scholarly journals Sediment Yield and Reservoir Sedimentation in Highly Dynamic Watersheds: The Case of Koga Reservoir, Ethiopia

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3374
Author(s):  
Gebiaw T. Ayele ◽  
Alban Kuriqi ◽  
Mengistu A. Jemberrie ◽  
Sheila M. Saia ◽  
Ayalkibet M. Seka ◽  
...  
Keyword(s):  
Water Management ◽  
Land Use ◽  
Sediment Yield ◽  
Management Practices ◽  
Sediment Load ◽  
Reservoir Sedimentation ◽  
Rating Curve ◽  
Management Decisions ◽  
Management Interventions ◽  
Land And Water Management

Soil erosion is exacerbated by unsustainable land-use activities and poor management practices, undermining reservoir storage capacity. To this effect, appropriate estimation of sediment would help to adopt sustainable land-use activities and best management practices that lead to efficient reservoir operations. This paper aims to investigate the spatial variability of sediment yield, amount of sediment delivery into the reservoir, and reservoir sedimentation in the Koga Reservoir using the Soil and Water Assessment Tool (SWAT). Sediment yield and the amount entered into the reservoir were also estimated using a rating curve, providing an alternative approach to spatially referenced SWAT generated suspended sediment load. SWAT was calibrated from 1991 to 2000 and validated from 2002 to 2007 using monthly observations. Model performance indicators showed acceptable values using Nash-Sutcliffe efficiency (NSE) correlation coefficient (R2), and percent bias (PBIAS) for flow (NSE = 0.75, R2 = 0.78, and PBIAS = 11.83%). There was also good agreement between measured and simulated sediment yields, with NSE, R2, and PBIAS validation values of 0.80, 0.79, and 6.4%, respectively. The measured rating curve and SWAT predictions showed comparable mean annual sediment values of 62,610.08 ton/yr and 58,012.87 ton/yr, respectively. This study provides an implication for the extent of management interventions required to meet sediment load targets to a receiving reservoir, providing a better understanding of catchment processes and responses to anthropogenic and natural stressors in mixed land use temperate climate catchments. Findings would benefit policymakers towards land and water management decisions and serve as a prototype for other catchments where management interventions may be implemented. Specifically, validating SWAT for the Koga Reservoir is a first step to support policymakers, who are faced with implementing land and water management decisions.

scholarly journals Review of Lessons Learned in Changing Agricultural Landscapes in Ethiopia: What Worked Well and What Didn’t Work so Well?

2020 ◽  
Author(s):  
Amare Haileslassie ◽  
Wolde Mekuria ◽  
Petra schmitter ◽  
Stefan Uhlenbrook ◽  
Eva Ludi
Keyword(s):  
Water Management ◽  
Management Practices ◽  
Local Community ◽  
Agricultural Landscape ◽  
Economic Benefits ◽  
Agricultural Landscapes ◽  
Lessons Learned ◽  
Management Interventions ◽  
Land And Water Management ◽  
The Impact

Ethiopia has decades of experience in implementing land and water management interventions. Nonetheless, there remains persisting challenges to follow an adaptive management (AM) approach in efforts of restoring and transforming agricultural landscapes. This review was carried out to synthesize evidences on the impact on agricultural landscapes following the implementation of land and water management practices and to evaluate the use of AM approaches. We explored how elements of the structures and functions of landscapes have been transformed, and how the components of AM, such as structured decision-making and learning processes, have been applied. Despite numerous environmental and economic benefits of land and water management interventions in Ethiopia, this review revealed gaps in AM approaches. These include: (i) insufficient efforts in relation to evidence based contextualization of interventions, (ii) insufficient efforts in monitoring of bio-physical and socio-economic processes and changes post implementation, (iii) lack of trade-off analyses, and (iv) inadequacy of local community engagement and provision of feedback. Given the many uncertainties we must deal with, efforts to restore and transform agricultural landscapes cannot follow a business-as-usual approach. Future investment, in AM approach, tailored to the needs and context would help to achieve the goals of sustainable agricultural landscape transformation. The success depends on three interdependent pillars of action: the ability to make a robust, co-developed plan of interventions, the ability to continuously monitor changes based on key variables, and to learn from the knowledge generated and apply the learning as implementation evolves.

scholarly journals Changing Agricultural Landscapes in Ethiopia: Examining Application of Adaptive Management Approach

2020 ◽  
Vol 12 (21) ◽  
pp. 8939
Author(s):  
Amare Haileslassie ◽  
Wolde Mekuria ◽  
Petra Schmitter ◽  
Stefan Uhlenbrook ◽  
Eva Ludi
Keyword(s):  
Water Management ◽  
Adaptive Management ◽  
Management Practices ◽  
Local Community ◽  
Economic Benefits ◽  
Agricultural Landscapes ◽  
Management Approach ◽  
Management Interventions ◽  
Land And Water Management ◽  
The Impact

Ethiopia has decades of experience in implementing land and water management interventions. The overarching objectives of this review were to synthesize evidences on the impact of implementation of land and water management practices on agricultural landscapes in Ethiopia and to evaluate the use of adaptive management (AM) approaches as a tool to manage uncertainties. We explored how elements of the structures and functions of landscapes have been transformed, and how the components of AM, such as structured decision-making and learning processes, have been applied. Despite numerous environmental and economic benefits of land and water management interventions in Ethiopia, this review revealed gaps in AM approaches. These include: (i) inadequate evidence-based contextualization of interventions, (ii) lack of monitoring of bio-physical and socioeconomic processes and changes post implementation, (iii) lack of trade-off analyses, and (iv) inadequacy of local community engagement and provision of feedback. Given the many uncertainties we must deal with, future investment in AM approaches tailored to the needs and context would help to achieve the goals of sustainable agricultural landscape transformation. The success depends, among other things, on the ability to learn from the knowledge generated and apply the learning as implementation evolves

scholarly journals Temporal variability and time compression of sediment yield in small Mediterranean catchments: impacts for land and water management

2018 ◽  
Vol 34 (3) ◽  
pp. 388-403 ◽  
Author(s):  
A. Smetanová ◽  
Y. Le Bissonnais ◽  
D. Raclot ◽  
J. Pedro Nunes ◽  
F. Licciardello ◽  
...  
Keyword(s):  
Water Management ◽  
Sediment Yield ◽  
Temporal Variability ◽  
Time Compression ◽  
Land And Water Management

scholarly journals Hydrogeology of Volcanic Highlands Affects Prioritization of Land Management Practices

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2702 ◽  
Author(s):  
Anwar A. Adem ◽  
Gashaw G. Addis ◽  
Dessalew W. Aynalem ◽  
Seifu A. Tilahun ◽  
Wolde Mekuria ◽  
...  
Keyword(s):  
Water Management ◽  
Soil Degradation ◽  
Management Practices ◽  
Potable Water ◽  
Water Source ◽  
Sediment Concentration ◽  
Agricultural Watershed ◽  
Land And Water Management ◽  
High Sediment ◽  
Tertiary Basalt

Volcanic highlands supply water to 40% of the world’s population. Soil degradation threatens this water supply. Studies on geohydrology that affect the effectiveness of land and water management (LWM) practices in reducing soil degradations are limited. To aid in the effectiveness of LWM practices, we conducted a field experiment in the Gomit watershed in the semihumid Ethiopian Highlands on the interaction of hydrogeology and LWM practices. We found that in a watershed with strongly faulted tertiary basalt, 30% of the rainfall was drained through faults to another basin. Consequently, the discharge at the outlet was less than half of that of other watersheds with quaternary basalts. Despite the high sediment concentration, i.e., around 15 g L−1, in the Gomit watershed, the sediment yield of less than 4 Mg ha−1 a−1 was below average for the agricultural watershed in Ethiopia because of the low runoff response. While some faults facilitated drainage, others acted as a barrier. Groundwater stored behind the barriers was used as a municipal potable water source. Since the effectiveness of LWM practices depends on the amount of erosion that can be prevented, considerations of country-wide prioritizing of investments in land and water management practices should include the geology of the watersheds.

Spatio-temporal analysis of soil erosion in Tokoro river watershed in eastern Hokkaido, Japan

2021 ◽  
Author(s):  
Kunihito Mihara ◽  
Kanta Kuramochi ◽  
Ryusuke Hatano
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Sediment Yield ◽  
Surface Runoff ◽  
Stream Flow ◽  
Erosion Rate ◽  
Sediment Load ◽  
Agricultural Lands ◽  
Sediment Movement ◽  
Water And Sediment

<p>Introduction</p><p>Accelerated erosion by human activities leads to degradation of soil ecosystem services and aquatic environment. It is unavoidable issue in Japan because it holds many sloped agricultural lands. Tokoro river watershed, TRW, in eastern Hokkaido, Japan has unique climate characterized with the least precipitation in Japan and cold winter with little snow which induces soil freezing. Frozen subsoil forms impermeable layers to increase surface runoff in early spring. The objectives of this study were i) to understand the spatial and seasonal variation of water and sediment movement in TRW using Soil and Water Assessment Tool, SWAT which is a process-based hydrological model and ii) to evaluate the impact of agricultural activities, topography of agricultural lands, and runoff characteristics on soil erosion through identification of highly erosive areas and seasons based on the simulation output.</p><p>Materials and methods</p><p>Water and sediment movement in TRW was simulated from 2011/1/1 to 2015/12/31. SWAT calculates water and sediment movement processes using spatial and temporal information of topography, land use, soil, weather, and land management in watershed. TRW was delineated into 17 subbasins based on topographic information and further divided into 764 HRUs which had homogenous combination of slope class, soil type, and land use in each subbasin. On-land processes were calculated in each HRU. After water and sediment yield from HRUs were summed in each subbasin, stream routing processes were calculated. Model parameters were calibrated so that the estimated stream flow and sediment load at the outlet would fit the measurements. From the simulation by the calibrated model, outputs were extracted as follows: 1) Contribution to the gross sediment yield and erosion rate of each land use; 2) Erosion rate of each subbasin; 3) Erosion rate of whole watershed on each month; and 4) Surface runoff and percentage of surface runoff in water yield in each month.</p><p>Results and Discussions</p><p>Calibrated SWAT reproduced well the fluctuation of stream flow and sediment load at the outlet of TRW. Although the model underestimated sediment load during large flood events with the average estimation error of -16.1±5.4% on peak-discharge months, it showed satisfactory performance with coefficient of determination: R<sup>2</sup>=0.88, Nash-Sutcliffe efficiency coefficient: Ens=0.86, and percentage of bias: PBIAS=0.34% for monthly sediment load estimation. Agricultural lands which covered 17.6% of the watershed were considered as the primary sediment sources contributing to 68.5% of estimated gross sediment yield of the watershed. Spatial variation of estimated erosion rate showed high sediment yield in the middle- and down-stream area of TRW where agricultural activities were intensive, and higher sediment yield particularly in the area where more agricultural lands had steep slopes (more than 51 t km<sup>-2</sup> yr<sup>-1</sup>). Monthly erosion rate estimation indicated that the most severe erosion occurred on March and April (6.9±1.4 and 7.3±1.9 t km<sup>-2</sup> mon<sup>-1</sup> respectively). On March, average percentage of surface runoff was estimated as 90.5±6.5%. Therefore, surface runoff in early snowmelt season when the frozen subsoil prevented infiltration was considered as an important driver of soil erosion.</p>

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