Abstract
Understanding the timing and variability of rainfall is crucial for the effective management of water resources in river basins dominated by rainfed agricultural practices. Our study aimed to characterize rainfall and analyze the trends in the length of wet spells (LWS) in the Upper Awash River Basin—one of the most water-stressed river basins in Ethiopia. We applied statistical descriptors and a Mann–Kendall (MK) test to determine the onset, end, and LWS for the small (Belg) and main (Kiremt) rainy seasons across different landscapes of the basin. We observed highly stable rainfall onsets in all stations during both seasons. However, unlike the Kiremt season, the LWS in the Belg season was too short and unreliable for rainfed agriculture. Based on the MK test, an increasing monotonic trend in LWS during the Kiremt season was detected only in the mountainous landscape of the basin. In contrast, we observed no trends in the remaining stations in the Upper Valley region of the basin, despite the linear regressions inferring an upward or downward pattern. Our findings provide accurate climatological information for the effective development of rainwater management strategies in the Upper Awash River Basin.
Highlights
The seasonal and interannual variability of rainfall in certain regions influences the management of rainwater for various anthropogenic uses [1,2]
The Food and Agricultural Organization (FAO) [38] water balance concept states that the onset of the rainy season occurs when rainfall is equal to half of the ETo
The length of wet spells (LWS) during the Kiremt season was adequate for supporting the growth of selected crops in the mountainous and valley landscapes of Debrezeit, Wonji, and Melkassa, but not Metehara
Summary
The seasonal and interannual variability of rainfall in certain regions influences the management of rainwater for various anthropogenic uses [1,2]. Various studies have attempted to characterize seasonal rainfall to determine the onset and end of wet spells across the world, including in Central America [15], Brazil [16,17,18], India and Nigeria [19], India [20], equatorial East Africa [21], Tanzania [22], West Africa [23,24], and Ethiopia [25,26,27] These studies show the importance of understanding the rainfall characteristics in terms of onset, end, and LWS for effective agricultural water management to avert the risk of crop failure and recurrent drought. We calculated the water requirements of the dominant crops to be used as threshold values for determining the onset and end of the rainy periods
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