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WuhaSense

Satellite screening of industrial water pollution in Ethiopia’s Upper Awash basin.

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Research & development · Ethiopia

Screening industrial discharge from orbit: a first look at Koka Reservoir

WuhaSense is our research into satellite screening of industrial wastewater discharge in Ethiopia’s Upper Awash basin. This page shares a preliminary analysis of the Copernicus Sentinel-2 archive over Koka Reservoir from January 2023 to September 2026. It has not yet been validated against measurements on the ground.

Why the Upper Awash

Ethiopia’s industrial heartland

The Awash is Ethiopia’s most utilized river basin,1 and more than 65% of the country’s industries are located in it, with Addis Ababa’s industrial corridor in the Upper Awash.2,4

A lifeline for millions

The basin provides water for 18.6 million people, 34.4 million livestock and nearly 200,000 hectares of irrigated land.1

Industry upstream of a reservoir

More than 90% of Addis Ababa’s industries discharge waste into nearby rivers without treatment.2 Along the Modjo River, which flows into Koka Reservoir, tanneries dispose of effluent while farmers irrigate vegetables from the same water.3,5

  1. Awash Basin Authority (2017). Awash Basin Water Allocation Strategic Plan. Ministry of Water, Irrigation and Electricity, Ethiopia.
  2. Assegide, E. et al. (2022). A synthesis of surface water quality in Awash Basin, Ethiopia. Frontiers in Water 4. doi:10.3389/frwa.2022.782124
  3. Tekile, A. K. (2023). Suitability assessment of surface water quality for irrigation: a case study of Modjo River, Ethiopia. Journal of Environmental and Public Health. doi:10.1155/2023/1482229
  4. Hailu, K. et al. (2024). Tracing contaminants of emerging concern in the Awash River basin, Ethiopia. Journal of Hydrology: Regional Studies 54, 101869. doi:10.1016/j.ejrh.2024.101869
  5. Tarekegn, M. M., Melka, A. R. and Alemayehu, Y. A. (2025). Dietary exposure and health risk assessment of heavy metal bioaccumulation in edible tissues of common carp (Cyprinus carpio) from Koka Reservoir, Ethiopia. Environmental Health Insights 19. doi:10.1177/11786302251403997
Preliminary results

What the archive already shows

We processed every Sentinel-2 acquisition over four zones of Koka Reservoir: two inflow mixing zones, where rivers enter, and two open-water zones used as a reference.

299Sentinel-2 scenes processed
114dates clear enough to use
9dry-weather alerts at the Awash inflow, against fewer than one expected by chance
When the satellite can see: usable observations by calendar month at the selected zone, 2023–2026.

Alert log

Dates when an inflow zone changed sharply while open water stayed normal. Select a row to see it on the chart.

DateZoneWhat changed
When the satellite can see. Usable observations by calendar month, four zones, 2023–2026. Cloud during the June–September rains leaves no usable optical images; October to February gives the most.
Usable Sentinel-2 observations by calendar monthUsable zone-dates per month summed over four Koka zones, 2023 to 2026: Jan 74, Feb 57, Mar 23, Apr 12, May 27, Jun 0, Jul 0, Aug 0, Sep 14, Oct 45, Nov 59, Dec 66.Kiremt rains74Jan57Feb23Mar12Apr27May0Jun0Jul0Aug14Sep45Oct59Nov66Dec
Local change, not basin-wide weather. Turbidity at the Awash inflow (green) against open water in the centre of the reservoir (grey). Highlighted points are alerts, where the inflow changed sharply in colour or turbidity while open water stayed normal. Shaded bands are the June–September rains.
Turbidity at the Awash inflow and in open water, Koka Reservoir, 2023 to 2026Zone-median turbidity from Sentinel-2. The Awash inflow mixing zone is shown against the open-water centre of the reservoir. 9 dates are marked as alerts, where the inflow changed in colour or turbidity while open water stayed normal. Shaded bands are the June to September rains.2050100200500100020002023202420252026Turbidity (FNU, log scale)Alert 2023-02-02Alert 2023-02-12Alert 2023-05-13Alert 2024-02-07Alert 2024-02-17Alert 2024-03-23Alert 2025-02-01Alert 2025-02-06Alert 2026-01-22

Next steps

  • Validate alerts against long-term water quality records and samples taken at the time of satellite overpass.
  • Extend screening from the reservoir to the Akaki and Modjo river reaches.
  • Measure how small a discharge, and how narrow a river, the method can still detect.
  • Develop a proof of concept that turns these alerts into a practical screening service for water and environmental authorities.

Contains modified Copernicus Sentinel data 2023–2026; header image: Sentinel-2, 16 February 2026. Rainfall: CHIRPS, Climate Hazards Center, UC Santa Barbara. Values are screening indicators, not regulatory measurements.

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