Citizen science data to improve rainfall-runoff model performance in urbanizing Akaki catchment, Awash Basin, Ethiopia

Abstract

Akaki is a headwater catchment of the Awash River Basin in Ethiopia and hosts Addis Ababa. The catchment remains ungauged despite providing diverse ecosystem services. Studies typically assume that calibrated model parameters remain valid outside the calibration period despite many catchments undergoing anthropogenic change. We evaluated the value of citizen science data to improve a rainfall-runoff model performance in the urbanizing Akaki catchment. Five and nineteen people trained as citizen scientists monitored river stage and rainfall data, respectively, for three years. Rating curves were developed for the conversion of stage data into river flow data. A HEC-HMS model, calibrated for a historical period, was evaluated using citizen science data. Next, we assessed the effectiveness of progressively updating model parameters using a recent land use land cover map and citizen science data. Then, the HEC-HMS model was recalibrated at the catchment outlet and validated at multiple sub-catchments’ outlets. Finally, the model was recalibrated at multiple sub-catchments’ outlets using citizen science data. the HEC-HMS model of the Akaki, which was calibrated for a historical period, does not capture the current rainfall-runoff response. However, the model simulations were made useful by revisiting the model calibration at multiple sub-catchments’ outlets using citizen science data. Overall, this article demonstrates the value of citizen science data for model calibration and validation.