Effects of land use and sustainable land management practices on runoff and soil loss in the Upper Blue Nile basin, Ethiopia

Ebabu, Kindiye; Tsunekawa, Atsushi; Haregeweyn, Nigussie; Adgo, Enyew; Meshesha, Derege Tsegaye; Aklog, Dagnachew; Masunaga, Tsugiyuki; Tsubo, Mitsuru; Sultan, Dagnenet; Fenta, Ayele Almaw; Yibeltal, Mesenbet

doi:10.1016/j.scitotenv.2018.08.273

Cited by 133 publications

(88 citation statements)

References 54 publications

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“…The mean annual rainfall was 1022, 1343, and 2454 mm at Dibatie, Aba Gerima, and Guder, respectively. Mean annual temperature varies from 25 to 32 °C at Dibatie, from 13 to 27 °C at Aba Gerima, and from 9.4 to 25 °C at Guder [43,44]. In the Koppen-Geiger classification [42], the climate is characterized as subtropical oceanic highland at Guder, humid subtropical at Aba Gerima, and tropical wet-dry at Dibatie.…”

Section: Study Sitesmentioning

confidence: 99%

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Effects of Land Use and Topographic Position on Soil Organic Carbon and Total Nitrogen Stocks in Different Agro-Ecosystems of the Upper Blue Nile Basin

et al. 2020

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Soil organic carbon (SOC) and total nitrogen (TN) are key ecological indicators of soil quality in a given landscape. Their status, especially in drought-prone landscapes, is associated mainly with the land-use type and topographic position. This study aimed to clarify the effect of land use and topographic position on SOC and TN stocks to further clarify the ecological processes occurring in the landscape. To analyze the status of SOC and TN, we collected 352 composite soil samples from three depths in the uppermost soil (0–50 cm) in four major land-use types (bushland, cropland, grazing land, and plantation) and three topographic positions (upper, middle, and lower) at three sites: Dibatie (lowland), Aba Gerima (midland), and Guder (highland). Both SOC and TN stocks varied significantly across the land uses, topographic positions, and agro-ecosystems. SOC and TN stocks were significantly higher in bushland (166.22 Mg ha−1) and grazing lands (13.11 Mg ha−1) at Guder. The lowest SOC and TN stocks were observed in cropland (25.97 and 2.14 Mg ha−1) at Aba Gerima, which was mainly attributed to frequent and unmanaged plowing and extensive biomass removal. Compared to other land uses, plantations exhibited lower SOC and TN stocks due to poor undergrowth and overexploitation for charcoal and firewood production. Each of the three sites showed distinct characteristics in both stocks, as indicated by variations in the C/N ratios (11–13 at Guder, 10–21 at Aba Gerima, and 15–18 at Dibatie). Overall, land use was shown to be an important factor influencing the SOC and TN stocks, both within and across agro-ecosystems, whereas the effect of topographic position was more pronounced across agro-ecosystems than within them. Specifically, Aba Gerima had lower SOC and TN stocks due to prolonged cultivation and unsustainable human activities, thus revealing the need for immediate land management interventions, particularly targeting croplands. In a heterogeneous environment such as the Upper Blue Nile basin, proper understanding of the interactions between land use and topographic position and their effect on SOC and TN stock is needed to design proper soil management practices.

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Section: Study Sitesmentioning

confidence: 99%

“…The mean annual rainfall was 1022, 1343, and 2454 mm at Dibatie, Aba Gerima, and Guder, respectively. Mean annual temperature varies from 25 to 32 • C at Dibatie, from 13 to 27 • C at Aba Gerima, and from 9.4 to 25 • C at Guder [43,44]. a Slope and soil texture data taken from [45].…”

Section: Study Sitesmentioning

confidence: 99%

Effects of Land Use and Topographic Position on Soil Organic Carbon and Total Nitrogen Stocks in Different Agro-Ecosystems of the Upper Blue Nile Basin

et al. 2020

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“…Relative to the current situation (Scenario B), the SWAT model simulations with alternative land management scenarios (Figure 4, There are 25-63% SY reductions by stone/soil bunds at experimental catchments located in the humid areas of LTB (e.g., Addis et al, 2016;Ebabu et al, 2019;Melaku et al, 2018), whereas the percentage value increased to 56-76% in the semiarid area of northern Ethiopia (e.g., Nyssen et al, 2007;Taye et al, 2013) as soil erosion here is relatively low. The effectiveness of 1-m-wide grass contour strips in SY reduction was also supported by Mekonnen et al (2016) who reported SY reductions due to implementing indigenous grass strips in northwestern Ethiopia.…”

Section: Impact Of Alternative Land Management Scenariosmentioning

confidence: 99%

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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“…Therefore, the objective of this study is directed toward more understanding the characteristics of interannual variability of rainfall in the country and investigating clearly the influence of global SSTs on Ethiopian rainfall peaks at various regions and seasons (summer and spring), to reinforce the skill of rainfall predictions that would be valuable for operations of reservoirs [22], assessment and allocation of water resources [23,24], and for mitigation of disasters related to rainfall such as flooding and drought [25]. Also, better understanding of the rainfall variability plays a key role in several applications including hydrological analysis [26][27][28][29][30][31] and soil erosion risk assessment [32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Seasonal Rainfall Variability in Ethiopia and Its Long-Term Link to Global Sea Surface Temperatures

Alhamshry

Fenta

Yasuda

et al. 2019

Water

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Investigating the influence of sea surface temperatures (SSTs) on seasonal rainfall is a crucial factor for managing Ethiopian water resources. For this purpose, SST and rainfall data were used to study a wide range of inhomogeneous areas in Ethiopia with uneven distribution of rainfall for both summer and spring seasons. Firstly, a preliminary subdivision of rainfall grid points into zones was applied depending on spatial homogeneity and seasonality of rainfall. This introduced new clusters, including nine zones for summer rainfall peak (July/August) and five zones for spring rainfall peak (April/May). Afterward, the time series for each zone was derived by calculating the rainfall averaged over grid points within the zone. Secondly, the oceanic regions that significantly correlated with the Ethiopian rainfall were identified through cross-correlations between rainfalls averaged over every homogeneous zone and the monthly averaged SST. For summer rainfall as a main rainy season, the results indicated that the Gulf of Guinea and southern Pacific Ocean had a significant influence on rainfall zones at a lag time of 5-6 and 6-7 months. Besides, for summer rainfall zones 8 and 9 at lag time 5-6 months, the common SST regions of the southern Pacific Ocean showed the opposite sense of positive and negative correlations. Thus, the difference in SSTs between the two regions was more strongly correlated (r ≥ 0.46) with summer rainfall in both zones than others. For the spring season, the results indicated that SST of the northern Atlantic Ocean had a strong influence on spring rainfall zones (3 and 5) at a lag time 6-7 months, as indicated by a significant correlation (r ≥ −0.40). Therefore, this study suggests that SSTs of southern Pacific and northern Atlantic oceans can be used as effective inputs for prediction models of Ethiopian summer and spring rainfalls, respectively.

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Effects of land use and sustainable land management practices on runoff and soil loss in the Upper Blue Nile basin, Ethiopia

Cited by 133 publications

References 54 publications

Effects of Land Use and Topographic Position on Soil Organic Carbon and Total Nitrogen Stocks in Different Agro-Ecosystems of the Upper Blue Nile Basin

Effects of Land Use and Topographic Position on Soil Organic Carbon and Total Nitrogen Stocks in Different Agro-Ecosystems of the Upper Blue Nile Basin

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

Seasonal Rainfall Variability in Ethiopia and Its Long-Term Link to Global Sea Surface Temperatures

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