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.     

Application of probabilistic-based frequency ratio model in groundwater potential mapping using remote sensing data and GIS

The main goal of this study is to investigate the application of the probabilistic-based frequency ratio (FR) model in groundwater potential mapping at Langat basin in Malaysia using geographical information system. So far, the approach of probabilistic frequency ratio model has not yet been used to delineate groundwater potential in Malaysia. Moreover, this study includes the analysis of the spatial relationships between groundwater yield and various hydrological conditioning factors such as elevation, slope, curvature, river, lineament, geology, soil, and land use for this region. Eight groundwater-related factors were collected and extracted from topographic data, geological data, satellite imagery, and published maps. About 68 groundwater data with high potential yield values of ≥11 m³/h were randomly selected using statistical software of SPSS. Then, the groundwater data were randomly split into a training dataset 70 % (48 borehole data) for training the model and the remaining 30 % (20 borehole data) was used for validation purpose. Finally, the frequency ratio coefficients of the hydrological factors were used to generate the groundwater potential map. The validation dataset which was not used during the FR modeling process was used to validate the groundwater potential map using the prediction rate method. The validation results showed that the area under the curve for frequency model is 84.78 %. As far as the performance of the FR approach is concerned, the results appeared to be quite satisfactory, i.e., the zones determined on the map being zones of relative groundwater potential. This information could be used by government agencies as well as private sectors as a guide for groundwater exploration and assessment in Malaysia.     

An extraction,analysis, and prioritization of Asna river sub-basins,based on geomorphometric parameters using geospatial tools

The Asna river basin is located in Hingoli and Nanded districts of Marathwada region of Maharashtra. A geomorphometric analysis is an important method for the investigation and management of natural resources of watershed. The geomorphometric analysis of Asna river basin classifies three sub-basins that have been delineated using GIS and remote sensing through measurements of linear, aerial, and relief aspects. The Asna river basin comprises an area of 1187 km² with seventh-order drainage pattern. As per Strahler classification, the upper part of the basin shows dendritic to sub-dendritic and the lower part exhibits parallel to sub-parallel drainage pattern. The total numbers of stream segments are 2422 and length of streams is 2187.92 km. The bifurcation value ranges from 1.26 to 5.58 indicating that there are no structural disturbances. The form factor value (0.49) indicates that the shape of the basin is moderately circular. The high values of drainage density, stream frequency, and low infiltration number indicate the high runoff due to impermeable lithology. The slope of the basin varies from 1 to 32.2%, terrain elevation ranges from 333 to 551 m, and overall relief of the basin is 218 m amsl. River sub-basin prioritization has an immense importance in natural resource management, especially in semi-arid regions. The present study is an attempt to prioritize the sub-basins of Asna river based on geomorphometric parameters. The weightage is assigned to different morphometric parameters of sub-basins based on erosion potential. The Asna river sub-basins have been classified into three categories as high, medium, and low on the basis of priorities for soil and water conservation. It is confirmed that sub-basin I is characterized as highly vulnerable to erosion and has high sedimentation load; sub-basin II has low priority, i.e., very low erodibility; and sub-basin III is of moderate type. The morphometric analysis and prioritization methods can be applied to hydrological studies in surface as well as subsurface water, climatic studies, rainwater harvesting, groundwater recharging sites, and watershed management.     

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%.     

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.     

Integration between morphometric parameters,hydrologic model,and geo-informatics techniques for estimating WADI runoff (case study WADI HALYAH—Saudi Arabia)

In arid and semiarid areas, the only surface and groundwater recharge source is the runoff generated through flash floods. Lack of hydrological data in such areas makes runoff estimation extremely complicated. Flash floods are considered catastrophic phenomena posing a major hazardous threat to cities, villages, and their infrastructures. The objective of this study is to assess the flash flood hazard and runoff in Wadi Halyah and its sub-basins. Integration of morphometric parameters, geo-informatics, and hydrological models has been done to overcome the challenge of scarcity of data.Advanced Spaceborne Thermal Emission and Reflection (ASTER) data was used to prepare a digital elevation model (DEM) with 30-m resolution, and geographical information system (GIS) was used in the evaluation of network, geometry, texture, and relief features of the morphometric parameters. Thirty-eight morphometric parameters were estimated and have been linked together for producing nine effective parameters for evaluation of the flash flood hazard in the study basin.Flash flood hazard in Wadi Halyah and its sub-basins was identified and grouped into three classes depending on nine effective parameters directly influencing the flood prone areas. Calculated runoff volume of Wadi Halyah ranges from 26.7 × 10⁶ to 111.4 × 10⁶ m³ with an inundation area of 15 and 27 km² at return periods of 5 and 100 years, respectively. Mathematical relationships among rainfall depth, runoff volume, infiltration losses, and rainfall excess demonstrate a strong directly proportional relationships with correlation coefficient of about 0.99.     

Flowing well potential zoning at Iraqi southern and western deserts using frequency ratio and geographic information system

The objective of this study is to integrate geographic information system and bivariate frequency ratio method for the mapping of flowing well zones in the west and southwest parts of the Euphrates river basin of Iraq. Ten groundwater conditioning factors are identified as controlling factors of groundwater movement based on data availability, literature review, and expert’s opinions. The spatial association between flowing well locations and groundwater controlling factors is investigated by means of a probabilistic frequency ratio approach. Seventy percent or 148 wells from an inventory of 211 flowing wells in the study area are randomly selected for training, and the remaining 30 or 63% wells are used for validation of the probabilistic frequency ratio model. The estimated probabilistic ratio values are overlaid and summed to produce the groundwater potential index map. The results reveal that groundwater potential in 128,547 km² or 84% of the total area is very low to low. The moderate potential zone covers an area of about 11,210 km² or 7%, while the high and very high potential zones are found in an area of 12,982 km² or 9% of the study area. Validation of obtaining results by means of a receiver operating characteristic technique reveals that the predictive accuracy of 94% indicating the excellent performance of the proposed approach for spatial zoning of groundwater flowing well boundary at Iraqi desert.     

Identification of potential groundwater recharge zones in Vaigai upper basin,Tamil Nadu,using GIS-based analytical hierarchical process (AHP) technique

Groundwater recharge is an important process for the management of both surface and subsurface water resources. The present study utilizes the application of analytical hierarchical process (AHP) on geospatial analysis for the exploration of potential zones for artificial groundwater recharge along Vaigai upper basin in the Theni district, Tamil Nadu, India. The morphology of earth surface features such as geology, geomorphology, soil types, land use and land cover, drainage, lineament, and aquifers influence the groundwater recharge in either direct or indirect way. These thematic layers are extracted from Landsat ETM+ image, topographical map, and other collateral data sources. In this study, the multilayers were weighed accordingly to the magnitude of groundwater recharge potential. The AHP technique is a pair-wise matrix analytical method was used to calculate the geometric mean and normalized weight of individual parameters. Further, the normalized weighted layers are mathematically overlaid for preparation of groundwater recharge potential zone map. The results revealed that 21.8 km² of the total area are identified as high potential for groundwater recharge. The gentle slope areas in middle-east and central part have been moderately potential for groundwater recharge. Hilly terrains in south are considered as unsuitable zone for groundwater recharge processes.     

Identification of groundwater potential zones within an area with various geomorphological units by using several field parameters and a GIS approach in Kulon Progo Regency, Java, Indonesia

A case study was conducted to find the groundwater potential zones in an area between the Serang and Bogowonto rivers, Kulon Progo Regency, Java, Indonesia. The objectives of this study were to delineate the groundwater potential zone based on a number of groundwater parameters that can be surveyed in the field and to incorporate the geomorphological conditions into these data. The geomorphology interpretation was conducted using the landform approach. This approach begins by preparing supporting data such as an Indonesian Topographic Map containing contour and land use data; a regional geology map containing lithology type and geology structures; and soil, climate, and hydrological data. The determination of the geomorphology unit was conducted manually by the visual interpretation of Digital Landsat ETM⁺ with some image interpretation keys. Four groundwater parameters were surveyed in the field: (a) depth to the water table, (b) water table fluctuation, (c) fluid electrical conductivity to represent groundwater quality, and (d) aquifer thickness. The groundwater potential zones were obtained by overlaying all the groundwater field parameters in terms of weighted overlay methods using the spatial analysis tool in ArcGIS 9.2. During the weighted overlay analysis, rankings were produced for each individual parameter of each groundwater field parameter, and weights were assigned based on the amount of influence they had (i.e., depth to the water table—30 %, water table fluctuation—20 %, aquifer thickness—30 %, and fluid conductivity—20 %). We then found the good, moderate, and poor zones in terms of groundwater potential, which had areas of 5.83, 4.53, and 2.36 km², respectively. Areas with good groundwater potential are located largely within sand dunes, beach ridges, beaches, and fluviomarine plain landforms, which are characterized by a shallow water table, low fluctuation, thick aquifer, and low EC value. Moderate groundwater zones are generally characterized by poor water quality (high EC value), which is found to some degree in the alluvial plain. The regions with poor groundwater potential are spread mainly across the landforms composed of igneous rock (thin aquifers), such as denudational hills, which act as run-off zones due to their steep slope.     

Morphometric analysis of Araniar river basin using remote sensing and geographical information system in the assessment of groundwater potential

Morphometric analysis using remote sensing (RS) and geographical information system (GIS), in the recent study, has become an efficient method in the assessment of groundwater potential of a river basin. The present study focused on the morphometric analysis of Araniar river basin using RS and GIS techniques in the identification of groundwater potential zones for effective planning and management of groundwater resources of the basin. The study area was divided into six subbasins for the purpose of micro-level morphometric analysis. The main stream of the basin is of fifth order and drainage patterns of subbasins are mostly of dendritic and parallel type. Based on the linear, areal and relief parameters of subbasins, the groundwater potential zones of the basin were identified and the results substantiated with geomorphology map derived from RS data. The elongated shape, favourable drainage network, permeable geologic formation and low relief of the subbasins WS3, WS5 and WS6 make them the promising groundwater potential zones of Araniar river basin. The statistical analysis and overlay analysis of the morphometric parameters also indicated the subbasins WS3, WS5 and WS6 as high groundwater potential zones. The groundwater potential zone map when overlaid with groundwater fluctuation map indicated the suitable sites for artificial recharge structures.     

Rainfall-runoff modeling of ungauged Wadis in arid environments (case study Wadi Rabigh—Saudi Arabia)

Flash flood forecasting of catchment systems is one of the challenges especially in the arid ungauged basins. This study is attempted to estimate the relationship between rainfall and runoff and also to provide flash flood hazard warnings for ungauged basins based on the hydrological characteristics using geographic information system (GIS). Morphometric characteristics of drainage basins provide a means for describing the hydrological behavior of a basin. The study examined the morphometric parameters of Wadi Rabigh with emphasis on its implication for hydrologic processes through the integration analysis between morphometric parameters and GIS techniques. Data for this study were obtained from ASTER data for digital elevation model (DEM) with 30-m resolution, topographic map (1:50,000), and geological maps (1,250,000) which were subject to field confirmation. About 36 morphometric parameters were measured and calculated, and interlinked to produce nine effective parameters for the evaluation of the flash flood hazard degree of the study area. Based on nine effective morphometric parameters that directly influence on the hydrologic behavior of the Wadi through time of concentration, the flash flood hazard of the Rabigh basin and its subbasins was identified and classified into three groups (High, medium, and low hazard degree). The present work proved that the physiographic features of drainage basin contribute to the possibility of a flash flood hazard evaluation for any particular drainage area. The study provides details on the flash flood prone subbasins and the mitigation measures. This study also helps to plan rainwater harvesting and watershed management in the flash flood alert zones. Based on two historical data events of rainfall and the corresponding maximum flow rate, morphometric parameters and Stormwater Management and Design Aid software (SMADA 6), it could be to generate the hydrograph of Wadi Rabigh basin. As a result of the model applied to Wadi Rabigh basin, a rainfall event of a total of 22 mm with a duration of 5 h at the station nearby the study area, which has an exceedance probability of 50 % and return period around 2 years, produces a discharge volume of 15.2?×?10⁶ m³ at the delta, outlet of the basin, as 12.5 mm of the rainfall infiltrates (recharge).     

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.     

Watershed morphometric analysis of Wadi Baish Dam catchment area using integrated GIS-based approach

The integration of Remote Sensing (RS) and Geographic Information Systems (GIS) constitutes a powerful tool for the evaluation of watershed morphometric parameters. The benefits of this integration include saving time and effort as well as improving the accuracy of the analysis. Moreover, this technique is appropriate for describing the watershed and its streams. In this study, a detailed morphometric analysis of the Wadi Baish catchment area has been performed using the Shuttle Radar Topography Mission (SRTM). The performed morphometric analysis includes linear, areal, and relief aspects. The results of the morphometric analysis reveal that the catchment can be described as of eighth stream order and consists of an area of 4741.07 km². Additionally, the basin is characterized by a relatively high mean value of bifurcation (4.012), indicative of the scarcity of permeable rocks with high slope in the area. This value of bifurcation ratio is consistent with the high drainage density value of 2.064 km/km² and confirms the impermeability of the subsurface material and mountainous relief. The hypsometric integral of the catchment is 47.4%, and the erosion integral of the catchment is 52.6%, both were indications of a mature catchment area.     

Evaluation of groundwater potential zones using electrical resistivity and GIS in Noyyal river basin,Tamil Nadu

The purpose of this study was to identify the groundwater potential zones in Noyyal river basin using GIS and electrical resistivity. River Noyyal was perennial with good flow till early seventies. In recent years, the scene has changed drastically and the river has become practically seasonal and receives copious water during northeast monsoon from September to November. The rest of the years it remains more or less dry. Since the surface water resources in the area are inadequate to meet the local needs it is necessary to explore groundwater resources which has not been done properly. Hence various thematic maps have been used for the preparation of groundwater prospective map by integrating geology, geomorphology, slope, drainage and lineament of the study area. Electrical resistivity survey was conducted at 52 locations by using Schlumberger configuration. From this weathered thickness and depth to basement have been taken and overlaid for identifying groundwater potential sites and finally this result was compared with yield data. The interpretation shows that the entire study area has moderate to good category of groundwater potential.     

Integrating remote sensing and GIS for identification of groundwater prospective zones in the Narava basin, Visakhapatnam region, Andhra Pradesh

This paper mainly deals with the integrated approach of remote sensing and Geographical Information System (GIS) to delineate groundwater prospective zones in Narava basin, Visakhapatnam region. The various thematic maps generated for delineating groundwater potential zones are geomorphology, geology, lineament density, drainage density, slope and land use/land cover (LULC). Weighted index overlay (WIO) technique is used to investigate a number of choice possibilities and evaluate suitability according to the associated weight of each unit. The integrated map of the area shows different zones of groundwater prospects, viz. very good (18.9% of the area), good (26.4% of the area), moderate (17.1% of the area) and poor (37.6% of the area). The categorization of groundwater potential was in good agreement with the available water column in the basin area.     

Application of remote sensing and GIS for delineating groundwater recharge potential zones of Kovilpatti Municipality,Tamil Nadu using IF technique

During the last three decades, remotely sensed data (both satellite images and aerial photographs) have been increasingly used in groundwater exploration and management exercises. An integrated approach has been adopted in the present study to delineate groundwater recharge potential zones using RS and GIS techniques. IRS-1C satellite imageries and Survey of India toposheets are used to prepare various thematic layers viz. geology, soil, land-use, slope, lineament and drainage. These layers were then transformed in to raster data using feature to raster converter tool in ArcGIS 9.3 software. The raster maps of these factors are allocated a fixed score and weight computed from Influencing Factor (IF) technique. The weights of factors contributing to the groundwater recharge are derived using aerial photos, geology maps, a land use database, and field verification. Subjective weights are assigned to the respective thematic layers and overlaid in GIS platform for the identification of potential groundwater recharge zones within the study area. Then these potential zones were categories as ‘high’, ‘moderate’, ‘low’, ‘poor’. The resulted map shows that 19 % of the area has highest recharge potential, mainly confined to buried pediplain, agriculture land-use and river terraces (considerable amount of precipitated water percolates into subsurface), 28 % of the area has moderate groundwater recharge potentiality and rest of the area has low to poor recharge potentiality. The residual hills and linear ridges with steep slopes are not suitable for artificial recharge sites. Finally, 13 % of total average annual precipitated water (840 mm) percolates downward and ultimately contributes to recharge the aquifers in the Kovilpatti Municipality area. The paper is an attempt to suggest for maintaining the proper balance between the groundwater quantity and its exploitation.     

The significance of morphometric analysis for obtaining groundwater potential zones in a structurally controlled terrain

Watershed development and management plans are more important for harnessing surface water and groundwater resources in arid and semi-arid regions. To prepare a comprehensive watershed development plan, it becomes necessary to understand the topography, erosion status and drainage patterns of the region. This study was undertaken to determine the drainage characteristics of Pageru River basin using topographical maps on a scale of 1:50,000. The total area of the Pageru River basin is 480 km². It was divided into X sub-basins for analysis. The drainage patterns of the basin are dendritic and include a sixth order stream. The quantitative analysis of various aspects of a river basin drainage network characteristics reveals complex morphometric attributes. The streams of lower orders mostly dominate the basin. The development of stream segments in the basin area is more or less affected by rainfall. The elongated shape of the basin is mainly due to the guiding effect of thrusting and faulting. The erosional processes of fluvial origin have been predominately influenced by the subsurface lithology of the basin.     

A GIS and remote sensing based evaluation of groundwater potential zones in a hard rock terrain of Vaigai sub-basin, India

In this paper, remote sensing, geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Vaigai basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity–hue–saturation transformation and decorrelation stretch were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps such as geology, geomorphology, soil hydrological group, land use/land cover and drainage map were prepared and analyzed using GIS Arc Map GIS Raster Calculator module as geomorphology?×?12?+?drainage?×?9?+?lineament?×?5?+?geology?×?8?+?land use?×?2?+?relief?×?4. The final cumulative map generated by applying the above equation had weight values ranging from 0.315 to 4.515. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan, the thematic maps for the study area.     

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.     

Hydrogeochemical characteristics of surface water (SW) and groundwater (GW) of the Chinnaeru River basin,northern part of Nalgonda District,Andhra Pradesh,India

Groundwater and surface water samples from 47 locations (28 groundwater, 10 tanks and 9 stream channel) were collected during the pre-monsoon (May–June) and post-monsoon season (November) from Chinnaeru River basin. Chinnaeru River basin is situated 30 km east of Hyderabad City and its area covers 250 km² and falls in the Survey of India Toposheet No. 56 K/15. The extensive agricultural, industrial and urbanization activities resulted in the contamination of the aquifer. To study the contamination of groundwater, water samples were collected from an area and analyzed for major cations and anions. Various widely accepted methods such as salinity, sodium absorption ratio, Kelly’s ratio, residual sodium carbonate, soluble sodium percentage, permeability index and water quality index are used to classify groundwater and surface water (tank and stream) for drinking as well as irrigation purposes. Besides this, Piper trilinear diagram, Wilcox diagram, Doneen’s classification and Gibb’s plot were studied for geochemical controls, and hydrogeochemistry of groundwater and surface water samples were studied.