Your search found 19 records
1 Steenhuis, T. S.; Easton, Z. M.; Awulachew, Seleshi Bekele; Ahmed, A. A.; Bashar, K. E.; Adgo, E.; Selassie, Y. G.; Tilahun, S. A. 2012. The Nile Basin sediment loss and degradation, with emphasis on the Blue Nile. In Awulachew, Seleshi Bekele; Smakhtin, Vladimir; Molden, David; Peden D. (Eds.). The Nile River Basin: water, agriculture, governance and livelihoods. Abingdon, UK: Routledge - Earthscan. pp.112-132.
River basins ; Sedimentation ; Sediment pollution ; Runoff ; Highlands ; Gully erosion ; Simulation models ; Reservoirs ; Watersheds ; Assessment ; Water balance ; Spatial distribution / Africa / Nile River Basin / Blue Nile River Basin
(Location: IWMI HQ Call no: IWMI Record No: H045314)
(1.40MB)
2 Selvi, V.; Singh, D. V.; Mohanraj, R. 2013. Status of water resources and water harvesting systems in the Nilgiris [India]. In Palanisami, Kuppannan; Sharda, V. N.; Singh, D. V. (Eds.). Water management in the hill regions: evidence from field studies. [Outcome of the IWMI and ICAR Workshop organized by IWMI-TATA Water Policy Research Program]. New Delhi, India: Bloomsbury Publishing India. pp.25-42.
Water resources ; Water harvesting ; Technology ; Rain ; Runoff ; Water balance ; Crop production ; Cropping patterns ; Land use ; Gully erosion ; Water power ; Sedimentation ; Reservoirs ; Watersheds ; Wells ; Dams ; Tanks ; Ponds / India / Tamil Nadu / Nilgiris
(Location: IWMI HQ Call no: 333.91 G635 PAL Record No: H045726)
3 Addisie, M. B.; Ayele, G. K.; Gessess, A. A.; Tilahun, S. A.; Moges, M. M.; Schmitter, Petra S.; Steenhuis, T. S. 2015. Hydro-geomorphological features at gully heads in the humid northern Ethiopian Highlands, Birr Watershed. Paper presented at the 3rd International Conference on the Advancements of Science and Technology [ICAST], Bahir Dar, Ethiopia, 8-9 May 2015. 7p.
Hydrogeology ; Geomorphology ; Morphology ; Humid zones ; Highlands ; Watersheds ; Water table ; Soil properties ; Gully erosion ; Landscape ; Case studies / Ethiopia / Ethiopian Highlands / Birr Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047312)
(0.36 MB)
The study was conducted in the Birr watershed at twelve gully heads located close to each other. The survey includes measurements of morphological features, soil properties, water table elevations and catchment characteristics including erosion at each gully head. The analysis showed that gully head morphology could be explained by the role of different gully head controlling factors. The result suggested the maximum rate of head cut retreat reaches from 0 to 22.5m. There was no head retreat recorded from the arrested heads relative to unprotected heads. Compared to semiarid highlands of northern Ethiopia, the average short term head cut retreat was 12 fold greater. From the direct shear test, angle of internal friction by far greater than the slope of gully heads which are located at flat lands. The width depth ratio showed that the shallow depth heads were controlled by fluvial erosion whereas for the deep gully heads both fluvial and mass wasting due tension cracks are operating. In this study a significant power relationship established between the volume of the gully head and the length of retreat at the active gullies with V = 4.85 L1.05 (R2 = 0.91 and P= 0.042) which is different from the relation obtained from the entire gully system as a result of varies controlling factors.
4 Addisie, M. B.; Ayele, G. K.; Gessesse, A. A.; Tilahun, S. A.; Zegeye, A. D.; Moges, M.; Schmitter, Petra; Langendoen, E. J.; Steenhuis, T. S. 2015. Reducing surface and subsurface water flow effect on gullies through low cost measures [Abstract only] Paper presented at the 10th Alexander von Humboldt Conference 2015 on Water-Food-Energy River and Society in the Tropics. EGU Topical Conference Series, Addis Ababa, Ethiopia, 18-20 November 2015. 1p.
Surface water ; Groundwater ; Flow discharge ; Gully erosion ; Erosion control ; Watersheds ; Water table ; Cost analysis ; Soil properties ; Case studies / Ethiopia / Amhara State / Birr Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047331)
(0.04 MB)
Gully erosion in the humid Ethiopian highlands intensified in recent decades. The study was conducted in the Birr watershed located south west of Bahir Dar the capital of Amhara regional state, Ethiopia. We studied 14 gullies having similar morphology at three sub watersheds. The watershed covers a total area of 414 ha. The monitoring continued over the 2013 to 2014 monsoon season to better understand the factors controlling gully erosion and the effectiveness of erosion control structures. Perched ground water table was measured at the gully heads and erosion pins were installed to monitor the rate of recession from uncontrolled heads. Though soil properties, ground cover, gully morphology had small contribution for the gully development; water fall effect at the head of the gully and elevated water table depth at both heads and banks played the key role. Therefore the study focused on reducing the water fall and elevated water table effect by applying two low cost gully control approaches. The first approach was regrading the gully heads and banks at 45o and the second approach follows regrading the gully heads at 45o and putting a graded type of stone rip rap. Large stones were anchored at the toe of the head maintaining the stable gully bed slope. The result shows that unprotected gully heads retreat an average of 4m which is equivalent to 37m3 volume of soil loss. The maximum and minimum head cut retreat was between 0 and 22.5m. The total area damaged by annual gully head retreat was 240m2 and total volume of soil lost was 444m3. The treated gully heads did not show any retreat during the monitoring period. Compared with simple reshaping of gully heads, integration with Stone rip rap was an effective and low cost measure in the study watershed. Plantation could not stop the upslope migration of heads though it had the potential to trap sediments down slope. Heads with stone rip rap allows fast re vegetation whereas unprotected reshaped heads and banks took longer time to re vegetate and stabilized. Time of reshaping was important for the stability of banks and heads.
5 Dagnew, D.; Guzman, C.; Zegeye, A.; Tebebu, T.; Akal, A.; Mekuria, Wolde; Ayana, E.; Tilahun, S.; Steenhuis, T. 2015. Effectiveness and sustainability of large scale soil and water conservation interventions in the sub-humid Ethiopian highlands: evidence from Debre Mawi watershed [Abstract only] Paper presented at the 10th Alexander von Humboldt Conference 2015 on Water-Food-Energy River and Society in the Tropics. EGU Topical Conference Series, Addis Ababa, Ethiopia, 18-20 November 2015. 1p.
Soil conservation ; Water conservation ; Humid climate ; Watersheds ; Highlands ; Sustainability ; Runoff ; Gully erosion ; Sediment / Ethiopia / Ethiopian Highlands / Debre Mawi Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047343)
http://meetingorganizer.copernicus.org/AvH10/AvH10-18-2.pdf
https://vlibrary.iwmi.org/pdf/H047343.pdf
https://vlibrary.iwmi.org/pdf/H047343.pdf
(0.04 MB) (39.04 KB)
Using measured runoff and sediment monitoring, the effectiveness of large scale soil and water conservation (SWC) implementations are analyzed from a five year (2010-2014) study, in the 95 ha Debre Mawi watershed and four nested sub-watersheds. Under the large scale government led SWC program, terraces with infiltration furrows were installed in 2012. The results indicate that runoff, sediment loads and sediment yields decreased significantly after the implementation of SWC practices. Sediment loads were reduced mainly because of the reduced runoff. Though sediment concentration decreased in the sub-watersheds, it decreased only marginally for the main watershed because of the entrainment of loose soil from the collapse of unstable banks of gullies. Infiltration furrows were effective in collecting runoff and suspended sediment (from rills) on the hillsides where Nitisols dominate (very deep, well-drained, permeable soils where rain water could infiltrate easily). But, on the saturated flat bottom lands and fields dominated by vertisols (that form wide-deep cracks during the dry season and swell during the rainy season), infiltration was restricted and conservation practices became conduits for carrying excess rainfall. Our continuous observations and photo monitoring of bunds on Nitisols and saturated bottomlands indicate that installing soil bunds on these areas caused the collapse of soil bunds in to the furrows. The soil from the collapsed bund is then easily washed away in a concentrated runoff and further initiated gullies in the Debre Mawi watershed. Large scale soil and water conservation interventions have short term effectiveness of reducing runoff and sediment loads. However, long term benefits can only be sustained with continuous maintenance of uphill infiltration furrows, as most ditches are filled up with sediments within two-three years. In addition, large scale soil and water conservation interventions should give priority to gully treatments, should consider local soil types and saturation dynamics to install bunds in the sub-humid Ethiopian highlands.
6 Addisie, M. B.; Ayele, G. K.; Gessess, A. A.; Tilahun, S. A.; Zegeye, A. D.; Moges, M. M. [NARS]; Schmitter, Petra; Langendoen, E. J.; Steenhuis, T. S. 2015. Hydrological and morphological factors at gully heads in the humid northern Ethiopian Highlands, Birr watershed [Abstract only] In Nyssen J., Enyew A., Poesen J et al. (Eds.). International Conference on Tropical Lakes in a Changing Environment: Water, Land, Biology, Climate and Humans (TropiLakes), Bahir Dar, Ethiopia, 23-29 September 2015. Book of Abstracts. Bahir Dar, Ethiopia: Bahir Dar University. pp.72.
Hydrological factors ; Gully erosion ; Humid climate ; Water table ; Watersheds ; Highlands ; Soils / Ethiopia / Birr Watershed / Ethiopian Highlands
(Location: IWMI HQ Call no: e-copy only Record No: H047416)
(0.10 MB)
In the Ethiopian highlands, gully erosion is severe. Although attempts to prevent gullying, it remains a challenge. Our objectives are to understand better the processes that control gully head cut retreat. The study was conducted in Birr watershed located at South West of Bahir Dar, Ethiopia. Twelve gully heads were selected and monitored from July to October, 2014. We measured gully head morphology, length of recession via pegging technique, soil analysis to determine soil shear strength, physical and chemical properties, water table elevations and catchment physical characteristics. Two active gully head cuts were arrested with stone riprap after regarding at 450. The result shows that the maximum rate of head cut retreat was between 0 to 22.5m. There was no head retreat observed from the protected heads compared with unprotected heads. The average short term head cut retreat was much greater than that observed in semiarid highlands of northern Ethiopia. The greater gulley rate of recession in the humid monsoon climate is likely caused by the water table that was above the gully bottom. In August when the soil became saturated, about 45% of head cut migration occurred. Thus the water table contributed to the slumping of gully heads and weakened the strength of the soil cohesion. The soil shear strength test result shows, angle of internal friction was by far greater than the slope of gully heads where heads are located in the periodically saturated flat lands. The width depth ratio showed that the shallow depth heads were controlled by fluvial erosion whereas for the deep gully heads both fluvial and mass wasting due to tension cracks was the main driving force. Both the water table control and protecting the head cuts of shallow gullies plays a key role in reducing the sediment contribution of gully in the humid Ethiopian highlands.
7 Addisie, M. B.; Ayele, G. K.; Gessesse, A. A.; Tilahun, S. A.; Moges, M. M.; Zegeye, A. D.; Mekuria, Wolde; Schmitter, Petra; Langendoen, E. J.; Steenhuis, T. S. 2016. Rehabilitating gullies with low cost methods, in the sub humid Ethiopian highlands. Paper presented at the International Conference of the Advancement of Science and Technology, Bahir Dar, Ethiopia, 17-18 July 2016. 10p.
Gully erosion ; Humid zones ; Highlands ; Environmental degradation ; Ecosystems ; Watersheds ; Riverbank protection ; Vegetation ; Plantations ; Sedimentation
(Location: IWMI HQ Call no: e-copy only Record No: H047636)
(691 KB)
Gully erosion in the highlands of Ethiopia has reduced agricultural productivity and degraded ecosystem services. To better understand the processes controlling gully erosion and design effective control measures, a study was conducted in the headwaters of the Birr watershed for three consecutive years (2013-2015). Fourteen gullies with similar morphology were studied in three adjacent sub-watersheds. Stabilization measures were applied to 5 of the 14 gully heads. Three gully control measures were compared: a) reshaping gully banks and head to a 45 degree slope with stone rip rap on the gully heads, b) controlling gully bed grade, and c) planting grasses and trees on shallow gullies (i.e., < 3 m deep). Results demonstrated that gully control measures were effective in controlling the expansion of gullies as no further retreat was observed for the 5 treated gully heads, whereas the average retreat was 3 meters with a maximum of 22.5 m for the 9 untreated gullies. The migration of untreated gully heads produced an average soil loss of 38 tons per gully. Compared with simple reshaping of gully heads, the additional integration with stone rip rap was an effective and low cost measure. Vegetative treatment by itself could not stop the upslope migration of gully heads, though it had the potential to trap sediments. Re-vegetation at gully heads stabilized with stone rip rap occurred faster than at unprotected, reshaped heads and banks. From the fourteen rehabilitation treatments, gully head protection integrated with plantation showed the largest potential in decreasing gully development in terms of labor, time and material it requires.
8 Dagnew, D. C.; Guzman, C. D.; Zegeye, A. D.; Akal, A. T.; Moges, M. A.; Tebebu, T. Y.; Mekuria, Wolde; Ayana, E. K.; Tilahun, S. A.; Steenhuis, T. S. 2017. Sediment loss patterns in the sub-humid Ethiopian Highlands. Land Degradation and Development, 28(6):1795-1805. [doi: https://doi.org/10.1002/ldr.2643]
Sediment ; Erosion ; Gully erosion ; Humid zones ; Highlands ; Watersheds ; Catchment areas ; Rainfall-runoff relationships ; Infiltration ; Precipitation / Ethiopia / Debre Mawi Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H047878)
Controlling soil erosion is important for maintaining land productivity and reducing sedimentation of reservoirs in the Ethiopian highlands. To gain insights on sediment loss patterns, magnitude of peak sediment events, and their contribution to annual loads, hydrometric and sediment concentration data were collected for five years (2010 – 2014) from the 95 ha Debre Mawi and four nested catchments (located 30 km south of Lake Tana). Soil and water conservation practices (SWCPs) consisting of soil bunds with 50 cm deep furrows were implemented in the third year, which made it possible to examine the effects of SWCPs on peak sediment loads. The results show that a 10-minute event causes soil loss of up to 11.4 Mg ha-1, which is 22% of the annual sediment yield. Thirty to seventy-five percent (up to 30 Mg ha-1day-1) of the sediment yield was contributed by the greatest daily flow in each year. The contribution increases to 86% for the two largest daily flows. SWCP interventions reduced sediment loss by half but did not affect the relative contribution of peak events to annual loads. Due to gully erosion, peak sediment loads at the outlet of the entire catchment were greater (up to 30 Mg ha-1day-1) as compared to the nested catchments without gullies (0.5 to 8 Mg ha-1day-1). Consequently, to reduce sediment loss, conservation measures should be designed to decrease runoff during large storms. This can be attained by deepening furrows on unsaturated hillsides and reducing the entrainment of unconsolidated sediment from failed gully banks.
9 Anwar A. A.; Aynalem, D. W.; Tilahun, S. A.; Mekuria, Wolde; Azeze, M.; Steenhuis, T. S. 2016. Effectiveness of land and water management interventions in reducing runoff and soil erosion in the northwestern highlands of Ethiopian [Abstract only] Paper presented at the First African ESP [Ecosystem Services Partnership] Conference, Nairobi, Kenya, 21-25 November 2016. 1p.
Ecosystem services ; Land management ; Landscape ; Land degradation ; Water management ; Soil fertility ; Nutrients ; Erosion ; Gully erosion ; Runoff ; Highlands ; Watersheds ; Downstream ; Upstream ; Cultivated land ; Grasslands ; Sediment / Ethiopia
(Location: IWMI HQ Call no: e-copy only Record No: H047882)
(64.9 KB)
10 Gebregziabher, Gebrehaweria; Abera, D. A.; Gebresamuel, G.; Giordano, Meredith; Langan, Simon. 2016. An assessment of integrated watershed management in Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 28p. (IWMI Working Paper 170) [doi: https://doi.org/10.5337/2016.214]
Integrated management ; Watershed management ; Erosion ; Soil texture ; Soil fertility ; Gully erosion ; Vegetation ; Biodiversity ; Land productivity ; Grazing lands ; Cultivated land ; Surface water ; Groundwater recharge ; Water availability ; Rainwater ; Water harvesting ; Downstream ; Upstream ; Crop production ; Livestock production ; Socioeconomic environment ; Farm income ; Farmers ; Smallholders ; Resource management ; Living standards ; Community involvement ; Sedimentation ; Institutions / Ethiopia
(Location: IWMI HQ Call no: IWMI Record No: H047915)
(2 MB)
Sustainable participatory watershed management is an approach promoted by the Ethiopian government to restore natural resources and agricultural productivity across the country. This comparative study between six watershed programs shows that this approach increases farmers’ food security and incomes (around 50% on average), as well as their resilience to drought and other climate shocks. However, the study also confirms that the nature and scale of impact can vary significantly between watershed programs. The success of watershed management depends on multiple factors from the hydrological profile of the watershed to the local social and economic environment. Tailoring watershed interventions to the local context, associating conservation and livelihoods activities, and providing further financial and technical support to watershed committees are among the recommendations of this paper.
11 Tamene, L.; Adimassu, Zenebe; Ellison, J.; Yaekob, D.; Woldearegay, K.; Mekonnen, K.; Thorne, P.; Bao Le, Q. 2017. Mapping soil erosion hotspots and assessing the potential impacts of land management practices in the highlands of Ethiopia. Geomorphology, 292:153-163. [doi: https://doi.org/10.1016/j.geomorph.2017.04.038]
Land management ; Land degradation ; Highlands ; Soils ; Erosion ; Sediment transport ; Erosion control ; Models ; Participatory approaches ; Soil conservation ; Water conservation ; Slopes ; Gully erosion ; Cultivated land ; Grazing lands ; Spatial distribution / Ethiopia / Basona District
(Location: IWMI HQ Call no: e-copy only Record No: H048134)
An enormous effort is underway in Ethiopia to address soil erosion and restore overall land productivity. Modelling and participatory approaches can be used to delineate erosion hotspots, plan site- and context-specific interventions and assess their impacts. In this study, we employed a modelling interface developed based on the Revised Universal Soil Loss Equation adjusted by the sediment delivery ratio to map the spatial distribution of net soil loss and identify priority areas of intervention. Using the modelling interface, we also simulated the potential impacts of different soil and water conservation measures in reducing net soil loss. Model predictions showed that net soil loss in the study area ranges between 0.4 and 88 t ha- 1 yr- 1 with an average of 12 t ha- 1 yr- 1. The dominant soil erosion hotspots were associated with steep slopes, gullies, communal grazing and cultivated areas. The average soil loss observed in this study is higher than the tolerable soil loss rate estimated for the highland of Ethiopia. The scenario analysis results showed that targeting hotspot areas where soil loss exceeds 10 t ha- 1 yr- 1 could reduce net soil loss to the tolerable limit (< 2 t ha- 1 yr- 1). The spatial distribution of soil loss and the sediment yield reduction potential of different options provided essential information to guide prioritization and targeting. In addition, the results can help promoting awareness within the local community of the severity of the soil erosion problem and the potential of management interventions. Future work should include cost-benefit and tradeoff analyses of the various management options for achieving a given level of erosion reduction.
12 Addisie, M. B.; Ayele, G. K.; Gessess, A. A.; Tilahun, S. A.; Zegeye, A. D.; Moges, M. M.; Schmitter, Petra; Langendoen, E. J.; Steenhuis, T. S. 2017. Gully head retreat in the sub-humid Ethiopian Highlands: the Ene-Chilala Catchment. Land Degradation and Development, 28(5):1579-1588. [doi: https://doi.org/10.1002/ldr.2688]
Gully erosion ; Erosion control ; Humid zones ; Highlands ; Catchment areas ; Sedimentation ; Wet season ; Monitoring ; Soil texture / East Africa / Ethiopia / Ene-Chilala Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H048152)
In the northern highlands of Ethiopia, gully erosion is severe. Despite many efforts to implement gully prevention measures, controlling gully erosion remains a challenge. The objective is to better understand the regional gully erosion processes and to prevent gully head retreat. The study was conducted in the Ene-Chilala catchment in the sub-humid headwaters of the Birr River located southwest of Bahir Dar, Ethiopia. Twelve gully heads were monitored during the 2014 and 2015 rainy monsoon phase. We measured gully head morphology and retreat length, soil shear strength, ground water table levels, and catchment physical characteristics. Two active gully head cuts were treated in 2014 and an additional three head cuts in 2015 by regrading their slope to 45° and covering them with stone riprap. These treatments halted the gully head advance. The untreated gullies were actively eroding due to groundwater at shallow depths. The largest head retreat was 22.5 m, of which about half occurred in August of the first year when the surrounding soil was fully saturated. Lowering both the water table and protecting the gully heads can play a key role in reducing gully expansion and soil loss due to gully erosion in the Ethiopian highlands.
13 Akale, A. T.; Dagnew, D. C.; Belete, M. A.; Tilahun, S. A.; Mekuria, Wolde; Steenhuis, T. S. 2017. Impact of soil depth and topography on the effectiveness of conservation practices on discharge and soil loss in the Ethiopian Highlands. Land, 6(4):1-17. [doi: https://doi.org/10.3390/land6040078]
Soil depth ; Soil conservation ; Slope ; Water conservation ; Gully erosion ; Runoff ; Discharges ; Sediment ; Highlands ; Agricultural production ; Watersheds ; Infiltration ; Wet season ; Land degradation / East Africa / Ethiopia / Blue Nile River Basin / Lake Tana
(Location: IWMI HQ Call no: e-copy only Record No: H048458)
(6.09 MB)
Restoration of degraded landscapes through the implementation of soil and water conservation practices is considered a viable option to increase agricultural production by enhancing ecosystems. However, in the humid Ethiopian highlands, little information is available on the impact of conservation practices despite wide scale implementation. The objective of this research was to document the effect of conservation practices on discharge and sediment concentration and load in watersheds that have different soil depths and topography. Precipitation, discharge, and sediment concentration were measured from 2010 to 2012 in two watersheds in close proximity and located in the Lake Tana basin, Ethiopia: Tikur-Wuha and Guale watersheds. The Tikur-Wuha watershed has deep soils and a gentle slope stream channel. The Guale watershed has shallow soils and a steep slope stream channel. In early 2011, the local community installed upland conservation measures consisting of stone and soil bunds, waterways, cutoff drains, infiltration furrows, gully rehabilitation, and enclosures. The results show that conservation practices marginally decreased direct runoff in both watersheds and increased base flow in the Tikur-Wuha watershed. Average sediment concentration decreased by 81% in Tikur-Wuha and 45% in Guale. The practices intended to increase infiltration were most effective in the Tikur-Wuha watershed because the deep soil could store the infiltrated water and release it over a longer period of time after the rainy season than the steeper Guale watershed with shallow soils.
14 Zegeye, A. D.; Steenhuis, T. S.; Mekuria, Wolde; Dagnaw, D. C.; Addisse, M. B.; Tilahun, S. A.; Kasse, T. A. 2017. Effect of gully headcut treatment on sediment load and gully expansion in the sub humid Ethiopian Highlands. Environment and Ecology Research, 5(2):138-144. [doi: https://doi.org/10.13189/eer.2017.050208]
Gully erosion ; Sedimentation ; Humid zones ; Highlands ; River banks ; Lakes ; Soil conservation ; Water conservation ; Water resources ; Watershed management ; Concentrating / East Africa / Ethiopia / Ethiopian Highlands / Lake Tana
(Location: IWMI HQ Call no: e-copy only Record No: H048461)
The Ethiopian government has been implementing a land restoration program that aimed to restore degraded ecosystems and double agricultural productivity throughout the country since 2010. However, the success of the restoration program has been limited due to the lack of integrating gully erosion control measures. Consequently, many reservoirs in Ethiopia and downstream riparian countries have lost their storage capacity due to sedimentation, and studies demonstrated that gully erosion is one of the degradation hotspots within watersheds and contribute considerable proportion of the total sediment loads from a particular watershed. This study was conducted in one of large gullies in the Debre-Mawi watershed, northwestern Ethiopia to quantify the effect of gully head treatment in reducing the amount of sediment load generated from uplands and from the gully itself. We measured discharge, and sediment load and concentration in 2013 and 2014 at the upstream (inlet) and downstream ends (outlet) of the studied gully. Before the 2014 rainy phase, a gully headcut was stabilized with gabions at the bed and the gully bank was regarded to 45o. The gully head retreated 12 m in 2013 but gully head retreat was stopped following the implementation of the treatment in 2014. The total sediment load and sediment concentration at the outlet was reduced by 42% and 30% respectively, in 2014 (i.e., after treatment) when compared to 2013 (i.e., before treatment). The result of this study support that controlling the upward retreat of gully head is effective in reducing sediment load and concentration as well as upward movement and expansion of gullies. However, maintenance of gully head control measures is the key to sustain the benefits.
15 Adimassu, Zenebe; Langan, Simon; Barron, Jennie. 2018. Highlights of soil and water conservation investments in four regions of Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 35p. (IWMI Working Paper 182) [doi: https://doi.org/10.5337/2018.214]
Soil conservation ; Water conservation ; Waterways ; Financing ; Investment ; Land degradation ; Land productivity ; Land management ; Landscape ; Farmland ; Farm management ; Hillside operations ; Sloping land ; Gully erosion ; Runoff ; Rural areas ; Rural communities ; Living standards ; Farmers ; Terraces ; Watershed management ; Dam construction ; Environmental monitoring ; Sediment ; Capacity building ; Nongovernmental organizations / Ethiopia
(Location: IWMI HQ Call no: IWMI Record No: H048867)
(1 MB)
This paper provides details of soil and water conservation (SWC) investments in Ethiopia over the past 20 years. It presents SWC practices and estimates the level of SWC investments in different regions. The paper focuses on four principal agricultural regions: Amhara, Oromia, SNNPR and Tigray. Primary and secondary data were collected for the analysis, and consultations were conducted at regional levels. Primary data on diverse SWC practices, their numbers and areal extent were obtained from the archives of regional Bureaus of Agriculture (BoAs). The results of this study show that several projects involving significant financial investment have been implemented to reverse land degradation and improve land productivity in Ethiopia since the 1970s. The list of projects is not comprehensive due to a lack of documentation at all levels, but it does provide some insights into the scale of SWC investments and implementation. The projects analyzed in the four regions fall into the following categories: farmland management, hillside management and gully rehabilitation practices, including check dams and cut-off drains. The analysis shows that these practices involved both paid and unpaid labor, together representing an estimated investment of more than ETB 25 billion (or approximately USD 1.2 billion) per year over the past 10 years. It is clear that large investments have been made in SWC activities in Ethiopia. However, the outcomes in terms of impact on yield and livelihood benefits are yet to be fully understood. A comprehensive assessment is needed to measure the impact of SWC activities on farmers’ livelihoods and the environment. A key recommendation arising from the analysis is that more data and information are needed on the successes and failures of SWC practices, which will assist stakeholders to better guide and target future projects and investments. An additional recommendation is to consider the biophysical and financial impact of soil erosion, both on and off farm.
16 Addisie, M. B.; Langendoen, E. J.; Aynalem, D. W.; Ayele, G. K.; Tilahun, S. A.; Schmitter, Petra; Mekuria, Wolde; Moges, M. M.; Steenhuis, T. S. 2018. Assessment of practices for controlling shallow valley-bottom gullies in the sub-humid Ethiopian Highlands. Water, 10(4):1-15.
Gully erosion ; Assessment ; Best practices ; Rehabilitation ; Sediment ; Highlands ; Valleys ; Vegetation ; Slope ; Farmers ; Watersheds ; Dams ; Grasses ; Soil conservation ; Water conservation / Africa / Ethiopia / Ethiopian Highlands
(Location: IWMI HQ Call no: e-copy only Record No: H048964)
Rehabilitation of large valley bottom gullies in developing countries is hampered by high cost. Stopping head cuts at the time of initiation will prevent large gullies from forming and is affordable. However, research on practices to control shallow gully heads with local materials is limited. The objective of this research was therefore to identify cost-effective shallow gully head stabilization practices. The four-year study was conducted on 14 shallow gullies (<3 m deep) in the central Ethiopian highlands. Six gullies were used as a control. Heads in the remaining eight gullies were regraded to a 1:1 slope. Additional practices implemented were adding either riprap or vegetation or both on the regraded heads and stabilizing the gully bed downstream. Gully heads were enclosed by fencing to prohibit cattle access to the planted vegetation. The median yearly head retreat of the control gullies was 3.6 m a-1 with a maximum of 23 m a-1. Vegetative treatments without riprap prevented gully incision by trapping sediments but did not stop the upslope retreat. The gully heads protected by riprap did not erode. Regrading the slope and adding riprap was most effective in controlling gully head retreat, and with hay grown on the fenced-in areas around the practice, it was profitable for farmers.
17 Zegeye, A. D.; Langendoen, E. J.; Steenhuis, T. S.; Mekuria, Wolde; Tilahun, S. A. 2020. Bank stability and toe erosion model as a decision tool for gully bank stabilization in sub humid Ethiopian highlands. Ecohydrology and Hydrobiology, 20(2):301-311. [doi: https://doi.org/10.1016/j.ecohyd.2020.02.003]
Gully erosion ; Erosion control ; Models ; Soil loss ; Soil stabilization ; Subhumid zones ; Highlands ; Watersheds ; Groundwater table ; Runoff ; Vegetation / Ethiopia / Blue Nile Basin / Debre Mawi Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H049936)
(2.29 MB)
Gullies that are expanding at alarming rate are responsible for the majority of soil losses in the (sub) humid highlands of Ethiopia. Few affordable and effective methods for gully erosion control are available in the highlands. The objective of the study was to develop cost-effective measures to halt gully expansion by determining stable-bank conditions under a variety of environmental situations using the Bank Stability and Toe Erosion Model (BSTEM). The study was carried out in the sub humid Debre Mawi watershed, located 30 km south of Lake Tana. Input data for the BSTEM model were collected using field surveys and soil sampling. After the BSTEM was tested on actual measured soil data, soil cohesion and internal friction angle were calibrated against observed gully bank retreat. Using the calibrated parameters, the model evaluated the stabilization of the existing gully bank under different scenarios in which groundwater table, bank angle and bank height, tension crack depth, vegetation, and toe protection were varied. Finally, the head-cut of the study gully was treated based on the model recommendation. The simulated results showed that a 5 m deep gully was stable under fully saturated conditions when the bank toe is protected, its upper surface is vegetated, and its bank angles do not exceed 45°. If the depth of the gully is less than 5 m or if its water table is deeper than 0.5 m, only regrading the gully bank to an angle of 45° can stabilize the gully. BSTEM showed to be an effective tool that can be used to evaluate gully control measures.
18 Bogale, A.; Aynalem, D.; Adem, A.; Mekuria, Wolde; Tilahun, S. 2020. Spatial and temporal variability of soil loss in gully erosion in Upper Blue Nile Basin, Ethiopia. Applied Water Science, 10(5):106. [doi: https://doi.org/10.1007/s13201-020-01193-4]
Gully erosion ; Soil loss ; Soil conservation ; Water conservation ; Spatial variation ; Groundwater assessment ; Groundwater table ; Stream flow ; Sediment ; Watersheds ; Catchment areas ; Highlands / Ethiopia / Upper Blue Nile Basin / Chentale Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H049937)
https://link.springer.com/content/pdf/10.1007/s13201-020-01193-4.pdf
https://vlibrary.iwmi.org/pdf/H049937.pdf
https://vlibrary.iwmi.org/pdf/H049937.pdf
(1.63 MB) (1.63 MB)
Gully erosion has many negative impacts on both cultivated and grazing lands in Ethiopian highlands. The present study was conducted in Chentale watershed, Ethiopia, to quantify the contribution of gully erosion, and to assess its temporal changes. Within the Chentale watershed, we selected a sub-watershed (104.6 ha) and nested gully catchment, and gauged for stream flow and sediment concentration data in 2015 and 2016. We measured gully dimensions before and after the onset of the rainy season in 2016 to determine soil loss due to gully erosion. The temporal changes of gully expansion were determined by digitizing gully plain area from Google earth images taken in 2005 and 2013. The results support that gullies were expanding at higher rate in recent years. Area covered by gullies in the watershed increased from 1.84 to 3.43 ha between 2005 and 2013, indicating that the proportion of the watershed covered by gullies was nearly doubled in the investigated period. The estimated soil loss from the main watershed and gullies catchment was 6 and 2 t ha-1 year-1 in 2015, and was 7 and 9 t ha-1 year-1 in 2016, respectively. The results support that gullies were the main contributors of soil erosion in the watershed, and that integrated soil and water conservation measures are required to reduce soil erosion.
19 Mekuria, Wolde; Gedle, A.; Tesfaye, Y.; Phimister, E. 2023. Implications of changes in land use for ecosystem service values of two highly eroded watersheds in Lake Abaya Chamo Sub-basin, Ethiopia. Ecosystem Services, 64:101564. [doi: https://doi.org/10.1016/j.ecoser.2023.101564]
Land use ; Land cover ; Ecosystem services ; Watershed management ; Farmland ; Grazing lands ; Gully erosion ; Livelihoods ; Land degradation ; Exclosures ; Shrublands ; Landscape conservation / Ethiopia / Lake Abaya Chamo Sub-Basin / Aba-Bora Watershed / Guder Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H052329)
(11.60 MB)
Ecosystems provide a variety of ecosystem services and functions for mankind, and their sustainable use plays an important role in livelihoods. However, the resulting land degradation due to land use and land cover changes leads to loss of valuable ecosystems and associated ecosystem functions and services. This study takes two highly degraded watersheds, Aba-Bora and Guder, in Ethiopia and uses the value transfer valuation method to estimate changes in ecosystem service values. The study shows how loss of cropland and grazing lands can significantly affect ecosystem services even when plantations and shrubland increase. The results suggest that over a period of 41 years, the ecosystem service value of exclosures/shrublands and plantations increased, whereas that of crop and grazing lands decreased. The loss of ecosystem service values due to the decrease in cropland and grazing lands outweigh the gains due to the expansion of plantations and exclosures and resulted in a total loss of ecosystem service values of US$ 1.6 million in Aba-Bora watershed and US$ 24.4 million in Guder. In both watersheds, the greatest contributor to ecosystem service loss was a decline in supporting services, while the increase in plantation and shrublands (mainly through establishment of exclosures) meant that regulating ecosystem services suffered the smallest loss. Given their importance to livelihoods in these areas, the loss in crop and grazing lands significantly increase the vulnerability to shocks and narrow future livelihood options for many households. Given that severe gully erosion is the major contributor to the reduction in crop and grazing lands, catchment management that integrates the conservation of upstream areas using diverse sustainable land management practices, and gully rehabilitation measures in downstream areas could be an important option to reducing the expansion of big gullies, and conserving crop and grazing lands and ecosystem service values. However, the results suggest that the risks to livelihoods may be underestimated while the effectiveness of current actions to address land degradation over-estimated by communities.
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