Theme-7-5-Forecasting of non-monsoon flows for river Mahanadi at Hirakud.

Abstract

The flow rates of most of the streams in India follow a yearly cycle. Consequently, the minimum flows occur in the same non-monsoon season (Nov.-May) which often does not have much rain. The major flow during this period is derived from the antecedent precipitation contributions during monsoon season (June-Oct.) available in the form of ground water storage. The lag between the antecedent precipitation and non-monsoon runoff enables one to forecast the flow one or more months in advance of the beginning of the forecast period. This paper describes a methodology for forecasting the flows during non-monsoon season utilizing the base flow recession curves and incremental precipitation at various probability levels. This methodology has been tested using monthly rainfall and flow data of non-monsoon season for Mahanadi river at Hirakud. Split sample approach has been used in which part of data has been used for calibration and remaining part for testing the performance, which is quite encouraging.