Estimating Water Resource in Wokha, Nagaland Using Geo-Informatics

Water is essential for sustenance of life on earth. But the problem is unequal distribution of water in space and time. Ancients developed innovative ways to manage water resources to meet their essential needs like drinking water supplies and irrigation. Many parts of India, especially Rajasthan have been practicing water conservation and rainwater harvesting since historical times. Arwari water shed in Alwar district of Rajasthan has brought to focus traditional techniques of integrated water management with community participation. This paper attempts to briefly present the water management scenario in India since Vedic times.

The water sector in Maharashtra is facing critical challenges. First, uneven availability of water over space and time is the biggest challenge and secondly, dramatically increasing competing demands for water from different sectors are giving rise todisputes and conflicts. Of the total water used in the state, about 82% goes to irrigation, 12% for domestic water supplies, 4% forindustrial use, and the remaining for other uses such as livestock, hydro and thermal power generation. With the urban population of about 51 million (45%), and rapidly growing urban centres and industries, there is considerable gap in demand and supply of thestate's scarce water resources. This has posed serious challenges to water security. There can be only limited dependence upon the groundwater resources for the protective irrigation in the State as 85% area is Deccan basalt having limited ground water recharge potential. Also access to safe drinking and other domestics is a challenge in the rural areas of the State. Planning and Management of water resources in a coordinated and holistic manner is needed. Considering the scarcity of water in large part of Maharashtra and substantial utilisation by irrigation sector, there is a need to expedite measures for improving Water Use Efficiency (WUE) so that water saved in irrigation can be utilised for other non-irrigation purposes. The paper gives an overview of the water resources scenario in Maharashtra with reference to surface water and discusses various water management issues that need focused attention. The paper brings out the impact of decision of various water dispute tribunals on the water availability for the State and also the need for inter-basin and intra-basin water transfer. It emphasises the need for upscaling use of Micro Irrigation (MI), Pipe distribution system, large scale integrated MI systems throughout the State etc. for not only to save substantial amount of water but also to help in increase the productivity and quality of agriculture produce. The paper also touches upon the issues of water quality and flood management in the State.

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.

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.

As per the assessment of the dynamic ground water resource in Gujarat the utilsable ground water resources have been assessed as 24905 MCM, after providing for natural discharge (March 2021). The annual ground water draft is 13296 MCM. The Stage of ground water development works out to be about 53%. However, this is not uniform across the state. The stage of development is exceedingly high in North Gujarat and Kachchh regions. Highly intensive development of ground water in these areas has resulted in over - exploitation leading to the decline of ground water levels, deterioration in the ground water quality and sea water intrusion in the coastal areas. The paper presents existing scenario of various supply and demand side interventions implemented in the state with their impact. Recommendations for various interventions necessary for sustainable ground water management have been made with particular emphasis on use of scientific inputs from the supply as well as demand side interventions to the community participation in planning, implementing and monitoring.