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 775 毫秒
1.
This paper focuses on the effects of tidal fluctuations on groundwater in the Konan groundwater basin of Japan and the methodology for estimating aquifer parameters by the tidal response technique. The field investigation revealed that the twowells (H-5 and I-2) near the coastline are significantly affectedby seawater intrusion, and the water quality is not suitable for most beneficial uses. The tidal cycle further aggravates the groundwater contamination by seawater intrusion into the basin. Using the tidal response model, the aquifer hydraulic conductivity(K) at these two sites is estimated to be 4.5 × 10-3 and 5.1 × 10-3 m s-1, respectively. It was also indicated by the inverse modeling that the tidal fluctuations affect the study area up to about 1 km from the coastline. Further, the tidal efficiency was determined in the range of 20 to 21% at Site I-2 and 38 to 41% at Site H-5. The estimates of the storage coefficient (S) based on the time lag equation were not found reliable for the phreatic aquifer. However, the tidal efficiency-factor equation yielded reliable S estimates in this study. Finally, it is concluded that the tidal response techniqueis effective and reliable for estimating aquifer parameters in the coastal region, and that the Konan basin must be managed judiciously to ensure sustainable utilization of its vital groundwater resources.  相似文献   

2.
Ecological water use (EWU) is urgent in need in the lower reaches of Tarim River in China. Estimation of water amount for EWU is depending on some parameters and modeling. EWU is mainly consists of two parts in no runoff area in the basin, i.e. total water amount for restoration groundwater table and total stand water amount of the all river courses. The former is including water amount for restoration of groundwater table, lateral discharge and evaporation of water surface. The estimated values are 8.18 × 108 m3, 0.68 × 108 m3/a and 0.132 × 108 m3/a respectively. Based on the groundwater depth rising 4.0 meters requiring 5 years, the total water amount for restoration groundwater table is 2.448 × 108 m3/a. The latter, i.e., total stand water amount is 1.992 × 108 m3/a. However, the development of water management measures could alleviate the issue and lead to sustainable EWU in the lower reaches of Tarim River.  相似文献   

3.
This study aims at developing Groundwater Quality Indices (GQIs) that constitute a reliable tool in defining aquifer vulnerability. For this purpose, water quality sampling campaigns were conducted on 60 groundwater wells during most vulnerable periods of early and late summer to ensure the representativeness of the targeted GQI under worst case conditions. The samples were tested for various water quality indicators, which were then used to develop the GQIs through GIS-based mapping with spatial geostatistical analysis. The results contribute in filling a gap in GQI definition and form a basis for planning effective water quality management towards sustainable exploitation of groundwater resources particularly during summer periods when recharge is limited.  相似文献   

4.
Groundwater is the only source of drinking water for the inhabitants of the Kalahari. Thus understanding spatial and temporal variations in groundwater recharge is very important and a regional-scale water balance model has therefore been set up for a 209,149 km2 catchment in north-eastern Namibia and north-western Botswana. The model has a spatial resolution of 1.5 × 1.5 km, daily model time-steps, and climatic input parameters for 19 years are used. The distributed, GIS-based, process-oriented, physical water balance model (MODBIL) used in this study considers the major water balance components: precipitation, evapotranspiration, groundwater recharge, and surface runoff/interflow. Mean precipitation for the study area is 409 mm a−1, while mean actual evapotranspiration is 402 mm a−1 and mean groundwater recharge is 8 mm a−1 (2% of mean annual precipitation). The recharge pattern is mainly influenced by the distribution of soil and vegetation units. Groundwater recharge shows a high inter- and intra-annual variability, but not only the sum of annual precipitation is important for the development of groundwater recharge; a large amount of precipitation in a relatively short period is more important. Published independent data from the Kalahari in Namibia, Botswana and the Southern African region under similar climatic conditions are used to verify the modelling results.  相似文献   

5.
In this study, total coliforms, thermotolerant coliforms, Escherichia coli and groundwater nitrate concentration were monitored at 127 groundwater sampling points (only 62 water points for bacteriological parameters) located in the southern part of Abidjan District. Each water sampling location was sampled in March and July 2007, representing respectively the long dry season and the long wet season. Geostatistical methods were used to analyze the spatial variability of nitrates and the groundwater nitrate pollution risk. The maximum seasonal content of total coliforms and thermotolerant coliforms ranged from 400 to 1000 CFU/100 mL and from 200 to 500 CFU/100 mL respectively. Moreover, 94% of these locations presented traces of bacteriological contamination. This contamination was mainly recorded during the rainy period. The degree of correlation between bacterial abundance and chemical parameters is variable. Nitrites, ammonium and potassium favoured coliform abundance. In the 127 water points, groundwater nitrate concentrations ranged from 4 to 198 mg L?1 and were log-normally distributed in the study area. The groundwater contamination risk map indicated that the strongly urbanized west side of the site presented a high probability of exceeding the WHO drinking water standard (50 mg L?1NO3?).  相似文献   

6.
Research on tropical fish ecology in South America is focused mainly on the effect of environmental variables on aquatic organisms. Physical, chemical and biological characteristics of water measured at a local scale (local variables) are used, although geomorphological and hydrological factors measured at a regional scale (regional variables), as well as temporal and spatial heterogeneity, can also be considered. However, the use of this multi‐scale approach increases the perceived complexity, heterogeneity and variability of rivers. Thus, it is important to determine the magnitude of habitat variability and those parameters having the greatest influence on it. In this study, 28 stations distributed on 16 different rivers in French Guiana were sampled during high water at a meso spatial scale. Physical features of the rivers were sampled along an 800‐m stretch, where nine transversal transects were established on the main channel. At each river, 17 local and six regional variables were measured. Local variables relating to the physical characteristics of the channel bank and main channel and regional variables characterizing the whole basin and the position of the station in the basin were qualitatively and quantitatively described. All variables were submitted to multivariate analysis in order to determine their relative contribution to total variance. Two quantitative regional variables (drainage area upstream from station and river drainage basin), five quantitative local variables (channel width, water temperature, channel depth, Secchi transparency and conductivity) and one qualitative local variable (channel substrate) were shown to differentiate the 16 rivers sampled. This result shows the poor contribution of qualitative variables compared with quantitative ones. Gradual change in qualitative variables is probably responsible for this poor contribution to the total variance; thus, the use of such variables is not possible for spatial habitat differentiation in this study. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

7.
多元统计方法能同时对多个变量进行分析研究,是一种可用于地下水水化学特征相关分析的有效工具。基于12组水样的9项指标,运用多元统计方法系统分析了新疆巴里坤盆地地下水水化学特征及其影响因素。结果表明:该地区内主要分布低矿化度的HCO3·SO4-Ca·Na型水(占总取样点的33.3%)和HCO3·SO4-Ca型水(占总取样点的25.0%),地下水中各离子的空间变异性为中等以上。地下水水化学特征主要受以Na+、Ca2+、Mg2+、Cl-、SO42-、总硬度(TH)、溶解性总固体(TDS)为主要荷载变量的蒸发浓缩作用和以HCO-3为主要荷载变量的溶滤作用影响,两种作用的贡献率分别达76.17%和14.87%。研究结果可为当地地下水资源的保护和可持续利用提供科学依据。  相似文献   

8.
Located in the centre of the Eurasian Continent, the Turpan Basin, as the second deepest lowland in the world, is extremely short of water resources. Aimed at this key scientific issue, this paper based on years of meteorological and hydrological observation data, carried out a scientific calculation and evaluation of surface and groundwater resources in the Turpan Basin, and then, with the help of modified Penman formula, calculated the virtual water potential in the basin in 2004. The results show that the average total usable surface water resources per year in the last decade were about 6.673×108 m3, while adduction volume of surface water in 2003 was about 4.94×108 m3, which means that most of the region has reached or approached the limit of water resources and, as a result serious crises and constraints on the development of the basin were thus caused. The exploitation content of groundwater in the Turpan Basin in 2003 was about 6.12×108 m3, which has basically reached its upper limit, and the ground water level has fallen about 10~40 m in the Turpan Basin in recent years. The daily reference crop water requirement in the Turpan Basin in 2004 was about 1,053.39 mm, and the total virtual water potential contained in six main crops was about 5.25 ×108 m3 in 2004. All these showed that research works on scientific assessment of water resources and regional virtual water strategy have great significance for the best social, ecological, economic benefits and regional sustainable development of the Turpan Basin.  相似文献   

9.
In arid and semiarid areas, bimodal and high rainfall leads to infrequent flood that can be extremely damaging. To reduce the impacts of persistent intra-seasonal drought and also to reduce flood damaging in arid and semiarid areas, rainwater storage is a prerequisite that keeps water far from evapotranspiration, increases groundwater level and decreases flood hazards modification to exchange between surface water and groundwater through flood spreading, dams, etc. The purpose of this paper is to delineate and explain variations in groundwater recharge and groundwater quality along an ephemeral stream that has been modified by flood spreading. Groundwater samples were collected from 14 deep wells located at different distances from flood spreading projection area (FSPA) in 1 month interval during September 2005 to September 2008. Groundwater quality was followed via Na+, K+, Ca2+, Mg2+, Cl-, Hco3- SO42-, Electrical Conductivity (EC) and pH measurements for two time periods between 2005 and 2008. The results show significant impact of flood spreading in groundwater table and groundwater salinity variation. Groundwater table decreased in all study wells, but groundwater drawdown increased by increasing the distance to FSPA (during 4 years study, 11.02 m in the well located at 20 m of FSPA versus 38.88 in the well located at 1,825 m). Also ion concentration increased in all of the wells during the study period, but the increasing ion concentration was significantly less important in FSPA closeness.  相似文献   

10.
The artificial recharge of groundwater aims at the modification of water quality, an increase of groundwater resources, and the optimization of the exploitation and recovery of contaminated aquifers. The purpose of this work is to develop a new mathematical model for the problem of an artificial recharge well, using the method of successive variations of steady states. Applying this method, one arrives at an expression of time as a double integral. This integral contains the time-dependent radius of the recharge boundary and the piezometric head of the well, calculated with the finite-element method. The new model is simple and useful, and can be applied to many practical problems, using the designed dimensionless graphs.Notations A area of the finite element (m2) - c the Euler constant (0.5772156649...) - e index of the finite element - E i the exponential integral function - F j nodal values of the functionF - h piezometric head, (m) - h 0 piezometric head at timet=0 (m) - h w piezometric head on the well contour (m) - i, j, k nodal indices of the finite element - K hydraulic contactivity (ms–1) - N i interpolation function - Q discharge (m3 s–1) - r cylindrical coordinate (m) - r 0 the action radius of the well (m) - r w the radius of the well (m) - S the effective porosity - t the time (s) - T the transmissivity of the aquifer (m2s–1) - V the stored water volume (m3) - x, y, dummy variables  相似文献   

11.
Impact of Urbanization on the Hydrology of Ganga Basin (India)   总被引:4,自引:3,他引:1  
Large scale emigrations from rural areas to urban areas and population growth have been uninterrupted and accelerating phenomena in parts of Ganga basin, where urbanization is increasing at an unprecedented rate. Urban agglomeration is causing radical changes in groundwater recharge and modifying the existing mechanisms. Majority of the cities are sited on unconfined or semi confined aquifers depend upon river water and groundwater for most of their water supply and disposal of most of their liquid effluents and solid residues to the rivers and ground. There has also been an inevitable rise in waste production. Drainage of surface water has been disrupted as the small natural channels and low lying areas have been in filled, often with municipal waste. Total water potential of the Ganga basin including surface water potential and ground water potential is around 525.02 km3 and 170.00 km3 respectively. Basin supports approximately 42% of the total population in India. Water tables are declining at approximately an average of 0.20 m per year in many parts of the basin and there is a trend of deteriorating groundwater quality. The demand of water has been increased many folds and most of the areas are highly reliant upon the groundwater to meet this increasing demand for water, but unfortunately degradation of groundwater both in terms of quantity and quality has deteriorated the situation. Studies shows that change in climate may increase temperature by 2 to 6°C and can reduce precipitation up to 16%, which could reduce the groundwater recharge by 50%. In densely populated Ganga basin urban drainage consumes a high proportion of the investments into urban infrastructure and needs integrated approach for the sustainable development of water management, water education regarding conservation and pollution caused by urbanization.  相似文献   

12.
The present study focuses on the in-depth hydrologic and hydrogeologic analyses of Kathajodi-Surua Inter-basin within the Mahanadi deltaic system of Orissa, eastern India to explore the possibility of enhanced and sustainable groundwater supply. The results of 6 years (2001–2006) streamflow analysis indicated that the river flow is highly seasonal and it reduces to almost no flow during summer seasons. Land use map of the study area for the monsoon (Kharif) and post-monsoon (Rabi) seasons was developed by remote sensing technique and runoff estimation was done by curve number method. The runoff estimated for the 20-year period (1990–2009) varied from a minimum of 10.2% of the total monsoon rainfall in 1995 to a maximum of 43.3% in 2003. The stratigraphy analysis indicated that a leaky confined aquifer comprising medium to coarse sand exists at depths of 15 to 50 m and has a thickness of 20 to 55 m. The analysis of pumping test data at 9 sites by Aquifer-Test software indicated that the aquifer hydraulic conductivity ranges from 11.3 to 96.8 m/day, suggesting significant aquifer heterogeneity. Overall groundwater flow is from north-west to south-east direction. There is a 5 to 6 m temporal variation and 3 to 4 m spatial variation of groundwater levels over the basin. The rainfall-groundwater dynamics and stream-aquifer interaction in the river basin were studied by correlation analysis of groundwater level with weekly rainfall and river stage. The correlation between the weekly rainfall and weekly groundwater level was found to vary from ‘poor’ to ‘fair’ (r = 0.333 to 0.659). In contrast, the weekly groundwater level was found to be strongly correlated with the weekly river stage (r = 0.686 to 0.891). The groundwater quality was found suitable for both irrigation and drinking purposes. It is recommended that a simulation-cum-optimization modeling following an integrated approach is essential for efficient utilization of groundwater resources in the study area.  相似文献   

13.
Petra region area was located in south part of Jordan has grown and urbanized rapidly. This area depends on the groundwater as a water resources. This study was undertaken to assess the physical, chemical quality of spring water of Petra region during a 36-months survey (September 2002 to September 2005). The samples were analyzed for temperature, conductivity, dissolved oxygen, pH, major cations (Ca2+, Mg2+, K+, and Na+), major anions (Cl, NO 3, HCO 3, SO2− 4, PO3− 4, F) and trace metals (Fe2+, Al3+, Cu2+, Ni2+ Pb2+, Zn2+ and Mn2+). Water quality for available springs in the study area showed high salinity due to longer period of contact with rocks. The chemistry of spring water samples were alkaline earth waters with prevailing bicarbonate and alkaline earth waters with prevailing bicarbonate chloride. Some springs showed that elevated nitrate, sulfate contents which could be due to percolation from septic tanks, cesspools and irrigational activities. The infiltration of wastewater from cesspools and septic tanks into groundwater was considered the major source of water pollution. The results showed that there were considerable variations among the examined samples with respect to their physical and chemical parameters, which lie below the maximum permissible levels of the Jordanian and WHO drinking water standards. The results indicate that the trace metals of springs water of Petra region do not generally pose any health or environmental problems.  相似文献   

14.
Groundwater in the Great Lakes Basin (GLB) serves as a reservoir of approximately 4000 to 5500 km3 of water and is a significant source of water to the Great Lakes. Indirect groundwater inflow from tributaries of the Great Lakes may account for 5–25% of the total water inflow to the Great Lakes and in Lake Michigan it is estimated that groundwater directly contributes 2–2.5% of the total water inflow. Despite these estimates, there is great uncertainty with respect to the impact of groundwater on surface water in the GLB. In terms of water quantity, groundwater discharge is spatially and temporally variable from the reach to the basin scale. Reach scale preferential flow pathways in the sub-surface play an important role in delivering groundwater to surface water bodies, however their identification is difficult a priori with existing data and their impact at watershed to basin scale is unknown. This variability also results in difficulty determining the location and contribution of groundwater to both point and non-point source surface water contamination. With increasing human population in the GLB and the hydrological changes brought on by continued human development and climate change, sound management of water resources will require a better understanding of groundwater surface–water interactions as heterogeneous phenomena both spatially and temporally. This review provides a summary of the scientific knowledge and gaps on groundwater–surface water interactions in the GLB, along with a discussion on future research directions.  相似文献   

15.
The present work aims at assessing the impact of MSW on the groundwater quality around dumping yard site, located near the Sangamner city by water quality index (WQI) and its integration in geographical information system (GIS). Groundwater samples (n?=?15) around the dumping yard were collected using Garmin GPS device in October 2013 and October 2014. Physico-chemical analysis of same samples was carried out for pH, EC, TDS, Na+, K+,Ca2+, Mg2+, TH, Cl?, HCO3 ?, SO4 2? and NO3 ? along with the heavy metals like Fe, Zn, Cd and Cr by using standard methods. Similarly, SAR, KRs, RSC and SSP were also calculated to know the groundwater quality into irrigation perspective. WQI for 15 samples were calculated using physico-chemical results/data of 12 parameters and its desirable limit of BIS standard. Generated WQI (z) for October 2013 and October 2014 were integrated with latitude (y) and longitude (x) values, collected using GPS during the field work. Integrated xyz data were then interpolated in Surfer-10 GIS software using inverse distance weight (IDW) method to estimate the groundwater quality of the study area. Study revealed that the groundwater quality around the dumping yard area does not confirm to drinking and domestic purposes as per the WQI and BIS standard. However, the groundwater quality is marginally suitable for irrigation as per SAR, KRs, RSC and SSP. The influence of leachate from MSW dumping site to surrounding groundwater is creating a serious concern and susceptible to potential health hazards. Thus, continuous monitoring of groundwater is desperately required in order to minimize the groundwater pollution for control the pollution-caused MSW.  相似文献   

16.
The southern part of Libya is a desert area of negligible population density overlying two of the largest ground‐water basins in the world: the Murzuk basin in the south‐west and Kufra‐Sarir basin in the south‐east. In situ utilization of these huge groundwater reserves is uneconomical due to poor soils and unsuitable climatic conditions. Extensive hydrogeological studies conducted during the last two decades have indicated the possibility of transferring over 6 million m3 per day to the coastal zones in the north. The Great Manmade River Project was launched in 1983 aiming at a rational utilization of the transported water for agricultural and urban developments, along with restoration of the affected aquifers. The project consists of five phases and is planned to be completed before the turn of the century. This article highlights the technical aspects of this major project in terms of water availability, water quality, future drawdowns, cost of water, well‐field design and other hydrogeological parameters. An analysis of the critical water supply conditions of Libya which necessitated the creation of this project as the most economically feasible solution is also provided.  相似文献   

17.
矿区地下水水质变化是影响矿区生态环境和矿井安全生产的制约因素之一,正确认识水质变化趋势是首要任务。根据以往实测水质参数pH、COD、Na~++K~+、Ca~(2+)、Mg~(2+)、Cl~-、SO_4~(2-)和HCO_3~-的数据,采用Mann-Kendall检验法(MK)和Innovative Trend Analysis(ITA)探讨新三矿由上而下6个不同含水层水质参数随时间的演变规律,并且针对不同的数值变化范围选用不同的ITA指数。通过比较,两种方法结果有很好的一致性,结论认为:相比MK检测法,定量的ITA法拥有更多的优点,可以图形化地表示分析结果,可以通过将水质参数值分为低、中、高水平更好地分析水质参数的趋势和次要趋势;8种水质参数中,Ca~(2+)和Mg~(2+)相较其他离子能表现出更显著的变化趋势;6种含水层中,大青灰岩含水层中Cl~-浓度的低、中值下降而高值上升,煤层顶板山西组砂岩含水层和底板奥陶系灰岩含水层大部分水质参数显著下降,矿化度逐渐降低。  相似文献   

18.
Quantifying and interpreting the impacts that land use/cover change (LUCC) have on hydrology at basin scales are of great significance for the sustainable development of watershed ecosystems, water resources, and land management. The Soil and Water Assessment Tool was used to establish the regional model. The Min River watershed was divided into 236 sub‐basins, and simulations showed the spatial distribution of runoff in each sub‐basin with GIS‐based image displays. We set five scenarios to investigate the negative hydrological effects characterized by reductions in the water yield. From 1995 to 2004, the effect of simulated mean annual runoff caused by LUCC was ?12.61 m3/s and the climate variability caused ?67.61 m3/s. From 2005 to 2014, the hydrological effect caused by LUCC was ?2.38 m3/s and the climate variability caused ?58.53 m3/s. The elevation, Shannon's diversity index, largest patch index, and interspersion and juxtaposition index were all characterized by strong relationships with the sub‐basin outlet flows (adjusted R2 = 0.572) using multivariate stepwise regression analysis. Redundancy analysis further proved that the reduction in grassland has led to a decrease in vegetation dominance while large increase in cultivated and residential lands has led to a higher degree of landscape richness and fragmentation, which has caused the reduced water yield. The restoration of grassland vegetation, as well as urban and agricultural water usage should be the primary focus of flow recovery.  相似文献   

19.

In semi-arid regions, the deterioration in groundwater quality and drop in water level upshots the importance of water resource management for drinking and irrigation. Therefore geospatial techniques could be integrated with mathematical models for accurate spatiotemporal mapping of groundwater risk areas at the village level. In the present study, changes in water level, quality patterns, and future trends were analyzed using eight years (2012–2019) groundwater data for 171 villages of the Phagi tehsil, Jaipur district. Kriging interpolation method was used to draw spatial maps for the pre-monsoon season. These datasets were integrated with three different time series forecasting models (Simple Exponential Smoothing, Holt's Trend Method, ARIMA) and Artificial Neural Network models for accurate prediction of groundwater level and quality parameters. Results reveal that the ANN model can describe groundwater level and quality parameters more accurately than the time series forecasting models. The change in groundwater level was observed with more than 4.0 m rise in 81 villages during 2012–2013, whereas ANN predicted results of 2023–2024 predict no rise in water level?>?4.0 m. However, based on predicted results of 2024, the water level will drop by more than 6.0 m in 16 villages of Phagi. Assessment of water quality index reveals unfit groundwater in 74% villages for human consumption in 2024. This time series and projected groundwater level and quality at the micro-level can assist decision-makers in sustainable groundwater management.

  相似文献   

20.
Delineation of groundwater potential zones (GWPZ) has been performed for a coastal groundwater basin of eastern India. The groundwater potential zone index (GWPZI) map is generated by using Analytic Hierarchy Process (AHP) from different influencing features, e.g., Land Use/Land Cover (LU/LC), soil (S), geomorphology (GM), hydrogeology (HG), surface geology (SG), recharge rate (RR), drainage density (DD), rainfall (RF), slope (Sl), surface water bodies (SW), lineament density (LD), and Normalized Difference Vegetative Index (NDVI). Recharge rate values are estimated from hydrological water balance model. Overlay weighted sum method is used to integrate all thematic feature maps to generate GWPZ map of the study area. Four zones have been identified for the coastal groundwater basin [very good: 36.39 % (273.53 km2, good: 43.57 % (327.47 km2), moderate: 18.27 % (137.30 km2), and poor: 1.77 % (13.27 km2)]. Areas in north to south-west and south-east direction show very good GWPZ due to the presence of low drainage density. GWPZ map and well yield values show good agreement. Sensitivity analysis reveals that exclusion/absence of rainfall and lineament density increases the poor groundwater potential zones. Omission of hydrogeology, soils, surface geology, and NDVI show maximum increase in good GWPZ. Obtained GWPZ map can be utilized effectively for planning of sustainable agriculture. This analysis demonstrates the potential applicability of the methodology for a general coastal groundwater basin.  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