UM-15 : Application of Tank model for Flood analysis

Abstract

Tank Models for daily analysis and flood analysis were developed in Japan by Sugawara (1967). The input requirements of the Tank Models for flood analysis and daily analysis are different. The former model requires the floods data at time unit In hours while the later model needs the continuous daily data at least for three to four years for the calibration purpose. The flood analysis model consists of three tanks which are laid vertically in series. First initial set of parameter values of the model is obtained based on the procedure stated in this user's manual for computer programme of the model. The model parameters along with the data related to floods are supplied as input. Evapotranspiration effect has been considered by including a SUBROUTINE in the programme. The programme simulates out flow hydrographs.

Five hydrographs are plotted simultaneously if river channel modification option is considered. These five hydrographs are plots of observed discharge, calculated discharge, sum of outputs from first, second, third and base discharge, and sum of output from second, third tanks and base discharge and sum of output from third tank and base discharge against time. However, only four hydrographs are plotted without considering the river channel modification viz., observed discharge, calculated discharge, sum of outputs from second, third tanks and base discharge and sum of output from third tank and base discharge. Trial and error procedure has been used to calibrate the parameters so as to get better fit of simulated hydrograph with observed one. These calibration parameters lead to final model structure.

The programme has been implemented on VAX-11/780 system at National Institute of Hydrology, Roorkee. In the appendix of this User's manual the input and output specifications for the programme have been described with an illustrative example. The programme can be run on computers other than VAX-11/780 system having FORTRAN Compiler after making suitable software modifications.