Evaluation of models and approaches for effective rainfall in irrigated agriculture - An overview

A precise estimation of effective rainfall (ER) is still needed not only for planning and management of rainfed crop production, but also for risk management strategies in farms. In this paper the most commonly used models/approaches, which are suitable for the estimation of ER for agricultural crops grown in different agro-climatic regions, are reviewed. Using different climatological data, ER have been estimated for crop growing seasons. Most commonly used empirical methods for the estimation of ER (Renfro Equation, U.S. Bureau of Reclamation Method, Potential Evapo-transpiration/Precipitation Ratio Method (India), USDA-SCS Method, Hersh field method, Indian1, Indian-2 method and Vietnam) are described in this paper. Apart from above mentioned methods, this paper reviewed performance evaluation of some models formulated for ER estimation. Precise estimation of ER is necessary for increasing agricultural production and design a soil-water balance model that provides more accurate calculation of. ER that directly satisfies crop water requirements. It is plays an important role for the determination of water requirements for crop as well as irrigation scheduling.