Effect of Data Length on Estimation of Seasonal and Annual Dependable Flow Using Flow Duration Curve

N VIVEKANANDAN

Abstract

For planning, design, and management of water-related projects such as hydro power generation, irrigation systems, reservoir sedimentation, etc., estimation of seasonal and annual dependable flow at different percentage levels is considered one of the important aspects in hydrological studies. For this purpose, the construction of the flow duration curve (FDC) using the plotting position formula (PPF) is considered one of the effective tools for the estimation of dependable flow at different percentage levels when an adequate length of observed stream flow data is not available. In this paper, a study on the effect of data length on the estimation of seasonal and annual dependable flow using FDC at the Kuppa barrage of river Baspa is presented. The study shows that the 75% and 90% dependable flow obtained from FDCs are in decreasing order when the data length increases for monsoon, post-monsoon, and winter seasons. The study also shows that the 75%, 90%, and 100% dependable flows obtained from FDCs using stream flow data series with different data lengths could be considered for planning and management of irrigation, hydropower, and drinking water projects respectively.