Estimation of flood frequency using statistical method: riverbasin for Sungai Jijan Malaysia

Abstract Flood frequency analysis is a crucial mathematical approach for predicting the probability of a specific discharge in a river, particularly at peaks. Floods are recurring phenomena in river basins that cause tremendous flow. Flood frequency analysis involves fitting a river yearly peak flow to various probability distributions. Flood frequency analysis often involves three statistical methods, Double Mass Curve, Development Of IDF Curve, and Time of Concentration, Tc. Floods cause heavy loss of life and property in the flood seasons. The selection of best probability distribution method in the studied river basin with the recent available records will definitely help the planners and administrators to estimate the major flood events and save life and property according the chosen method which is the three methods used are Double Mass Curve, Development Of IDF Curve, and Time of Concentration, Typically, double mass curve it’s used to analyse the relationship between two sets of data points by plotting the cumulative values of one variable against the cumulative values of another variable. By examining the resulting curve, analysts can identify patterns, trends, or discrepancies between the datasets. IDF curve are developed based on historical rainfall data for a specific location and are used in engineering and urban planning to design drainage systems, flood control measures, and other infrastructure to manage stormwater runoff. The time of concentration depends on various factors, including watershed size, slope, land use, soil type, and rainfall intensity. Several empirical equations and methods exist to estimate the time of concentration for different watershed conditions. The findings of the study are confirmed by direct computation and analysis of rainfall records. The authors point out that real precipitation throughout time and spacetime deviates from multifractality at both the small and big scales.