Deriving Rainfall Intensity-Duration-Frequency Relationships fo Kerbala

Abstract

Intensity-Duration-Frequency (IDF) relationship of rainfall amount is one of the most commonly used tools in water resources engineering for planning designing, and operation of water resources projects. The objective of this research is therefore, to develop operational IDF relationships for the provinceof Kerbala based on historical data. The IDF curves have been developed considering application to Kerbala area and presented in the form of general mathematical equation, curves relating Intensity–Duration-Frequency of rainfall. The IDF curves are plotted for 2, 5, 10, 25, 50 and 100-year return periods in Kerbala. The values of the constants α, γ and exponents β, τ in the IDF function are calculated from the observed precipitation data by using different methods.Using themethods ofgoodness of fit has been reached in Kerbala that the Log Pearson type III is the best method of other methods.