Geohydrology and Structure: Groundwater Resource Estimation

Geohydrology and Structure Ground pissing Resource adherenceSYNOPSISThe ult few decenniums defy witnessed an ever increasing use up for groundwater and its scar urban center related problems, particularly in semi-arid hard rock terrains, argon well known and draw attention of many geoscientists. Deccan Volcanic res publica (DVP) comprises a sequence of basaltic lava flows of Cretaceous to Eocene age which are application an estimated subjectl extent of 5,00,000 Km2 in west central part of peninsular India. Groundwater strength of the basaltic aquifers (considered to be multiple aquifer systems due to the flow characteristics) constituting DVP is exceedingly variable and inconsistent due to the heterogeneity and anisotropy in the aquifer characteristics (Deolankar, 1980 Duraiswami, 2008 Duraiswami et al., 2012). Presence of basal dams in such an environment makes the hydrologic characteristics of the basaltic aquifers more complex. There exists a characteristic pattern in t he distribution of the dykes and distribution of simple and chemical compound lava flows in DVP (Deshmukh and Sehgal, 1988 Ju et al., 2013 Ray et al., 2007 Vanderkluysen et al., 2011). A grand variation in the climate, physical geography and rainwater is likewise an important aspect musical composition estimating the groundwater potentiality of the DVP area.An try is made to canvass the kernel of the dyke intrusions on hydrogeology of Nandurbar area, which is dictated pricy the Narmada Tapi Rift zone. Approximately 640 Km2 in Nandurbar rule (primarily a tribal district in Maharashtra state) around Nandurbar city was considered for detailed skand so forth. A detailed involve was carried out to estimate the groundwater resources, keeping in mind the marked festering in agricultural activities and human population over the last decade in the consider area and its proximity to Narmada Tapi rift zone and heading of dyke intrusions . The area under composition is located ar ound the city between East Longitude 74 05 00 to 74 25 00 and North analog 21 15 00 to 21 25 00 and included within the postdate of India topographic lay out numbers 46 K/3 and 46 K/7.The main objectives of the present work areTo describe the prevalent burn, and structure of the lineaments (fractures and dykes) development field evidences, topographical maps and transmit imageries.To come across the effect of dykes and fractures on the permeability and porosity of rocks in the learning area depending on their distribution, orientation and assiduity. analytic thinking and integration of remote sensing and ground found hydrogeological selective information through Geographic Information System (GIS) to prepare groundwater potential zonation map for the study area.To collapse the water samples covering the entire area to understand the groundwater persona and its related problems.military rating of the groundwater potential zones and resource idea in relation to the struc tures ( in general dykes) in the area together with the quality zonation map would be useful for strategic planning and management of groundwater resources in the DVP.The study was carried out with the help of six componentsInput from remote sensing dataTopographic mapsData collected from field visitsGroundwater quality abridgment.Preparation of thematic maps integrating and analysis of the results in a GIS platform.As this area is intruded by dyke swarms, identification of lineaments and preparation of the thematic maps were carried out using topographical maps, satellite imageries and field data. Field work included water aim measurement, litho-log preparation, collection of water from wells for quality analysis, well inventory etc. The geological and geomorphological maps were prepared and cross checked during field flora and final maps were prepared with necessary modifications. Compilation of the observation from well data, rainfall data and the previous records collected f rom GSDA and CGWB were carried out to know the long shape trend of the groundwater conditions. Laboratory analysis of the water samples and the petrographic studies of the rock samples reveal the quality and geological aspects.Geology, geomorphology and the hydrogeological characteristics of the rocks have considerable effect on arbitrary the occurrence and movement of groundwater. geological investigating of the area reveals that the area is in general constituted by simple and compound basaltic flows. Quaternary alluvial deposits of moderate thickness are located in the north eastern part of the study area. Dykes being the major morphological features present in the area stands out as prominent ridges due to the resistance to weathering and are mainly trending in the ENE-WSW directions. Dykes are of basaltic to doleritic composition and are of change length, mainly exposed in the central and southern part of the study area.Landforms are classified mainly into structural, denudational and fluvial origin. Dykes being the major structural features in the study area, are studied in detail and analysis of their orientation, thickness, length and density were carried out. Slope, slope aspect, digital elevation model, curvature and topographic wetness index parameters were utilise to generate results to understand the relationship between the geomorphology and hydrogeology, which is indicating towards a greater control of dykes on hydrogeological frame-up of the area. Tributaries of Tapi River drain the study area and follow the regional slope from South to North and which intersects dykes at many locations. This structural relation is of great importance and it reveals a real control of dykes on groundwater occurrence and movement. Drainage textural analysis is apply to analyze their control on permeability characteristics of the terrain and also to demarcate the potential reload zones. Hypsometric analysis of the watersheds constituting the study area helped to understand the erosional susceptibility of different watersheds and their stages of evolution.The place of lineaments can be of great importance while carrying out hydrogeological investigation of an area. Due to varying aquifer characteristics basaltic flows in the study area shows wide variation in the occurrence and movement of groundwater. Observation wells were monitored for the spatial and secular variation in water levels and quality. Input from eight-spoty eight (88) observation wells were used to generate various hydrogeological maps and to analyze the hydrogeological setup of the area. Analytical results indicate the occurrence of three different types of aquifers namely, basaltic, alluvial and dyke aquifers. Wells tapping the dyke aquifers or which are located near the dykes sight to be more productive compare to the rest, indicating the momentous influence of the dykes. Dykes also show unique joint pattern and can be correlated with their lithology i.e. d oleritic (characterized by moderately to largely spaced joints) and basaltic (closely spaced joints).Evaluation of the groundwater flow direction and hydraulic gradient results of the study area shows a close correlational statistics with the lineaments. Lineaments which are parallel to the hydraulic gradient located in the south eastern part of the study area have little influence on groundwater movement. However lineaments located perpendicular to the hydraulic gradient has considerable effect on the occurrence and movement of groundwater. much(prenominal) dykes in the study area can also used as artificial recharge structures, which in turn could promote the recharge of groundwater. clock series analysis of four observation well data of past twenty years were analyzed to understand the rising and falling trend of water levels in the study area.The chemical qualities of the groundwater sample collected during devil seasons were analyzed from th state level water testing labor atory of Tamil Nadu weewee supply and Drainage (TWAD) Board at Chennai. Analysis of the results shows that groundwater chemistry is controlled mainly by the climatic and rock water fundamental interaction and there exists a spatial and temporal variation in groundwater quality. The cationic values in groundwater show increasing trend from higher elevations to start out elevations indicating the control of basaltic rock lithology. treat, sulphate and chloride concentration in groundwater is mainly indicative of the anthropogenic factors. Analysis based on drinking water standards (BIS, 2012) indicates the degradation of groundwater quality in this area due to nitrate contaminations and groundwater hardness. Nitrate levels exceeding the desirable limits were observed in major part of the study area can be correlated with the increased agricultural activities and other(a) anthropogenic factors. thematic maps based on various chemical parameters were generated to understand the spat ial and temporal variation in the groundwater chemistry. Suitability of groundwater for irrigation was verified using United States Salinity Laboratorys(USSL) graphic classification, Sodium Adsorption proportion (SAR), Sodium percentage, Conductivity (Todd, 2003) and Kellys Ratio(Kelly, 1957). Analysis helped to delineate areas exceeding the allowable limits and such areas needs proper care and management while selecting the crops and adequate method of irrigation.Dykes which stand out as ridges were also noted by characteristic joint pattern. Nature of boulders present on the dyke surfaces were used to analyze the joint pattern of the dykes using high resolution satellite imagery and field evidences. This approach found to be useful in delineating the carrier and barrier stretches of dykes in the groundwater exploration stage and shows significant correlation with their water bearing characteristics. Topographic lows in the dykes proven to be of significant importance in groundwat er development. Data acquired through remote sensing of the study area was also used to generate different thematic maps. Thematic maps generated and validated through field work ( i.e, Lineament map, dyke density map, geomorphological map, drainage density, Land Use/ Land Cover map etc.), were integrated using multi criteria analyses in GIS platform to delineate the groundwater potential zones. Integration of water quality maps generated for different parameters based on groundwater chemistry were used to prepare groundwater quality zonation map and has been used to delineate the spatial and temporal variations of groundwater in the study area. Results obtained from this analyzes can be used effectively while planning and managing the groundwater resources of similar areas globally.ReferencesBIS, 2012. Indian Standard Drinking Water -Specification ( minute of arc Revision). Bureau of Indian Standards (BIS), IS 10500, New Delhi.Deolankar, S.B., 1980. The Deccan Basalts of Maharasht ra, India- Their Potential as Aquifers. Ground Water 18, 434437.Deshmukh, S.S., Sehgal, M.N., 1988. Mafic dyke swarms in Deccan Volcanic Province of Madhya Pradesh and Maharashtra, in Subbarao, K. V (Ed.), Deccan flush Basalts. Memoir of the Geological Society of India, v.10, pp. 323340.Duraiswami, R.A., 2008. Changing geohydrological scenario in the hard- rock terrain of Maharashtra Issues, Concerns and management forward, in Das, S. (Ed.), Changing Geohydrological Scenario, Hardrock Terrain of Peninsular India. Golden Jubily Volume. 69, Geological Society of India, Bangalore, pp. 86121.Duraiswami, R.A., Das, S., Shaikh, T.N., 2012. Hydrogeological framework of aquifers in the Deccan Traps, India Some Insights, in Pawar, N.J., Das, S., Duraiswami, R.A. (Eds.), Hydrogeology of Deccan Traps and Associated Formations in Peninsular India. Memoir. 80, Geological Society of India, Bangalore, pp. 115.Ju, W., Hou, G., Hari, K.R., 2013. 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