Getahun Yitea Seneshaw, Li Ming-Hsu, Pun Iam-Fei
Taiwan International Graduate Program (TIGP), Earth System Science Program, Academia Sinica, Taipei, 115, Taiwan.
Graduate Institute of Hydrological and Oceanic Sciences, National Central University, Taoyuan, 320, Taiwan.
Heliyon. 2021 Sep 20;7(9):e08024. doi: 10.1016/j.heliyon.2021.e08024. eCollection 2021 Sep.
Awash River basin (ARB) as a system is in a state of continuous change that requires successive studies to discern the changes or trends of climatic elements through time due to climate change/variability, and other socio-economical developmental activities in the basin. The livelihood of communities in the ARB is primarily based on rainfall-dependent agriculture. Effects of rainfall anomalies such as reduction of agricultural productivity, water scarcity, and food insecurity are becoming more prevalent in this area. In recent years, ARB has been experiencing more frequent rainfall anomalies that change-point detection test and trend analyses of basin rainfall associated with sea surface temperature is crucial in providing guidance to improve agricultural productivity in ARB. Change-point detection tests such as Pettit's, the von Neumann ratio (VNR), Buishand's range (BR) and standard normal homogeneity (SNH) plus trend analysis Mann-Kendall (MK) test of rainfall and temperature data from 29 meteorological stations in the ARB were carried out from 1986 to 2016. A significant increasing trend of annual and seasonal temperature was found. The temperature change-points for the annual and major rainy season (MRS) were detected in 2001, while for the minor rainy season (mRS) in 1997. A significant decreasing trend, shift, and high variability of rainfall were detected in the downstream part of the ARB. The BR and SNH results showed that the mRS rainfall change-point was in 1998, with a subsequent mean annual decrease of 52.5 mm. The increase (decrease) of rainfall in the annual and MRS was attributable to La Niña (El Niño) events. The significant decreasing trend and change-point of rainfall in the mRS was attributable to the steady warming of the Indian and Atlantic Oceans, local warming, and La Niña events. With this knowledge of the current trends and change-point for rainfall and temperature in the ARB, it is therefore essential that appropriate integrated water management and water-harvesting technologies are established, especially in the downstream areas. Moreover, early detection of El Niño episodes would provide invaluable warning of impending rainfall anomalies in the ARB and would enable better preparations to mitigate its negative effects.
阿瓦什河流域（ARB）作为一个系统处于持续变化的状态，这需要进行连续研究，以通过气候变化/变率以及该流域内的其他社会经济发展活动来识别气候要素随时间的变化或趋势。ARB地区社区的生计主要依赖于依赖降雨的农业。降雨异常的影响，如农业生产力下降、水资源短缺和粮食不安全，在该地区正变得越来越普遍。近年来，ARB经历了更频繁的降雨异常，对与海表温度相关的流域降雨进行变点检测测试和趋势分析，对于提高ARB地区的农业生产力至关重要。对1986年至2016年期间ARB地区29个气象站的降雨和温度数据进行了诸如佩蒂特检验、冯·诺依曼比率（VNR）、布伊尚范围（BR）和标准正态同质性（SNH）等变点检测测试，以及趋势分析曼-肯德尔（MK）检验。发现年温度和季节温度呈显著上升趋势。年温度和主要雨季（MRS）的温度变点在2001年被检测到，而次要雨季（mRS）的温度变点在1997年被检测到。在ARB的下游地区检测到降雨呈显著下降趋势、发生了变化且具有高度变异性。BR和SNH结果表明，mRS降雨变点在1998年，随后年平均降雨量减少了52.5毫米。年降雨和MRS降雨的增加（减少）归因于拉尼娜（厄尔尼诺）事件。mRS降雨的显著下降趋势和变点归因于印度洋和大西洋的持续变暖、局部变暖以及拉尼娜事件。鉴于对ARB地区降雨和温度当前趋势及变点的了解，因此至关重要的是要建立适当的综合水资源管理和集水技术，特别是在下游地区。此外，提前检测到厄尔尼诺事件将为ARB地区即将出现的降雨异常提供宝贵预警，并能够更好地做好准备以减轻其负面影响。
