Trend analysis of extreme precipitation in the Northwestern Highlands of Ethiopia with a case study of Debre Markos

H Shang,S M Ayalew,M Gebremichael,J Yan

doi:10.5194/hess-15-1937-2011

Abstract

Abstract. Understanding extreme precipitation is very important for Ethiopia, which is heavily dependent on low-productivity rainfed agriculture but lacks structural and non-structural water regulating and storage mechanisms. There has been an increasing concern about whether there is an increasing trend in extreme precipitation as the climate changes. Existing analysis of this region has been descriptive, without taking advantage of the advances in extreme value modeling. After reviewing the statistical methodology on extremes, this paper presents an analysis based on the generalized extreme value modeling with daily time series of precipitation records at Debre Markos in the Northwestern Highlands of Ethiopia. We found no strong evidence to reject the null hypothesis that there is no increasing trend in extreme precipitation at this location.

Highlights

In Ethiopia, rainfall is by far the most important factor climate, as is true for most of Africa
Low-productivity agriculture, which accounts for a majority of the national economy, relies heavily on rainfall. Climate extremes such as drought or flood often lead to famine and disaster for the vulnerable agricultural, social and economic environment in Ethiopia, which lacks structural and non-structural water regulating
Given the increasing public concern on climate change, it is of particular interest to test whether there is a long term increasing trend in extreme precipitation

Summary

Introduction

In Ethiopia, rainfall is by far the most important factor climate, as is true for most of Africa. Low-productivity agriculture, which accounts for a majority of the national economy, relies heavily on rainfall. Climate extremes such as drought or flood often lead to famine and disaster for the vulnerable agricultural, social and economic environment in Ethiopia, which lacks structural and non-structural water regulating and storage mechanisms. Flood, as a result of extreme precipitation, poses serious threat on food security and public safety. Estimating the probability of extreme precipitation and characterizing the uncertainty of the estimates are crucial to, for instance, structural design, public safety alerts, evacuation management, and loss mitigation. Given the increasing public concern on climate change, it is of particular interest to test whether there is a long term increasing trend in extreme precipitation. Kunkel et al (1999) reported an increasing trend in the United States at a rate of 3 % per decade from 1931 to 1996, but no significant trend during 1951–1993 in Canada; Kunkel (2003) showed a sizeable increase in the frequency of extreme precipitation events since the 1920s/1930s in the US; Frei and Schar (2001) found an increase in the frequency of heavy precipitation during 1901–1994 in the Alpine region of Switzerland; Goswami et al (2006) detected a significant rising trend in both the frequency and the magnitude of extreme rainfall events from 1951 to 2000 in central India; Karagiannidis et al (2009) reported no significant trend in extreme precipitation of the European continent from the mid 1970’s to 2000

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