Delineation of Aquifers through Ground Water Exploration in Goa State

India is a water stressed country. Regionwise scenario is different but in general surface water resources are not sufficient to fulfil the need of the country. Available sites for water storage are limited and are located in reach regions which makes it difficult to rationally distribute the available surplus water resources to the deprived regions. This compels the extraction of groundwater in the deprived regions. Even in the command areas of the dams the tail enders do not get water and hence they have to depend on groundwater. Cropping pattern has been continuously changing due to market variations and hence the regions which are not expected to grow water-intensive crops have started growing them by meeting the water demand from precious groundwater. Objective of agriculture has been changed from food production to profit-making. Urbanization and Industrialization have furthered the dependence on groundwater. The erratic rainfall sometime is the cause of depending on groundwater. In all, the reasons for dependence on groundwater are many and the overall dependence on groundwater has been at present between 50 % to 90 % in different parts of India. For last so many years that the dependence on groundwater has been on increase which has posed a serious threat of quantity and quality of water almost in the entire country and the present model of economy, agriculture and development as a whole has become a subject of reconsideration on the ground of sustainability and environmental change. The root cause of this situation is the unsustainable ways of resource management we have adopted. Gujarat is one of the most suffering states in water scarcity because of all the aforesaid factors. The objective of the paper is to discuss the issues and the probable solutions such that that the future course could be corrective and is approached early to save the future of the state and the entire country.

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.

The Upper Nira River Basin (378.83 km2), in the Upland Deccan Traps is witnessing a transition from being a traditional rain fed, non-command entity to a predominantly surface irrigation command area. Understanding and accurately computing the change in groundwater storage is a vital component in groundwater estimation. The lava flows constitute 3 aquifers in the basin, UNR-1 , UNR-2 and UNR-3. The efficacy of the methodologies used for estimating the groundwater potential of the Upper Nira River Basin is evaluated. Groundwater assessment based on the GEC 2015 methodology has been undertaken to estimate a net available recharge of 4419 Ham in the aquifers and gross groundwater draft of 461.49 ham. The basin has been categorised as Safe due to low stage of exploitation (~11%). The people residing in the basin however face severe scarcity of groundwater during the summer season annually in spite of receiving copious rainfall (about 1500 mm) during the monsoon. The likely reasons for such a paradox are high surface runoff, low permeability, low storativity of aquifers, high base flow plus draft, etc. According to the new and simple aquifer-based methodology proposed in this paper the quantity of recharge (Q) for Aquifer UNR-1, Aquifer UNR-2 and Aquifer UNR-3 are 1146.70, 1691.02 and 16.97 km3 respectively. Thus, there is a difference in recharge to the tune of 1411 hams i.e. about 24% less recharge compared to the results obtained by the aquifer based methodology as per GEC (2015) guidelines. When the new recharge values are used in the GEC 2015 methodology a scenario close to reality emerges in the Nira River basin which proves the efficacy of the new methodology.

Air, Solar energy, Land, and Water are the four life support systems of which, only ?Water? is amenable for its development and management to meet human needs of water. Water Resource Development structures had to be compatible to the characteristics of ?Water Resource?. With the advancement of civilization, ingenuity of man prompted him to evolve different types and sizes of infrastructure to meet changing patterns and increasing magnitude of water demand. It also stressed the need to have an integrated approach in such development. Subsequently as a soft option, improvement in management of infrastructure was the next logical step. As the issue of complexities in the competing and conflicting demands on water surfaced prominently, need for taking a holistic approach towards them was thought of and there emerged the viable solution in the form of better governance of water resources. An attempt has been made here in below to present evolution of all these developments by citing a case study of Maharashtra State in the Peninsular India. It mentions at the end a ?Vision Statement? for the future development of the State in the water sector and an outline of future planning and policies which need to be adopted. In conclusion it states a framework of desirable actions to be taken in future, to transform the ?Vision? into a reality.

Goa is drained by several rivers like Terekhol, Mandovi, Zuari, etc. and their tributaries, many of which show tidal influence and related saltwater intrusion. The surface water resources of the state have been assessed at about 8570 Mcum with 1465 Mcum utilizable resources (1125 Mcum surface water, 340 Mcum ground water). Presently, surface storages available are to the tune of 335.87 Mcum in the tanks, diversion structures such as bandharas, weirs, etc. The macro level surveys indicate ground water available is to the tune of 43.83 Mcum and utilization is to the tune of 33% which is considered as safe. Major and medium schemes like Salaulim, Tillari, Anjunem and minor irrigation schemes like Chapoli, Panchawadi, and Amthane irrigation projects cater to the agricultural needs of Goa State. The Sal-Amthane, Salauli-Kalay River Inter Linking Projects in Goa augmented the source to a tune of 156 lakh cubic meter. The paper discusses the water requirement and water resources management of Goa by 2051.