Catchment response modelling of a typical river basin in odisha using scs-cn method

Abstract

Estimation of discharge normal and peak and/or hydrograph is often used for small to medium sized gauged and un-gauged catchments for the design of hydraulic structures. Hydrological modeling is the tool which simulates the catchment behaviour by solving the equations that govern the physical processes occurring within the catchment hydrologic models are usually used to simulate the catchment response for a given input. This paper discusses the applicability of the curve number procedure developed by the US Soil Conservation Service (SCS) to estimate runoff from the available information onantecedent soil moisture condition of the catchment.The proposed area is located in geographical latitude 190 – 23’ N and 830 – 21’ – 45”E longitudes. The study area is marked from the Survey of India Topo-sheets and the Digital Elevation Model (DEM) is generated. SCS-CN method is used to calculate runoff from the rainfall and then the results are compared with the observed data Based on the soil classification, the given area falls under the soil; groups B, C and D with soil moisture condition of AMC-II. Standard error estimate are computed between the observed and computed values.In addition to knowing the total runoff,it is equally important to know the peak runoff,as it is the peak runoff which may act as a precursor to a flood. The peak rate of runoff is a function of the average rainfall rate during the time of concentration. An empirical relationship has been tried to establish between peak runoff (Qp) and catchment coefficient (C),rainfall (P) ,catchment area in the form of a power function. The empirical relationships are generally applicable for a particular region where the relationships are developed taking into account the effect of data of that region.In all other area it can give approximate values