Salt and Water Balance Studies using SALTMOD for TungabhadraCommand, Peninsular India

摘要

Long-term field experiments are required to develop suitable salt and water balance strategies, but are expensive, site-specific and time consuming. Simulation models, once calibrated using experimental information, could aid as management and decision tools to obtain quantitative guidance in developing and evaluating drainage and irrigation strategies. SALTMOD, a computer programme has been found to be useful for prediction of the salinity of soil water and water table depth in irrigated agricultural lands using different (geo) hydrologic conditions. Field experiments on subsurface drainage (drain spacing, 150 m and drain depth, 0.75 m) were conducted during 1998-2006 near Sindhanur, Karnataka, India in an area of 62 ha. Data collected from the pilot area, where rice-rice cropping sequence was followed, have been used to develop various scenarios of salt build-up and status of the water table. The SALTMOD model predicts that due to existence of subsurface drainage system, root zone soil salinity may be reduced to about 2.5 dS m~(-1) (from an initial value of 8.5 dS m~(-1)) within two years. Controlled drainage during rabi (dry winter season) only and during the critical crop growth stages in both the cropping seasons (rabi and kharif, the wet summer season) had little effect on the build-up in root zone soil salinity; the root zone soil salinity was maintained within a safe limit (< 4.0 dS m~(-1)). Complete blocking of the drainage system during both the cropping seasons had adverse effect and led to be build-up of soil salinity.