Stormwater Modeling in a Steep, Poorly Drained Contributing Micro-Watershed Zone of Addis Ababa
MSU Affiliation
College of Forest Resources; Department of Wildlife, Fisheries and Aquaculture
Creation Date
2025-11-03
Abstract
Urban micro-watersheds with steep slopes and poorly draining soils generate excessive runoff and pollutant loads, posing significant management challenges. This study introduces a novel focus on a contributing zone within a 30-ha micro-watershed in Addis Ababa to assess how climate change, urbanization and their combined effects influence stormwater runoff and water quality. The Personal Computer Stormwater Management Model (PCSWMM) was employed to simulate four scenarios: baseline, climate change, urbanization, and combined impacts. The baseline model was calibrated and validated with observed storm data using the Sensitivity-Based Radio Tuning Calibration (SRTC) tool, achieving Nash–Sutcliffe Efficiency (NSE), Root Mean Square Error (RMSE)-standard deviation ratio (RSR), and Integral Square Error (ISE) values within accepted thresholds. Over a 3-h, 6,870 m3 storm, 72% became surface runoff, 18.2% infiltrated, 2% evaporated, and 6.4% remained in storage, producing a peak flow of 3.6 m3/s and localized node flooding. The climate change scenario employed an ensemble of Global Circulation Models (GCMs)—five for precipitation and seven for temperature—selected from twelve and sixteen models, respectively, based on their statistical performance. Under shared socio-economic pathway (SSP)2–4.5, 2-year return period peak flows increased to 3.8 m3/s (2024–2053) and 4.7 m3/s (2054–2083); under SSP5-8.5, they rose to 5.8 m3/s and 6.6 m3/s, respectively. An 80% imperviousness urbanization scenario increased peak flow to 4.1 m3/s. The combined scenario yielded a peak of 7.2 m3/s and a 10.3% pollutant load increase, which were (1.7%: climate change, and 7.1%: urbanization alone), highlighting urbanization as the principal driver of water quality decline. These findings highlight the need for integrated green–grey infrastructure (IGGI) and upgraded drainage systems to strengthen urban resilience. The study supports data-driven planning and advances sustainable development goals (SDGs) 6 (clean water and sanitation), 11 (sustainable cities and communities), and 13 (climate action).
Publication Date
9-9-2025
Publication Title
Earth Systems and Environment
Publisher
Springer
Recommended Citation
Kemal, B., Hailu, D., Fekersillassie, D. et al. Stormwater Modeling in a Steep, Poorly Drained Contributing Micro-Watershed Zone of Addis Ababa. Earth Syst Environ (2025). https://doi.org/10.1007/s41748-025-00765-1
