The study develops a water balance of a sub-basin, Pachaiar, of the Tambarapani river basin in Tamil Nadu. The various components of water balance have been estimated by using the process generating module of Simulator for Water Resources in Rural Basins (SWRRB), a model developed by the United States Department of Agriculture (USDA).
The performance of the USDA model has been validated internationally by various researchers. Since the model required continuous weather data, a time series of it has been generated using another model. The efficiency of this model has been checked with a meteorological station outside the basin.
The SWRRB model was used to assess the future scenario of water availability in the basin by simulating the water balance components. The study provided insights into the hydrology of the basin through the use of monthly water balance.
The analysis ascertains that the basin experiences 18.47 water stress days annually, which is a very low figure, indicating sufficient water availability for agricultural purposes. Given that Pachaiar is a major sub-basin of the Tambarapani river, the analysis is vital for understanding the rainfall-runoff relationship for forecasting purposes.
The results are useful for forecasting flows into downstream reservoirs. The water balance study can be used to determine the effects of climate change on the volume of water that is cycled under various hydrological processes in the basin. Such an analysis could be valuable in water resources planning and management of the reservoirs in the basin.
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