Assefa, Romha

Deckers, Jozef

Dinssa, Etefa Guyassa

Frankl, Amaury

Gebreslassie, Seifu

Nyssen, Jan

Poesen, Jean

English

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 19, EGU2017-2228, 2017EGU General Assembly 2017© Author(s) 2016. CC Attribution 3.0 License.Boulder-Faced Log Dams and other Alternatives for Gabion Check Damsin First-Order Ephemeral Streams with Coarse Bed Load in EthiopiaJan Nyssen (1), Seifu Gebreslassie (2,3), Romha Assefa (4,5), Jozef Deckers (6), Etefa Guyassa (1,7), JeanPoesen (6), and Amaury Frankl (1)(1) Department of Geography, Ghent University, Gent, Belgium (jan.nyssen@ugent.be), (2) Previously at Selam-WatsaniProject, Dogu’a Tembien, Tigray, Ethiopia, (3) Current address: EthioTrees Project, Dogu’a Tembien, Tigray, Ethiopia, (4)Previously at Ma’ar Project, Dogu’a Tembien, Tigray, Ethiopia, (5) Current address: Relief Society of Tigray, Mekelle,Ethiopia, (6) Department of Earth and Environmental Sciences, KULeuven, Leuven, Belgium, (7) Department of LandResources Management and Environmental Protection, Mekelle University, Mekelle, EthiopiaMany thousands of gabion check dams have been installed to control gully erosion in Ethiopia, but several chal-lenges still remain, such as the issue of gabion failure in ephemeral streams with coarse bed load, that abrades atthe chute step. As an alternative for gabion check dams in torrents with coarse bed load, boulder-faced log damswere conceived, installed transversally across torrents and tested (n = 30). For this, logs (22-35 cm across) wereembedded in the banks of torrents, 0.5-1 m above the bed and their upstream sides were faced with boulders (0.3-0.7 m across). Similar to gabion check dams, boulder-faced log dams lead to temporary ponding, spreading ofpeak flow over the entire channel width and sediment deposition. Results of testing under extreme flow conditions(including two storms with return periods of 5.6 and 7 years) show that 18 dams resisted strong floods. Beyondcertain flood thresholds, represented by proxies such as Strahler’s stream order, catchment area, D95 or channelwidth), 11 log dams were completely destroyed. Smallholder farmers see much potential in this type of structureto control first-order torrents with coarse bed load, since the technique is cost-effective and can be easily installed.

Boulder-faced log dams and other alternatives for gabion check dams in first-order ephemeral streams with coarse bed load in Ethiopia

https://biblio.ugent.be/publication/8519012/file/8519013

Boulder-faced log dams and other alternatives for gabion check dams in first-order ephemeral streams with coarse bed load in Ethiopia

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Ghent University Academic Bibliography