Variability and trends of rainfall extreme events in north east highlands of Ethiopia

Yimer, Mohammed; Yimer, Fantaw; Tadesse, Menfese; Tesfaye, Kindie

doi:10.15406/ijh.2018.02.00131

Cited by 31 publications

(34 citation statements)

References 28 publications

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“…The irrigation infrastructure periods. Similarly, no significant trend in annual rainfall has been reported in a number of studies for some stations in the Awash River Basin [14,[17][18][19]. On the other hand, Rosell [20] found an increasing trend in annual rainfall in six out of the seven stations in the Awash River Basin; whereas, Bekele et al [18] and Asfaw et al [21] reported a significant decreasing trend in annual rainfall over some stations in the basin.…”

Section: Introductionmentioning

confidence: 90%

“…Linear regression is severely affected by outliers, missing data, and the starting and ending values of the time series [22][23][24]. However, linear regression based on ordinary least square (OLS)-based has been used for trend analysis in a number of studies [1,14,15,17,19,[25][26][27][28]. For the non-parametric tests, no assumption is made about the distribution of the population.…”

Section: Introductionmentioning

confidence: 99%

“…There are few studies for the entire or parts of the basin. Some station-based climatic trend studies have included few locations from the Awash River Basin [14,17,[19][20][21]. While only a few of these studies have included significant parts of the basin or the entire basin [1,15,18,31].…”

Section: Introductionmentioning

confidence: 99%

“…Obviously, this is very low data intensity to represent a 116,374 square-km basin with diverse climatological zones. Secondly, most of the studies are based on data analysis at point-scale or arbitrarily defined areas [14,[17][18][19][20]31]. Cheung et al [1] also identified these problems over a number of publications.…”

Section: Introductionmentioning

confidence: 99%

“…He and Gautam [24] noted that the results of trend analysis can be significantly affected by the use of linear regression. Additionally, most of the studies did not consider serial correlation in time series that would result in errors in trend detection [1,14,15,[17][18][19][20][21]. Overall, as most of local studies citied above are carried out for areas outside the Awash River basin, it is clear that there are no studies covering significant portion of the Awash River basin with sufficient level of details.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Long-Term Trends of Annual and Seasonal Rainfall in the Awash River Basin, Ethiopia

Mulugeta

Fedler

Ayana

2019

Water

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With climate change prevailing around the world, understanding the changes in long-term annual and seasonal rainfall at local scales is very important in planning for required adaptation measures. This is especially true for areas such as the Awash River basin where there is very high dependence on rain- fed agriculture characterized by frequent droughts and subsequent famines. The aim of the study is to analyze long-term trends of annual and seasonal rainfall in the Awash River Basin, Ethiopia. Monthly rainfall data extracted from Climatic Research Unit (CRU 4.01) dataset for 54 grid points representing the entire basin were aggregated to find the respective areal annual and seasonal rainfall time series for the entire basin and its seven sub-basins. The Mann-Kendall (MK) test and Sen Slope estimator were applied to the time series for detecting the trends and for estimating the rate of change, respectively. The Statistical software package R version 3.5.2 was used for data extraction, data analyses, and plotting. Geographic information system (GIS) package was also used for grid making, site selection, and mapping. The results showed that no significant trend (at α = 0.05) was identified in annual rainfall in all sub-basins and over the entire basin in the period (1902 to 2016). However, the results for seasonal rainfall are mixed across the study areas. The summer rainfall (June through September) showed significant decreasing trend (at α ≤ 0.1) over five of the seven sub-basins at a rate varying from 4 to 7.4 mm per decade but it showed no trend over the two sub-basins. The autumn rainfall (October through January) showed no significant trends over four of the seven sub-basins but showed increasing trends over three sub-basins at a rate varying from 2 to 5 mm per decade. The winter rainfall (February through May) showed no significant trends over four sub-basins but showed significant increasing trends (at α ≤ 0.1) over three sub-basins at a rate varying from 0.6 to 2.7 mm per decade. At the basin level, the summer rainfall showed a significant decreasing trend (at α = 0.05) while the autumn and winter rainfall showed no significant trends. In addition, shift in some amount of summer rainfall to winter and autumn season was noticed. It is evident that climate change has shown pronounced effects on the trends and patterns of seasonal rainfall. Thus, the study contribute to better understanding of climate change in the basin and the information from the study can be used in planning for adaptation measures against a changing climate.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of Long-Term Trends of Annual and Seasonal Rainfall in the Awash River Basin, Ethiopia

Mulugeta

Fedler

Ayana

2019

Water

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Spatio‐temporal rainfall variability and trend analysis in the Tekeze‐Atbara river basin, northwestern Ethiopia

Abebe

Grum

Degu

et al. 2022

Meteorological Applications

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Spatial and temporal rainfall variability analysis at a basin scale is essential to understand water availability for sustainable water resource management. This study investigated the spatial distribution and temporal rainfall trend in the Tekeze river basin using daily rainfall data collected from 43 meteorological stations with records from 1960 to 2019. Coefficient of variation, seasonality index (SI) and trend index were used to evaluate monthly, seasonal and annual rainfall variability in the basin. The non‐parametric Mann‐Kendall's test was used to understand any rainfall trends. Results showed that there is moderate annual rainfall variability in the basin. Rainfall variability is higher in the Tsedey, Bega and Belg than kiremt season. SI results showed that majority of the Tekeze river basin is categorized as seasonal, most of the rain occurring in less than 3 months. Overall, Mann‐Kendall's test result revealed that there is no significant annual rainfall trend in the basin except for four stations. The seasonal rainfall characteristics and short duration of rain in the basin indicate that there is a need to implement water harvesting measures during the wet season for use in the dry periods.

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Spatiotemporal variability and trend detection of hydrological and climatic variables of Modjo catchment, central Ethiopia

Besha,

Demessie,

Feyessa

2023

Theor Appl Climatol

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Understanding hydro-climatic trends in space and time is crucial for water resource planning and management, agricultural productivity and climate change mitigation of a region. This study examined the spatiotemporal variations in precipitation, reference evapotranspiration (ETo) and streamflow in a tropical watershed located in the central highlands of Ethiopia. Temporal trend implications were analyzed using the Mann-Kendall test, and Theil-Sen approach, whereas the inverse distance weighted interpolation method was applied for spatial trend variability analysis. The result showed that a significant decreasing trends in streamflow for the major rainy (Kiremt: Jun -Sept) season and annual time scales. At the same time, the annual and monthly ETo followed significantly increasing trends, but there has been a trendless time series for most of the months and annual mean precipitation series for the period 1986 -2015. The study indicated that the spatial variability of annual and seasonal precipitation series decreased from north to south and west to east, while this was increased for ETo both for annual and seasonal time series over the study watershed. The contribution of rainfall and mean temperature to streamflow decline was insignificant. It is pointed out that river flow regime is weakly affected by climate changes, hence human activities are stronger in explaining the river flow trends of the watershed. Therefore, urgent calls on the needs for reducing human-induced impacts, and implementing appropriate watershed management, conservation measures and an efficient use of water resources. KeywordsClimatic changes • Modjo watershed • Spatiotemporal dynamics • Water Resources. IntroductionClimate change and its phenomenon influences almost all the processes in the biosphere one way or another. As a result, it affects environmental and hydrological variables negatively in many countries (Yavuz and Erdoğan 2012;Fathian et al. 2015;Birkmann and Mechler 2015;Wang et al. 2018). Precipitation is the major climatic variables that plays an irreplaceable role in balancing the fresh water budget of a basin and directly affect the spatial and temporal patterns of water availability for agriculture, industry, food security, hydropower water supply, and energy balance (Pal et al. 2017; Bayable et al. 2021). Temperature, on the other hand plays an important role in water demand in terms of evaporation, and transpiration, as a result of this significantly affects water requirements, and availability. Similarly, evapotranspiration is a key parameter for evaluating the climatic changes and to determine appropriate strategies in planning and management of agricultural activities and regional water resources (Amo-Boateng et al. 2014; Amirataee et al. 2015;Mubialiwo et al. 2020). The changes in the precipitation patterns along with the rise in surface air temperature are one of the most obvious effects of the human-induced climate change (IPCC 2007), which are observable at the catchment scale. In general, climate change has diverse...

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Variability and trends of rainfall extreme events in north east highlands of Ethiopia

Cited by 31 publications

References 28 publications

Analysis of Long-Term Trends of Annual and Seasonal Rainfall in the Awash River Basin, Ethiopia

Analysis of Long-Term Trends of Annual and Seasonal Rainfall in the Awash River Basin, Ethiopia

Spatio‐temporal rainfall variability and trend analysis in the Tekeze‐Atbara river basin, northwestern Ethiopia

Spatiotemporal variability and trend detection of hydrological and climatic variables of Modjo catchment, central Ethiopia

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