals the occurrence of a single aquifer to a depth of 126 m below ground level which is intercalated by sub-regional clay beds. The depth to water level ranges from 9.55 to 28.96 m below ground level. The general groundwater flow direction is northwest to southeast. Groundwater is the major source of water supply for agricultural, domestic, and industrial uses. The overuse of groundwater has resulted in the depletion of water and also quality deterioration in certain parts of the area. This has become the basis for the preparation of a groundwater vulnerability map in relation to contamination. The vulnerability of groundwater to contamination was assessed using the modified DRASTIC-LU model. The parameters like depth to water, net recharge, aquifer media, soil media, topography, impact of vadose zone, hydraulic conductivity of the aquifer, and land use pattern were considered for the preparation of a groundwater vulnerability map. The DRASTIC-LU index is computed as the sum of the products of weights and rating assigned to each of the inputs considered. The DRASTIC-LU index ranges from 158 to 190, and is classified into four categories, i.e., <160, 160–170, 170–180, and >180, corresponding to low, medium, high, and very high vulnerability zones, respectively. Using this classification, a groundwater vulnerability potential map was generated which shows that 2 % of the area falls in the low vulnerable zone, 38 % falls in the medium vulnerable zone, and 49 % of the area falls in the high vulnerable zone. About 11 % of the study area falls in the very high vulnerability zone. The groundwater vulnerability map can be used as an effective preliminary tool for the planning, policy, and operational levels of the decision-making process concerning groundwater management and protection.  相似文献   

7.
A detailed hydrogeological and hydrochemical study was carried out in Yamuna-Krishni sub-basin which is a part of the vast central Ganga plain. Groundwater is the major source of water supply for agricultural, domestic and industrial uses. The excess use of groundwater has resulted in depletion of water levels. The groundwater quality, too, has deteriorated in areas dominated by industrial activity. This has led to the preparation of a groundwater vulnerability map in relation to contamination. Groundwater vulnerability maps are valuable derivative maps that show, quantitatively or qualitatively, certain characteristics of the sub-surface environment that determine vulnerability of groundwater to contamination. The modified DRASTIC method was used to prepare vulnerability map. The parameters like depth to water, net recharge, aquifer media, soil media, impact of vadose zone, hydraulic conductivity and land use pattern, owing to its bearing on groundwater regime, were considered to prepare vulnerability map. The vulnerability index is computed as the sum of the products of weight and rating assigned to each of the input considered as above. The vulnerability index ranges from 140 to 180, and is classified into four classes i.e. 140–150, 150–160, 160–170 and 170–180 corresponding to low, medium, high and very high vulnerability zones respectively. Using this index, a groundwater vulnerability potential map was generated which shows that 7%, 40% and 53% of the study area falls in low, medium and high to very high vulnerability zones respectively. The map, thus generated, can be used as a tool for protection and management of aquifers from contamination.  相似文献   

8.
A multi-methodological approach based on monitoring and spatio-temporal analysis of groundwater quality changes is proposed. The presented tools are simple, quick and cost-effective to give service to all sorts of users. The chief purpose of the monitoring network is the detection of the piezometric or potenziometric level in the aquifer. The spatial and multi-temporal analysis of usual chemical and physical data provides both an assessment of the spatial vulnerability of the aquifer to seawater intrusion, defining a salinity threshold between fresh groundwater and brackish groundwater and of the water quality trend in terms of salinity. The evaluation of the salinity trend or of salinity-correlated parameters highlights the effects of groundwater mismanagement. The multiparameter logging provides a rapid groundwater quality classification for each well. The whole approach allows evaluating the effects of current management criteria and designing more appropriate management targets. The Apulian karstic coastal aquifers have been selected as a case study (Southern Italy). Three types of aquifer zones can be distinguished: (1) areas with low vulnerability to seawater intrusion, (2) areas with high vulnerability and (3) areas with variable vulnerability in which the salt degradation largely depends on the ability to manage the well discharge. The water quality degradation caused by seawater intrusion appears to be a combined effect of an anomalous succession of drought periods observed from about 1980 onwards and increased groundwater pumping, particularly during drought periods. A management criterion based on aquifer zones is proposed.  相似文献   

9.
In arid and semi-arid countries worldwide, conflicts between human development activities and conservation of groundwater resources are widespread and attract many public debates. This research aims to propose groundwater management alternatives for a coastal aquifer by studying its vulnerability and in particularly the risk of seawater intrusion. An additional objective is to propose some agricultural policies aimed to conserve groundwater resources in Mahdia and Ksour Essaf. Intensive groundwater mining, for irrigation and for water drinking, has caused an overexploitation of the water resources. In addition, the degradation of water quality, caused by septic tanks and intensive agricultural activities, has given rise to notable crucial state of the groundwater resources. With the aim of tackling the groundwater degradation problem, integration into a common platform of vulnerability assessment, seawater intrusion modelling and hydrochemical analysis is proposed. This platform can considerably reflect the water resources state in order to propose some solutions reducing the contamination of the Mahdia–Ksour Essaf aquifer. The groundwater management alternatives, proposed in this study, were prepared within a geographical information system.  相似文献   

10.
A numerical assessment of seawater intrusion in Gaza, Palestine, has been achieved applying a 3-D variable density groundwater flow model. A two-stage finite difference simulation algorithm was used in steady state and transient models. SEAWAT computer code was used for simulating the spatial and temporal evolution of hydraulic heads and solute concentrations of groundwater. A regular finite difference grid with a 400 m2 cell in the horizontal plane, in addition to a 12-layer model were chosen. The model has been calibrated under steady state and transient conditions. Simulation results indicate that the proposed schemes successfully simulate the intrusion mechanism. Two pumpage schemes were designed to use the calibrated model for prediction of future changes in water levels and solute concentrations in the groundwater for a planning period of 17 years. The results show that seawater intrusion would worsen in the aquifer if the current rates of groundwater pumpage continue. The alternative, to eliminate pumpage in the intruded area, to moderate pumpage rates from water supply wells far from the seashore and to increase the aquifer replenishment by encouraging the implementation of suitable solutions like artificial recharge, may limit significantly seawater intrusion and reduce the current rate of decline of the water levels.  相似文献   

11.
Groundwater is of a paramount importance in arid areas, as it represents the main water resource to satisfy the different needs of the various sectors. Nevertheless, coastal aquifers are generally subjected to seawater intrusion and groundwater quality degradation. In this study, the groundwater quality of the coastal Jeffara aquifer (southeastern Tunisia) is evaluated to check its suitability for irrigation purposes. A total of 74 groundwater samples were collected and analyzed for various physical and chemical parameters, such as, electrical conductivity, pH, dissolved solids (TDS), Na, K, Ca, Mg, Cl, HCO3, and SO4. Sodium adsorption ratio, magnesium adsorption ratio, Sodium percentage, and permeability index were calculated based on the analytical results. The analytical results obtained show a strong mineralization of the water in the studied aquifer. TDS concentrations range from 3.40 to 18.84 g?L?1. Groundwater salinity was shown to be mainly controlled by sodium and chloride. The dominant hydrochemical facieses are Na–Cl–Ca–SO4, mainly as a result of mineral dissolution (halite and gypsum), infiltration of saline surface water, and seawater intrusion. Assessment of the groundwater quality of the different samples by various methods indicated that only 7% of the water, in the northwest of the study area, is considered suitable for irrigation purposes while 93% are characterized by fair to poor quality, and are therefore just suitable or unsuitable for irrigation purposes.  相似文献   

12.
江苏南通地下水补给源、水化学特征及形成机理   总被引：8，自引：0，他引：8  
在地下水的大规模开采条件下,江苏沿海一带,特别是南通许多地区的地下水一度出现咸化趋势,对区域水资源及环境产生了极大的影响,已成为制约生态环境建设和经济社会发展的重要因素.为查明地下水的补给来源、水化学特征和矿化度增高的机理,对南通地区深浅层地下水开展了野外调查取样.通过对各种水化学参数的讨论分析,系统地研究了该区地下水...  相似文献   

13.
Hydrogeochemical investigation of groundwater has been carried out in the coastal aquifers of southern Tamil Nadu, India. Seventy-nine dug well samples were collected and analyzed for various physicochemical parameters. The result of the geochemical analysis indicates the groundwater in the study area is slightly alkaline with moderate saline water. The cation and anion concentrations confirm most of the groundwater samples belong to the order of Na+ > Mg2+ > Ca2+ > K+ and Cl? > SO4 2? > HCO3 ?. Thereby three major hydrochemical facies (Ca–Cl, mixed Ca–Mg–Cl and Na–Cl) were identified. Based on the US Salinity diagram, majority of the samples fall under medium to very high salinity with low to high sodium hazard. The cross plot of Ca2+ + Mg2+ versus chloride shows 61 % of the samples fall under saline water category. Higher EC, TDS and Cl concentrations were observed from Tiruchendur to Koodankulam coastal zone. It indicates that these regions are significantly affected by saltwater contamination due to seawater intrusion, saltpan deposits, and beach placer mining activities.  相似文献   

14.
A hydrochemical study has been carried out on the fresh groundwater resources of Potharlanka, Krishna Delta, India. Groundwater samples were collected at 58 sites and analyzed in June and December 2001. The groundwater is mildly alkaline with a pH of 7.2–8.2, electrical conductivity (EC) varies from 645–4,700 µS/cm in June 2001 (pre-monsoon) and from 605–5,770 µS/cm in December 2001 (post-monsoon). More than 75% of the samples have >1000 mg/l TDS which is higher than the maximum permissible limit for potable water. Na and Cl are the dominating cations and these are directly proportional to TDS. Extremely low HCO 3/Cl and variable high Mg/Ca (molar ratios) indicated the transformation of the fresh groundwater aquifer systems to saline. Groundwater of this island is classified as Na–Cl, Na–Ca–Cl–HCO 3, Na–Mg–Cl–SO 4 and mixed types. A high percentage of mixed water types indicates the possibility of simultaneous fresh groundwater dilution activity along with a seawater ingression/intrusion process. Low rainfall and excessive withdrawal of groundwater has caused the increase of saline water intrusion.  相似文献   

15.
Groundwater salinization in the Azores archipelago (Portugal)   总被引：1，自引：1，他引：0  
Groundwater salinization in coastal regions causes severe constraints to water supply and economic losses to society worldwide. In the Azores archipelago, groundwater abstraction in wells drilled in coastal aquifers is very important for water supply, and quality problems have been reported. Therefore, a groundwater chemistry dataset from wells was compiled to study groundwater salinization in these aquifers. Waters are mainly of the Na–Cl type, presenting a slightly acidic to slightly alkaline character, with a pH between 5.63 and 8.50 (median 7.40). Electrical conductivity measurements range from 127 to 9,670 μS/cm (median 862), suggesting highly variable mineralization, with higher values observed on Santa Maria, São Miguel, Pico, Graciosa, and São Jorge islands. The major-ion composition reflects the contribution of seawater to the groundwater compositional evolution, which is essentially explained by seawater intrusion into wells. In many samples, exchange reactions of Na+ + K+ for Ca2+ + Mg2+ are associated with salinization. The seawater fraction in groundwater composition reaches a maximum of 22.5%. These results are extremely challenging to water managers in the Azores because failure to comply with national water quality regulations and with European Union groundwater directive requirements often occurs.  相似文献   

16.
Seawater intrusion and coastal aquifer management in China: a review   总被引：1，自引：1，他引：0  
Seawater intrusion has been an important topic in hydrogeology in China in recent decades. The rapid growth of the population and economy in the coastal regions has been consuming a tremendous amount of groundwater resources and has increased the extent of seawater intrusion. The spatial discrepancy of water resource distribution has caused the studies of seawater intrusion into China to mainly be concentrated on the area around the Bohai Sea in the northern part of China. The total area of seawater-intruded land due to excessive groundwater utilization in the area was estimated to be approximately 2,457 km2 in 2003. Great efforts have been made to mitigate the extent of seawater intrusion and to secure more freshwater resources, including building monitoring networks, subsurface barrier and groundwater reservoirs, and artificial infiltration facilities. Management projects over the years were evaluated to satisfy the objectives and to provide valuable experiences for future research and planning. It is expected that the coastal groundwater conditions of the northern region will improve through the development of a national water resource plan, such as the ongoing south-to-north water diversion project.  相似文献   

17.
环境同位素特征对滨海岩溶地区海水入侵过程的指示意义   总被引：1，自引：0，他引：1  
大连大魏家水源地位于中国北方典型滨海岩溶地区。近30年来,地下淡水的不合理开采造成的地下水位降落漏斗引发了严重的海水入侵。以大魏家水源地为研究对象,通过大量的水文地质调查和水化学及同位素采样测试分析,探讨海水入侵形成的水动力条件,通过分析滨海岩溶含水层中地下水主要水化学和多种同位素(δ2H-δ18O,δ34S,δ13C)组成特征,识别了海水入侵过程中发生的主要水文地球化学作用,并对其进行了定量模拟,从而阐明了岩溶含水层中的海水入侵机理。研究结果表明:大连大魏家海水入侵主要通道为大魏家地区存在的导水断裂、岩溶裂隙以及第四系松散地层。对δ2H-δ18O同位素的组成分析表明,研究区地下水主要来自大气降水补给,结合Cl-浓度分布,认为除海水入侵淡水含水层后增加了地下水中的盐分外,浅层地下水的蒸发也对地下水中盐分的累积起到了重要作用。根据不同水体中δ34SSO4,δ13CHCO3等同位素特征,结合水化学成分(如SO2-4,Cl-)分析认为,研究区微咸水和咸水并不是地下水淡水和海水简单混合而成。利用反向水文地球化学模拟揭示了控制滨海岩溶含水层中水化学演化的主要水文地球化学反应有方解石、蒙脱石和石膏的溶解作用,伊利石的沉淀作用以及Ca-Na离子交换作用,伴随着CO2的释放。  相似文献   

18.
Korba aquifer is one of the most typical examples of overexploited coastal aquifer in the Mediterranean countries. In fact, from 1985, a considerable piezometric level drop, water salinization, and seawater intrusion were registered in the aquifer. In December 2008, Tunisian authorities initiated a general plan to groundwater management in order to augment groundwater resources, restore the piezometric levels, and improve water quality. The plan consists of artificial recharge of groundwater used treated wastewater through three infiltration basins. During the first 4 years (from December 2008 to December 2012), 1.41 Mm3 of treated wastewater was injected to the Korba aquifer. This study presents a hydrogeological assessment of groundwater evolution during the recharge processes. In this study, 32 piezometric and chemical surveys of 70 piezometers and observed wells are used to present hydrogeological investigation and water quality evolution of wastewater reuse through artificial recharge in Korba coastal aquifer. The piezometric evolution maps are used to specify the positive effect in groundwater level that exceeding 1.5 m in some regions. The interpretation of salinity evolution maps are used to indicate the improving of groundwater quality.  相似文献   

19.
The Batinah coastal plain in northern Oman has experienced a severe deterioration of groundwater quality due to seawater intrusion as a result of excessive groundwater abstraction for agricultural irrigation. Upgrading all farms to fully automated irrigation technology based on soil moisture sensors may significantly reduce the water demand and lead to recovering groundwater levels. This study compares the effects of smart irrigation technology, recharge dams, and a combination of both on seawater intrusion in the coastal aquifer of the Batinah. A groundwater flow and transport model is used to simulate the effect of reduced pumping rates on seawater intrusion for various intervention scenarios over a simulation period of 30 years, and an economic analysis based on cost-benefit analysis is conducted to estimate the potential benefits. Results indicate that a combination of smart irrigation and recharge dams may prevent further deterioration of groundwater quality over the next 30 years. In conjunction with increased efficiency, this combination also generates the highest gross profit. This outcome shows that the problem of seawater intrusion needs to be tackled by a comprehensive, integrated intervention strategy.  相似文献   

20.
Coastal aquifers are considered as major sources for freshwater supply worldwide, especially in arid zones. The weak rainfall as well as the intensive extraction of groundwater from coastal aquifers reduce freshwater budget and create local water aquifer depression, causing both seawater intrusion and a threat to groundwater. This phenomenon was observed in the Jerba Island which is located in southeast Tunisia. Jerba??s unconfined aquifer shows high values of groundwater salinity reaching, locally, 17?g/l and a strong contrast between some zones of the aquifer. High pumping rates and weak recharge disturb the natural equilibrium between fresh and saline water causing water salinization in most areas of the island. This study aims at establishing the salinity map of the aquifer and identifying the origin of groundwater salinization. The salinity map shows that zones characterized by low groundwater salinity are located in the center of the study area. High groundwater salinities are observed near the coast and in some parts having low topographic and piezometric levels. Groundwater geochemical characterization, and Br/Cl and Na/Cl ratios suggest that the origin of abnormal salinity is seawater intrusion. Considering groundwater salinity values and Br concentrations, a seawater intrusion map is established. It shows that many areas of the unconfined aquifer are contaminated by mixed groundwater and seawater. The statistical analysis demonstrates that high mineralization of the groundwater is due to gypsum and carbonate dissolution coupled with the mixed groundwater and seawater in many areas.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号