Evaluating the impact and uncertainty of reservoir operation for malaria control as the climate changes in Ethiopia

Promising environmental mechanisms to control malaria are presently underutilized. Water level fluctuations to interrupt larval development have recently been studied and proposed as a low-impact malaria intervention in Ethiopia. One impediment to implementing such new environmental policies is the uncertain impact of climate change on water resources, which could upend reservoir operation policies. Here we quantified the potential impact of the malaria management under future climate states. Simulated time-series were constructed by resampling historical precipitation, temperature, and evaporation data (1994–2002), imposing a 2 °C temperature increase and precipitation changes with a range of ±20 %. Runoff was generated for each climate scenario using the model GR4J. The runoff was used as input into a calibrated HEC ResSim model of reservoir operations. The malaria operation management increased the baseline scenario median energy generation by 18.2 GWh y −1 and decreased the energy generation at the 0.5 percentile (during dry conditions) by 7.3 GWh y −1 . In scenarios with −20 % precipitation, malaria control increased average annual energy generation by 1.3 GWh y −1 but only decreased the lowest 0.5 percentile of energy by 0.2 GWh y −1 ; the irrigation demand was not met on 8.5 more days, on average, per year. Applying the malaria control rule to scenarios with +20 % precipitation decreased the likelihood of flooding by an average of 1.0 day per year. While the malaria control would divert some water away from other reservoir operational goals, the intervention requires 3.3–3.7 % of the annual precipitation budget, which is much less than reduction from potential droughts.