Trend analysis of runoff and sediment fluxes in the Upper Blue Nile basin: A combined analysis of statistical tests, physically-based models and landuse maps

Gebremicael, Tesfay Gebretsadkan; Mohamed, Yasir A.; Betrie, G.; Zaag, Pieter van der; Teferi, Ermias

doi:10.1016/j.jhydrol.2012.12.023

Cited by 236 publications

(170 citation statements)

References 34 publications

Supporting

Mentioning

148

Contrasting

Order By: Relevance

“…Conway and Hulme (1993) reported declining annual rainfall over the Blue Nile and Atbara basins, resulting in a reduction of river flows between 1945 and 1984. In contrast, recent investigations by Tesemma et al (2010), Tekleab et al (2013) and Gebremicael et al (2013) agreed that rainfall over the Upper Blue Nile Basin did not show a statistically significant trend for the last 40 years . Despite the fact that the pattern of rainfall remained constant, hydrological flows in the basin showed a heterogeneous trend.…”

Section: Introductionmentioning

confidence: 75%

See 1 more Smart Citation

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.

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 75%

“…There are also a number of studies (e.g. Tekleab et al, 2013;Gebremicael et al, 2013;Wang et al, 2015;Hannaford, 2015;Saraiva-Okello et al, 2015) who found that changes in rainfall are not sufficient to explain the trends in the streamflow.…”

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.

View full text Add to dashboard Cite

show abstract

“…a drainage area upstream of the El Diem gaging station) is about 175,000 km 2 as compared to the whole Blue Nile basin area, which is about 325,000 km 2 . Over 95% of the land cover in the basin consists of rain-fed cropland, grassland, wooded grassland, wood land, shrubs and bushes (Gebremicael et al, 2013). The headwater starts at Lake Tana in the Ethiopian highlands, and most of the flow originates from a large number of downstream tributaries.…”

Section: Study Areamentioning

confidence: 99%

“…Second, this basin's local hydrology is less influenced by reservoirs when compared to the lower Blue Nile basin which includes Roseires Dam in Sudan, the White Nile basin which includes Lake Victoria, and the main Nile basin which includes Merowe Dam in Sudan and Aswan Dam in Egypt (FAO, 2011). Also, rain-fed agriculture is more dominant than irrigated cropland in the upper Blue Nile basin (Gebremicael et al, 2013). Therefore, incorporation of reservoir operation rules and irrigation impacts are less important for this regional hydrological modeling system.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Upper Blue Nile basin water budget from a multi-model perspective

Jung

Getirana

Policelli

et al. 2017

Journal of Hydrology

View full text Add to dashboard Cite

a b s t r a c tImproved understanding of the water balance in the Blue Nile is of critical importance because of increasingly frequent hydroclimatic extremes under a changing climate. The intercomparison and evaluation of multiple land surface models (LSMs) associated with different meteorological forcing and precipitation datasets can offer a moderate range of water budget variable estimates. In this context, two LSMs, Noah version 3.3 (Noah3.3) and Catchment LSM version Fortuna 2.5 (CLSMF2.5) coupled with the Hydrological Modeling and Analysis Platform (HyMAP) river routing scheme are used to produce hydrological estimates over the region. The two LSMs were forced with different combinations of two reanalysis-based meteorological datasets from the Modern-Era Retrospective analysis for Research and Applications datasets (i.e., MERRA-Land and MERRA-2) and three observation-based precipitation datasets, generating a total of 16 experiments. Modeled evapotranspiration (ET), streamflow, and terrestrial water storage estimates were evaluated against the Atmosphere-Land Exchange Inverse (ALEXI) ET, insitu streamflow observations, and NASA Gravity Recovery and Climate Experiment (GRACE) products, respectively. Results show that CLSMF2.5 provided better representation of the water budget variables than Noah3.3 in terms of Nash-Sutcliffe coefficient when considering all meteorological forcing datasets and precipitation datasets. The model experiments forced with observation-based products, the Climate Hazards group Infrared Precipitation with Stations (CHIRPS) and the Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA), outperform those run with MERRA-Land and MERRA-2 precipitation. The results presented in this paper would suggest that the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System incorporate CLSMF2.5 and HyMAP routing scheme to better represent the water balance in this region.

show abstract