Applications of SAC-SMA Hydrological Model over Godavari and Narmada River Basins

Abstract:

Transformation of rainfall to runoff is a complex hydrological phenomenon involving various interconnected processes such as evaporation, abstractions, infiltration, surface and subsurface runoff generation. Hydrologists have used various hydrological models to understand the transformation of rainfall into runoff. Conceptual models developed in the 1960s represent various individual components of the hydrological cycle via interconnected conceptual elements, thus modeling various aspects of the hydrological cycle. SAC-SMA being a conceptual model, represents simplification of the hydrologic cycle. The watershed is visualised as a soil column with the drying and wetting process simulating infiltration, percolation, interflow and baseflow. Very few studies reported the application of a widely used conceptual model, Sacramento Soil Moisture Accounting model (SAC-SMA), in the Indian river basins context even though the model has modest input requirements in comparison to some of the widely used lumped and distributed models. In Indian river basins, the need to account for catchment heterogeneity and spatial and temporal variations of inputs may have hindered the application of an otherwise well-validated model such as SAC-SMA. In this study, the SAC-SMA model was applied in lumped and semi-distributed modes at different spatial scales for the Godavari and Narmada river basins. In the semi-distributed mode, spatial variation of inputs and parameters was introduced to understand the influence of the same in the context of model performance. Gauge-discharge sites at Polavaram in Godavari river basin and Garudeshwar in the Narmada river basin are considered, and the period of the record considered for Polavaram is 1966-2014 and for Garudeshwar is 1973-2014.