Author(s): Nishi Bhuvandas; P. V. Timbadiya; P. L. Patel; P. D. Porey
Linked Author(s): Prafulkumar V Timbadiya, Prem Lal Patel
Keywords: Climate variability; Extreme daily rainfall; Generalized Extreme Value; Tapi basin; Trend analysis
Abstract: Changes in climate may lead to abrupt variation in extreme rainfall intensity in many regions. Keeping in mind the non-stationary climate conditions, it is essential to incorporate potential future changes in hydrological studies. In present study, the variability in time series of extreme daily rainfall has been analyzed using Generalized Extreme Value (GEV) distribution (Type I) and its suitability has been examined by superimposing on to Gringorten plotting positions. The trend analysis of extreme daily rainfall is carried out using an innovative methodology proposed by Sen (2012) and non parametric Mann-Kendall (MK) trend test. The trend detection and variability of extreme daily rainfall of four rain gauge stations namely Bhusaval, Burhanpur, Gidhade and Ukai over Tapi basin, India is also carried out in this study. More than 30 years of rainfall data have been used for aforesaid analysis. The statistical parameters like standard deviation, coefficient of variance and coefficient of skewness are also determined for extreme annual daily rainfall time series. All the data points of the time series are found to be well within the calculated values of high and low outliers. Also the time series of the extreme daily rainfall have been checked for their serial correlation. The peak values observed during the period taken into consideration at stations Bhusaval, Burhanpur, Gidhade and Ukai are 229. 2mm, 246. 2 mm, 168. 8 mm and 483. 1 mm having a return period of 68, 57, 65 and 68 years respectively along with an increasing trend in extreme daily rainfall at all stations except for a decreasing trend at Ukai.