Generation of Monthly Precipitation Under Climate Change for the Upper Blue Nile River Basin, Ethiopia<sup>1</sup>

Kim, Ungtae; Kaluarachchi, Jagath J.; Smakhtin, Vladimir

doi:10.1111/j.1752-1688.2008.00220.x

Cited by 60 publications

(67 citation statements)

References 41 publications

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“…The dry season runs from October to January followed by a short rainy season (called "Belg") from February to May. According to Kim et al (2008), about 70% of the annual precipitation in the study area (UBN basin) is observed during the Kiremt season. The UBN basin receives up to 2,200 mm of annual rainfall.…”

Section: Site Descriptions 30mentioning

confidence: 99%

“…The UBN basin receives up to 2,200 mm of annual rainfall. The annual mean rainfall varies between 1200-1800 mm (Conway, 2000) with an increasing trend from northeast to southwest 10 (Kim et al 2008). However, the basin is characterized by large temporal fluctuations in rainfall (Conway, 2000;Taye and Willems, 2013) both in intra-annual and inter-annual scale.…”

Section: Site Descriptions 30mentioning

confidence: 99%

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Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Ayehu¹,

Tadesse²,

Gessesse³

et al. 2017

Preprint

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Abstract. Accurate measurement of rainfall is vital to analyze the spatial and temporal patterns of precipitation at variousscales. However, the conventional rain gauge observations in many parts of the world such as Ethiopia are sparse and unevenly distributed. An alternative to traditional rain gauge observations could be satellite-based rainfall estimates. Satellite 15 rainfall estimates could be used as a sole product (e.g. in areas with no (poor) ground observations) or through integrating with rain gauge measurements. In this study, the newly available Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data has been evaluated in comparison to rain gauge data for the period of 2000 to 2015 across the Upper Blue Nile basin in Ethiopia. Besides, the Tropical Applications of Meteorology using SATellite and ground-based observations (TAMSAT) version 2 and 3 (TAMSAT 2 and TAMSAT 3) and the African Rainfall Climatology (ARC 2) products have 20 been used as a benchmark and compared with CHIRPS. The TAMSAT 2 rainfall estimate was used in this study mainly to assess the improvements made with the recent version of a TAMSAT product (TAMSAT 3). From the overall analysis at dekadal and monthly temporal scale, CHIRPS exhibited higher skills and the best bias value in comparison to ARC 2 but overestimates the frequency of rainfall occurrence particularly during the dry months. On the other hand, TAMSAT 3 has shown very comparable performance with that of CHIRPS product, particularly with regards to bias. The ARC 2 product 25 was found to have the weakest performance underestimating rainfall amounts by about 24%. The skill of CHIRPS is less affected by variation in elevation in comparison to TAMSAT 3 and ARC 2 products. While ARC 2 was found to be affected by elevation with the average biases of 1.53, 0.86 and 0.77 at lower (< 1000 m a.s.l), medium (1000 to 2000 m a.s.l) and higher elevation (> 2000 m a.s.l), respectively. Comparing the overall performance of the three products, CHIRPS exhibited the best performance followed closely by TAMSAT 3. This validation study also shows that the TAMSAT 3 has overcome 30 the main weaknesses of TAMSAT 2, which is underestimation of high rainfall amounts by up to 31% in this study. Overall, the finding of this validation study shows the potentials of CHIRPS product to be used for various operational applications such as rainfall pattern and variability study in the Upper Blue Nile basin in Ethiopia.Atmos. Meas. Tech. Discuss., https://doi

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Section: Site Descriptions 30mentioning

confidence: 99%

Section: Site Descriptions 30mentioning

confidence: 99%

Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Ayehu¹,

Tadesse²,

Gessesse³

et al. 2017

Preprint

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“…Knowledge on the relations between HBV MPs and the PCCs allows us to estimate MPs for ungauged catchment systems when the PCCs from these catchments are known. To set up a regional model for estimation of model parameters in ungauged catchments, often regression analysis are applied (see Bastola et al, 2008;Heuvelmans et al, 2006;Kim et al, 2008;Xu, 2003;Deckers et al, 2010). Such analysis is selected for this study as well.…”

Section: Establishing the Regional Modelmentioning

confidence: 99%

Regionalisation for lake level simulation – the case of Lake Tana in the Upper Blue Nile, Ethiopia

Rientjes

Perera

Haile

et al. 2011

Hydrol. Earth Syst. Sci.

102

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Abstract. In this study lake levels of Lake Tana are simulated at daily time step by solving the water balance for all inflow and outflow processes. Since nearly 62% of the Lake Tana basin area is ungauged a regionalisation procedure is applied to estimate lake inflows from ungauged catchments. The procedure combines automated multi-objective calibration of a simple conceptual model and multiple regression analyses to establish relations between model parameters and catchment characteristics.A relatively small number of studies are presented on Lake Tana's water balance. In most studies the water balance is solved at monthly time step and the water balance is simply closed by runoff contributions from ungauged catchments. Studies partly relied on simple ad-hoc procedures of area comparison to estimate runoff from ungauged catchments. In this study a regional model is developed that relies on principles of similarity of catchments characteristics. For runoff modelling the HBV-96 model is selected while multiobjective model calibration is by a Monte Carlo procedure. We aim to assess the closure term of Lake Tana's water balance, to assess model parameter uncertainty and to evaluate effectiveness of a multi-objective model calibration approach to make hydrological modeling results more plausible.For the gauged catchments, model performance is assessed by the Nash-Sutcliffe coefficient and Relative Volumetric Error and resulted in satisfactory to good performance for six, large catchments. The regional model is validated and indicated satisfactory to good performance in most Correspondence to: T. H. M. Rientjes (t.h.m.rientjes@utwente.nl) cases. Results show that runoff from ungauged catchments is as large as 527 mm per year for the simulation period and amounts to approximately 30% of Lake Tana stream inflow. Results of daily lake level simulation over the simulation period 1994-2003 show a water balance closure term of 85 mm per year that accounts to 2.7% of the total lake inflow. Lake level simulations are assessed by Nash Sutcliffe (0.91) and Relative Volume Error (2.71%) performance measures.

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“…Understanding climate change and its impact on hydrological variability is important for water management, and thus has received attention from researchers in different parts of the world (e.g. Kim et al, 2008;Ma et al, 2008;Pano et al, 2010;Tekleab et al, 2013;Wang et al, 2013;Zhan et al, 2014;Zhao et al, 2015). These studies investigate how climate change, reflected in changing rainfall patterns, affects the hydrological regimes of river basins.…”

Section: Introductionmentioning

confidence: 99%

Temporal and spatial changes of rainfall and streamflow in the Upper Tekezē–Atbara river basin, Ethiopia

Gebremicael

Mohamed

Zaag

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. The Upper Tekezē-Atbara river sub-basin, part of the Nile Basin, is characterized by high temporal and spatial variability of rainfall and streamflow. In spite of its importance for sustainable water use and food security, the changing patterns of streamflow and its association with climate change is not well understood. This study aims to improve the understanding of the linkages between rainfall and streamflow trends and identify possible drivers of streamflow variabilities in the basin. Trend analyses and changepoint detections of rainfall and streamflow were analysed using Mann-Kendall and Pettitt tests, respectively, using data records for 21 rainfall and 9 streamflow stations. The nature of changes and linkages between rainfall and streamflow were carefully examined for monthly, seasonal and annual flows, as well as indicators of hydrologic alteration (IHA).The trend and change-point analyses found that 19 of the tested 21 rainfall stations did not show statistically significant changes. In contrast, trend analyses on the streamflow showed both significant increasing and decreasing patterns. A decreasing trend in the dry season (October to February), short season (March to May), main rainy season (June to September) and annual totals is dominant in six out of the nine stations. Only one out of nine gauging stations experienced significant increasing flow in the dry and short rainy seasons, attributed to the construction of Tekezē hydropower dam upstream this station in 2009. Overall, streamflow trends and change-point timings were found to be inconsistent among the stations. Changes in streamflow without significant change in rainfall suggests factors other than rainfall drive the change. Most likely the observed changes in streamflow regimes could be due to changes in catchment characteristics of the basin. Further studies are needed to verify and quantify the hydrological changes shown in statistical tests by identifying the physical mechanisms behind those changes. The findings from this study are useful as a prerequisite for studying the effects of catchment management dynamics on the hydrological variabilities in the basin.

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Generation of Monthly Precipitation Under Climate Change for the Upper Blue Nile River Basin, Ethiopia¹

Cited by 60 publications

References 41 publications

Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Regionalisation for lake level simulation – the case of Lake Tana in the Upper Blue Nile, Ethiopia

Temporal and spatial changes of rainfall and streamflow in the Upper Tekezē–Atbara river basin, Ethiopia

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Generation of Monthly Precipitation Under Climate Change for the Upper Blue Nile River Basin, Ethiopia1

Cited by 60 publications

References 41 publications

Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Validation of new satellite rainfall products over the Upper Blue Nile Basin, Ethiopia

Regionalisation for lake level simulation – the case of Lake Tana in the Upper Blue Nile, Ethiopia

Temporal and spatial changes of rainfall and streamflow in the Upper Tekezē–Atbara river basin, Ethiopia

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Generation of Monthly Precipitation Under Climate Change for the Upper Blue Nile River Basin, Ethiopia¹