Changes in water flows and water productivity upon vegetation regeneration on degraded hillslopes in northern Ethiopia: a water balance modelling exercise
Katrien Descheemaeker A B F , Dirk Raes B , Jan Nyssen C , Jean Poesen D , Mitiku Haile E and Jozef Deckers BA Present address: International Water Management Institute (IWMI)/International Livestock Research Institute (ILRI), PO Box 5689, Addis Ababa, Ethiopia.
B Division Soil and Water Management, Katholieke Universiteit Leuven, Celestijnenlaan 200E, BE-3001 Leuven, Belgium.
C Geography Department, Ghent University, Krijgslaan 281 (S8), BE-9000 Gent, Belgium.
D Physical and Regional Geography Research Group, Katholieke Universiteit Leuven, Celestijnenlaan 200E, BE-3001 Leuven, Belgium.
E Department of Land Resource Management and Environmental Protection, Mekelle University, PO Box 231, Mekelle, Ethiopia.
F Corresponding author. Email: k.descheemaeker@cgiar.org
The Rangeland Journal 31(2) 237-249 https://doi.org/10.1071/RJ09010
Submitted: 16 January 2009 Accepted: 18 May 2009 Published: 19 June 2009
Abstract
The establishment of exclosures (i.e. areas closed for grazing and agriculture) is a common practice to reverse land degradation through vegetation regeneration in the semiarid highland areas of northern Ethiopia. In order to assess the effect of exclosures on water flows, the water balance components for different vegetation regeneration stages were assessed through field measurements and modelling. Successful model calibration and validation was done based on soil water content measurements conducted during 2 years in 22 experimental plots. In the protected areas, vegetation regeneration leads to an increase in infiltration and transpiration and a more productive use of water for biomass production. In areas where additional lateral water (runon) infiltrates, source–sink systems are created. Here, up to 30% of the annual rainfall percolates through the root-zone towards the groundwater table. Increased biomass production in exclosures leads to possibilities for wood harvesting and cut and carry of grasses for livestock feeding. Together with water conservation and more productive use of water, the latter contributes to increased livestock water productivity. At the landscape scale, the creation of vegetation filters, capturing resources like water and nutrients, reinforces the rehabilitation process and healthy landscape functioning.
Additional keywords: deep percolation, evapotranspiration, livestock grazing, runoff.
Acknowledgements
The research was conducted within the framework of two VLIR (Flemish Interuniversity Council) funded projects (Zala Daget project and Forest Rehabilitation project) at Mekelle University and sponsored by an FWO-Vlaanderen Aspirant scholarship and travel credit. Katrien Descheemaeker was supported by the Research fund K.U.Leuven and wants to thank IWMI and ILRI for supporting her time spent in revising this paper. The support from Mekelle University and the Faculty of Bioscience Engineering, K.U. Leuven, is greatly appreciated. Furthermore, we want to thank the local Bureau of Agriculture branch, the authorities and exclosure guards of several villages of the Dogu’a Tembien district and Yikuno Teklebirhan, Girmay Hailemariam, Haftu Assefa and Haileselassie Gebremedhin for their field assistance.
Aerts R.,
Maes W.,
November E.,
Behailu M.,
Poesen J.,
Deckers J.,
Hermy M., Muys B.
(2006a) Surface runoff and seed trapping efficiency of shrubs in a regenerating semiarid woodland in northern Ethiopia. Catena 65, 61–70.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 11 May 2009).
Rockström J.,
Jansson P.-E., Barron J.
(1998) Seasonal rainfall partitioning under runon and runoff conditions on sandy soil in Niger. On-farm measurements and water balance modeling. Journal of Hydrology 210, 68–92.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 11 May 2009).
Yayneshet T.,
Eik L. O., Moe S. R.
(2009) The effects of exclosures in restoring degraded semi-arid vegetation in communal grazing lands in northern Ethiopia. Journal of Arid Environments 73, 542–549.
| Crossref | GoogleScholarGoogle Scholar |
