Hydrological design of hydraulic infrastructure in a changing climate – Insights for practitioners in Chile

Chile is one of the most vulnerable countries to the impacts of climate change. This suggests challenges to mitigate their impacts and adapt existing infrastructure. Despite a consensus that future climate change will lead to an increase in hydrometeorological extremes and the importance of including this factor in the hydrological design of hydraulic infrastructure, clear national guidelines on how to achieve and implement this in practice are still lacking. To address this gap, this study aims to align national hydrological design methodologies with international best practices by offering recommendations for addressing extreme precipitation and surface runoff generation.

Key considerations include the temporal and spatial scales of precipitation and temperature, and methodologies for flow estimation in gauged and ungauged basins. Dynamic modeling, statistical methods, and synthetic unit hydrograph approaches are explored, with applied examples highlighting the integration of climate change in estimating peak flows, extreme precipitation, and intensity-duration-frequency (IDF) curves.

Our results show that dynamic hydrological modeling yields projections with lower associated uncertainty by accurately capturing historical patterns. Dynamic models account for interactions such as antecedent soil moisture and snowline shifts during extreme events. For northern Chile, spatially distributed or semi-distributed models are recommended to capture the heterogeneity of extreme events. In contrast, statistical and synthetic hydrograph methods present limitations due to their reliance on historical precipitation-runoff relationships and lack of spatial heterogeneity.

Finally, the study underscores the need for flexible, transdisciplinary approaches to address future climate challenges, advocating for hydrological system modeling and a deeper understanding of processes driving extreme hydrometeorological responses.