Morphological changes of Gumara River channel over 50 years, upper Blue Nile basin, Ethiopia

Abate, Mengiste; Nyssen, Jan; Steenhuis, Tammo S.; Moges, Michael M.; Tilahun, Seifu A.; Enku, Temesgen; Adgo, Enyew

doi:10.1016/j.jhydrol.2015.03.044

Cited by 74 publications

(62 citation statements)

References 60 publications

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“…Anjeni Tilahun et al, 2013bTilahun et al, , 2015 to hundreds of thousands square kilometers (e.g. Blue Nile, 180,000 km 2 ) and showed good performance (Steenhuis et al, 2009;Tilahun et al, 2013a;Tilahun et al, 2015). Comparing the predictions with other models used in the humid Blue Nile basin, PED performs as well or better (see Table S1 with model performance statistics in the supplementary material).…”

Section: Model Selectionmentioning

confidence: 94%

“…It has been applied to catchments ranging from few square kilometers (e.g. Anjeni Tilahun et al, 2013bTilahun et al, , 2015 to hundreds of thousands square kilometers (e.g. Blue Nile, 180,000 km 2 ) and showed good performance (Steenhuis et al, 2009;Tilahun et al, 2013a;Tilahun et al, 2015).…”

Section: Model Selectionmentioning

confidence: 99%

“…Easton et al (2010) and White et al (2011) modified SWAT to include saturation excess runoff which is one of the major runoff mechanisms in the highlands. Water balance approaches have been utilized as well with some success (Conway, 2000;Mishra et al, 2004;Kebede et al, 2006;Steenhuis et al 2009;Rientjes et al, 2011;Tilahun et al 2015).…”

mentioning

confidence: 99%

“…More recently, sediment flows have been simulated in the Blue Nile basin employing various models: SWAT in which sediment predictions are based on MUSLE (Easton et al, 2010;Betrie et al, 2011;Yasir et al, 2014), the modified SWAT-WB Water Balance model (Easton et al, 2010), Parameter efficient model (PED) that is based on the Hairsine and Rose model 25 (Hairsine and Rose, 1992;Steenhuis et al, 2009;Tilahun et al 2013aTilahun et al , 2013bTilahun et al , 2015, WATEM/SEDEM (Haregeweyn et al 2013) and Water Erosion Prediction Project (WEPP) model (Zeleke, 2000).…”

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confidence: 99%

“…Gumara and Rib rivers have a large flood plain area and the additional land formed offshore which is around 0.8 by 3 km (Abate et al, 2015) is comparatively smaller.…”

mentioning

confidence: 99%

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Calculating the sediment budget of a tropical lake in the Blue Nile basin: Lake Tana

Zimale

Mogus

Alemu

et al. 2016

Preprint

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Soil erosion decreases soil fertility of the uplands and causes siltation of lakes and reservoirs. However, very little data exists to quantify accurately the impact of sediment on lakes in tropical monsoonal areas in the African highlands. Lake Tana is one of these lakes in Ethiopia. The objective of this study is to quantify the sediment budget for Lake Tana watershed with limited observational data. To overcome these limitations we use the Parameter Efficient Distributed (PED) model that has shown to perform well in the Ethiopian highlands. PED model parameters are calibrated using daily discharge data and 20 sediment concentration infrequently measured for establishing sediment rating curves for the major rivers. The calibrated model parameters are then used to predict the sediment budget for the period 1994-2009. Sediment retained in the lake is calculated from two bathymetric taken 15 years apart and the sediment leaving the lake is based on measured discharge and observed sediment concentrations. Results show that annually on average 34 Mg/ha/year of sediment is removed from the gauged part of the Lake Tana watersheds. Depending on the up scaling method, 14 to 32 Mg/ha/year is transported from the 25 watershed of which 82% to 96% (with the upper estimate more likely) is trapped on the floodplains and in the lake.

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Section: Model Selectionmentioning

confidence: 94%

Section: Model Selectionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Gumara and Rib rivers have a large flood plain area and the additional land formed offshore which is around 0.8 by 3 km (Abate et al, 2015) is comparatively smaller.…”

mentioning

confidence: 99%

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Calculating the sediment budget of a tropical lake in the Blue Nile basin: Lake Tana

Zimale

Mogus

Alemu

et al. 2016

Preprint

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Retracted: Revisiting lake sediment budgets: how the calculation of lake lifetime is strongly data and method dependent

2017

Earth Surf Processes Landf

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The above article, first published online in Wiley Online Library (wileyonlinelibrary.com), and in Earth Surface Processes and Landforms on 19th February 2017 (10.1002/esp.4111), has been retracted by agreement between theauthors, the journal Editor‐in‐Chief, Stuart Lane, and John Wiley & Sons Ltd.The retraction has been agreed due to calculation errors which could constitute an environmental hazard if not corrected. Since publication of the above article, several colleagues have brought to the attention of the authors that the presented sediment budget is inconsistent with suspended sediment concentrations reported in the same manuscript. This was not picked up during the review or the editing process. The authors have revisited the huge measured dataset on which this paper is based and found indeed a systematic error in calculations of sediment fluxes, as they had been using a wrong constant in conversions from water pressure data recorded every ten minutes and suspended sediment concentration to annual sediment transport rates. This has resulted in an underestimation of sediment transport rates by all rivers by an order of magnitude.The authors apologise for these calculation errors, and, with agreement of all parties, it was decided that the appropriate corrective action is retraction of this paper. A new corrected version will be submitted to the journal. We apologise for any inconvenience the premature publication of this work may have caused our readers. Reference

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Revisiting lake sediment budgets: How the calculation of lake lifetime is strongly data and method dependent

Lemma

Admasu

Dessie

et al. 2017

Earth Surf Processes Landf

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Lake sedimentation has a fundamental impact on lake lifetime. In this paper, we show how sensitive calculation of the latter is to the quality of data available and assumptions made during analysis. Based on the collection of a large new dataset, we quantify the sediment masses (1) mobilized on the hillslopes draining towards Lake Tana (Ethiopia), (2) stored in the floodplains, (3) transported into the lake, (4) deposited in the lake and (5) delivered out from the lake so as to establish a sediment budget. In 2012–2013, suspended sediment concentration (SSC) and discharge measurements were made at 13 monitoring stations, including two lake outlets. Altogether, 4635 SSC samples were collected and sediment rating curves that account for land cover conditions and rainfall seasonality were established for the 11 river stations, and mean monthly SSC was calculated for the outlets. Effects of the floodplain on rivers' sediment yield (SY) were investigated using measurements at both sides of the floodplains. SY from ungauged rivers was assessed using a model that includes catchment area and rainfall, whereas bedload and direct sediment input from lake shores were estimated. As a result, the gross annual SY was c. 39.55 (± 0.15) Mt, dominantly from Gilgel Abay and Gumara Rivers. The 2.57 (± 0.17) Mt sediment deposited in floodplains indicate that the floodplains serve as an important sediment sink. Moreover, annually c. 1.09 Mt of sediment leaves the lake through the two outlets. Annual sediment deposition in the lake was c. 36.97 (± 0.22) Mt and organic matter accumulation was 2.15 Mt, with a mean sediment trapping efficiency of 97%. Furthermore, SSC and SY are generally higher at the beginning of the rainy season because soils in cultivated fields are bare and loose due to frequent ploughing and seedbed preparation. Later in the season, increased crop and vegetation cover lead to a decrease in sediment production. Based on the established sediment budget with average rainfall, the lifetime of Lake Tana was estimated as 764 to 1032 years, which is shorter than what was anticipated in earlier studies. The sedimentation rate of Lake Tana (11.7 ± 0.1 kg m−2 yr−1) is in line with the sedimentation rates of larger lakes in the world, like Lake Dongting and Lake Kivu. Copyright © 2017 John Wiley & Sons, Ltd.

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Morphological changes of Gumara River channel over 50 years, upper Blue Nile basin, Ethiopia

Cited by 74 publications

References 60 publications

Calculating the sediment budget of a tropical lake in the Blue Nile basin: Lake Tana

Calculating the sediment budget of a tropical lake in the Blue Nile basin: Lake Tana

Retracted: Revisiting lake sediment budgets: how the calculation of lake lifetime is strongly data and method dependent

Revisiting lake sediment budgets: How the calculation of lake lifetime is strongly data and method dependent

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