Homogeneity Analysis of Rainfall event by Using ROI Approach

Abstract

The main purpose of this paper is to present and apply one of the statistical methodologies-the region of influence (ROI) approach-and form homogenous region/regions for rainfall frequency analysis in order to extract rainfall information guidelines for the Sudan basin. 15 gauging stations are selected, with recorded annual data ranging from 25 to 102 years in length. The aim here is to provide a regional curve with the capacity of taking into account the spatial pattern of variation of hydrologic phenomena across many gauging sites and which can be used for estimating rainfall quantiles at both gauged and ungauged sites within a specified region. This regional curve can also provide the possibility of the transfer of hydrologic behavior of a region to a site of interest in order to improve at-site estimates. The study results are analyses and compared. At first rainfall quantile for selected sites were estimated. In addition, the regression analysis between estimated quantiles (for 100 years) and the geographical features of the basin (drainage area (A), longitude (X dist .) and latidute (Y dist .)) was derived. In an aim to extend the methodologies to the case of ungauged site, a nonlinear regression model is derived and the results are investigated.