Analyzing Extremes of Rainfall Using L-Moments for The Northwestern Sites of Pakistan

Abstract

Climate change refers to the rising changes in the measures of climate over a longer period of time. It includes rainfall, temperature and wind patterns. The variations in the climate cycles are causing more rain to fall than usual at a site or dry period extends to the extent of drought. These variations in extremes are causing adverse effects on human, social and economic sectors including agricultural production and water resources. Pakistan being an agricultural country with depleting resources of dealing with climate change is one of the major affected countries due to climate change. Therefore, there is a need to analyze the impacts of climate change on the extremes of rainfall and to forecast the magnitude and frequency associated with these extremes. Accurate and reliable prediction of extremes of rainfall will be useful for disaster management, irrigation and water resources management, especially in the areas with frequent rainfall. This study is an application of L-moments based regional frequency analysis using winter maximum rainfall series of six sites of north-western region of Pakistan. The discordancy measure (Di) shows that none of the site in a group of six sites is discordant. The regional heterogeneity measure (H) shows that the region of six sites is homogeneous. L-moment ratio diagram and |ZDIST| statistic is in favor of Generalized Extreme Value (GEV) as best-fit regional distribution. Parameters of GEV distribution and regional as well as at-site quantiles up- to 100-year, return period have been accurately estimated. The results of this study will be useful for the scientists/researchers dealing with disaster management, hydro-met projects for sustainable water resources management, planning for weather related emergencies and agricultural management. Keywords: Extremes of rainfall