Crop calendar adjustment study in Sathanur irrigation system

Abstract

Irrigation scheduling deals with two questions: when to irrigate and how much to newlineirrigate. Before starting a crop, the availability of water in the reservoir, chances of newlineinflow, chances of rainfall during the crop growth periods, groundwater potential etc, newlineare to be checked. The start of crop cultivation period plays a vital role in efficient newlinefunctioning of any irrigation system. In the Sathanur irrigation system in India, water newlineis collected in the reservoir during rainfall season and crops are cultivated after that. newlineThe designated crop in the post monsoon period is groundnut. Since the crop is newlinecultivated in the post monsoon period the entire Crop Water Requirement of newlinegroundnut crop cannot be fulfilled by the irrigation release from the reservoir and newlinethere is very less or no rainfall contribution. Hence the crop is under water stress. To newlineknow the farmers opinion about the existing system management and their desire to newlinechange the pattern of cultivation, a questionnaire survey was conducted in the newlinecommand area, which shows that the farmers are willing to change the crop and crop newlinecalendar. newlineThe crop calendar is adjusted for groundnut crop by simulation and the best crop newlinestarting period is obtained. In this system, the order of priority is as follows: drinking newlinewater supply, supply to the system of tanks and downstream supply. For fulfilling the drinking water supply, hedging policy is adopted. Further, the possibility of diverting a sizable quantity of water during October and November to other basin is also newlineanalyzed. newlineThe farmers in the Sathanur command are consistently cultivating paddy crop instead newlineof groundnut crop in the post monsoon period though the water release is for newlinegroundnut crop. This is due to the increased net benefit of paddy crop over groundnut newlineand also free supply of electricity to pump ground water. Hence a bi-level simulationoptimization newlinemodel is developed using Genetic algorithm for maximizing the net newlinebenefit from the cultivation of paddy crop. Hence the cultivation of paddy crop may newlinebe started fr