OPTIMAL USE AND DEVELOPMENT OF WATER RESOURCES IN NARMADA BASIN

Abstract

Narmada basin is among those very few basins of India, which are endowed with rich water resources but have the lowest irrigation development. There have been hardly any study on efficient utilization of land and water resources of Narmada basin which has considered multi-period and multi-level analysis integrating the use of fertilizer, land and water resources. None of the study seems to have been done to examine the effect of irrigation command area. The present study is therefore, an attempt to examine the economic feasibility/economic viability of development/utilization of water resources of Narmada basin for irrigation and to estimate the costs and benefits of water utilization with the help of latest analytical techniques. Modified simplex method of linear programming was used as the analytical tool for optimizing land, water and fertilizer resources of Narmada basin under four phases of development. The conjunctive use of surface and ground water for irrigation was done with the help of water budget equations in the linear programming model. In each phase, development was done in two steps. In the first step, reservoirs, canals and pumping capacities were developed to increase the availability of water for irrigation and in second step, the irrigated command area was increased. Thus, there were in all eight levels of resources. At each level of resources, two optimal plans were derived, one with crop area flexibility constraints and the other with additional regional minimum fodder crop area constraints. In existing cropping pattern, the sequence of rank of crops was oil seeds, wheat, cotton, rice, kharif jowar, ground nut and rabi pulses. This ranking was completely changed in the optimal plans, where the largest area was observed under rabi pulses in all the eight plans. The next largest crop areas in the sequence were rice, gram, cotton and oil seeds in the optimal Plan 1, for which the resource levels were the same as those for existing cropping pattern. The cropping intensity increased in optimal plans. At full development of resources (plan 8), the sequence was rabi pulses, oil seeds, cotton, kharif pulses, kharif jowar and rice. Another important change in the cropping pattern was that in optimal plans, regional specialization of crops emerged as the main feature as compared to no regional specialization of crops in the existing cropping pattern. Comparison of optimal Plan 1 with the existing plan showed that utilization of total water in the existing plan was 3% lower than that in the optimal Plan 1. It was observed that in the existing plan, more than optimal levels of irrigated area and water were used in rabi crops like wheat, oil seeds and gram and less than optimal levels of irrigated area and water were used in kharif crops like rice and ground nut. Also more than optimal levels of water were consumed in the months of March and April and less than optimum in the months of May and June. Thus on one hand there was over irrigation (more than optimum) in some months and under irrigation (less than optimum) in other months. As the available water and irrigated co.,„d areas were increased by increasing reservoir capacity, canai capacity. utilisable puling capacity and irrigable land under optimal Plan I to optical Pian 8, it was observed that all the utilisable river water inflow of the basin could be fully utilised as the development approached uP to Plan 6 (Phase III), but the utilisation of ground water could reach only up to 53* of the total available entity of ground water in the basin. The Marginal Value Product CMVP, of water was higher than its price and reached up to Rupees 4434 per hectare metre As the capacities of reservoirs, canals, pumping a„d irrigable area increased from optimal Plan 6to 8, the MVP of water increased to ».. 5721 per hectare Betre ^^ ^ ^ ^^ availability of canal water decreased due to increase in irrigated area with the same level (upper limit, of available canal water The huge retirements of water in tail regions were fulfilled by transfer of river water in all the periods from the head regions The reservoirs in the head regions carried the water from the peas flow periods to the lean flow periods for transferring the water through inter- regional transfer activity to meet the retirements of taxi regions.In optimal Plan 8, 98* of the land was brought under irrigation and 100, of the available (net, surface water and 87* of the available ground water was utilised. The net return of crops increased in the optimal Plan 1at existing level of resources. This increase i„ „-» s increase In net return (79%, was due to improved aaggrriiccuullttuurraall «pr«a„c+t*ices and optimal use of land and water resources. The n*>t re.+,, • net returns in the optimal Plan 8 increased by 242% over the optimal Plan 1. This increase was due to optimal use and development of land and water resources.