DECISION SUPPORT SYSTEM FOR AN FARM WATER MANAGEMENT-FARM WAT.

摘要

Farm Wat is a decision support system for on-farm water management in canal command areas. It takes into account the various decision elements like canal water supply, root zone water balance, effective rainfall and direct surface runoff. It computes reference evapotranspiration and crop water requirement, water balance and surface runoff. Farm Wat has four modules namely Canal water supply module (CWSM), surface runoff module (SRM), root zone water balance module for non-paddy crops (RZWBM-non paddy crops) and root zone water balance module for paddy crop (RZWBM-paddy). Computer programmes written in Visual Basic separately for each module were interfaced with the Microsoft Window. Pull down menus makes it more users friendly. The CWSM estimates the canal water availability at the command level. RZWBM for non-paddy and paddy crops computes the water balance in the root zone by calculating reference evapotranspiration (ET0), crop evapotranspiration (ETC), surface runoff (Q) and deep percolation (DP) from the root zone. ET0 is estimated using FAO Penman Monteith method. Surface runoff is estimated using any of the three methods namely (i) fixed percentage method, (ii) USDA SCS curve number method and (iii) modified curve number method by Sharpley and William. Soil water balance is calculated on daily basis using the various input and output components of water balance equation. A separate procedure has been used for calculation of root zone water balance for paddy field. FarmWat is a modular programme, which can be used for irrigation scheduling of crops including paddy and deciding groundwater pumping schedule. It can also be used for planning rainwater harvesting to supplement the canal and groundwater.