This research report by the National Institute of Hydrology deals with optimum water management in a command area. The dynamics of water within the unsaturated zone of soil is a complex phenomenon dependent on properties of the atmosphere, soil and vegetation. For agriculture water management, it is necessary to have models that accurately predict the behavior of soil moisture.
In this study, a model is developed to stimulate the dynamics of soil moisture within the root zone in an agriculture command. Focus is given to incorporate the spatial variation in crop type, soil type and rainfall in the command area and the dynamics of soil-water-plant interaction is stimulated.
The soil water balance is simulated using a simple distributed conceptual model. It is applied to the field data of the Lakhaoti command area under the Madhya Ganga Canal system. The data inputs to the model include rainfall, potential evapotranspiration, and various crop and soil characteristics. The output of the model is the actual evapotranspiration during the day/week, the soil moisture content at the end of the week, supplementary water requirement, water stress condition in the crop, and the recharge.
The developed procedure will allow us to estimate the spatial and temporal distribution of irrigation demands in the command area that can be usefully incorporated into larger computer-based irrigation management models.