TR-38 : Statistical analysis of low flow in typical river basin to investigation drought characteristics

Abstract

Low flow is a broadly used term to describe stream flows that are significantly below average or normal flow levels. In the traditional planning, design and operation of water related projects, the low flow characteristics of a river system have been important in determining the critical capacity of that system to provide adequate water supply and to meet power demands. This knowledge must be understood quantitatively. Furthermore, the question of quality of the environment often depends on the availability of low river flows particularly in areas of urban living, or on problems of public health, such as combating endemic diseases, as well as for thermal or chemical pollution. Thus, the connection between quantitative and qualitative aspects of water resources is especially sensitive during low water periods. For various reasons(health, environmental conditions), it is necessary to maintain a minimum discharge in river and, consequently, this water is not available for other water users.

The low flow computation methods can be divided into the three groups, namely, deterministic approach, statistical approach and stochastic approach. In the present report attempts have been made to carry statistical analysis of low flow using 20 years data (1966-86) for six selected sites in drought affected Krishna basin. The hydrologic drought characteristics have been investigated by developing/carrying out flow duration curve, frequency curves, low flow spell analysis and maximum deficit volume and maximum deficit duration analysis. The results of these analysis are presented herein.