DEVELOPMENT OF FLOW DURATION CURVE FOR UNGAUGED BASINS USING VARIOUS REGIONALIZATION METHODS

Abstract

The planning and development of water resource structures of a region requires a proper understanding of the hydrological behaviour of the river basin. The analysis of available historical information is necessary to decide about water availability estimation of the available water resource. Water availability generally refers to the volume of water available from a basin or stream. The planning, development and operation of water resource project is very much depend upon the availability of hydrological data of desired quantity and quality. Generally, for most basin in the country, rainfall records of sufficient length are available. However, the available runoff data is either short or has gaps due to missing data. The shorter length of data along with other problems, always lack the true representation of natural behaviour of the time series. In the absence of data, the best suited alternative is to use the regionalisation method. Regionalisation techniques provide a mechanism to relate the hydrological behaviours of ungauged catchments in a region. This techniques can be helpful to utilise to derive stream flow characteristics at ungauged catchments of the region. In the present study the data of gauged catchments of the upper Krishna basin has been used to find out the discharge of ungauged sites of the corresponding catchments. Data from eleven river gauging stations has first been taken to find out the flow in the upstream ungauged tributaries of these gauged catchments. Water availability with time variability at the proposed project site is essential to estimate the power potential and annual energy generation. The Flow Duration Curve (FDC) is a simple depiction of water availability with time variability. It shows a discharge which has equalled or exceeded certain percentage of time out of the total time period which is generally taken as one year. The FDC at the ungauged site has been developed using the regionalization of the parameters of chosen probability distribution for the gauged sites and concluded that which regionalisation method is best for the upper Krishna basin.