Climate change impacts on hydrometeorological and river hydrological extremes in Quito, Ecuador

Study region: Quito, Ecuador Study focus: The study region faces two water-related challenges, which, to date, have only been studied to a minimal extent: extreme precipitation events and water shortage in the dry season. This study investigates the current conditions and future changes in short-duration events, low river discharges and associated uncertainties. Daily precipitation and temperature projections from 19 state-of-the-art global climate models (CMIP6) and four future scenarios (SSP1–2.6, SSP2–4.5, SSP3–7.0 and SSP5–8.5) are downscaled with delta change and more advanced quantile perturbation methodologies. Temporal disaggregation is applied to obtain sub-daily precipitation with five extreme value distributions (EVDs). Three conceptual hydrological models are implemented to quantify the impacts on river flows. Variance decomposition is applied to estimate the uncertainty share of climate models, hydrological models, and EVDs in the results. New hydrological insights: The results indicate an intensification of extreme precipitation events, with short-duration events expected to be more intense by up to 30% in the near future (2021–2050) and up to 60% in the far future (2070–2099). The river peak discharges are projected to increase by 5–20% and 10–50% in the near and far future, respectively. On the contrary, the low river flows are projected to decrease by 0–13% and 0–30% for the respective time horizons. Overall, climate models are the dominant source of uncertainty.