Use of geospatial technology for delineating groundwater potential zones with an emphasis on water-table analysis in Dwarka River basin,Birbhum, India

Dwarka River basin in Birbhum, West Bengal (India), is an agriculture-dominated area where groundwater plays a crucial role. The basin experiences seasonal water stress conditions with a scarcity of surface water. In the presented study, delineation of groundwater potential zones (GWPZs) is carried out using a geospatial multi-influencing factor technique. Geology, geomorphology, soil type, land use/land cover, rainfall, lineament and fault density, drainage density, slope, and elevation of the study area were considered for the delineation of GWPZs in the study area. About 9.3, 71.9 and 18.8% of the study area falls within good, moderate and poor groundwater potential zones, respectively. The potential groundwater yield data corroborate the outcome of the model, with maximum yield in the older floodplain and minimum yield in the hard-rock terrains in the western and south-western regions. Validation of the GWPZs using the yield of 148 wells shows very high accuracy of the model prediction, i.e., 89.1% on superimposition and 85.1 and 81.3% on success and prediction rates, respectively. Measurement of the seasonal water-table fluctuation with a multiplicative model of time series for predicting the short-term trend of the water table, followed by chi-square analysis between the predicted and observed water-table depth, indicates a trend of falling groundwater levels, with a 5% level of significance and a p-value of 0.233. The rainfall pattern for the last 3 years of the study shows a moderately positive correlation (R ² = 0.308) with the average water-table depth in the study area.     

Integration of hydrological factors and demarcation of groundwater prospect zones: insights from remote sensing and GIS techniques

The study demonstrates the potential of geographical information system and statistical-based approaches to identify the hydrological processes and demarcate the groundwater prospect zones of the Gangolli basin, Karnataka State, India. The basin is situated in humid tropical climate and influenced by three major rivers viz. Kollur (6th order stream), Chakra (6th order stream) and Haladi (7th order stream) which cover an area of ~1,512 km² and cumulative length of ~84 km. Various thematic maps—drainage, geomorphology, geology, slope, soil, lineament and lineament density—were prepared using Survey of India topographic maps, Indian remote sensing (IRS-P6) images and other published maps. Hydrogeomorphologic characteristics were correlated with different morphometric parameters to identify the hydrological processes and demarcate the groundwater potential zones of the basin. All the hydrological units and morphometric parameters were assigned suitable weightages according to their relative importance to groundwater potentiality to identify the most deficit/surplus zones of groundwater. Based on hydrological characteristics, integrated thematic maps reveal that ~14 % (~217 km²) of basin area falls under very good, ~32 % (~486 km²) under good, ~23 % (~353 km²) under moderate, and 30 % (~443 km²) under poor zones for groundwater potential. From the sub-basin-wise prioritisation, it has been inferred that SB-III scored highest groundwater potential, followed by SB-X. Result of morphometric analyses with the hydrologic parameters indicates that ~99 % area of SB-III and SB-X are under very good to moderate groundwater potential zone. This study clearly demonstrates that hydrological parameters in relation with morphometric analyses are useful to demarcate the prospect zones of groundwater.     

Geospatial and MCDM tool mix for identification of potential groundwater prospects in a tropical river basin,Kerala

The efficiency of GIS, RS and multi-criteria tools in isolating potential groundwater (GW) zones in the Kuttiyadi River basin (KRB), Kerala, has been robustly demonstrated by analysis of relevant data. To infer geohydrological makeup and consequent behavior of the KRB in respect of GW potential, firstly, various thematic layers viz. geomorphology, geology, slope, soil, lineament density and drainage density, were created. Secondly, thematic layers and their features were assigned suitable weights on the Saaty’s scale according to their relative significance for the presence and potential of GW. The assigned weights of the layers and their features were normalized using analytic network process method, and then the selected thematic maps were integrated in GIS using weighted overlay method to create the final groundwater prospect zone map. From the outcomes, the groundwater prospect zones of the KRB basin was found to be very good (166.21 km²), good (92.01 km²), moderate (180.33 km²), poor (237.25 km²), which constitute 24, 15, 26 and 35% of the study area, respectively. The GW prospect zone map was finally validated using geohydrology of area and GW level data from 43 phreatic wells in the study area. This study showed that groundwater prospect zone demarcation along with multi-criteria decision making is a powerful tool for proper utilization, planning and management of the precious groundwater resource.     

Delineation of groundwater potential zone in Chhatna Block, Bankura District, West Bengal, India using remote sensing and GIS techniques

Groundwater is one of the most valuable natural resources, which is an immensely important and dependable source of water supply in all climatic regions over the world. Groundwater is in demand in areas where surface water supply is inadequate and nonsexist in the Chhatna Block, Bankura district and is located on the eastern slope of Chotonagpur Plateau, which is mapped on 73 I/15, 73 I/16 and 73 M/3, and falls between latitude 23°10′–23°30′N and longitude 86°47′–87°02′E. It represents plain land and gentle slope, which is responsible for infiltration and groundwater recharge. The groundwater in this region is confined within the fracture zones and weathered residuum. The present investigation is, therefore, undertaken to delineate potential zones for groundwater development with the help of a remote-sensing study. IRS–LISS-III data along with other data sets, e.g., existing toposheets and field observation data, have been utilized to extract information on the hydrogeomorphic features which include valley fills, buried pediment moderate, buried pediment shallow and structural hills, lineament density contour and slope map of this hard rock terrain. The target of this study is to delineate the groundwater potential zones in Chhatna block, Bankura District, West Bengal. Satellite imagery, along with other data sets, has been utilized to extract information on the groundwater controlling features of this study area. Three features (hydrogeomorphology, slope, and lineaments) that influence groundwater occurrences were analyzed and integrated. All the information layers have been integrated through GIS analysis and the groundwater potential zones have been delineated. The weighted index overlay method has been followed to delineate groundwater potential zones. The results indicate that good to excellent groundwater potential zones are available in almost the entire block. The results show that there is good agreement between the predicted groundwater potential map and the existing groundwater borehole databases. The area is characterized by hard rock terrain—still due to the presence of planation surface along valley fills; it became the prospective zone. The area has been categorized into four distinct zones: excellent, good, fair and poor. Excellent groundwater potential zones constitute 30–35 % of the total block area; good groundwater potential zones occupy a majority of the block, covering approximately 55–60 % and the fair potential zones occupy about 10–15 % of the total block. Poor potential zones occupy a very insignificant portion (less than 1 %).     

Groundwater assessment in Salboni Block, West Bengal (India) using remote sensing, geographical information system and multi-criteria decision analysis techniques

An approach is presented for the evaluation of groundwater potential using remote sensing, geographic information system, geoelectrical, and multi-criteria decision analysis techniques. The approach divides the available hydrologic and hydrogeologic data into two groups, exogenous (hydrologic) and endogenous (subsurface). A case study in Salboni Block, West Bengal (India), uses six thematic layers of exogenous parameters and four thematic layers of endogenous parameters. These thematic layers and their features were assigned suitable weights which were normalized by analytic hierarchy process and eigenvector techniques. The layers were then integrated using ArcGIS software to generate two groundwater potential maps. The hydrologic parameters-based groundwater potential zone map indicated that the ‘good’ groundwater potential zone covers 27.14% of the area, the ‘moderate’ zone 45.33%, and the ‘poor’ zone 27.53%. A comparison of this map with the groundwater potential map based on subsurface parameters revealed that the hydrologic parameters-based map accurately delineates groundwater potential zones in about 59% of the area, and hence it is dependable to a certain extent. More than 80% of the study area has moderate-to-poor groundwater potential, which necessitates efficient groundwater management for long-term water security. Overall, the integrated technique is useful for the assessment of groundwater resources at a basin or sub-basin scale.     

Extracting of prospective groundwater potential zones using remote sensing data,GIS, and a probabilistic approach in Bojnourd basin,NE of Iran

Various groundwater potential zones for the assessment of groundwater availability in the Bojnourd basin have been investigated using remote sensing, GIS, and a probabilistic approach. Five independent groundwater factors, including topography, ground slope, stream density, geology units, lineament density, and a groundwater productivity factor, i.e., springs’ discharge, were applied. Discharge rates of 226 springs over the area were collected, and the probabilistic model was designed by the discharge rates of springs as the dependent variable. For training the probabilistic model, a ratio of 70/30% of springs’ discharge was applied and discharge rates of 151 springs were selected to randomly train the model. The frequency ratio for each factor was calculated, and the groundwater potential zones were extracted by summation of frequency ratio maps. The groundwater potential map was also classified into four classes, viz., “very good” (with a frequency ratio of >6.75), “good” (5.5FR6.75), “moderate” (4.75FR5.5), and “poor” (FR4.75). Then, the model was verified based on a success-rate curve method which resulted in obtaining an accuracy ratio of 75.77%. Finally, sensitivity analysis was applied by a factor removal method in five steps. Results reveal that topography factor has the biggest effect on the groundwater potential map and removing this factor eventuates in the lowest accuracy of the final map (AUC = 63. 73%). The groundwater potential map is fairly affected by removing the lineament density factor with an accuracy of 68.80%. Removing the lineament density factor has the lowest effect on the final map with accuracy of 68.80%.     

Groundwater potential mapping by combining fuzzy-analytic hierarchy process and GIS in Beyşehir Lake Basin,Turkey

Delineation of the groundwater potential zones is one of the most essential process for the sustainable management of the groundwater sources. However, groundwater studies are quite hard and complex for many regions besides consuming time and cost. This study focused on the groundwater potential mapping in Bey?ehir Lake Basin. Mainly, fuzzy-analytic hierarchy process (fuzzy-AHP) integrated with GIS was used to determine potential zones for groundwater. Seven parameters, namely lithology, lineament, drainage density, land use, slope, soil type, and rainfall were evaluated and Groundwater Potential Index (GWPI) was calculated using weight and rating coefficients of each parameter. According to obtained results, GWPI varies from 0.07665 to 0.28243 in the basin. The low, moderate, and high groundwater potential classes were determined with quantile classification method. The groundwater potential map demonstrates that the high groundwater potential area is located around the lake shore, in the alluvium and limestone fields because high permeability rates depend on soil type, low slope, karstic structure, and agricultural activities in these regions. In addition, the distribution of the springs confirms with groundwater potential area determined with this study.     

Holistic approach of GIS based Multi-Criteria Decision Analysis (MCDA) and WetSpass models to evaluate groundwater potential in Gelana watershed of Ethiopia

Appropriate quantification and identification of the groundwater distribution in a hydrological basin may provide necessary information for effective management, planning and development of groundwater resources. Groundwater potential assessment and delineation in a highly heterogeneous environment with limited Spatiotemporal data derived from Gelana watershed of Abaya Chamo lake basin is performed, using integrated multi-criteria decision analysis (MCDA), water and energy transfer between soil and plant and atmosphere under quasi-steady state (WetSpass) models. The outputs of the WetSpass model reveal a favorable structure of water balance in the basin studied, mainly using surface runoff. The simulated total flow and groundwater recharge are validated using river measurements and estimated baseflow at two gauging stations located in the study area, which yields a good agreement. The WetSpass model effectively integrates a water balance assessment in a geographical information system (GIS) environment. The WetSpass model is shown to be computationally reputable for such a remote complex setting as the African rift, with a correlation coefficient of 0.99 and 0.99 for total flow and baseflow at a significant level of p-value<0.05, respectively. The simulated annual water budget reveals that 77.22% of annual precipitation loses through evapotranspiration, of which 16.54% is lost via surface runoff while 6.24% is recharged to the groundwater. The calibrated groundwater recharge from the WetSpass model is then considered when determining the controlling factors of groundwater occurrence and formation, together with other multi-thematic layers such as lithology, geomorphology, lineament density and drainage density. The selected five thematic layers through MCDA are incorporated by employing the analytical hierarchy process (AHP) method to identify the relative dominance in groundwater potential zoning. The weighted factors in the AHP are procedurally aggregated, based on weighted linear combinations to provide the groundwater potential index. Based on the potential indexes, the area then is demarcated into low, moderate, and high groundwater potential zones (GWPZ). The identified GWPZs are finally examined using the existing groundwater inventory data (static water level and springs) in the region. About 70.7% of groundwater inventory points are coinciding with the delineated GWPZs. The weighting comparison shows that lithology, geomorphology, and groundwater recharge appear to be the dominant factors influence on the resources potential. The assessment of groundwater potential index values identify 45.88% as high, 39.38% moderate, and 14.73% as low groundwater potential zones. WetSpass model analysis is more preferable in the area like Gelana watershed when the topography is rugged, inaccessible and having limited gauging stations.     

Remote Sensing and GIS Based Groundwater Potential Zone Mapping in Ariyalur District,Tamil Nadu

The groundwater is the most precious resources around the world and is shrinking day by day. In connection, there is a need for demarcation of potential ground-water zone. The geographical information system (GIS) and remote sensing techniques have become important tools to locate ground-water potential zones. This research has been carried out to identify groundwater potential zone in Ariyalur of south India with help of GIS and remote sensing techniques. To identify the groundwater potential zone used by different thematic layers of geology, geomorphology, drainage, drainage density, lineaments, lineaments density, soil, rainfall, and slope with inverse distance weightage (IDW) methods. From the overall result the potential zone of groundwater in the study area classified into five classes named as very good (13.34 %), good (51.52 %), moderate (31.48 %), poor (2.82 %) and very poor (0.82 %). This study suggested that, very good potential zone of groundwater occur in patches in northern and central parts of Jayamkondam and Palur regions in Ariyalur district. The result exhibited that inverse distance weightage method offers an effective tool for interpreting groundwater potential zones for suitable development and management of groundwater resources in different hydro-geological environments.     

Integrated multi-parameter approach for delineating groundwater potential zones in a crystalline aquifer of southern India

Groundwater resources in the semi-arid regions of southern India are under immense pressure due to large-scale groundwater abstraction vis-à-vis meager rainfall recharge. Therefore, understanding and evaluating the spatial distribution of groundwater is essential for viable utilization of the resource. Here, we assess groundwater potential at the watershed scale, in a semi-arid environment with crystalline aquifer system without a perennial surface water source using remote sensing, geophysical, and GIS-based integrated multi-parameter approach. GIS-based weighed overlay analysis is performed with input parameters, viz., geology, geomorphology, lineament density, land use, soil, drainage density, slope, and aquifer thickness. The watershed is categorized into four zones, namely, “very good” (GWP4), “good” (GWP3), “moderate” (GWP2), and “low” (GWP1) in terms of groundwater potential. Overall, ~?70% of the study area falls under moderate to low groundwater potential, indicating a serious threat to the future availability of the resource. Therefore, serious measures are required for maintaining aquifer resilience in this over-exploited aquifer (e.g., restricting groundwater withdrawal from GWP1 and GWP2 zones). Further, as the aquifer is under tremendous anthropogenic pressure, rainwater harvesting and artificial recharge during monsoon are advocated for sustainable aquifer management. Due to the direct dependence of crop production vis-à-vis farmer economy on groundwater, this study is an important step towards sustainable groundwater management and can be applied in diverse hydrological terrains.     

Groundwater targeting in a hard-rock terrain using fracture-pattern modeling, Niva River basin, Andhra Pradesh, India

In hard-rock terrain, due to the lack of primary porosity in the bedrock, joints, fault zones, and weathered zones are the sources for groundwater occurrence and movement. To study the groundwater potential in the hard-rock terrain and drought-prone area in the Niva River basin, southern Andhra Pradesh state, India, Landsat 5 photographic data were used to prepare an integrated hydrogeomorphology map. Larsson's integrated deformation model was applied to identify the various fracture systems, to pinpoint those younger tensile fracture sets that are the main groundwater reservoirs, and to understand the importance of fracture density in groundwater prospecting. N35°–55°E fractures were identified as tensile and N35°–55°W fractures as both tensile and shear in the study area. Apparently, these fractures are the youngest open fractures. Wherever N35°–55°E and N35°–55°W fracture densities are high, weathered-zone thickness is greater, water-table fluctuations are small, and well yields are high. Groundwater-potential zones were delineated and classified as very good, good to very good, moderate to good, and poor. Electronic Publication     

GIS based groundwater modeling study to assess the effect of artificial recharge: A case study from Kodaganar river basin,Dindigul district,Tamil Nadu

Groundwater is a dynamic and replenishable natural resource. The numerical modeling techniques serve as a tool to assess the effect of artificial recharge from the water conservation structures and its response with the aquifers under different recharge conditions. The objective of the present study is to identify the suitable sites for artificial recharge structures to augment groundwater resources and assess its performance through the integrated approach of Geographic Information System (GIS) and numerical groundwater modeling techniques using MODFLOW software for the watershed located in the Kodaganar river basin, Dindigul district, Tamil Nadu. Thematic layers such as geology, geomorphology, soil, runoff, land use and slope were integrated to prepare the groundwater prospect and recharge site map. These potential zones were categorized as good (23%), moderate (54%), and poor (23%) zones with respect to the assigned weightage of different thematic layers. The major artificial recharge structures like percolation ponds and check dams were recommended based on the drainage morphology in the watershed. Finally, a threelayer groundwater flow model was developed. The model was calibrated in two stages, which involved steady and transient state condition. The transient calibration was carried out for the time period from January 1989 to December 2008. The groundwater model was validated after model calibration. The prediction scenario was carried out after the transient calibration for the time period of year up to 2013. The results show that there is 15 to 38% increase in groundwater quantity due to artificial recharge. The present study is useful to assess the effect of artificial recharge from the proposed artificial structures by integrating GIS and groundwater model together to arrive at reasonable results.     

Groundwater recharge zones mapping using GIS: a case study in Southern part of Jordan Valley,Jordan

This paper aims at mapping the potential groundwater recharge zones in the southern part of Jordan Valley (JV). This area is considered as the most important part for agricultural production in Jordan. The methodology adopted in this study is based on utilizing the open ended SLUGGER-DQL score model, which was developed by Raymond et al (2009). Geographic information systems were used in this study to build up the different layers of this model and to create the potential groundwater recharge zones. Based on the generated SLUGGER-DQL potential map, it was found that about 70.8 % of the investigated area was categorized as high potential for groundwater recharge, 18.7 % as moderate, and 10.5 % as low potential for groundwater recharge. To validate the model results, sensitivity analysis was carried out to assess the influence of each model parameter on the obtained results. Based on this analysis, it was found that the slope parameter (S) is the most sensitive parameter among SLUGGER-DQL model parameters, followed by water level in summer (L), well density (D), water quality (Q), runoff availability (R), land use/land cover, geology (GE), whereas the lowest sensitive parameter is the geology parameter (GE). Moreover, the parameters R, D, and Q show the lowest effective weights. The effective weight for each parameter was found to differ from the assigned theoretical weight by SLUGGER-DQL index model.     

Mapping groundwater recharge potential using GIS approach in Darwha block

Groundwater is the most important source of water in meeting irrigation, drinking, and other needs in India. The assessment of the potential zone for its recharge is critical for sustainable usage, quality management, and food security. This study reports alternative mapping of the groundwater recharge potential of a selected block by including large-scale soil data. Thematic layers of soil, geomorphology, slope, land use land cover, topographical wetness index, and drainage density of Darwha block (District Yavatmal, Maharashtra, India) were generated and integrated in a geographic information system environment. The topographic maps, thematic maps, field data, and satellite image were processed, classified, and weighted using analytical hierarchical process for their contribution to groundwater recharge. The layers were integrated by weighted linear combination method in the GIS environment to generate four groundwater potential zones viz., “poor,” “poor to moderate,” “moderate to high,” and “high.” Based on the generated groundwater potential map, about 9830 ha (12%) of the study area was categorized as high potential for recharge, 25,558 ha (31%) as poor to moderate, 33,398 ha (40%) as moderate to high, and 12,565 ha (15%) as poor potential zone. The zonation corresponds well with the field data on greater well density (0.22/ha) and irrigated crop area (27%) in the high potential zone as against 0.02 wells/ha and only 6% irrigated area in the poor zone. The map is recommended for use in regulating groundwater development decisions and judicious expenditure on drilling new wells by farmers and the state authorities.     

A knowledge-driven GIS modeling technique for groundwater potential mapping at the Upper Langat Basin, Malaysia

The aim of this paper is to use a knowledge-driven expert-based geographical information system (GIS) model coupling with remote-sensing-derived parameters for groundwater potential mapping in an area of the Upper Langat Basin, Malaysia. In this study, nine groundwater storage controlling parameters that affect groundwater occurrences are derived from remotely sensed imagery, available maps, and associated databases. Those parameters are: lithology, slope, lineament, land use, soil, rainfall, drainage density, elevation, and geomorphology. Then the parameter layers were integrated and modeled using a knowledge-driven GIS of weighted linear combination. The weightage and score for each parameter and their classes are based on the Malaysian groundwater expert opinion survey. The predicted groundwater potential map was classified into four distinct zones based on the classification scheme designed by Department of Minerals and Geoscience Malaysia (JMG). The results showed that about 17% of the study area falls under low-potential zone, with 66% on moderate-potential zone, 15% with high-potential zone, and only 0.45% falls under very-high-potential zone. The results obtained in this study were validated with the groundwater borehole wells data compiled by the JMG and showed 76% of prediction accuracy. In addition statistical analysis indicated that hard rock dominant of the study area is controlled by secondary porosity such as distance from lineament and density of lineament. There are high correlations between area percentage of predicted groundwater potential zones and groundwater well yield. Results obtained from this study can be useful for future planning of groundwater exploration, planning and development by related agencies in Malaysia which provide a rapid method and reduce cost as well as less time consuming. The results may be also transferable to other areas of similar hydrological characteristics.     

Application of geospatial modelling technique in delineation of fluoride contamination zones within Dwarka Basin,Birbhum, India

Dwarka River Basin is one of the fluoride affected river basin in Birbhum, West Bengal. In the present research work, various controlling factors for fluoride contamination in groundwater i.e., geology, aquifer type, groundwater table, soil, rainfall, geomorphology, drainage density, land use land cover, lineament and fault density, slope and elevation were considered to delineate the potential fluoride contamination zones within Dwarka River Basin in Birbhum. Assigning weights and ranks to various inputs factor class and their sub-class respectively was carried out on the basis of knowledge driven method. Weighted overlay analysis was carried out to generate the final potential fluoride contamination zones which are classified into two broad classes i.e., ‘high’ and ‘low’, and it is observed that major portion of the study area falls under low fluoride contamination category encompassing 88.61% of the total area which accounts for 759.48 km² and high fluoride contaminated region accounts for 11.40% of the total study area encompassing an area of about 97.67 km². Majority of high fluoride areas fall along the flood plain of Dwarka River Basin. Finally, for validation 197 reported points within Dwarka having fluoride in underground water are overlaid and an overall accuracy of 92.15% is observed. An accuracy of 83.21% and 84.24% is obtained for success and prediction rate curve respectively.     

Mapping of groundwater prospective zones integrating remote sensing,geographic information systems and geophysical techniques in El-Qaà Plain area,Egypt

The geospatial mapping of groundwater prospective zones is essential to support the needs of local inhabitants and agricultural activities in arid regions such as El-Qaà area, Sinai Peninsula, Egypt. The study aims to locate new wells that can serve to cope with water scarcity. The integration of remote sensing, geographic information systems (GIS) and geophysical techniques is a breakthrough for groundwater prospecting. Based on these techniques, several factors contributing to groundwater potential in El-Qaà Plain were determined. Geophysical data were supported by information derived from a digital elevation model, and from geologic, geomorphologic and hydrologic data, to reveal the promising sites. All the spatial data that represent the contributing factors were integrated and analyzed in a GIS framework to develop a groundwater prospective model. An appropriate weightage was specified to each factor based on its relative contribution towards groundwater potential, and the resulting map delineates the study area into five classes, from very poor to very good potential. The very good potential zones are located in the Quaternary deposits, with flat to gentle topography, dense lineaments and structurally controlled drainage channels. The groundwater potential map was tested against the distribution of groundwater wells and cultivated land. The integrated methodology provides a powerful tool to design a suitable groundwater management plan in arid regions.     

Groundwater potential zone assessment in Wadi Watir area,Egypt using radar data and GIS

The exploration of new locations for possible groundwater potentiality is required to support the needs of urban and agricultural activities in arid regions such as Wadi Watir basin. The aim of this study is to locate new groundwater wells that can help overcome the water shortage. In order to define favorable zones for groundwater potentiality, several essential factors contributing to groundwater potentiality were identified. These factors include textural classification of alluvial deposits, lithological units, surface and subsurface structures, topographic parameters, geomorphological features and land use/land cover. A hydrogeological prospective model was developed using spatial data which represent these factors. For final groundwater potential map, all factors were converted to raster data to integrate spatially as important thematic layers based on weightage analysis. The groundwater potential map was classified to five classes including very poor to very good potential. The classes of groundwater potential map were checked against the distribution of the groundwater wells, Bedouin communities and agriculture areas, which present a general knowledge of groundwater potential in the study area.     

Delineation of groundwater potential zones in Wadi Saida Watershed of NW-Algeria using remote sensing,geographic information system-based AHP techniques and geostatistical analysis

Sustainable management of groundwater resources has now become an obligation,especially in arid and semi-arid regions given the socio-economic importance of this resource.The optimization in zoning for groundwater exploitation helps in planning and managing groundwater supply works such as boreholes and wells in the catchment.The objective of this study is to use remote sensing and GIS-based Analytical Hierarchy Process(AHP)techniques to evaluate the groundwater potential of Wadi Saida Watershed.Spatial analysis such as geostatistics was also used to validate results and ensure more accuracy.Through the GIS tools and remote sensing technique,earth observation data were converted into thematic layers such as lineament density,geology,drainage density,slope,land use and rainfall,which were combined to delineate groundwater potential zones.Based on their respective impact on groundwater potential,the AHP approach was adopted to assign weights on multi-influencing factors.These results will enable decision-makers to optimize hydrogeological exploration in large-scale catchment areas and map areas.According to the results,the southern part of the Wadi Saida Watershed is characterized as a higher groundwater potential area,where 32%of the total surface area falls in the excellent and good class of groundwater potential.The validation process revealed a 71%agreement between the estimated and actual yield of the existing boreholes in the study area.     

Evaluation of aquifers vulnerability to contamination in the Yarmouk River basin, Jordan, based on DRASTIC method

The existing different human activities and planned land uses put the groundwater resources in Jordan at considerable risk. There are evidences suggesting that the quality of groundwater supplies in north Jordan is under threat from a wide variety of point and non-point sources including agricultural, domestic, and industrial. Vulnerability maps are designed to show areas of greatest potential for groundwater contamination on the basis of hydrogeological conditions and human impacts. DRASTIC method incorporates the major geological and hydrogeological factors that affect and control groundwater movement: depth to groundwater (D), net recharge (R), lithology of the aquifer (A), soil texture (S), topography (T), lithology of vadose zone (I), and hydraulic conductivity (C). The main goal of this study is to produce vulnerability maps of groundwater resources in the Yarmouk River basin by applying the DRASTIC method to determine areas where groundwater protection or monitoring is critical. ArcGIS 9.2 was used to create the groundwater vulnerability maps by overlaying the available hydrogeological data. The resulting vulnerability maps were then integrated with lineament and land use maps as additional parameters in the DRASTIC model to assess more accurately the potential risk of groundwater to pollution. The general DRASTIC index indicates that the potential for polluting groundwater is low in the whole basin, whereas the resulting pesticide DRASTIC vulnerability map indicates that about 31% of the basin is classified as having moderate vulnerability, which may be attributed to agricultural activities in the area. Although high nitrate concentrations were found in areas of moderate vulnerability, DRASTIC method did not depict accurately the nitrate distribution in the area.