Prediction of soil and water conservation structure impacts on runoff and erosion processes using SWAT model in the northern Ethiopian highlands

Abstract

Purpose Land degradation due to soil erosion is a serious threat to the highlands of Ethiopia. Various soil and water conservation (SWC) strategies have been in use to tackle soil erosion. However, the effectiveness of SWC measures on runoff dynamics and sediment load in terms of their medium-and short-term effects has not been sufficiently studied. Materials and methods A study was conducted in 2011 to 2015 in the Gumara-Maksegnit watershed to study the impacts of SWC structures on runoff and soil erosion processes using the soil and water analysis tool (SWAT) model. The study was conducted in two adjacent watersheds where in one of the watersheds, SWC structures were constructed (treated watershed (TW)) in 2011, while the other watershed was a reference watershed without SWC structures (untreated watershed (UW)). For both watersheds, separate SWAT and SWAT-CUP (SWAT calibration and uncertainty procedure) projects were set up for daily runoff and sediment yield. The SWAT-CUP program was applied to optimize the parameters of the SWAT using daily observed runoff and sediment yield data. Results and discussion The runoff simulations indicated that SWAT can reproduce the hydrological regime for both watersheds. The daily runoff calibration (2011)(2012)(2013) results for the TW and UW showed good correlation between the predicted and the observed data (R 2 = 0.78 for the TW and R 2 = 0.77 for the UW). The validation (2014)(2015) results also showed good correlation with R 2 values of 0.72 and 0.70 for the TW and UW, respectively. However, sediment yield calibration and validation results showed modest correlation between the predicted and observed sediment yields with R 2 values of 0.65 and 0.69 for the TW and UW for the calibration and R 2 values of 0.55 and 0.65 for the TW and UW for the validation, respectively. Conclusions The model results indicated that SWC structures considerably reduced soil loss by as much as 25-38% in the TW. The study demonstrated that SWAT performed well for both watersheds and can be a potential instrument for upscaling and assessing the impact of SWC structures on sediment loads in the highlands of Ethiopia.

Micro-Watershed Management for Erosion Control Using Soil and Water Conservation Structures and SWAT Modeling

“…This is the first study in this area where the SWAT model has been used for the evaluation of effectiveness of soil and water conservation structures for soil erosion control. For this purpose, appropriate parameters responsible for soil erosion were modified according to the type of soil and water conservation structures, as performed by different researchers in literature such as Betrie et al [61] in the Upper Blue Nile River basin, Gebremichael et al [66] in the northern part of Ethiopia, and Melaku et al [38] in the Gumara Maksegnit watershed in northwest Ethiopia. The SWAT model has been found to be a useful tool for understanding the hydrologic processes and the sediment dynamic in the study area watersheds, and it assessed the impacts of soil and water conservation structures on the erosion process.…”

“…This validated model was further modified for the application of soil and water conservation structures, eventually to be recommended by this study as a strategy to counteract the soil erosion with soil and conservation structures at a broader scale. Several studies related to soil and water conservation intervention were carried out to control soil erosion at the field and sub-watershed scale within the Gumara-Maksegnit watershed in the northern Highlands of Ethiopia [35][36][37], while Melaku et al predicted the impact of soil and water conservation structures on runoff and erosion processes using the SWAT model [38]. However, studies on the impacts of soil and water structures on the erosion process at the watershed scale that have used the SWAT model have been limited.…”

Predicting nitrous oxide emissions after the application of solid manure to grassland in the United Kingdom

“…The SWAT model (Arnold et al., ) is a continuous, semidistributed, process‐based watershed‐scale model. The model requires climate, soil, land cover, and land management data to simulate surface and subsurface hydrology, various chemicals, nutrients, and sediment fluxes (Addis, Strohmeier, Ziadat, Melaku, & Klik, ; Melaku et al., ; Melaku & Wang, ). Although the model considers both nitrification and denitrification processes in its nitrogen cycle, the amount of N 2 O emitted during these processes is not explicitly reported in the original version of the model.…”

Prioritization of critical source areas for soil and water conservation by using a one‐at‐a‐time removal approach in the upper Huaihe River basin

“…Statistics also show that there are nearly 5 billion tons of soil lost per year in China, which account for 20% of the global total losses. Soil erosion washes away the fertile topsoil, reduces the land productivity, accelerates the desertification, pollutes waterways and induces flooding, thus threatening the ecological environment, society, and economic (Melaku et al, 2018; Ricci, Girolamo, Abdelwahab, & Gentile, 2018; Zhao, Mu, Wen, Wang, & Gao, 2013).…”