Abstract
This study investigated the annual and seasonal rainfall variability at five selected stations of Amhara Regional State, by using the innovative trend analysis method (ITAM), Mann-Kendall (MK) and Sen’s slope estimator test. The result showed that the trend of annual rainfall was increasing in Gondar (Z = 1.69), Motta (Z = 0.93), and Bahir Dar (Z = 0.07) stations. However, the trends in Dangla (Z = −0.37) and Adet (Z = −0.32) stations showed a decreasing trend. As far as monthly and seasonal variability of rainfall are concerned, all the stations exhibited sensitivity of change. The trend of rainfall in May, June, July, August, and September was increasing. However, the trend on the rest of other months showed a decreasing trend. The increase in rainfall during Kiremt season, along with the decrease in number of rainy days, leads to an increase of extreme rainfall events over the region during 1980–2016. The consistency in rainfall trends over the study region confirms the robustness of the change in trends. Innovative trend analysis method is very crucial method for detecting the trends in rainfall time series data due to its potential to present the results in graphical format as well. The findings of this paper could help researchers to understand the annual and seasonal variability of rainfall over the study region and become a foundation for further studies.
Highlights
Water resource has become a prime concern for any development activities and planning including effective water resources management [1,2,3,4]
Amhara regional state is found in north-west of Ethiopia lying between 9◦ –13◦ 450 north latitude, and 36◦ –40◦ 300 east longitude (Figure 1)
The variability of rainfall on monthly, seasonal, and annual basis were analyzed for five representative meteorological stations of Amhara Regional State
Summary
Water resource has become a prime concern for any development activities and planning including effective water resources management [1,2,3,4]. The frequent occurrence of extreme climatic events such as flooding and drought became a global concern [5]. Since these phenomena negatively affect societies, water resources, ecosystem and the economy at large, all the concerned body should aware [6]. Precipitation is the key climatic variable that affect both the spatial and temporal patterns of water resources [9]. Analyzing the long-term trends and variability of rainfall is very important for sustainable water resources management [1,10,11]. Studying the trends of precipitation and temperature have enormous use for researchers to describe the spatial and temporal
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