Assessment of climate change impacts on the hydrology of Gilgel Abay catchment in Lake Tana basin, Ethiopia

Abdo, K. S.; Fiseha, Bm; Rientjes, T.H.M.; Gieske, A.S.M.; Haile, Alemseged Tamiru

doi:10.1002/hyp.7363

Cited by 162 publications

(112 citation statements)

References 19 publications

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“…[15]). In this study calibration is done by using selected Screen Variables and level of the variance in the local predictand of daily precipitation, maximum and minimum temperature of Gondar, Bahir Dar, Debra Tabor, Aykel, Dangila and Adet stations data for the period 1981-2010.…”

Section: Statistical Downscalingmentioning

confidence: 99%

Hydrological Impact Assessment of Climate Change on Lake Tana’s Water Balance, Ethiopia

Nigatu¹,

Rientjes²,

Haile³

2016

AJCC

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The aim of this study is to evaluate the hydrological impacts of climate change on the water balance of Lake Tana in Ethiopia. Impact assessments are by downscaled General Circulation Model (GCM) output and hydrological modeling. For A2 and B2 emission scenarios, precipitation, maximum and minimum temperature estimates from the HadCM3 GCM were used. GCM output was downscaled using the Statistical DownScaling Model (SDSM 4.2). Impact analyses were applied for three future time periods: early, mid and late 21st century. Over-lake evaporation is estimated by Hardgrave's method, and over-lake precipitation is estimated by inverse distance weighing interpolation, whereas inflows from gauged and ungauged catchments are simulated by the HBV hydrological model. Findings indicate increases in maximum and minimum temperature on annual base for both emission scenarios. The projection of mean annual over lake precipitation for both A2 and B2 emission scenarios shows increasing pattern for 21 st century in comparison to the baseline period. The increase of mean annual precipitation for A2 emission scenario is 9% (112 mm/year), 10% (125 mm/year) and 11% (137 mm/year) for the three future periods respectively. B2 emission scenario mean annual precipitation shows increase by 9% (111 mm/year), 10% (122 mm/year) and 10% (130 mm/year) respectively for the three future periods. Findings indicate consistent increases of lake storage for all three future periods for both A2 and B2 emission scenarios.

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Section: Statistical Downscalingmentioning

confidence: 99%

Hydrological Impact Assessment of Climate Change on Lake Tana’s Water Balance, Ethiopia

Nigatu¹,

Rientjes²,

Haile³

2016

AJCC

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“…In the literature, the delimitation of rain events is variable and depends greatly on the subject of study and on the time resolution of the data. According to Brown et al (1985), rain events are a convenient way to dissect a time series into a set of sections, which is useful for specific applications such as the study of runoff (de Vos and Rientjes, 2008;Zhang et al, 2005), soil erosion (Angel et al, 2005), interception losses (Zeng et al, 2000) and the modelling of rainfall (Abdo et al, 2009;Woolhiser and Osborn, 1985). It seems there is not a 'natural' way to separate events, and we can always relate rainfall and runoff without separating events, by comparing the totals of both series or, if available, the yearly or monthly totals.…”

Section: Introductionmentioning

confidence: 99%

Rainfall timing and runoff: The influence of the criterion for rain event separation

Molina-Sanchis

Lázaro

Arnau-Rosalén

et al. 2016

Journal of Hydrology and Hydromechanics

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Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT) is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T 0 ) and three descriptive variables of rain. Our results show that the optimum MIT is 1 hour, which seems to be the minimum period of time required for water in larger macropores to drain and sufficiently modify the effect of antecedent soil moisture on the runoff generation process. Rain events are classified into three significantly different groups: (1) large and intense rains, (2) light rains on wet soil, and (3) light rains on dry soil. Intense rains produce most of the runoff, but there were significant differences between small events in the runoff generated. Of rain events, 63.75% are single-tip events, and many could be dew.

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“…The summer precipitation over the intermediate future period changes by 2.6 and 5.7% as projected by CNCM3 and IPSL GCMs respectively, while a reduction by 5.8% was given by European Centre for medium-range weather forecasts with HAMburg parameterization pachage (ECHAM) GCM projection. Abdo et al (2009) assessed the impact of climate change on the hydrological cycle of the Gilgel Abbay watershed using the Hydrologiska Byrȃns Vattenbalansavdelning Model (HBV) hydrological model and found that precipitation does not manifest a systematic increase or decrease in all future time windows unlike the minimum and maximum temperatures and related evaporations. However, significant changes and variations in seasonal and monthly flows are to be expected for the 2080s the runoff volume in the wet season will be reduced by approximately 11.6 and 10.1% for the A2 and B2 emission scenarios, respectively.…”

Section: Introductionmentioning

confidence: 99%

Assessing Climate Change Impact on Gilgel Abbay and Gumara Watershed Hydrology, the Upper Blue Nile Basin, Ethiopia

Ayele¹,

Li²,

Tung³

et al. 2016

Terr. Atmos. Ocean. Sci.

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Climate change and variability have significant influences on hydrological cycles and the availability of water in the Horn of Africa. Projections of six General Circulation Models (GCMs) in association with high (A2) and low (B1) emission scenarios were adopted in this study from the Special Report on Emission Scenarios (SRES) for the period 2020 -2039 to assess the impacts of climate changes on the Gilgel Abbay and Gumara watershed hydrology, the upper Blue Nile basin, Ethiopia. The GCMs selected were screened in accordance with baseline climate statistics of study areas. A weather generator was employed to generate daily temperature and precipitation to drive the General Water Loading Function (GWLF) hydrological model for simulating runoffs. Projected changes in temperature differences and precipitation ratios relative to the baseline were analyzed to explain the variations in evapotranspiration and the influences on runoff. Despite the fact that the projected magnitude varies among GCMs, increasing runoff in both wet and dry seasons was observed for both watersheds, attributable mainly to the increase in precipitation projected by most GCMs. In contrast to the great increases in runoff, variations in evapotranspiration are less significant. The projected runoff in both watersheds implies increased potential for promoting agricultural irrigation in the dry season. Furthermore, it would allow greater inflow to Lake Tana, the largest contributor to the Ethiopian Renaissance Dam on the Blue Nile. Therefore, concerned local, state, and federal government organizations shall be prepared to harness opportunities from the projected increase in runoff.

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Assessment of climate change impacts on the hydrology of Gilgel Abay catchment in Lake Tana basin, Ethiopia

Cited by 162 publications

References 19 publications

Hydrological Impact Assessment of Climate Change on Lake Tana’s Water Balance, Ethiopia

Hydrological Impact Assessment of Climate Change on Lake Tana’s Water Balance, Ethiopia

Rainfall timing and runoff: The influence of the criterion for rain event separation

Assessing Climate Change Impact on Gilgel Abbay and Gumara Watershed Hydrology, the Upper Blue Nile Basin, Ethiopia

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