Foundation Day Seminar – Integrated and Sustainable Water Management – Abstracts Volume

In western India, the states Goa, Gujarat, Maharashtra and Rajasthan having area of 0.11%, 5.97%, 9.36% and 10.41% of India respectively have 0.24%, 6.83%, 13.48% and 4.52% of the total population of the country. The area, except Goa which records high precipitation, receives moderate rainfall. Arid conditions prevail in north Gujarat and major part of Rajasthan. The utilization pattern of ground water is uneven across the region resulting in ground water stressed conditions and over exploitation in some parts, particularly the arid regions and sub-optimal ground water utilization in others. Water level varies widely being very shallow in the southern part and deep to alarmingly deep in the northern part, having deepest water level of the country in Bikaner district of Rajasthan. Water quality is of concern in the major parts. In considerable areas, some chemical constituents exceed the permissible limit for drinking water, and large patches with brackish to saline water are encountered in Rajasthan and Gujarat. Sporadic occurrences of Fluoride and Nitrate in ground water exceeding the permissible limit for drinking water are spread almost throughout the region which necessitates cautious use of ground water in these areas for drinking purposes. The stage of ground water development is 37%, 68% and 54% in Goa, Gujarat and Maharashtra respectively. In Rajasthan, the stage of ground water development is 140% and 164 out of 248 ground water assessment units are overexploited and 23 ground water assessment units in Gujarat are over exploited. This requires immediate judicious intervention without which some areas will not be able to meet even the drinking water needs. Groundwater withdrawal requires to be strictly regulated so that it does not exceed the annual recharge and also that it does not disturb the hydro-chemical balance. Alarming declines in groundwater levels warrant immediate attention for taking-up of recharge schemes to arrest further decline and augment the groundwater resources. In areas of scanty recharge, ground water should be allowed only for drinking water purposes. In other areas, along with water conservation and ground water augmentation measures, demand side management using micro irrigation techniques and change of cropping pattern etc should be religiously adopted.

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.

Palghar, Thane, Raigad, Ratnagiri, Sindhudurg and Greater Mumbai districts of Maharashtra form the Konkan Coastal belt of Maharashtra. In the coastal areas the immediate effect of high groundwater development is often sea water intrusion. Although there were sporadic studies by earlier workers (Umrikar et al., 2007, Gupta et al. 2010) into some reported isolated cases of seawater intrusion in the coastal areas, this has been a maiden attempt to decipher the extent of seawater intrusion in the entire coastal tract of Maharashtra.The area is underlain by Dharwarian meta-sediments (Lower Precambrian age), Deccan Trap lava flows (Upper Cretaceous to Lower Eocene age), Laterites (Pleistocene age) and Coastal alluvial deposits (Recent to Sub-Recent age). Groundwater occurs under phreatic condition in the Coastal and riverine alluvium, laterites and weathered/fractured rocks. The area has been covered by systematic hydrogeological surveys, reappraisal Surveys and groundwater monitoring by CGWB. in these formations depth to water levels range from 0.6 m bgl to 8.07 m bgl. Groundwater is mildly alkaline with pH range of 6.9 to 9.0. Electrical conductivity ranges from 61 to 29370 ?S/cm at 25?C. Only two Samples from Dapoli in Raigad district show EC values higher than 3000 ?S/cm at 25?C. In general, water quality is good and suitable for domestic use and irrigation. In order to confirm the sea water intrusion, ionic ratios like Na:Cl, and Cl:CO3 + HCO3, were computed. From the analysis it is found that about 2 to 10 km wide coastal belt and the inland tidal backwaters are affected by salinity intrusion. It is revealed that about 55% of the analysed samples have indicated salinity ingress. The extent of sea water intrusion is more in the southern part progressively diminishing towards northern area. The maximum effect is observed in Sindhudurg district followed by Ratnagiri, Raigad, Palghar and Greater Mumbai.Over-exploitation of groundwater in pockets and diminishing seaward freshwater flow in the rivers are the major reasons for sea water ingression. Regulation of groundwater development in the coastal area and areas adjacent to estuaries, maintaining adequate stream flow, stopping of riverbed sand mining, construction of tidal regulators at suitable places and creation of fresh water barrier through rainwater harvesting and groundwater recharge are essential to control further sea water intrusion in the area.

Drylands of arid Rajasthan are well known for Drought and hot Desert having diversified hydro-geological conditions. Potential aquifer systems include unconsolidated (Quaternaries deposits), semi-consolidated (Tertiary Sandstone, Lathi Sandstone etc.) and fissured consolidated formations. Groundwater level is generally deep especially in western Rajasthan, where it reaches even 150m below land surface. Quality of groundwater is poor in many parts due to geogenic and anthropogenic reasons. Stage of groundwater development in the State is 139.88% with 185 blocks categorized as over-exploited. Groundwater related issues include deep and declining water levels, low groundwater recharge, over-exploitation, drying up of potential aquifer systems, high salinity, fluoride and nitrate concentration, industrial pollution, water logging and lack of appropriate water management. Management options include supply side and demand side measures i.e. water conservation, regulation, protection and especially structural measures for augmentation of resources by large scale artificial recharge of aquifers, for which financial provisions by the Government/incentives to individuals need to be introduced. Scope for artificial recharge of aquifers exists on account of availability of thick permeable geo-formations, deep & declining water levels, and availability of surplus monsoon water in northwest India, which otherwise goes waste flowing to the neighbouring country. Regulatory measures including notification of 35 block areas, mandatory provision for issuance of NOC for industries/ infrastructure/mining projects for controlled groundwater withdrawal. etc. are being taken up by Govt. organizations. State Water Policy is in place and rooftop rainwater harvesting is to be made mandatory for all buildings. State Ground Water Legislation and State Ground Water Authority need to be constituted and regulatory measures be enforced by Rajasthan Government in line with CGWA. There is need for integrated participatory approach of water management. Rajasthan being the most water deficit State in India, deserve to be given ?Special Status for Water Resources? for financial and other purposes by Government of India.

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.