Your search found 7 records
1 Tadesse, A.; Dagnew, D. C.; Belete, M. A.; Tilahun, S. A.; Mekuria, Wolde; Steenhuis, T. 2015. Impact of soil and water conservation practices on sediment losses and discharge in the headwaters of the Lake Tana Basin in the Ethiopian highlands [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 ; Sediment ; Water erosion ; Watersheds ; Discharges ; River basins ; Highlands ; Runoff / Ethiopia / Blue Nile Basin / Lake Tana Basin / Tikur-Wuha Watershed / Guali Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047342)
http://meetingorganizer.copernicus.org/AvH10/AvH10-42-1.pdf
https://vlibrary.iwmi.org/pdf/H047342.pdf
https://vlibrary.iwmi.org/pdf/H047342.pdf
(0.04 MB) (37.63 KB)
Donor and governmental sponsored soil and water conservation measures has been carried out in the last half century in the Lake Tana basin, Ethiopia. However, sediment loads in to the lake has never been reduced suggesting that the effectiveness of integrated soil and water conservation measures reducing soil loss needs to be investigated. The present study was conducted in two watersheds (Tikur-Wuha covers 500 ha and Guali covers190 ha) located in the headwaters of Lake Tana to investigate the impacts of soil and water conservation practices on discharge and sediment loads. In both watersheds different soil and water conservation technologies have been implemented since 2010 by the Tana Belese integrated watershed management project: gully treatment, stone buds, soil bunds, stone faced soil bunds, water ways, cut- off drains, hill side terracing, micro basins and area closures. Daily rainfall, runoff and sediment concentration were collected from 2010 – 2012. The results showed that average runoff volume was reduced by 13% in Tikur-wuha and by 7% in Guali from 2010-2012. The sediment load in Tikur-wuha watershed was reduced by 48% in 2011 and 30% in 2012, while sediment load in Guali watershed was reduced by 1% and 35% in 2011 and 2012 respectively. The results support that the implemented integrated SWC measures through government sponsored with full participation of the community and through incorporating different SWC technology options were effective in reducing runoff and sediment load. We recommend fortifying the government led SWC campaign with full participation of the local community to reduce soil erosion and siltation of Lake Tana.
2 Dagnew, D. C.; Guzman, C. D.; Tebebu, T. Y.; Zegeye, A. D.; Akal, A. T.; Mekuria, Wolde M.; Ayana, E. K.; Tilahun, S. A.; Steenhuis, T. S. 2015. Contributions of peak sediment events to annual loads and the effects of best management practices on peak loads in the sub-humid Ethiopian highlands: the Debre Mawi 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.94.
Sedimentation ; Watersheds ; Highlands ; Management techniques ; Soil conservation ; Water conservation ; Water erosion / Ethiopia / Ethiopian Highlands
(Location: IWMI HQ Call no: e-copy only Record No: H047344)
(0.66 MB)
Intense rainfall/runoff events produce large proportion of suspended sediment concentrations and sediment load responses. With an aim to mitigate land degradation problems in Ethiopia, soil and water conservation projects are being massively implemented. The effect of these conservation measures in reducing sediment in streams have never been quantified due to unavailability of sediment data. In a quantitative evaluation to quantify the contribution of intense event/daily sediment loads to annual sediment loads and effect of conservation measures in reducing erosion, we monitored three nested experimental sub-watersheds and a 95 ha main watershed in the sub-humid Ethiopian highlands, Debre Mawi watershed for four consecutive years. The contribution of the largest 10–minute events and peak daily sediment loads to annual sediment loads and the effect of Best Management Practices (BMPs) on peak sediment transport processes were evaluated. The contribution of the largest event loads reached up to 22% of the total annual sediment loads. The peak event sediment loads reached up to 11 t ha-1. The contribution of the largest daily sediment load events to annual loads is up to 86%. For the two largest daily sediment load events, the contribution reached up to 95%. The total sediment loads of the two largest daily sediment load events ranged from 40-68 t ha-1day-1 indicating that most of the annual sediment loads are transported with in one or two intense daily sediment load events in the (sub) humid Ethiopian highlands. Comparison of peak sediment loads before and after the implementation of BMPs indicates that conservation practices such as soil bunds, stone faced soil bunds and stone bunds substantially reduced the contribution and magnitude of peak sediment loads. The sediment trap efficiency of the BMPs can be further improved by making ditches deeper than existing practice of 50 cm depth in the Ethiopian highlands.
3 Moges, M. A.; Schmitter, Petra; Tilahun, S. A.; Langan, Simon; Dagnew, D. C.; Akale, A. T.; Steenhuis, T. S. 2017. Suitability of watershed models to predict distributed hydrologic response in the Awramba Watershed in Lake Tana Basin. Land Degradation and Development, 28(4):1386-1397. [doi: https://doi.org/10.1002/ldr.2608]
Watershed management ; Hydrology ; Catchment areas ; Models ; Land degradation ; River basin management ; Spatial distribution ; Rainfall-runoff relationships ; Infiltration water ; Wet season ; Calibration ; Groundwater ; Water table ; Water levels / Ethiopia / Lake Tana River Basin / Awramba Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047780)
Planning effective landscape interventions is an important tool to fight against land degradation and requires knowledge on spatial distribution of runoff. The objective of this paper was to test models that predict temporal and spatial distribution of runoff. The selected models were PED-WM, HBV-IHMS and SWAT. We choose 7 km2 Awramba watershed in the Lake Tana basin with detailed hydrological information for testing these models. Discharge at the outlet, rainfall and distributed information on infiltration rates, water table and extent of the saturated area were collected from 2013 to 2015. The maximum saturated area was 6.5% of the watershed. Infiltration rates exceeded rainfall intensities 91% of the time. Hence saturation excess runoff was the main runoff mechanism. Models were calibrated for the rainy seasons 2013, 2014 and validated for 2015. For daily flow validation, the PED-WM model (Nash Sutcliff efficiency, NSE = 0.61) outperformed HBV-IHMS (NSE = 0.51) and SWAT (NSE = 0.48). Performance on monthly time step was similar. Difference in model behavior depended on runoff mechanism. In PED-WM saturation excess is the main direct runoff process and could predict the maximum extent of the saturated area closely at 6.9%. HBV-IHMS model runoff simulation depended on soil moisture status and evapotranspiration, and hence was able to simulate saturation excess flow but not the extent of the saturated area. In SWAT where infiltration excess is the main runoff mechanism could only predict the monthly discharges well. This study shows that prevailing runoff mechanisms and distribution of runoff source areas should be used for proper model selection.
4 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.
5 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.
6 Akale, A. T.; Dagnew, D. C.; Giri, S.; Belete, M. A.; Tilahun, S. A.; Mekuria, Wolde; Steenhuis, T. S. 2017. Groundwater quality in an upland agricultural watershed in the sub-humid Ethiopian Highlands. Journal of Water Resource and Protection, 9(10):1199-1212. [doi: https://doi.org/10.4236/jwarp.2017.910078]
Groundwater ; Water quality ; Water pollution ; Sampling ; Highlands ; Agriculture ; Intensification ; Watershed management ; Humid zones ; Surface water ; Drinking water ; Contamination ; Wells ; Electrical conductivity ; Elements / Ethiopia / Lake Tana / Tikur-Wuha Watershed / Ribb Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H048459)
(3.75 MB)
Agricultural intensification to meet the food needs of the rapidly growing population in developing countries is negatively affecting the water quality. In most of these countries such as Ethiopia, information on surface and especially groundwater quality is lacking. This limits the measure that can be taken to stop pollution. We, therefore, investigated the spatial and temporal variation of groundwater quality in the upland watershed. Tikur-Wuha watershed was selected because it is located in the Lake Tana watershed, which is seeing the first signs of eutrophication. Groundwater samples were collected from July 2014 to June 2015 from 19 shallow wells located throughout the watershed. Collected water samples were analyzed both in situ and in the laboratory to determine pH, electric conductivity (EC) and total dissolved solid (TDS), concentration of chemicals (nitrate, dissolved phosphorus, calcium, magnesium, aluminum and iron) and Escherichia coli (E. coli). We found that shallow groundwater had greater chemical concentrations and E. coli level in the monsoon rain phase than in the dry phase. Wells located down slope exhibited greater concentrations than mid- and upper-slope positions, with the exception of the nitrate concentration that was less down slope, due to denitrification in the shallow groundwater. Only E. coli level was above the WHO drinking water quality standards. Further studies on groundwater quality should be carried out to understand the extent of groundwater contamination.
7 Dagnew, D. C.; Guzman, C. D.; Akale, A. T.; Tebebu, T. Y.; Zegeye, A. D.; Mekuria, Wolde; Tilahun, S. A.; Steenhuis, T. S. 2017. Effects of land use on catchment runoff and soil loss in the sub-humid Ethiopian highlands. Ecohydrology and Hydrobiology, 17:274-282. [doi: https://doi.org/10.1016/j.ecohyd.2017.07.004]
Land use ; Land management ; Catchment areas ; Runoff ; Soil properties ; Soil organic matter ; Soil disturbance ; Erosion ; Subhumid zones ; Hydrology ; Highlands ; Sedimentation ; Grasslands ; Cultivated land ; Tillage ; Watersheds / Ethiopia / Ethiopian Highlands
(Location: IWMI HQ Call no: e-copy only Record No: H048463)
Land use and management affects runoff and soil loss from a catchment. The present study investigated the effects of land use on runoff and suspended sediment concentration and yield in the northwestern Ethiopia. We selected two small catchments: cultivated land and grassland dominated catchments within the 95 ha Debre Mawi catchment. Hydrometric and sediment concentration data were collected for five years (i.e., 2010–2014). Significant (p < 0.05) differences in daily, monthly and annual runoff, as well as suspended sediment concentrations were observed between cultivated land and grassland dominated catchments. The greater runoff, suspended sediment concentration and yield in the cultivated catchment could be attributed to repeated tillage and low soil organic matter. Repeated tillage in the cultivated land lead to soil disturbance and the low organic matter lead to aggregate instability, both of which consequently increase the detachment of soil particles and transport by generated runoff. Our results support that land management practices that involve lower soil disturbance and increase ground cover on degraded highland areas such as the Ethiopian highlands could help reduce runoff and soil loss.
Powered by DB/Text WebPublisher, from
