Tilahun et al. (2026) Modeling and quantifying surface water resource potential in Awash Bello watershed, Upper Awash River Basin, Ethiopia, using SWAT model

Identification

• Journal: Frontiers in Water
• Year: 2026
• Date: 2026-01-08
• Authors: Rahel Abebe Tilahun, H. Worku, Aramde Fetene Mengistu
• DOI: 10.3389/frwa.2025.1720895

Research Groups

• Department of Urban Engineering and Surveying, College of Urban Studies, Ethiopian Public Service University, Addis Ababa, Ethiopia
• Department of Urban and Regional Planning, College of Technology and Built Environment, Addis Ababa University, Ethiopia

Short Summary

This study quantified the surface water resource potential and its seasonal variation in the Awash Bello watershed, Ethiopia, using the SWAT model, estimating an annual surface runoff of 949.43 million cubic meters. The findings provide crucial insights for sustainable water resource management and planning in the Upper Awash River Basin.

Objective

• To quantify the surface water resource potential, including its seasonal variation and spatial distribution, in the Awash Bello watershed, Upper Awash River Basin, Ethiopia, to inform sustainable water resource management strategies.

Study Configuration

• Spatial Scale: Awash Bello watershed, Upper Awash River Basin, Ethiopia, covering approximately 4,489.96 square kilometers. The watershed was delineated into 35 sub-catchments and 236 Hydrological Response Units (HRUs).
• Temporal Scale: Meteorological data from 1990–2022 (33 years); stream flow data from 1993–2016 (24 years). A 3-year warm-up period (1990–1992) was used, followed by calibration (1993–2008) and validation (2009–2016).

Methodology and Data

• Models used: Soil and Water Assessment Tool (SWAT) model (ArcGIS 10.4.1, Arc SWAT 2012, SWAT-CUP with SUFI-2 algorithm). Supporting tools included SWAT-Checker and WGEN.
• Data sources:
  • Spatial data: 30 meter × 30 meter resolution Digital Elevation Model (DEM) from earthexplorer.usgs.gov, Land Use/Land Cover (LULC) map from Water and Land Resource Center (WLRC), soil map from Harmonized World Soil Database (fao.org/soils-portal), and slope map derived from the DEM.
  • Meteorological data: Daily time series (1990–2022) for precipitation (PCP), temperature (TMP), solar radiation (SLR), humidity (HMD), and wind speed (WND) from 14 rain gauges provided by the Ethiopia Meteorological Institute (EMI).
  • Hydrological data: Monthly average stream flow data (1993–2016) from 5 gauging stations, primarily the Melka Kunture gauge station, provided by the Ministry of Water Irrigation and Electricity (MoWIE).

Main Results

• The Awash Bello watershed, with an area of 4,489.96 square kilometers, has an estimated annual surface runoff of 949.43 million cubic meters, corresponding to an annual runoff depth of 211.46 millimeters from a total annual rainfall of 1,074.78 millimeters.
• Seasonal variations show the "Kiremt" (June–September) rainy season contributing 71.21% of the annual rainfall (765.35 millimeters) and 161.67 millimeters of runoff depth. The "Belg" (February–May) season contributes 23.21% of rainfall (249.49 millimeters) and 34.29 millimeters of runoff depth, while the "Bega" (October–January) season contributes only 5.58% of rainfall (59.94 millimeters) and 15.5 millimeters of runoff depth.
• Key water balance ratios include a stream flow/precipitation ratio of 0.32, a base flow/total flow ratio of 0.38, a surface runoff/total flow ratio of 0.62, and an evapotranspiration/precipitation ratio of 0.63.
• The SWAT model demonstrated strong performance during calibration (Nash–Sutcliffe Efficiency (NSE) = 0.80, R² = 0.80, Percent Bias (PBIAS) = -11.1%) and good performance during validation (NSE = 0.63, R² = 0.66, PBIAS = -12.1%).
• The most sensitive parameters influencing stream flow were identified as soil depth (SOLZ), SCS runoff curve number (CN2), deep aquifer percolation fraction (RCHRGDP), threshold depth of water in shallow aquifer for return flow (GWQMN), and available water capacity of the soil layer (SOL_AWC).
• Spatial distribution of average annual surface runoff revealed that 53.42% of the watershed area falls into the low runoff category (50–150 cubic meters per second), with 19.67% having very low runoff (0–50 cubic meters per second), 19.8% moderate runoff (150–400 cubic meters per second), and 7.11% high runoff (>400 cubic meters per second).

Contributions

• Quantified the surface water potential, including its seasonal variation and spatial distribution, in the Awash Bello watershed, addressing existing research gaps in the Upper Awash River Basin.
• Enhanced the accuracy and reliability of the SWAT model through rigorous sensitivity analysis, calibration, and validation using comprehensive and recent hydrological and meteorological datasets.
• Provided essential data and insights for water resource management sectors, stakeholders, and policymakers to formulate long-term strategies for sustainable water resource planning and allocation in the region.

Funding

• Addis Ababa University provided funds for this study.

Citation

@article{Tilahun2026Modeling,
  author = {Tilahun, Rahel Abebe and Worku, H. and Mengistu, Aramde Fetene},
  title = {Modeling and quantifying surface water resource potential in Awash Bello watershed, Upper Awash River Basin, Ethiopia, using SWAT model},
  journal = {Frontiers in Water},
  year = {2026},
  doi = {10.3389/frwa.2025.1720895},
  url = {https://doi.org/10.3389/frwa.2025.1720895}
}