**8. Conclusions**

The correlation of the yield potential of Aquifer-I with the depth of occurrence and weathered/fractured thickness indicates that even though the aquifer occurs down to the moderate depth of 10–15 m with a sufficient thickness of 8 to 12 m it does not guarantee adequate yield in hard rock basaltic aquifer. Similarly, the correlation of the yield potential of Aquifer-II with the depth of occurrence and fractured thickness also indicates that even though the aquifer occurs down to moderate to deep depths of 80 to 140 m in a major part of the area, the yield is not dependent on the depth of occurrence of the aquifer. Thus, the common tendency of the borewell culture of going deep for getting more groundwater does not hold in hard rock areas, especially in basaltic aquifers.

The deeper water level of more than 50 m bgl is observed in major parts of the district covering an area of 7097.14 Sq.km. This may be due to the overexploitation of groundwater and it also indicates that the shallow aquifer is not able to sustain the demand; hence, groundwater resources are also being withdrawn from deeper aquifers in this area. The net groundwater resources of the aquifer are 1849.90 MCM, whereas that of Aquifer-II are only 382.77 MCM, which is about 21% of dynamic resource availability indicating that the deeper groundwater resources are scarce and more vulnerable to overextraction. Devising a groundwater management strategy or plan for hard rock aquifers is always challenging [7] as compared to alluvium aquifers, which occur in the vast expanses of major alluvial basins of India. This is due to the highly diversified occurrence and considerable variations in the hard rock groundwater availability. The problem is further compounded as in this case, the area has witnessed droughts, declining water levels, and low yield potentials. The multipronged aquifer management plan is suggested for the area, that is. supply-side (augmentation), demand-side (savings), and development side to resolve the issues.

The supply-side interventions, that is. recharge measures in the district are feasible in 6334.28 sq.km.; however in 5 talukas namely Igatpuri, Nasik, Peth, Surgana, and Trambakeshwar, there is no scope for aquifer recharge due to shallow post-monsoon water levels and rising water level trends. However, in patches, these talukas also face water scarcity in the peak summer season. This dichotomy of availability and nonavailability of groundwater concerning the season is very common in hard rock aquifers. The total noncommitted surface runoff required for recharging the aquifers in feasible areas of 6334 sq. km is 33836.28 MCM, whereas the surface water available in the district is only 265.41 MCM, thus there is a huge shortfall of the surface water

*Management of Hard Rock Basaltic Aquifer through Aquifer Mapping: A Case Study of Nashik… DOI: http://dx.doi.org/10.5772/intechopen.111644*

required for recharging the aquifers. The available surplus surface runoff water can be utilized for aquifer recharge through the construction of 649 percolation tanks, 1857 check dams/gabion, and various other site-specific structures such as underground bandharas, Nala bunds, and CCT (continuous contour trenching).

The demand side interventions, that is., water saving measures are proposed in the areas with the high level of the stage of extraction, an area of 116.84 sq. km. of groundwater irrigated sugarcane crop and 790 sq. km. of onion crop is proposed to be brought under drip irrigation. The volume of water expected to be saved is estimated at 66.60 MCM for sugarcane and 205.40 MCM for onion, totaling 272 MCM of groundwater savings.

If we compare, the supply-side interventions by aquifer recharge measures can augment resources to the tune of 139.30 MCM; however, demand-side interventions by micro-irrigation are much higher @ 272 MCM. Thus, demand-side interventions are more beneficial, economical, and suitable for areas, where there is limited source water availability for recharge and areas with high groundwater consumption for irrigation, especially cash crops and water-intensive crops. The study has indicated that the supply-side interventions have got apparent limitations due to inadequate availability of surplus/noncommitted surface water, as well as the low storage potential of hard rock aquifers.

With supply-side and demand-side interventions, it is expected that about 411 MCM of groundwater would be available to bring down the overall stage of groundwater development of the district from 58.45 to 47.81%. This plan would also address the issue of overextraction in some talukas such as Baglan Satana, Chandwad, Deola, Niphad, Sinnar, and Yeola, where the stage of extraction can be brought down to 70% (safe category).

The management plan provides a scope for the development of available and additional groundwater resources added/saved to the system through the construction of 34,967 dug wells and 5828 borewells in a phased manner in the selected areas. This will provide assured irrigation to an additional area of 896.60 sq. km. The management plan suggested for the area is holistic and implementable with further finetuning/inputs at the local scale. It will also lead to the upliftment of the socioeconomic status of the people, especially of those located in tribal pockets of the district. These interventions also need to be supported by capacity building measures, self-regulation, and an institutional framework for participatory groundwater management.
