EFFECT OF DATA ERRORS AND LENGTH OF DATA ON DESIGN FLOOD ESTIMATES

Abstract

Estimation of a flood of desired return, period from the analysis of historical peak flood data is required in the hydraulic design and operation of surface of water projects and other engineering structures. The, historical data has to meet certain criteria with reqard to (a)quality of data (b)the principles of random sampling with particular emphasis on sample size and (c)homogeneity of the time series. In practice, annual flood peak values are only the estimates of actual flood flows which could be in error by a significant amount. Further, sample size is generally limited and fitting of a theoretical probability distribution; parameters of which are estimated from limited sample size, has been an area of extensive research for last few decades. The design flood value based on frequency analysis of limited annual flood peak data which itself is in significant error needs further scrutiny with respect to (a)length of data (b)sensi-tivity to parameters estimates (c)errors in data. In this study flood frequency analysis has been made considering the effect of data errors and length of data on the statistical parameters and flood estimates....