CS(AR)-16/97-98 : Daily rainfall-runoff modelling of Rushikulya river, Orissa

Abstract

A hydrologic simulation model known as HYSIM is applied to the Rushikulya river basin to model the daily flows of the river at Purushottampur. The model used in the study is a menu driven P.C. based version and contains modes both for optimisation and production runs. The model can use five types of input data namely, precipitation, PET, potential snowmelt rate, discharges to/abstractions from river channels and abstraction from ground water. In addition, it can use a gauged flow record for comparison with the simulated flows. The model can use the input data and simulate the flows either on monthly, daily or on any other shorter time increment including hourly. The model also has the capability to model the natural inhomogeneity of a catchment by sub-dividing the catchment into as many sub-catchments as necessary to have the reasonable homogeneous sub-catchments with respect to soil types and meteorology. In such a case the flows from upstream catchments are routed through the catchment being modelled together with flows from local runoff. For this purpose, either the recorded flows from upstream catchments may be used or they may be simulated separately for each of the upstream sub-catchments.

The river Rushikulya having a drainage area of about 8200 sq.km. is one of the medium sized east flowing rivers in the state of Orissa. The modelling of flows from the basin is carried out for a drainage area of 7112 sq.km. at Purushottampur G-D site. The entire drainage area upto the site has been considered as a single unit in applying the model. The model is calibrated using three years data of rainfall, PET and gauged flow record. The model validation is performed by simulating flows for three different data sets. The results of the study show that the model has simulated the flow hydrographs to a fair degree of accuracy despite some short-comings in the input data. Based on the results, it is concluded that the model can be effectively used for simulation studies of Rushikulya basin and its sub-basins.