• Shakeel Ahmed

      Articles written in Journal of Earth System Science

    • Implications of Kali–Hindon inter-stream aquifer water balance for groundwater management in western Uttar Pradesh

      Rashid Umar M Muqtada A Khan Izrar Ahmed Shakeel Ahmed

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      The Kali–Hindon inter-stream region extends over an area of 395 km2 within the Ganga–Yamuna interfluve. It is a fertile tract for sugarcane cultivation. Groundwater is a primary resource for irrigation and industrial purposes. In recent years, over-exploitation has resulted in an adverse impact on the groundwater regime. In this study, an attempt has been made to calculate a water balance for the Kali–Hindon inter-stream region. Various inflows and outflows to and from the aquifer have been calculated. The recharge due to rainfall and other recharge parameters such as horizontal inflow, irrigation return flow and canal seepage were also evaluated. Groundwater withdrawals, evaporation from the water table, discharge from the aquifer to rivers and horizontal subsurface outflows were also estimated. The results show that total recharge into the system is 148.72million cubic metres (Mcum), whereas the total discharge is 161.06 Mcum, leaving a deficit balance of −12.34Mcum. Similarly, the groundwater balance was evaluated for the successive four years. The result shows that the groundwater balance is highly sensitive to variation in rainfall followed by draft through pumpage. The depths to water level are shallow in the canal-irrigated northern part of the basin and deeper in the southern part. The pre-monsoon and post-monsoon water levels range from 4.6 to 17.7m below ground level (bgl) and from 3.5 to 16.5m bgl respectively. It is concluded that the groundwater may be pumped in the canal-irrigated northern part, while withdrawals may be restricted to the southern portion of the basin, where intense abstraction has led to rapidly falling water table levels.

    • Assessing variability of water quality in a groundwater-fed perennial lake of Kashmir Himalayas using linear geostatics

      S Sarah Gh Jeelani Shakeel Ahmed

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      This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the KashmirValley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Resultsindicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO3, Mg–HCO3 and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca2+, Mg2+, Na+, K+, NO3 and HCO$^{−}_{3}$, CO3 and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO3 concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.

    • Deciphering heavy metal contamination zones in soils of a granitic terrain of southern India using factor analysis and GIS

      D Purushotham Mahjoor Ahmad Lone Mehnaz Rashid A Narsing Rao Shakeel Ahmed

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      Soil contamination by heavy metals has been a major concern for last few decades due to increase in urbanization and industrialization. The main objective of this research was to identify the heavy metal contaminated zones in the study area. Twenty five soil samples collected throughout the agriculture, residential and industrial areas were analysed by X-ray Fluorescence Spectrometer (XRF) for trace metals and major oxides. These metals can affect the quality of soil and infiltrate through the soil, thereby causing groundwater pollution. Based on the chemical analysis of major oxides (SiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, TiO2, and P2O5) and their distribution; it is observed that these soils are predominantly siliceous type with slight enrichment of alumina component in the study area. Correlation matrix (CM) and factor analysis (FA) is employed to the heavy metal variables, viz., Ba, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn and Zr of the soil to determine the dominant factors contributing to the soil contamination in the area. In the analysis, five factors emerged as significant contributors to the soil quality. The total contribution of these five factors is about 90%. The contribution of the first factor is about 45% and has significant positive loadings of Co, Cr, Cu, Ni and Zn. The contribution of second factor is 22% and has significant positive loadings of Rb, Sr and Y. The contribution of third, fourth and fifth factors is 10, 8 and 5% and show positive loadings for lead, molybdenum and barium respectively to the soil contamination. The spatial variation maps deciphering different zones of heavy metal concentration in the soil were generated in a GIS (geographic information system) based environment using ArcGIS 9.3.1. The results reveal that heavy metal contamination in the area is mainly due to anthropogenic activities.

    • Exploring deep potential aquifer in water scarce crystalline rocks

      Subash Chandra E Nagaiah D V Reddy V Ananda Rao Shakeel Ahmed

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      Characterization of the shear zone with pole–pole electrical resistivity tomography (ERT) was carried out to explore deep groundwater potential zone in a water scarce granitic area. As existing field conditions does not always allow to plant the remote electrodes at sufficiently far of distance, the effect of insufficient distance of remote electrodes on apparent resistivity measurement was studied and shown that the transverse pole–pole array affects less compared to the collinear pole–pole array. Correction factor have been computed for transverse pole–pole array for various positions of the remote electrodes. The above results helped in exploring deep aquifer site, where a 270 m deep well was drilled. Temporal hydro-chemical samples collected during the pumping indicated the hydraulic connectivity between the demarcated groundwater potential fractures. Incorporating all the information derived from different investigations, a subsurface model was synthetically simulated and generated 2D electrical resistivity response for different arrays and compared with the field responses to further validate the geoelectrical response of deep aquifer set-up associated with lineament.

    • Vertical electrical sounding to delineate the potential aquifer zones for drinking water in Niamey city, Niger, Africa

      Joy Choudhury K Lohith Kumar E Nagaiah S Sonkamble Shakeel Ahmed Venay Kumar

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      Niger is a landlocked African country and the only source of surface water is the Niger River which flows in the western part of Niger and only few villages near to the river gets benefited from it, leaving most of the areas dependent on groundwater solely. The groundwater resources in Niger are mainly used for drinking, livestock and domestic needs. It can be observed that the water exploitation is minimal there due to several factors like undeveloped areas, less population, limited wells, rain-fed irrigation, etc. The delineation of potential aquifer zones is an important aspect for groundwater prospecting. Hence, the direct current (DC) resistivity soundings method also known as vertical electrical sounding (VES) is one of the most applied geophysical techniques for groundwater prospecting that was used in the capital city, Niamey of Niger. Twelve VES surveys, each of AB spacing 400 m were carried out in lateritic and granitic rock formations with a view to study the layer response and to delineate the potential zones. Potential aquifer zones were at shallow depth ranging from 10 to 25 m for the drilled borehole depth of 80–85 m in every village. Analysis of the result showed a good correlation between the acquired data and the lithologs.

    • Spatial estimation of groundwater storage from a 2D specific yield in the crystalline aquifer of the Maheshwaram watershed

      Syed Adil Mizan Shakeel Ahmed Adrien Selles

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      Crystalline aquifers are present in most parts of southern India with limited resources of groundwater. The groundwater storage map in the Maheshwaram watershed has been estimated from the product of specific yield (Sy) and saturate aquifer thickness as a system being an unconfined weathered–fractured combined aquifer. Land-use data has been used for the estimation of groundwater abstraction at a spatial scale. Storage and scarcity mapping demonstrate that the watershed is clearly vulnerable to drought in some areas because of significant pumping. Therefore, the result shows that on average, the availability of groundwater storage corresponds to 1.5 yr of the present groundwater abstraction rate with successive low monsoons (i.e., insignificant recharge). Additionally, 13% of the area shows no storage at present, 28% of the area has less than 1 yr, 40% area has less than 2 yr and 12% area has less than 3% of storage. Very few cells can sustain for more than 3 yr. Additionally, the Sy of the aquifer ranges from 0.2% to 5% with a mean value of 1.8%. A geo-statistical technique has been applied for the estimation of Sy at unknown cells where either the cell was dry or no pumping occurred. This estimated two-dimensional Sy value can also be used in classical groundwater numerical modelling for a better understanding of groundwater resource management.

    • Multiparametric coupling and constrained interpolation to improve natural recharge estimation


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      The inverse modelling technique seeks to improve the existing estimates of natural recharge in hard rocks by coupling multiple hydrogeophysical parameters that jointly affect natural hydrogeological processes. This approach involves coupling of an initial set of multiple hydrogeophysical (soil resistivity, bedrockdepth and rainfall) parameters in the form of exponents assigned to each parameter and a multiplication coefficient to obtain natural recharge. These model parameters (i.e., exponents and coefficients) are then quantified using linear least squares inversion against the known recharge values. To reduce the effect of geomorphic heterogeneity, viz., hills on natural recharge, laterally constrained inversion has been employed to integrate data sets (e.g., recharge measured at various points and logical expectation over exposed hills in an area) and constrained interpolation is then carried out along the grid lines for increaseddata density. Finally, Kriging interpolation over dense data obtained through data integration and constrained interpolation is used to significantly minimise the risks of overshooting the observations. Thus, the present approach provides a realistic spatial distribution of natural recharge values in a highly heterogeneous hard rock terrain.

    • Integration of geophysics and petrography for identifying the aquifer and the rock type: A case study from Giddalur, Andhra Pradesh, India


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      A comprehensive geophysical and petrological study was carried out at Giddalur area in Prakasam district, Andhra Pradesh, which is geologically a highly deformed area and is difficult to delineate the aquifer zone(s). The task was to find out the exact rock type in which aquifer is concealed as well as to delineate the aquifer zone, which can yield sufficient quantity of water. The resistivity models derived from geophysical dataset were interpreted in terms of hydrogeology and the results revealed substantial resistivity contrast of the geological formations within the study area. We have delineated two major groundwater potential zones based on this study. These zones were tapped at different depths in diverse rock types. Drilled hand specimens (rock cuttings) were not adequate, so these specimens were petrographically studied to reveal the exact contact zones of the rock type. On integration of the geophysical and the petrographic results, it was illustrated that two aquifer zones were struck at a depth of 92 and 122 m between shale-phyllite and phyllite-quartzite, respectively. These findings were correlated, which matched with the lithology of the drilled borehole. This integrated approach will be helpful in strategy for groundwater assessment as well as prospecting groundwater resources in different geological terrain.

    • Electrical imaging of karst terrene for managed aquifer recharge: A case study from Raipur, central India


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      Supply of sustainable water is a priority for urbanization of the country. Managed aquifer recharge (MAR) is recommended to enhance the groundwater resources, but finding the favorable site for MAR is quite challenging, particularly, in urbanized karst terrains because of highly heterogeneous and anisotropic properties of carbonate aquifers. The expansion along Naya Raipur is posing a severe threat to its groundwater resources by altering the hydrological framework in the area. In this work, we characterize the unsaturated zone for finding potential pathways for MAR in karst terrain of central India by using hydro-geophysical techniques. Sub-surface geophysical investigations including electrical sounding and profiling, captured the shallow surface of the area to the depth of around 40 m. The Wenner–Schlumberger and gradient methods could decipher strong lateral and vertical anomalies. The low resistivity in the unsaturated zone, as compared to the high resistivity of limestone bedrock is the main path for infiltration. The low resistivity anomalies in the 2D inverted sections might be water filled conduits or solution channels with uncertain geometry. Hydrogeological heterogeneity based on geophysical data helped to locate the favourable zones for construction of MAR structures. The Chokra Nala in the Telibandha area of Raipur is the favorable zone along which MAR could be more effective in replenishing the groundwater. The Telibandha lake area with the indication of the presence of hidden mafic dyke later intruding the limestone after its deposition, was also inferred from the geophysical data.


      $\bullet$ Characterizing the unsaturated zone for finding potential pathways for MAR in karst terrain using hydro-geophysical techniques.

      $\bullet$ Establishing MAR along the solution channels, conduits and fracture network.

      $\bullet$ 3D fracture system in limestone from 2D ERT profiles.

      $\bullet$ Mapping hydrogeological heterogeneity based on geophysical data.

    • Integrated approach to delineate sites for implementation of managed aquifer recharge (MAR) structures in fluoridated crystalline aquifer of south India


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      Managed aquifer recharge (MAR) emerged as a potential technique to solve groundwater problems in stressed aquifer systems but the site selection for implementation of MAR structures in crystalline and contaminated aquifers is a challenging task. The current study intends a methodology to demarcate the suitable sites for MAR in fluoride-contaminated crystalline aquifer using integrated approach of remote sensing, geographic information system (GIS) and analytical hierarchy process associated with groundwater quality data. Seven thematic layers were considered in this study, viz., geology, geomorphology, slope, soil, drainage density, lineament density and land use-land cover. These thematic layers were then integrated in the GIS environment to identify the aquifer recharge potential zones according to their suitability for groundwater recharge in the area and it was found to be covenant with the mean groundwater fluctuation over the area. After superimposing of drainage and lineament on obtained aquifer recharge zone map, 41 possible sites for artificial recharge were delineated. Among 41 sites, only 13 were considered as MAR sites based on groundwater Cuoride level fluctuation with recharge in the area. The proposed methodology could be applicable to other fluoride-contaminated aquifers also.


      $\bullet$ Managed aquifer recharge (MAR) sites in the fluoride-contaminated aquifer were delineated.

      $\bullet$ A total of 41 artificial recharge sites were delineated, among them only 13 sites were considered as suitable for implementation of MAR structures.

      $\bullet$ Showed the importance of chemical behaviour of groundwater during the recharge.

      $\bullet$ Behaviour of fluoride with water level fluctuation was used as a key factor.

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