RAINWATER HARVESTING: AN OPTION FOR DRYLAND AGRICULTURE AND POTABLE DRINKING WATER IN ARID AND SEMI-ARID IN MERTA BLOCK OF NAGAUR DISTRICT RAJASTHAN, INDIA

Rainwater Harvesting is the principle of collecting and using rainfall from a catchment surface. Due to the regular occurrence of draught in Rajasthan, the rainwater harvesting structures like Tanka, Anicut, Pond, Nadi, etc., are constructed by local peoples to fulfil their water needs. They are doing rainwater harvesting either for drinking or for agricultural purposes since time immemorial. In Rajasthan, Nagaur district is a part of the Thar Desert and has experienced issues of declining groundwater levels, high salinity, and fluoride and nitrate concentrations in form last few decades. The Nagaur district is divided into14 blocks (PanchayatSamitis), and one of them is Merta. Groundwater forms a major source of drinking water in the district as well as in the Merta area. Straight use of groundwater for industry, agriculture, city supply, and non-completion of surface water schemes is laying stress upon groundwater. The situation can be slowed down by launching massive rainwater harvesting and recharging programmers in the Nagaur district. Many methods are available for harvesting rainwater. The choice of a method depends upon the suitability of a particular site. Residents are constructing tanksin every house for the storage of drinking water. These tanks can be connected to the roof of houses to collect rainwater. JK White Cement Works has constructed artificial recharge structures (pits with bore well technology) near Dhanpa village, resulting in increased groundwater levels and quality improvement in the surrounding areas. Rainwater harvesting and artificial recharge methods are interlinked and dependable on one another.There are two main techniques of rainwater harvesting: (a) Storage of rainwater on the surface for future use (b) Direct recharge to groundwater Rainwater harvesting can be admitted in urban areas by the collection of rooftop water for recharge and domestic purposes. This water can be collected in an underground water tank constructed within the house. It is fresh water and free from TDS and other pollutants. It is good for drinking and cooking purposes. In any rural area getting low to moderate rainfall during a single monsoon season, a sustained effort of water conservation of in situ rainfall is required. Other than collecting rainwater in underground tanks, the importance of rainwater harvesting lies in recharging aquifers by artificial methods. The artificial recharge of groundwater is the process by which the infiltration of surface water into the groundwater system is increased by modifying the natural movement of surface water by utilizing suitable construction techniques. There are different methods available for rainwater harvesting like Gully plugs, Bench Terracing, Contour trenching and bounding, rockfill dam, Check dam, Percolation tanks, and Subsurface dams. The main objectives of the artificial recharge of groundwater are to enhance the water table, decrease the dark zone, expand the life of the aquifer, reduce runoff and soil erosion, to decrease the hazards of floods and get better soil fertility.