TR-68 : Simulation of daily runoff of two sub-basin of river Krishna using Tank model

Abstract

The tank model developed by Sugawara for daily analysis has been used to simulate stream flow of Malaprabha sub-basin up to Khanapur and Malathi sub-basin up to Kalmane.

Malaprabha is a tributary of river Krishna. The Catchment area of Malaprabha upto discharge measuring site khanapur is 326.0 sq.km. Using daily observed flow data Malaprabha at Khanapur for the period 1981 to 1984, the Tank model has been calibrated. The input rainfall data are based on the observed daily rainfall at Kankumbi, Gunji, Desur and Khanapur. The calibration of the model was carried out by simulation of observed flows in 1981 and 1982. The simulation was good, the fit of 1982 being better than that of 1981. The calibrated model has been used to simulate daily stream flows during 1984 and 1985 which were found be within 10% of observed stream flows. The model was calibrated using data of 1979 and 1980. The tank model has been tested with independent data of 1984 and 1985. In first and last week of July 1984 flow was under estimated performance of the model in general was satisfactory. Good fit of the computed hydrograph was observed except first week of Oct in 1985. The model performed well for peak flows as well as lien season flows.

Malathi is a tributary of river Tunga in the Krishna basin. It has a catchment area of 280.3 sq.km. upto the discharge measuring site Kalmane. Observed daily rainfall data at Agumbe. Sringeri and Magaravalli were used for simulation of daily stream flows at Kalmane . The comparison of computed hydrograph with observed hydrograph for the monsoon period of 1979 and 1980 was found to be satisfactory. The model has been tested with two sets of independent data of streamflow of two years each; 1981-82 and 1983-84. The performance of the model was satisfactory. The simulation of flows during 1982 and 1984 were found to be good than those of 1981 and 1983. This was due to the fact that the antecedent conditions get adjusted during the simulation of the starting year of comparison.