CS(AR)-3/97-98 : Application of Topmodel to Malapbraha catchment

Abstract

The TOPMODEL (TOPography MODEL) is a variable contributing area conceptual model in which the predominant factors determining the formation of runoff are represented by the topography of the basin and a negative exponential law linking the transmissivity of the soil with the vertical distance from the ground level. Though the TOPMODEL is a conceptual model, i.e. one in which the physical reality is represented, in a simplified manner, the TOPMODEL is frequently described as being 'physically based', in the sense that its parameters can be measured directly in situ.

In the present study, the TOPMODEL has been applied to Malaprabha catchment in Karnataka to simulate the daily flows at Khanapur. River Malaprabha is a tributary of river Krishna. The catchment area of Malaprabha upto discharge measuring site Khanapur is 520 Sq. Km. The model uses topographic index for the formation of runoff. The topographic index for Malaprabha catchment was derived by developing a Digital Elevation Model (DEM) by interpolating the contours in the basin at 300 m grid size.

The results indicates that the model can be used to simulate the flows in the catchment quite accurately ( the efficiency of the model is 0.89 and 0.79 respectively in calibration and validation run). Also, model is able to simulate the timing and magnitude of the peak flows satisfactorily.