2D Resistivity Imaging for Identification of Successful Bore Well Locations in the Fractured Rock Aquifer System

Maharashtra is one of the largest states of the country and playing a vital role in the India?s economy through its agricultural and industrial growth. Agriculture is the most predominant occupation in the state and is dependent mainly on ground water irrigation. However, specific focus is being given for the demand side intervention rather than supply side interventions for management of limited ground water resources that available in the state, as the 92% of the state is underlain by hard rocks bearing limited yield potential. The rainfall is the sole source of natural recharge to aquifers and the rainy season extends for three months with barely 55 to 60 rainy days. This is the period during which aquifers get replenished and during the remaining part of this water is utilized for agriculture, domestic and industrial uses. Highest rainfall is received in the coastal areas which have very high runoff rate, whereas remaining part of the state receives rainfall varying from <400mm to 1500 mm per year. A concept plan to recharge the aquifers has been prepared, and details of the artificial recharge structures suitable for the varying geological and topographical setups have been suggested. Besides, micro irrigation techniques are also suggested for water intensive crops to regulate the ground water draft.

Chemical quality of surface and groundwater of an area is influenced by the climate, hydrological conditions, soil characteristics and geological formation. Irrespective of their source, all natural waters contain some chemical constituents and their quality changes progressively as they traverse over the land surface or infiltrate downward due to various hydro-geochemical processes. Anthropogenic factors also contribute substantially towards quality change of both surface water and ground water. In the present study an attempt has been made to understand the aquifer vulnerability to pollution, at the regional scale (Goa State), which takes into account the intrinsic hydraulic and hydrogeological parameters and environmental impacts. It is noticed that a variety of activities, such as agricultural, industrial and urban land uses, are carried out in the area, thus exposing the aquifers to a wide range of contaminants. Groundwater quality data of Goa state for the pre-monsoon seasons of 2014 and 2018 were obtained from CGWB (Bengaluru) and analysed statistically. A regional scale approach was developed which is known as ABHESHT (Aquifer type, Boundary conditions, Hydraulic Head representing static water level, Environmental impact, Solute concentration, Head variation (Water Table Fluctuation) during pre-monsoon and post-monsoon seasons and Transmissivity). The method has been applied to Goa State, west coast of India and compared with the observed groundwater quality parameters. It is found that the model has successfully delineated the wells which are prone to pollution. Using GALDIT model, seawater intrusion impact was also assessed. The study revealed that the groundwater of Goa State did not show any significant pollution indicator, however, seasonal variations in water quality parameters were observed. It is also found that the North Goa coast as well as the other tourist spots spread over the entire state show signs of pollution at various locations (Anjuna. Baga, Mapusa. Concona etc). This calls for immediate attention from the concerned authorities.

The high reliability of rural and urban settlements on groundwater in India and the individualistic nature of groundwater usage make groundwater management and governance extremely challenging. Groundwater resources development in India, even today, has progressively become synonymous with increasing the accessibility of the resource through more and more sources and meeting the growing demand through the infrastructure of distribution. Management of groundwater becomes selflimiting when the focus is on exploration for new sources, without understanding resource behaviour. On the other hand, experience has shown that bringing aquifers to the centre stage of groundwater management is important. The concept of aquifers changes the way in which communities begin to perceive groundwater and becomes the first step in developing socioecological resilience to groundwater-related vulnerability. Building resilience to groundwater-related vulnerability further includes developing a governance mechanism that strikes a balance between supply management and demand regulation through an understanding of the resource, i.e., the aquifer.Aquifer systems in India are highly diverse and complex because of the variation in their inherent properties such as storativity, transmissivity and groundwater quality. Aquifer vulnerability is a consequence of not only how the rampant exploitation and contamination of groundwater occur, but also how different aquifers react to these fluxes. Moreover, irrespective of the scales of groundwater accumulation and movement, micro-level analysis of aquifers becomes imperative because of the atomistic nature of groundwater access and use. A systematic hydrogeology-based approach that requires delineating aquifers, understanding the dynamics of groundwater and mapping the demand and dependence of community on the resource holds the key to decentralized groundwater governance in India. Such an approach can be undertaken through participatory monitoring, decision support and action.The inherently heterogeneous nature of aquifers and communities in western and central India demand a strategic application of mapping, characterizing and managing local aquifers through a participatory groundwater management protocol. This nuanced approach beginning with aquifers as both a resource and a system, ensures equitable, efficient and hence, the sustainable management and governance of aquifers in this region.

Rajasthan is the largest state of India covering an area of 3,42,239 sq.km and represents 10.5% of the country?s geographical area. On the other hand it has only 1.15% of total surface water and 2.6% of dynamic groundwater resources of the country?s resources due to arid climatic conditions. Surface water availability is restricted to command areas of canal system; hence groundwater is the only dependable source in major part of the state. Groundwater quality deterioration with depth coupled with low and erratic rainfall has generated constraints as regards availability and development potential of groundwater resources. Over exploitation of groundwater has caused mining of groundwater, which has set in declining trend in water level and threatening depletion of limited available fresh groundwater resources at an alarming rate. Management of groundwater resources in this context is an extremely complex proposition. The highly uneven distribution of groundwater and its utilization make it impossible to have single management strategy for Rajasthan as a whole. Any strategy for scientific management of groundwater resources should involve a combination of supply side and demand side measures depending on the regional setting and local geology and also on use of saline water. There are saline water tracts in various parts of the state. Recently conservation of water through crop diversification and use of saline water in several parts of the state has gained momentum.

The Ground Water Resources play an important role in agro-economy of the Chhattisgarh State being heavily dependent on rain?fed agriculture. The Ground water resources are controlled by normal monsoon rainfall of 1201 mm with four aquifer systems, viz a) Sandstone aquifers, b) Limestone aquifers, c) Crystalline aquifers comprising granites, gneisses schists, ultrabasics and basalts of Archean, Proterozoic and Cenozoic age respectively forming discontinuous, unconfined and semi-confined aquifers, and d). Alluvial aquifers comprising alluvium, clays, silts, laterites etc. forming thin and extensive unconfined aquifers in several isolated patches and near major river courses. These are unconsolidated formations of Quaternary age. During pre-monsoon period in the 70% area of the state groundwater level remains under 5 to 10m, 21% under 10 ? 20 m and less than 1% under more than 20 mbgl. In the Post-monsoon period, 71% area shows the groundwater level in the range of 2 to 5 m, 24% area, 5 to 10m and 2% more than 10 m bgl. In general, 23% wells show rise in the range of 0-2m, 35 % 2-4 m and 42%, > 4 m in response to rainfall. Ground water quality is bicarbonate type and suitable for all purposes. Isolated patches of Arsenic, Sulphate, Fluoride and NO3 contamination have also been reported. Ground water meets 84.5 % and 14.5 % of total irrigation and drinking water requirements respectively. The annual ground water recharge has been estimated as 11,579 MCM. The existing ground water extraction for all uses is 4691MCM. Out of 146 blocks, 41 blocks have Stage of Ground Water Extraction < 30 %, 46 blocks, between 30 to 50%, 35 blocks within 50 and 70 % and 24 blocks have > 70%. The groundwater utilization over the years has increased drastically from 5.11 % in 1990 to 44.37% in the year 2017.The immediate attention is needed on (a) Creation of additional Irrigation potential, (b) Supply of contaminant free water through alternate source, (c) Promotion of rainwater harvesting and sartificial recharge with community participation,. (d) Regulation of overuse of ground water and (e) Sensitizing Farmers through incentivizing water efficient irrigation techniques.

Gujarat State is located in the western part of India, it is well known for entrepreneurship of its peoples. Water resources in the state are very much unevenly distributed. There are very high rainfall areas in the southern part of state, whereas the northern and western parts face desert like climate. Hydrogeologically there are diverse aquifer systems. Some form prolific aquifer system like alluvial formations of North and Central Gujarat plains. There are also hard rock formations like Granites, Deccan Basalts which form poor aquifers. Due to frequent and persistent droughts water resources management has been a challenge in northern and western parts of the state. Total annual availability of water in the state is estimated at 51 BCM/ out of which surface water contribution is 38 BCM, whereas groundwater accounts for 13.58 BCM. The groundwater plays a very important role in agriculture as well as water supply in this drought prone state. The total annual Groundwater Recharge has been assessed as 22.37bcm and Annual Extractable Ground Water Resources as 21.25bcm. The Annual Ground Water extraction has been assessed as 13.58bcm and Stage of Ground Water extraction as 64%. There are 248 assessment units (talukas) out of which 25 Talukas have been categorized as ?Over- exploited?, 5 are ?Critical?, 11 are ?Semi-Critical?,194 as ?Safe? and 13 saline talukas in the state. A well-planned strategy is required for management of water resources in the state. Number of water conservation and augmentation measures have been taken up in the state in the form of Sujalam Suflam Yojna, Sauni Yojna, Participatory irrigation management, ATAL-JAL, Hydrology Project, Interlinking of Rivers to name a few. Further steps suggested for conservation and sustainable use of ground water can be augmentation of groundwater resources through Artificial Recharge, revival of ponds, reuse and recycling of wastewater, protection of water sources from pollution, conjunctive use of surface and ground water, etc