Homogeneity Analysis of Rainfall Data Series in the Long Xuyen Quadrangle of Vietnam

Abstract

The main aim of this study is to assess homogeneity of rainfall patterns through the analysis of rainfall data series in the Long Xuyen Quadrangle of Vietnam. First, the study evaluates the applicability of homogeneity analysis methods for assessing annual and seasonal rainfall data series. Second, optimal homogeneity methods will be selected to detect the change trends of rainfall patterns for study area in the next studies. The homogeneity methods are applied in the homogeneity analysis of seasonal and annual rainfall, homogeneity tests were applied for 9 climate stations using the Pettit, Standard Normal Homogeneity (SNH), Buishand (BR), and Von Neumann (VNR) tests. The analyzed results at a significance level of 0.05 indicated that among four tests investigated across all gauge stations recorded homogeneity except for Pettitt test was found to be inhomogeneity. The break captured by the Pettitt test in the period 2008-2015. The analyzed results for the Mann-Kendall test and Sen’s slope estimator at a significance level 0.05 recorded that a decreasing trend of annual rainfall recorded at eight out of 9 stations and Sen’s slope estimator also indicates a trend line at eight out of nine-gauge stations. Generally, based on trend analysis, most of the rainfall staions across the Long Xuyen Quadrangle were recorded a decreasing trend during 1978-2015.