Integrated impact assessment of soil and water conservation structures on runoff and sediment yield through measurements and modeling in the Northern Ethiopian highlands

Melaku, Nigus Demelash; Renschler, Chris S.; Flagler, J.; Bayu, Wondimu; Klik, Andreas

doi:10.1016/j.catena.2018.05.035

Cited by 42 publications

(23 citation statements)

References 39 publications

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“…Like the rainfall pattern in LTB, this severe rate of sediment delivery to main rivers also follows an increasing trend from north to south in clockwise direction, that is, SY in subbasins located in Megech catchment (57 Mg ha −1 yr −1 ) is lower than subbasins located in north‐east (65 Mg ha −1 yr −1 ), Gumara (73 Mg ha −1 yr −1 ), and Gilgel Abay (80 Mg ha −1 yr −1 ) catchments. This estimated SY in this study is within the range reported data that were observed in and around LTB (Ayele et al, ; Ebabu et al, ; Lemma et al, ; Melaku et al, ; Subhatu et al, ). In contrasts, relatively lower sediment is produced in the low‐lying floodplains of the basin.…”

Section: Discussionsupporting

confidence: 91%

“…Selection of land management scenarios and their parametric values is site specific and should reflect the study area reality (Abdelwahab et al, ). Therefore, five scenarios were selected and simulated based on documented local research experiences and recently introduced practices in the Ethiopian Highlands (e.g., Addis et al, ; Ebabu et al, ; Hurni, ; Melaku et al, ; Nigussie et al, ; Sultan et al, ). The scenarios encompass land use changing (reforestation of hilly cropland areas as Scenario R), physical (stone/soil bunds as Scenario S) and biological (grass contour strips as Scenario G) conservation practices, and agronomic measures ( Acacia decurrens ‐based crop rotation as Scenario A and zero free grazing as Scenario Z).…”

Section: Methodsmentioning

confidence: 99%

“…Selection of land management scenarios and their parametric values is site specific and should reflect the study area reality (Abdelwahab et al, 2014). Therefore, five scenarios were selected and simulated based on documented local research experiences and recently introduced practices in the Ethiopian Highlands (e.g., Addis et al, 2016;Ebabu et al, 2018;Hurni, 1985;Melaku et al, 2018;Nigussie et al, 2017;Sultan et al, 2017). The scenarios Ethiopia (Hurni et al, 2016;National Planning Commission, 2015).…”

Section: Scenarios For Alternative Catchment Managementmentioning

confidence: 99%

“…Among these models, the Water Erosion Prediction Project, Agricultural Non-Point Source, Limburg Soil Erosion Model, and Soil and Water Assessment Tool (SWAT) have been applied in the Blue Nile Basin usually to evaluate their runoff and soil erosion model components (Betrie et al, 2011;Easton et al, 2010;van Griensven, Ndomba, Yalew, & Kilonzo, 2012). The Water Erosion Prediction Project simulation performance showed overpredicted runoff and slightly underpredicted soil loss in the 271-km 2 Dembecha catchment (Zeleke, 2000) and performed satisfactorily in 0.3-km 2 Gumara-Maksegnit catchment (Melaku, Renschler, Flagler, Bayu, & Klik, 2018). The Agricultural Non-Point Source model was tested in 2.2-km 2 Augucho catchment but could not reproduce observed runoff (Haregeweyn & Yohannes, 2003), whereas a nonvalidated Limburg Soil Erosion Model performance to simulate the effect of reforestation on soil erosion in the 3.7-km 2 Gobo Deguat catchment (Hengsdijk, Meijerink, & Mosugu, 2005) was challenged by Nyssen et al (2006).…”

Section: Introductionmentioning

confidence: 99%

“…The Agricultural Non-Point Source model was tested in 2.2-km 2 Augucho catchment but could not reproduce observed runoff (Haregeweyn & Yohannes, 2003), whereas a nonvalidated Limburg Soil Erosion Model performance to simulate the effect of reforestation on soil erosion in the 3.7-km 2 Gobo Deguat catchment (Hengsdijk, Meijerink, & Mosugu, 2005) was challenged by Nyssen et al (2006). Whereas, the SWAT model was widely tested in small catchments (Addis, Strohmeier, Ziadat, Melaku, & Klik, 2016;Ayele, Teshale, Yu, Rutherfurd, & Jeong, 2017;Melaku et al, 2018;Setegn, Srinivasan, Melesse, & Dargahi, 2010) to large basins (Betrie et al, 2011;Easton et al, 2010;Setegn, Srinivasan, & Dargahi, 2008) and obtained quite acceptable results (Moriasi et al, 2007). Being the most versatile model used for various applications, the SWAT model allows to predict the effect of soil and water management strategies and is capable of assessing the best management alternatives Neitsch, Arnold, Kiniry, & Williams, 2011).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Identifying erosion hotspots in Lake Tana Basin from a multisite Soil and Water Assessment Tool validation: Opportunity for land managers

et al. 2019

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Extensive catchment degradation throughout the Ethiopian Highlands induced by long‐term intensified land use, erosion‐prone topography, and climate causes substantial soil erosion that limits agricultural productivity and results in lake sedimentation. However, before taking soil conservation measures, management of the soil loss problem essentially needs catchment‐level modelling to estimate the geographic distribution of erosion hotspots. With the increasing availability of sediment and spatial data and development of physically based models, this study aims multisite calibration of Soil and Water Assessment Tool (SWAT) to map erosion hotspot areas and to assess the effect of well‐known land management alternatives in sediment reduction in the Lake Tana Basin. The SWAT simulations indicated that the goodness of fit between predicted and observed data was satisfactory for all gauge stations except for one, and the model performance was within acceptable evaluation ratings. Simulated average sediment yield (SY) for the period 2001–2016 at subbasin level varies from negligible to about 169 Mg ha−1 yr−1 (basin average 32 Mg ha−1 yr−1). High potential SY (>50 Mg ha−1 yr−1) was simulated for 23% of the subbasins in Megech, upper Rib, upper Gumara, and Gilgel Abay catchments due to steep slope topography, aggressive rainfall, croplands dominance, and low rock fragment cover. The differences in level of erosion risk among subbasins help to prioritize and target specific areas of the basin that need urgent soil conservation activities. Scenario analysis also showed that implementing stone bunds, Acacia decurrens‐based crop rotation, reforestation, and grass contour strips reduces the existing SY by 51–61% at basin level. The potential sediment production could reach tolerable levels by implementing stone bunds, tree‐based crop rotation, reforestation in steep slope areas, and grass contour strips on gentle slopes. Overall, the multisite calibration of SWAT model using the measured run‐off and sediment data produces reasonable results that may support decision makers and planners to implement relevant land management measures and thereby reduce the alarming problems of soil loss in the basin and sedimentation of Lake Tana.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Scenarios For Alternative Catchment Managementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Identifying erosion hotspots in Lake Tana Basin from a multisite Soil and Water Assessment Tool validation: Opportunity for land managers

et al. 2019

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Event‐based run‐off and sediment yield dynamics and controls in the subhumid headwaters of the Blue Nile, Ethiopia

et al. 2022

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Land degradation due to soil erosion presents a major challenge for sustainable development. We investigated run-off and sediment yield (SY) dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 to 1715 m 2 . V-notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Run-off (RO) depth at the weir was registered manually at 5-min intervals during two rainy seasons in 2018 and 2019, and a total of 618 events were monitored. Rainfall was measured using tipping-bucket rain gauges. RO samples were collected in 1-L bottles, and suspended sediment concentration was determined. The mean event RO coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual SY was lowest for forests (0.8 Mg ha À1 yr À1 ) and highest for badlands (43.4 Mg ha À1 yr À1 ), with significant differences among land-use types (14.8 Mg ha À1 yr À1 in cropland, 5.7 Mg ha À1 yr À1 in grazing land, and 2.9 Mg ha À1 yr À1 in plantations). Soil organic matter (SOM) reduced RO and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and hence contribute to the sustainability of land uses in the subhumid highlands.

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Evaluating the Effectiveness of Best Management Practices On Soil Erosion Reduction Using the SWAT Model: for the Case of Gumara Watershed, Abbay (Upper Blue Nile) Basin

Gashaw

Dile

Worqlul³

et al. 2021

Environmental Management

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This study was conducted to evaluate the effectiveness of best management practices (BMPs) to reduce soil erosion in Gumara watershed of the Abbay (Upper Blue Nile) Basin using the Soil and Water Assessment Tool (SWAT) model. The model was calibrated (1995-2002) and validated (2003-2007) using the SWAT-CUP based on observed streamflow and sediment yield data at the watershed outlet. The study evaluated four individual BMP Scenarios; namely, filter strips (FS), stone/soil bunds (SSB), grassed waterways (GW) and reforestation of croplands (RC), and three blended BMP Scenarios, which combines individual BMPS of FS and RC (FS & RC), GW and RC (GW & RC), and SSB and GW (SSB & GW). Mean annual sediment yield at the baseline conditions was estimated at 19.7 t ha −1 yr −1 , which was reduced by 13.7, 30.5, 16.2 and 25.9% in the FS, SSB, GW, and RC Scenarios, respectively at the watershed scale. The highest reduction efficiency of 34% was achieved through the implementations of the SSB & GW Scenario. The GW & RC, and FS & RC Scenarios reduced the baseline sediment yield by 32% and 29.9%, respectively. The study therefore concluded that the combined Scenarios mainly SSB & GW, and GW & RC can be applied to reduce the high soil erosion in the Gumera watershed, and similar agro-ecological watersheds in Ethiopia. In cases where applying the combined scenarios is not possible, the SSB Scenario can yield significant soil erosion reduction.

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Integrated impact assessment of soil and water conservation structures on runoff and sediment yield through measurements and modeling in the Northern Ethiopian highlands

Cited by 42 publications

References 39 publications

Identifying erosion hotspots in Lake Tana Basin from a multisite Soil and Water Assessment Tool validation: Opportunity for land managers

Identifying erosion hotspots in Lake Tana Basin from a multisite Soil and Water Assessment Tool validation: Opportunity for land managers

Event‐based run‐off and sediment yield dynamics and controls in the subhumid headwaters of the Blue Nile, Ethiopia

Evaluating the Effectiveness of Best Management Practices On Soil Erosion Reduction Using the SWAT Model: for the Case of Gumara Watershed, Abbay (Upper Blue Nile) Basin

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