Your search found 47 records
1 Engda, T. A.; Bayabil, H. K.; Legesse, E. S.; Ayana, E. K.; Tilahun, S. A.; Collick, A. S.; Easton, Z. M.; Rimmer, A.; Awulachew, Seleshi Bekele; Steenhuis, T. S. 2011. Watershed hydrology of the (semi) humid Ethiopian highlands. In Melesse, A. M. (Ed.). Nile River Basin: hydrology, climate and water use. Dordrecht, Netherlands: Springer. pp.145-162.
Watersheds ; Hydrology ; Highlands ; Rainfall-runoff relationships ; Water table ; Simulation models / Ethiopia
(Location: IWMI HQ Call no: 551.483 G136 MEL Record No: H044027)
(0.35 MB)
2 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)
3 Yilak, D. L.; Tilahun, S. A.; Schmitter, Petra; Nakawuka, Prossie; Enku, T.; Kassawmar, N. T.; Steenhuis, T. S. 2015. Determining the groundwater potential for agricultural use in 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. 2p.
Agriculture ; Groundwater irrigation ; Groundwater recharge ; Water levels ; Water use ; Highlands ; Irrigation water ; Water levels ; Watersheds ; Sustainability ; Case studies / Ethiopia / Ethiopian Highlands / Robit-Bata watershed / Lake Tana
(Location: IWMI HQ Call no: e-copy only Record No: H047278)
(0.01 MB)
The Ethiopian government has declared the Lake Tana - Beles region to be a growth corridor and irrigation development is one of the priorities. Since the dry season river flow is limited, groundwater has the greatest potential for increasing irrigation in the near future. The main drawback is lack of information on sustainable groundwater use and specifically the ground water potential. Therefore the objective of this research is to calculate the annual groundwater recharge. The study was conducted in Robit-Bata, an experimental watershed of 911 ha, located at the south-eastern edge of Lake Tana. Farmers have excavated more than 300 hand dug wells for irrigation use from which, we used 50 wells for water table fluctuation observations for one year starting from April, 2014. Daily Precipitation was recorded for the same period. The annual recharge was estimated using the water – level fluctuation method. Specific yield was defined as the difference of porosity and field capacity of the subsurface formation. The annual average areal groundwater recharge was 640 mm/year, which is 41% of the rainfall and ranged from 50mm to 390mm per week for the various locations in the watershed. The greatest recharge amounts were found in the plains at the foot of the hills and river course areas consisting mostly weathered basalt rock. At those locations the groundwater rose steadily during the rainy monsoon phase. Smaller amount of recharge occurred both near the top of the hills with tough rock formation and in the, flat areas near to stream with sandy and clay deposits and groundwater at, shallow well depth. Our study indicates that the current use of the groundwater seems sustainable. Further research is required for optimized utilization of the limited groundwater resources for irrigation development to meet the food security of the community.
4 Yilak, D. L.; Tilahun, S. A.; Schmitter, Petra; Nakawuka, Prossie; Haile, Alemseged Tamiru; Kassawmar, N. T.; Guzman, C. D.; Steenhuis, T. S. 2015. Adaptation of the SCS [Soil Conservation Service] runoff equation for a (Sub) humid monsoon climate. Paper presented at the 3rd OpenWater Symposium, Addis Ababa, Ethiopia, 16-17 September 2015. 19p.
Climate change ; Monsoon climate ; Humid climate ; Runoff ; Adaptation ; Soil conservation ; Soil moisture ; Watersheds ; Water shortage ; Water balance ; Hydrology ; Models ; Highlands ; River basins ; Rain ; Runoff / Ethiopia / Ethiopian Highland / Maybar Watershed / Anjeni Watershed / Blue Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047279)
(0.01 MB)
The Soil Conservation Service Runoff equation was developed and tested for the temperate climate in the United States. Application to the monsoon climates has been only partially successful. The objective to adapt the SCS equation to a monsoon climate equation is to predict watershed runoff. The adaptation is based on the fact that in many humid areas the main mechanism for direct runoff is saturation excess and in monsoon climates the contributing area expands as a function of the cumulative effective rainfall ( Pe). This then translate in smaller watershed storage (S) in the equation. When estimating runoff contributing area within a watershed and assessing the runoff mechanisms, we have used the original concept of SCS-CN approach in a 113 ha Anjeni and 113ha Maybar Watersheds in the headwaters of the Blue Nile Basin, North Ethiopian highland. Analysis was done at daily, weekly and biweekly base using nine years of hydrological data (1988-97) by classifying the rainfall seasons in to six based on the seasonal cumulative of effective rainfall (Pe). The initial abstraction (Ia) was taken to be equal to the evapotranspiration loss (E) computed by Thornthwaite-Mather water balance method in replacement of the 20% of the potential storage (S). Effective rainfall (Pe) is the difference of total rainfall and Ia. The model performed more as the seasonal cumulative Pe is increased indicating that runoff responses occurred as the watershed saturated. The proportion of runoff contributing area (Af) increased linearly until the cumulative Pe up to nearly 500mm and then the watershed reaches in equilibrium for addition increase of Pe, which is in line with the concept of partial source area hydrology.
5 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.
6 Yiak, D. L.; Tilahun, S. A.; Schmitter, Petra; Nakawuka, Prossie; Steenhuis, T. S. 2015. Groundwater recharge of Robit - Bata Experimental Watershed, Lake Tana Basin, Ethiopia [Abstract only] Paper presented at the 3rd International Conference on the Advancements of Science and Technology [ICAST], Bahir Dar, Ethiopia, 8-9 May 2015. 1p.
Groundwater recharge ; Groundwater irrigation ; Watersheds ; Water use ; Water table ; River basins ; Rain / Ethiopia / Lake Tana Basin / Robit - Bata Experimental Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047313)
(0.04 MB)
Irrigation development is a policy priority for the Laka Tana basin. However available baseflow can irrigate less than 3% of area. The irrigated area can be increased from water stored in constructed reservoirs, pumping water from Lake Tana and by using groundwater. While groundwater has the greatest potential for increasing irrigation in the near future, the main drawback is a lack of information on sustainable groundwater use and specifically the ground water recharge. Therefore the objective of this research is to calculate the annual recharge to the ground water. The study is conducted in Robit-Bata, an experimental watershed of 911 ha, located at the south-eastern edge of Lake Tana. Farmers have excavated more than 300 hand dug wells for irrigation and we used 50 shallow groundwater wells and observed water table fluctuation and precipitation for the past one year. The annual recharge was estimated using water – level fluctuation method. Specific yield was taken to be the difference of porosity and field capacity of the subsurface formation. The annual average areal groundwater recharge of the watershed was 200 mm/year, which is 12% of the rainfall and ranged from 80mm to 500mm for the various locations in the watershed. The greatest recharge amounts were found at the foot of the hillside in river course plane areas consisting mostly weathered basalt rock. Here the groundwater was up to 15 m deep and rose steadily during the rainy monsoon phase. Smaller amount of recharge occurred both near the top of the hills with tough rock formation and in the, flat areas near to stream sandy and clay deposits and groundwater at, shallow well depth. Our study indicates that the current use of the groundwater is sustainable, but will become unsustainable if many more wells are constructed. Sufficiency and sustainable use of the shallow groundwater needs further research.
7 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.
8 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.
9 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.
10 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.
11 Tesema, M.; Schmitter, Petra; Nakawuka, Prossie; Tilahun, S. A.; Steenhuis, T.; Langan, Simon. 2016. Evaluating irrigation technologies to improve crop and water productivity of onion in Dangishta watershed during the dry monsoon phase. Paper presented at the International Conference of the Advancement of Science and Technology, Bahir Dar, Ethiopia, 17-18 July 2016. 10p.
Crop production ; Crop management ; Water productivity ; Water use efficiency ; Water conservation ; Water management ; Onions ; Monsoon climate ; Dry season ; Watershed services ; Wet cultivation ; Soil moisture ; Soil water balance ; Rhizosphere ; Rain ; Agriculture ; Fertilizer application / Ethiopia / Dangishta Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047635)
(611 KB)
12 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.
13 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.
14 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.
15 Aynalem, D.; Adem, A. A.; Tilahun, S. A.; Mekuria, Wolde; Nicholson, C. F.; Steenhuis, T. S. 2016. Enhancing ecosystem services in the upper Blue Nile Basin, Ethiopia through soil and water conservation implementation [Abstract only] Paper presented at the First African ESP [Ecosystem Services Partnership] Conference, Nairobi, Kenya, 21-25 November 2016. 1p.
Ecosystem services ; River basins ; Water conservation ; Soil conservation ; Soil fertility ; Nutrients ; Erosion ; Highlands ; Sediment ; Watersheds ; Infiltration / Ethiopia / Blue Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047881)
(33.1 KB)
16 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)
17 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.
18 Moges, M. A.; Schmitter, Petra; Tilahun, S. A.; Steenhuis, T. S. 2018. Watershed modeling for reducing future non-point source sediment and phosphorus load in the Lake Tana Basin, Ethiopia. Journal of Soils and Sediments, 18(1):309-322. [doi: https://doi.org/10.1007/s11368-017-1824-z]
Watershed management ; Models ; Sediment ; Phosphorus ; River basins ; Saturation ; Intensification ; Water quality ; Water balance ; Humid climate ; Runoff ; Hydrometeorology ; Calibration / Ethiopia / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048307)
Purpose - Agricultural intensification to meet the food needs of the rapidly growing population in developing countries affects water quality. In regions such as the Lake Tana basin, knowledge is lacking on measures to reduce non-point source pollutants in humid tropical monsoon climates. The aim of this paper was, therefore, to develop a non-point model that can predict the placement of practices to reduce the transport of sediment and phosphorus (P) in a (sub) humid watershed. Materials and methods - In order to achieve the objective, hydrometeorological, sediment, and P data were collected in the watershed since 2014. The parameter efficient semi-distributed watershed model (PED-WM) was calibrated and validated in the Ethiopian highlands to simulate runoff and associated sediments generated through saturation excess. The P module added to PED-WM was used to predict dissolved (DP) and particulate P (PP) loads aside from discharge and sediment loads of the 700 ha of the Awramba watershed of Lake Tana basin. The PED-WM modules were evaluated using the statistical model performance measuring techniques. The model parameter based prediction of source areas for the non-point source sediment and P was also evaluated spatially and compared with the Topographic Wetness Index (TWI) of the watershed. Results and discussion - The water balance component of the non-point source model performed well in predicting discharge, sediment, DP, and PP with NSE of 0.7, 0.65, 0.65, and 0.63, respectively. In addition, the predicted discharge followed the hydrograph with insignificant deviation from its pattern due to seasonality. The model predicted a sediment yield of 28.2 t ha-1 year-1 and P yield of 9.2 kg ha-1 year-1 from Awrmaba. Furthermore, non-point source areas contributed to 2.7 kg ha-1 year-1 (29%) of DP at the outlet. The main runoff and sediment source areas identified using PED-WM were the periodically saturated runoff areas. These saturated areas were also the main source for DP and PP transport in the catchment. Conclusions - Using the PED-WM with the P module enables the identification of the source areas as well as the prediction of P and sediment loading which yields valuable information for watershed management and placement of best management practices.
19 Taye, B. M.; Schmitter, Petra; Tilahun, S. A.. 2017. Evaluating crop yield and water productivity of onion and potato through the use of wetting front detectors by water user associations in Koga irrigation Scheme, Ethiopia. Paper presented at the International Symposium on Sustainable Water Resource Development, Arba Minch, Ethiopia, 23-24 June 2017. 12p.
Water productivity ; Water allocation ; Water availability ; Irrigation water ; Crop yield ; Onions ; Potatoes ; Water user associations ; Irrigation schemes ; Wetting front ; Farmers ; Cultivated land / Africa / Ethiopia / Koga Irrigation Scheme
(Location: IWMI HQ Call no: e-copy only Record No: H048335)
Whilst irrigation schemes and technologies are extensively promoted in Africa, proper water management guidance for farmers is often lacking. Improper on-farm irrigation management practices lead to poor water distribution, non-uniform crop growth, and disputes in irrigation schemes due to unequal water allocation. Hence, the objective of the study was evaluating crop yield and water productivity of onion and potato through the use of wetting front detectors by water user association. In Koga irrigation scheme, there are 11 night storage, which irrigate 12 blocks (7000 ha). From those three blocks (Tagel, Adibera and Chihona blocks) were selected. From each block two water users association (WUA) have been selected and training on how to use the Wetting front detector (WFD) was given: one WUA grew onion while another one cultivated potato. For onion 2.04 ha of land were managed by 9 WFD and 0.82ha were managed by farmer’s own irrigation system. For potato 1.68 ha of land were managed by 10 WFD and 0. 42 ha of land were managed by farmers own irrigation system. In this study a total of 43 farmers irrigated using WFD while 13 farmers were irrigating based on their traditional knowledge. During installation the furrow length for onion was 5m and for potato 20m. The WFD was placed at ¾ of the furrow length from the entrance of the furrow. The shallow detector installed at 1/3 of the root zone (20 cm in this case) and the deep detector installed at 2/3 of the root zone (40 cm). Potato fields that were irrigated based on WFD response received on average 43% less water compared to control fields (i.e. 431mm instead of 753mm) (p<0.05). This resulted in a significant yield increase of 6 % (p<0.05) in the WFD plots. Similarly, for onion a reduction in irrigation depth of 25% was obtained when farmers were guided by WFD (i.e. 504 mm instead of 676mm (p<0.05). While yield increased in the WFD fields by 4%, this was not significant. At scheme level, if all fields were onion guided by WFD, 1509 ha additional could be irrigated. Similarly if all fields were potato guided by WFD, additional land to be irrigated could be 2966 ha. This study has shown that available water in dams can irrigate more land by using on farm water management technologies.
20 Taye, B. M.; Schmitter, Petra; Tilahun, S. A.. 2017. Evaluating crop yield and water productivity of onion and potato through the use of wetting front detectors by water user associations in Koga irrigation Scheme, Ethiopia. Paper presented at the Ethoipian Institute of Water Resource Annual Research Symposium, Addis Ababa, Ethiopia, 27 June 2017. 12p.
Water productivity ; Water allocation ; Water availability ; Irrigation water ; Crop yield ; Onions ; Potatoes ; Water user associations ; Irrigation schemes ; Wetting front ; Farmers ; Cultivated land / Africa / Ethiopia / Koga Irrigation Scheme
(Location: IWMI HQ Call no: e-copy only Record No: H048339)
Whilst irrigation schemes and technologies are extensively promoted in Africa, proper water management guidance for farmers is often lacking. Improper on-farm irrigation management practices lead to poor water distribution, non-uniform crop growth, and disputes in irrigation schemes due to unequal water allocation. Hence, the objective of the study was evaluating crop yield and water productivity of onion and potato through the use of wetting front detectors by water user association. In Koga irrigation scheme, there are 11 night storage, which irrigate 12 blocks (7000 ha). From those three blocks (Tagel, Adibera and Chihona blocks) were selected. From each block two water users association (WUA) have been selected and training on how to use the Wetting front detector (WFD) was given: one WUA grew onion while another one cultivated potato. For onion 2.04 ha of land were managed by 9 WFD and 0.82ha were managed by farmer’s own irrigation system. For potato 1.68 ha of land were managed by 10 WFD and 0. 42 ha of land were managed by farmers own irrigation system. In this study a total of 43 farmers irrigated using WFD while 13 farmers were irrigating based on their traditional knowledge. During installation the furrow length for onion was 5m and for potato 20m. The WFD was placed at ¾ of the furrow length from the entrance of the furrow. The shallow detector installed at 1/3 of the root zone (20 cm in this case) and the deep detector installed at 2/3 of the root zone (40 cm). Potato fields that were irrigated based on WFD response received on average 43% less water compared to control fields (i.e. 431mm instead of 753mm) (p<0.05). This resulted in a significant yield increase of 6 % (p<0.05) in the WFD plots. Similarly, for onion a reduction in irrigation depth of 25% was obtained when farmers were guided by WFD (i.e. 504 mm instead of 676mm (p<0.05). While yield increased in the WFD fields by 4%, this was not significant. At scheme level, if all fields were onion guided by WFD, 1509 ha additional could be irrigated. Similarly if all fields were potato guided by WFD, additional land to be irrigated could be 2966 ha. This study has shown that available water in dams can irrigate more land by using on farm water management technologies.
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