Generation of Rainfall Intensity-Duration-Frequency curves for the Barak River Basin

Abstract

Analysis of a design storm, explained as the expected rainfall intensity for a given storm duration and return period is carried out to establish Rainfall Intensity-Duration-Frequency (IDF) relationships. The IDF relationships are essential for the designing of hydraulic structures for future planning and management. The intent was to determine IDF relationship for the Barak River Basin in India. This region receives heavy rainfall but lacks potential in harnessing the available water resources. Rain gauge stations are not so frequent in this region. Under this condition, the engineers are bound to use IDF relationships. Using the 24-hour annual maximum rainfall and disaggregated hourly maximum rainfall as a measure of rainfall intensity for each station, IDF curves and isopluvial maps of rainfall intensities of 30-minute to 24-hour durations were generated. Analysis was done using the best fit amongst the Gumbel, Log Pearson Type III and Lognormal probability distribution functions. The goodness-of-fit tests indicated the Log Pearson Type III distribution was a suitable distribution for the area. After developing IDF curves for each station, an average IDF curve was developed using the Thiessen Polygon method in ArcGIS. The IDF relationship developed can be used as valuable information for the planning and management of hydraulic structures in the region.