DEVELOPMENT OF RAINFALL INTENSITY DURATION FREQUENCY CURVES FOR ROORKEE CITY

Abstract

Rainfall intensity of a particular frequency and duration is required for estimation of average annual flood and sediment yield from the catchments. The design Engineers do not have simple and reliable method for estimation of rainfall intensity, particularly for short duration. This necessitates going for the regionalisation of IDF relationships. The limitation of such study is the scarcity of data from self-recording raingauges for sufficiently long time. Again, studies for less than 1-hour data are also scarce. However, many reseacher's from India and abroad have done a significant work on rainfall intensity-duration-frequency analysis and development of IDF curves. In the present study, we have estimated the parameters K, x, a and n involved in the equation: KTX (D+a) Where 1= maximum intensity (cm!h), T= return period (years), D= duration (hours) K, x, a and n are parameters for the area represented by the station. For this estimation, we have used hourly rainfall data for Roorkee city for 9 years ( from 2003 to 2011 ). Based on estimated parameters peak intensities were modeled for different durations ( 1, 2, 3, 6, 12 and 24 hours) and different return periods. The Intensity duration Frequency curves were drawn for modeled and observed peak intensities.