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Assessing gully headcut retreat rates in the semi-arid highlands of northern Ethiopia

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Abstract
In the semi-arid Highlands of North Ethiopia, dense gully and river networks dissect the landscape, with gully depth and width frequently exceeding 5 and 15 m respectively. The magnitude of gully erosion is caused by the topography of steep slopes, which are often depleted from vegetation, offering little resistance to the heavy storms which especially strike during August and early September. Gully erosion has been recognized as a serious problem for sustainable development in the Northern Ethiopian Highlands as it reduces agricultural production through soil loss and aridification, disconnects rural areas, and enhances landscape connectivity for runoff and sediment, causing flooding and water pollution by sediment in down stream areas. To counter soil erosion, soil and water conservation measures are being implemented at a catchment scale. Data on gully headcut retreat rates and changes therein is however non-existent for North Ethiopia. This paper presents gully headcut retreat rates over a period of 1 to 45 years. In the 3 km² large catchment of May Bati, 24 gully headcuts were monitored during the rainy season (July – September) of 2010. In order to understand the retreat rates, data were collected on topography (catchment area, slope gradient), climate (daily rainfall) and the environment (lithology, soil) and land use. In addition, gully headcut retreat rates over a period up to 45 years were assessed by identifying the location of headcuts on aerial photographs and on historical terrestrial photographs, and by localizing the previous and current (2010) position of the headcuts in the field. The results serve as input for testing several empirical models that predict headcut retreat rates based on findings from elsewhere in the world. The 2010 field observations show that many headcuts do not retreat further because of improved land management and that especially Vertisol areas are still prone to rapid gully headcut retreat as the occurrence of piping at the gully headcuts makes them difficult to manage.

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Chicago
Frankl, Amaury, Jean Poesen, Morgan De Dapper, J Deckers, Mitiku Haile, and Jan Nyssen. 2011. “Assessing Gully Headcut Retreat Rates in the Semi-arid Highlands of Northern Ethiopia.” In IAG/AIG Regional Conference 2011 : Geomorphology for Human Adaptation to Changing Tropical Environments, Abstracts, ed. Asfawossen Asrat, Francesco Dramis, Jan Nyssen, and Mohammed Umer, 65–65.
APA
Frankl, A., Poesen, J., De Dapper, M., Deckers, J., Haile, M., & Nyssen, J. (2011). Assessing gully headcut retreat rates in the semi-arid highlands of northern Ethiopia. In A. Asrat, F. Dramis, J. Nyssen, & M. Umer (Eds.), IAG/AIG regional conference 2011 : geomorphology for human adaptation to changing tropical environments, Abstracts (pp. 65–65). Presented at the IAG/AIG Regional Conference 2011 : Geomorphology for Human Adaptation to Changing Tropical Environments.
Vancouver
1.
Frankl A, Poesen J, De Dapper M, Deckers J, Haile M, Nyssen J. Assessing gully headcut retreat rates in the semi-arid highlands of northern Ethiopia. In: Asrat A, Dramis F, Nyssen J, Umer M, editors. IAG/AIG regional conference 2011 : geomorphology for human adaptation to changing tropical environments, Abstracts. 2011. p. 65–65.
MLA
Frankl, Amaury, Jean Poesen, Morgan De Dapper, et al. “Assessing Gully Headcut Retreat Rates in the Semi-arid Highlands of Northern Ethiopia.” IAG/AIG Regional Conference 2011 : Geomorphology for Human Adaptation to Changing Tropical Environments, Abstracts. Ed. Asfawossen Asrat et al. 2011. 65–65. Print.
@inproceedings{1186179,
  abstract     = {In the semi-arid Highlands of North Ethiopia, dense gully and river networks dissect the landscape, with gully depth and width frequently exceeding 5 and 15 m respectively. The magnitude of gully erosion is caused by the topography of steep slopes, which are often depleted from vegetation, offering little resistance to the heavy storms which especially strike during August and early September. Gully erosion has been recognized as a serious problem for sustainable development in the Northern Ethiopian Highlands as it reduces agricultural production through soil loss and aridification, disconnects rural areas, and enhances landscape connectivity for runoff and sediment, causing flooding and water pollution by sediment in down stream areas. To counter soil erosion, soil and water conservation measures are being implemented at a catchment scale. Data on gully headcut retreat rates and changes therein is however non-existent for North Ethiopia. This paper presents gully headcut retreat rates over a period of 1 to 45 years. In the 3 km{\texttwosuperior} large catchment of May Bati, 24 gully headcuts were monitored during the rainy season (July -- September) of 2010. In order to understand the retreat rates, data were collected on topography (catchment area, slope gradient), climate (daily rainfall) and the environment (lithology, soil) and land use. In addition, gully headcut retreat rates over a period up to 45 years were assessed by identifying the location of headcuts on aerial photographs and on historical terrestrial photographs, and by localizing the previous and current (2010) position of the headcuts in the field. The results serve as input for testing several empirical models that predict headcut retreat rates based on findings from elsewhere in the world. The 2010 field observations show that many headcuts do not retreat further because of
improved land management and that especially Vertisol areas are still prone to rapid gully headcut retreat as the occurrence of piping at the gully headcuts makes them difficult to manage.},
  author       = {Frankl, Amaury and Poesen, Jean and De Dapper, Morgan and Deckers, J and Haile, Mitiku and Nyssen, Jan},
  booktitle    = {IAG/AIG regional conference 2011 : geomorphology for human adaptation to changing tropical environments, Abstracts},
  editor       = {Asrat, Asfawossen and Dramis, Francesco and Nyssen, Jan and Umer, Mohammed},
  language     = {eng},
  location     = {Addis Ababa, Ethiopia},
  pages        = {65--65},
  title        = {Assessing gully headcut retreat rates in the semi-arid highlands of northern Ethiopia},
  url          = {http://www.geomorph.org/sp/arch/RCG-ET2011abs.pdf},
  year         = {2011},
}