Study of Spatial Variation of Rainfall Intensities over Mumbai

摘要

Intensity-Duration-Frequency (IDF) curves are used by engineers and scientists to estimate the intensities of rainfall for various frequencies of occurrence at a location. Mumbai, the capital of Maharashtra state and commercial and financial centre of India, have two sets of IDF curves namely Colaba and Santacruz are used for design of SWD system in Mumbai. After the unprecedented floods in Mumbai on 26.07.2005, MCGM established 32 rain gauges to get an idea of spatial variation of rainfall at various location in Mumbai. The present study attempts to assess spatial variation of rainfall intensities over Mumbai. Eight numbers of representative rain gauging stations from total 32 stations were selected for this study. Based on rainfall data of 2006 onwards, IDF relationships were developed for these select locations. The IDF relationship thus developed were compared with IDF relationship already developed by Chawathe et al for Colaba in the past. City, Western Suburbs and Southern part of Eastern Suburbs did not show any significant spatial variation. Spatial Variation was observed between City and Eastern Suburbs. Spatial Variation was also observed amongst Northern part and extreme Northern part of Eastern Suburbs. The spatial variation was translated in terms of multiplication factors which can be applied to intensities of rainfall developed by Chawathe et al for Colaba to compute intensities of rainfall to be used for designing Storm Water Drainage system in Mumbai enabling recognition of spatial variation of rainfall.