Rainfall Characterization and Trend Analysis of Wet Spell Length across Varied Landscapes of the Upper Awash River Basin, Ethiopia

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.

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Hydro-Climatic Variability: A Characterisation and Trend Study of the Awash River Basin, Ethiopia

Hydrology ◽

10.3390/hydrology6020035 ◽

2019 ◽

Vol 6 (2) ◽

pp. 35 ◽

Cited By ~ 7

Author(s):

Mahtsente Tibebe Tadese ◽

Lalit Kumar ◽

Richard Koech ◽

Birhanu Zemadim

Keyword(s):

River Basin ◽

Climatic Variability ◽

Management Strategies ◽

Annual Rainfall ◽

Sustainable Water Management ◽

Mk Test ◽

Awash River Basin ◽

Research Findings ◽

Droughts And Floods ◽

The Impact

The objective of this study was to characterize, quantify and validate the variability and trends of hydro-climatic variables in the Awash River Basin (ARB) in Ethiopia using graphical and statistical methods. The rainfall and streamflow trends and their relationships were evaluated using the regression method, Mann–Kendall (MK) test and correlation analysis. The analysis focused on rainfall and streamflow collected from 28 and 18 stations, respectively. About 85.7% and 75.3% of the rainfall stations exhibited normal to moderate variability in annual and June to September rainfall, respectively, whereas 96.43% of rainfall stations showed high variability in March to May. The MK test showed that most of the significant trends in annual rainfall were decreasing except in two stations. These research findings provide valuable information on the characteristics, variability, and trend of rainfall and streamflow necessary for the design of sustainable water management strategies and to reduce the impact of droughts and floods in the ARB.

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Long-Term Variability in Potential Evapotranspiration, Water Availability and Drought under Climate Change Scenarios in the Awash River Basin, Ethiopia

Atmosphere ◽

10.3390/atmos11090883 ◽

2020 ◽

Vol 11 (9) ◽

pp. 883 ◽

Cited By ~ 1

Author(s):

Mahtsente Tadese ◽

Lalit Kumar ◽

Richard Koech

Keyword(s):

Climate Change ◽

River Basin ◽

Water Availability ◽

Potential Evapotranspiration ◽

Management Strategies ◽

Water Shortage ◽

Climate Change Scenarios ◽

Awash River Basin ◽

Mitigate Climate Change

Understanding the hydrological processes of a watershed in response to climate change is vital to the establishment of sustainable environmental management strategies. This study aimed to evaluate the variability of potential evapotranspiration (PET) and water availability in the Awash River Basin (ARB) under different climate change scenarios and to relate these with long-term drought occurrences in the area. The PET and water availability of the ARB was estimated during the period of 1995–2009 and two future scenarios (2050s and 2070s). The representative concentration pathways (RCP4.5 and RCP8.5) simulations showed an increase in the monthly mean PET from March to August in the 2050s, and all the months in the 2070s. The study also identified a shortage of net water availability in the majority of the months investigated and the occurrence of mild to extreme drought in about 40–50% of the analysed years at the three study locations (Holetta, Koka Dam, and Metehara). The decrease in water availability and an increase in PET, combined with population growth, will aggravate the drought occurrence and food insecurity in the ARB. Therefore, integrated watershed management systems and rehabilitation of forests, as well as water bodies, should be addressed in the ARB to mitigate climate change and water shortage in the area.

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ANALYSIS OF TRENDS OF EXTREME RAINFALL EVENTS USING MANN KENDALL TEST: A CASE STUDY IN PAHANG AND KELANTAN RIVER BASINS

Jurnal Teknologi ◽

10.11113/jt.v78.9696 ◽

2016 ◽

Vol 78 (9-4) ◽

Cited By ~ 2

Author(s):

Mazlina Alang Othman ◽

Nor Azazi Zakaria ◽

Aminuddin Ab. Ghani ◽

Chun Kiat Chang ◽

Ngai Weng Chan

Keyword(s):

Climate Change ◽

River Basin ◽

Extreme Event ◽

Extreme Rainfall ◽

River Basins ◽

Peninsular Malaysia ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Mk Test ◽

Kelantan River Basin

Climate change leads to changes in rainfall and extreme event. This phenomenon has already begun to transform the rainfall patterns in Malaysia. It was clearly proven when the northern and eastern states of Peninsular Malaysia such as Kelantan, Terengganu, Pahang, Perak and Johor were hit by the catastrophic floods in December 2014, events that have been described as the worst in decades. Although there are a number of studies in climate change and extreme rainfall events in Malaysia, there are still large knowledge gaps about their relationship. Understanding the shifts and predicting changing trends in rainfall distribution is needed for predicting and managing the floods. In this paper, Mann Kendall (MK) test and Sen's Slope estimator are employed to determine the trend of extreme rainfall events of various storm durations in the Pahang and Kelantan river basins. The results indicate that annual maximum daily rainfall for Pahang River basin and Kelantan River basin increased throughout 45 years. Results show that the percentage of stations with statistically significant trend (at 0.05 significance level) in the Kelantan River basin are higher compared to the Pahang River basin. Percentage of stations showing increasing trends were much higher for short duration rainfall (10, 30 and 60 minutes and 3 hours) compared to long duration rainfall (6, 12, 24, 48, 120 and 240 hours). This study will be useful for planning, designing and managing floods and stormwater systems in this area

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Trend Analysis of Climatic and Hydrological Variables in the Awash River Basin, Ethiopia

Water ◽

10.3390/w10111554 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1554 ◽

Cited By ~ 10

Author(s):

Mohammed Gedefaw ◽

Hao Wang ◽

Denghua Yan ◽

Xinshan Song ◽

Dengming Yan ◽

...

Keyword(s):

Trend Analysis ◽

River Basin ◽

River Discharge ◽

Statistical Significance ◽

Annual Precipitation ◽

Precipitation Temperature ◽

Modern Agriculture ◽

Mk Test ◽

Awash River Basin ◽

Slope Estimator

The Awash river basin has been the most extensively developed and used river basin in Ethiopia since modern agriculture was introduced. This paper investigated the annual precipitation, temperature, and river discharge variability using the innovative trend analysis method (ITAM), Mann–Kendall (MK) test, and Sen’s slope estimator test. The results showed that the trend of annual precipitation was significantly increasing in Fitche (Z = 0.82) and Gewane (Z = 0.80), whereas the trend in Bui (Z = 69) was slightly decreasing and the trend in Sekoru (Z = 0.45) was sharply decreasing. As far as temperature trends were concerned, a statistically significant increasing trend was observed in Fitche (Z = 3.77), Bui (Z = 4.84), and Gewane (Z = 5.59). However, the trend in Sekoru (Z = 1.37) was decreasing with statistical significance. The discharge in the study basin showed a decreasing trend during the study period. Generally, the increasing and decreasing levels of precipitation, temperature, and discharge across the stations in this study indicate the change in trends. The results of this study could help researchers, policymakers, and water resources managers to understand the variability of precipitation, temperature, and river discharge over the study basin.

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Evaluation and Comparison of Satellite-Derived Estimates of Rainfall in the Diverse Climate and Terrain of Central and Northeastern Ethiopia

Remote Sensing ◽

10.3390/rs13071275 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1275

Author(s):

Girma Berhe Adane ◽

Birtukan Abebe Hirpa ◽

Chul-Hee Lim ◽

Woo-Kyun Lee

Keyword(s):

River Basin ◽

Hydrological Cycle ◽

Rainfall Data ◽

Data Availability ◽

Trend Test ◽

Climate Data ◽

Significance Level ◽

Monotonic Trend ◽

Mk Test ◽

Satellite Rainfall

Understanding rainfall processes as the main driver of the hydrological cycle is important for formulating future water management strategies; however, rainfall data availability is challenging for countries such as Ethiopia. This study aims to evaluate and compare the satellite rainfall estimates (SREs) derived from tropical rainfall measuring mission (TRMM 3B43v7), rainfall estimation from remotely sensed information using artificial neural networks—climate data record (PERSIANN-CDR), merged satellite-gauge rainfall estimate (IMERG), and the Global Satellite Mapping of Precipitation (GSMaP) with ground-observed data over the varied terrain of hydrologically diverse central and northeastern parts of Ethiopia—Awash River Basin (ARB). Areal comparisons were made between SREs and observed rainfall using various categorical indices and statistical evaluation criteria, and a non-parametric Mann–Kendall (MK) trend test was analyzed. The monthly weighted observed rainfall exhibited relatively comparable results with SREs, except for the annual peak rainfall shifts noted in all SREs. The PERSIANN-CDR products showed a decreasing trend in rainfall at elevations greater than 2250 m above sea level in a river basin. This demonstrates that elevation and rainfall regimes may affect satellite rainfall data. On the basis of modified Kling–Gupta Efficiency, the SREs from IMERG v06, TRMM 3B43v7, and PERSIANN-CDR performed well in descending order over the ARB. However, GSMaP showed poor performance except in the upland sub-basin. A high frequency of bias, which led to an overestimation of SREs, was exhibited in TRMM 3B43v7 and PERSIANN-CDR products in the eastern and lower basins. Furthermore, the MK test results of SREs showed that none of the sub-basins exhibited a monotonic trend at 5% significance level except the GSMap rainfall in the upland sub-basin. In ARB, except for the GSMaP, all SREs can be used as alternative options for rainfall frequency-, flood-, and drought-monitoring studies. However, some may require bias corrections to improve the data quality.

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Identification of sibling species in the genus Eucyclops from water-bodies of Ukraine and Russia using crossbreeding studies

Ecology and Noospherology ◽

10.15421/031406 ◽

2014 ◽

Vol 25 (1-2) ◽

pp. 61-68 ◽

Cited By ~ 1

Author(s):

V. I. Monchenko ◽

L. P. Gaponova ◽

V. R. Alekseev

Keyword(s):

Cryptic Species ◽

River Basin ◽

Black Sea ◽

Species Complex ◽

River Basins ◽

Water Bodies ◽

Similar Species ◽

Basin Water ◽

Different Populations ◽

Baltic Sea Basin

Crossbreeding experiments were used to estimate cryptic species in water bodies of Ukraine and Russia because the most useful criterion in species independence is reproductive isolation. The problem of cryptic species in the genus Eucyclops was examined using interpopulation crosses of populations collected from Baltic Sea basin (pond of Strelka river basin) and Black Sea basin (water-reservoires of Dnieper, Dniester and Danube rivers basins). The results of reciprocal crosses in Eucyclops serrulatus-group are shown that E. serrulatus from different populations but from water bodies belonging to the same river basin crossed each others successfully. The interpopulation crosses of E. serrulatus populations collected from different river basins (Dnipro, Danube and Dniester river basins) were sterile. In this group of experiments we assigned evidence of sterility to four categories: 1) incomplete copulation or absence of copulation; 2) nonviable eggs; 3) absence of egg membranes or egg sacs 4) empty egg membranes. These crossbreeding studies suggest the presence of cryptic species in the E. serrulatus inhabiting ecologically different populations in many parts of its range. The same crossbreeding experiments were carries out between Eucyclops serrulatus and morphological similar species – Eucyclops macruroides from Baltic and Black Sea basins. The reciprocal crossings between these two species were sterile. Thus taxonomic heterogeneity among species of genus Eucyclops lower in E. macruroides than in E. serrulatus. The interpopulation crosses of E. macruroides populations collected from distant part of range were fertile. These crossbreeding studies suggest that E. macruroides species complex was evaluated as more stable than E. serrulatus species complex.

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