scholarly journals Streamflow and Sediment Yield Prediction for Watershed Prioritization in the Upper Blue Nile River Basin, Ethiopia

Water ◽  
2017 ◽  
Vol 9 (10) ◽  
pp. 782 ◽  
Author(s):  
Gebiaw Ayele ◽  
Engidasew Teshale ◽  
Bofu Yu ◽  
Ian Rutherfurd ◽  
Jaehak Jeong

Inappropriate use of land and poor ecosystem management have accelerated land degradation and reduced the storage capacity of reservoirs. To mitigate the effect of the increased sediment yield, it is important to identify erosion-prone areas in a 287 km2 catchment in Ethiopia. The objectives of this study were to: (1) assess the spatial variability of sediment yield; (2) quantify the amount of sediment delivered into the reservoir; and (3) prioritize sub-catchments for watershed management using the Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated using SUFI-2, GLUE, ParaSol, and PSO SWAT-CUP optimization algorithms. For most of the SWAT-CUP simulations, the observed and simulated river discharge were not significantly different at the 95% level of confidence (95PPU), and sources of uncertainties were captured by bracketing more than 70% of the observed data. This catchment prioritization study indicated that more than 85% of the sediment was sourced from lowland areas (slope range: 0–8%) and the variation in sediment yield was more sensitive to the land use and soil type prevailing in the area regardless of the terrain slope. Contrary to the perception of the upland as an important source of sediment, the lowland in fact was the most important source of sediment and should be the focus area for improved land management practice to reduce sediment delivery into storage reservoirs. The research also showed that lowland erosion-prone areas are typified by extensive agriculture, which causes significant modification of the landscape. Tillage practice changes the infiltration and runoff characteristics of the land surface and interaction of shallow groundwater table and saturation excess runoff, which in turn affects the delivery of water and sediment to the reservoir and catchment evapotranspiration.

Land ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 650
Author(s):  
Wakjira Takala Dibaba ◽  
Tamene Adugna Demissie ◽  
Konrad Miegel

Excessive soil loss and sediment yield in the highlands of Ethiopia are the primary factors that accelerate the decline of land productivity, water resources, operation and function of existing water infrastructure, as well as soil and water management practices. This study was conducted at Finchaa catchment in the Upper Blue Nile basin of Ethiopia to estimate the rate of soil erosion and sediment loss and prioritize the most sensitive sub-watersheds using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was calibrated and validated using the observed streamflow and sediment data. The average annual sediment yield (SY) in Finchaa catchment for the period 1990–2015 was 36.47 ton ha−1 yr−1 with the annual yield varying from negligible to about 107.2 ton ha−1 yr−1. Five sub-basins which account for about 24.83% of the area were predicted to suffer severely from soil erosion risks, with SY in excess of 50 ton ha−1 yr−1. Only 15.05% of the area within the tolerable rate of loss (below 11 ton ha−1yr−1) was considered as the least prioritized areas for maintenance of crop production. Despite the reasonable reduction of sediment yields by the management scenarios, the reduction by contour farming, slope terracing, zero free grazing and reforestation were still above the tolerable soil loss. Vegetative contour strips and soil bund were significant in reducing SY below the tolerable soil loss, which is equivalent to 63.9% and 64.8% reduction, respectively. In general, effective and sustainable soil erosion management requires not only prioritizations of the erosion hotspots but also prioritizations of the most effective management practices. We believe that the results provided new and updated insights that enable a proactive approach to preserve the soil and reduce land degradation risks that could allow resource regeneration.


Heliyon ◽  
2019 ◽  
Vol 5 (7) ◽  
pp. e02106 ◽  
Author(s):  
J. Daramola ◽  
T.M. Ekhwan ◽  
J. Mokhtar ◽  
K.C. Lam ◽  
G.A. Adeogun

Hydrology ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 75
Author(s):  
Ryan T. Bailey ◽  
Katrin Bieger ◽  
Jeffrey G. Arnold ◽  
David D. Bosch

Watershed models are used worldwide to assist with water and nutrient management under conditions of changing climate, land use, and population. Of these models, the Soil and Water Assessment Tool (SWAT) and SWAT+ are the most widely used, although their performance in groundwater-driven watersheds can sometimes be poor due to a simplistic representation of groundwater processes. The purpose of this paper is to introduce a new physically-based spatially-distributed groundwater flow module called gwflow for the SWAT+ watershed model. The module is embedded in the SWAT+ modeling code and is intended to replace the current SWAT+ aquifer module. The model accounts for recharge from SWAT+ Hydrologic Response Units (HRUs), lateral flow within the aquifer, Evapotranspiration (ET) from shallow groundwater, groundwater pumping, groundwater–surface water interactions through the streambed, and saturation excess flow. Groundwater head and groundwater storage are solved throughout the watershed domain using a water balance equation for each grid cell. The modified SWAT+ modeling code is applied to the Little River Experimental Watershed (LREW) (327 km2) in southern Georgia, USA for demonstration purposes. Using the gwflow module for the LREW increased run-time by 20% compared to the original SWAT+ modeling code. Results from an uncalibrated model are compared against streamflow discharge and groundwater head time series. Although further calibration is required if the LREW model is to be used for scenario analysis, results highlight the capabilities of the new SWAT+ code to simulate both land surface and subsurface hydrological processes and represent the watershed-wide water balance. Using the modified SWAT+ model can provide physically realistic groundwater flow gradients, fluxes, and interactions with streams for modeling studies that assess water supply and conservation practices. This paper also serves as a tutorial on modeling groundwater flow for general watershed modelers.


2011 ◽  
Vol 47 (2) ◽  
pp. 339-356 ◽  
Author(s):  
MWANGI GATHENYA ◽  
HOSEA MWANGI ◽  
RICHARD COE ◽  
JOSEPH SANG

SUMMARYClimate change and land use change are two forces influencing the hydrology of watersheds and their ability to provide ecosystem services, such as clean and well-regulated streamflow and control of soil erosion and sediment yield. The Soil Water Assessment Tool, SWAT, a distributed, watershed-scale hydrological model was used with 18 scenarios of rainfall, temperature and infiltration capacity of land surface to investigate the spatial distribution of watershed services over the 3587 km2 Nyando basin in Western Kenya and how it is affected by these two forces. The total annual water yield varied over the 50 sub-basins from 35 to 600 mm while the annual sediment yield ranged from 0 to 104 tons ha−1. Temperature change had a relatively minor effect on streamflow and sediment yield compared to change in rainfall and land surface condition. Improvements in land surface condition that result in higher infiltration are an effective adaptation strategy to moderate the effects of climate change on supply of watershed services. Spatial heterogeneity in response to climate and land use change is large, and hence it is necessary to understand it if interventions to modify hydrology or adapt to climate change are to be effective.


2020 ◽  
Author(s):  
Peter Jeffrey Maloles ◽  
Adonis Gallentes ◽  
Cesar Villanoy

<p>The Philippines is known for its rich marine biodiversity and is deemed as the apex of the world’s coral triangle. However, sediment yield studies and river discharge measurements in the country are sparse if not non-existent. High sediment rates have detrimental effects on water quality and consequently to coral reef health and marine biodiversity. Thus, modeling of runoff and sediment yield at a watershed level is important in assessing coral community environments.</p><p>In this study, a Soil and Water Assessment Tool (SWAT) based sediment yield simulation was done for Lanuza Bay-- a site with high productivity but increasing mining activity. Two simulations were conducted. The first utilized a land-use map before January 2011 and was made to run from January 1998 to August 2018 in order to simulate a scenario in which mining operations did not occur in the area. The second simulation utilized an updated land-use map that incorporated mining sites from January 2011 to August 2018.</p><p>SWAT model results indicate that slope class was the primary determinant of erosion rates (slope band > 20%). The study suggests that consecutive precipitation occurrences affected soil erodability and induced a time lag between precipitation and sediment yield peaks. The highest contributors to sediment yield at a sub-basin level were identified to be areas adjacent to or coinciding in mining or excavation sites. Comparing the scenarios with and without mining, mining contributed to 4% of the increase in the watershed’s total annual sediment yield.</p><p>Qualitative and historical validation shows reasonable agreement between simulated values and satellite images. The output of this study can be used as a science-based reference in crafting laws and policies for land-use management and Marine Protected Area (MPA) planning.</p>


Author(s):  
Cihangir Koycegiz ◽  
Meral Buyukyildiz ◽  
Serife Yurdagul Kumcu

Abstract There are many empirical, semi-empirical and mathematical methods that have been developed to estimate sediment yield by researchers. In the last decades, the advancement in computer technologies has increased the use of mathematical models as they can solve the system more rapidly and accurately. The Soil and Water Assessment Tool (SWAT) is one of the physically based hydrological models that is preferred to compute sediment yield. In this study, spatial and temporal analysis of sediment yield in the Çarşamba Stream located at the Konya Closed Basin has been investigated using the SWAT model. Streamflow and sediment data collected during the 2003–2015 time period have been used in the analysis. Consequently, the SWAT presented satisfactory results compared with R2 = 0.68, Nash–Sutcliffe Efficiency (NSE) = 0.68 in calibration and R2 = 0.76, NSE = 0.66 in validation. According to the model results, spatial asymmetry in terms of sediment yield was determined in the sub-basins of the study area.


2015 ◽  
Vol 737 ◽  
pp. 762-765 ◽  
Author(s):  
Yuan Yuan Han ◽  
Tao Cai

To investigate the impacts of land-use patterns on the sediment yield characteristics in the upper Huaihe River, Xixian hydrological controlling station was selected as the case study site. Soil and Water Assessment Tool (SWAT) model was used to simulate land-use change effects on sediment yield by the use of three-phase (1980s, 1990s and 2000s) land-use maps, soil type map (1:200000) and 1987 to 2008 daily time series of rainfall from the upper Huaihe River basin. On the basis of the simulated time series of daily sediment concentration, land-use change effects on spatio-temporal change patterns of soil erosion modulus. The results revealed that under the same condition of soil texture and terrain slope the advantage for sediment yield was descended by woodland, paddy field and farmland. The outputs of the paper could provide references for soil and water conservation and river health protection in the upper stream of Huaihe River.


Author(s):  
Sarvat Gull ◽  
Shagoofta Rasool Shah

Abstract The conjunction of heavy snowfall during winters and intensive rainfall during monsoons along with the mountainous topography expose the Lidder watershed to serious erosion and flood aggravation issues. Barely any attempts have been made for an in-depth examination of Lidder watershed for precise estimation of sub-basin level runoff and erosion. In this study Soil and Water Assessment Tool (SWAT) was calibrated using Sequential Uncertainty Fitting algorithm (SUFI-2) for modelling streamflow and sediment yield of the Lidder watershed. Daily runoff and sediment event data from 2003–2013 were used in this study; data from 2003–2008 was used for calibration and 2009–2013 for validation. Model performance was evaluated using various statistical tools which showed good results revealing excellent potential of SWAT model to simulate streamflow and sediment yield for both calibration and validation periods. The annual rate of average upland sediment drawn from the watershed was approximately 853.96 Mg/ha for an average surface runoff of 394.15 mm/year. This study identifies the vulnerable areas of the Lidder watershed which can be thoroughly examined by decision-makers for effective management and planning. Further, the calibrated model can be applied to other watersheds with similar characterization to influence strategies in the management of watershed processes.


2018 ◽  
Vol 30 (3) ◽  
Author(s):  
Ayodele Olanrewaju Ogunlela ◽  
Odunayo Babatunde Omole ◽  
Kamorudeen Olaniyi Yusuf

Reservoir sedimentation is a serious problem that normally reduces the capacity of a dam (reservoir) for water storage over a given period of time. This can lead to insufficient availability of water for domestic uses, irrigation and hydropower. This study was conducted to determine the rate of sedimentation, sediment yield and the capacity of the University of Ilorin dam (Ilorin, Nigeria) between June 2007 and June 2014. Geographic Information System (GIS), Global Positioning System (GPS), canoe and lead-line techniques were used for the measurement of depth of the reservoir of the dam. Soil and Water Assessment Tool (SWAT) model was used to simulate the sediment yield. The initial capacity of the dam after construction in 2007 was 1.800 x 106 m3 but this capacity was reduced to 1.411 x 106 m3 in 2014 due to sedimentation. The sediment was found to be clay soil which covered 389,170 m3 of the reservoir and the mean bulk density of the clay soil sediment was 1139 kg/m3. The mean values of clay, silt and sand contents of the sediment yield were 46.5, 35.6 and 17.9 %, respectively. The annual sediment yield was high in the reservoir due to farming activities at the upstream end of the dam, annual rate of sedimentation was 12.78 m3/ha/yr and sediment yield was 14,557.14 kg/ha/yr. Farming activities should be prevented at the upstream of the dam and dredging should be done every 10 years when 30.87% of the storage capacity would be occupied by sediment.


2020 ◽  
Vol 5 (2) ◽  
pp. 194-206
Author(s):  
Carolyne Wanessa Lins de Andrade Farias ◽  
Suzana Maria Gico Lima Montenegro ◽  
Abelardo Antônio de Assunção Montenegro ◽  
José Romualdo de Sousa Lima ◽  
Raghavan Srinivasan ◽  
...  

Land-use change has a significant influence on runoff process of any watershed, and the deepening of this theme is essential to assist decision making, within the scope of water resources management. The study was conducted for Mundaú River Basin (MRB) using the Soil and Water Assessment Tool (SWAT) model. The study aims to assess the issue of land-use change and its effect on evapotranspiration, surface runoff, and sediment yield. Input data like land use, topography, weather, and soil data features are required to undertake watershed simulation. Two scenarios of land use were analyzed over 30 years, which were: a regeneration scenario (referring to use in the year 1987) and another scene of degradation (relating to use in the year 2017). Land use maps for 1987 and 2017 were acquired from satellite images. Overall, during the last three decades, 76.4% of forest was lost in the MRB. The grazing land increased in 2017 at a few more than double the area that existed in 1987. Changes in land use, over the years, resulted in an increase of about 37% in the water yield of MRB. Changes have led to increased processes such as surface runoff and sediment yield and in the decrease of evapotranspiration. The spatial and temporal distribution of land use controls the water balance and sediment production in the MRB.


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