Drought and flood statistics in regulated catchments: a multivariate perspective (DFStaR)

• Applicant: Professorin Dr. Manuela Brunner
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465747089

The impacts of droughts and floods can be particularly severe if they occur in areas with high human presence, if they affect a large region, or if droughts are abruptly terminated by floods. Suitable management and adaptation strategies can help minimize the negative impacts related to such extreme events and rely on well-founded estimates of their frequency and magnitude.A key unresolved problem in drought and flood estimation is to quantify the probability of extreme events in regions where flow is impacted by human regulation e.g. through reservoir operation or lake regulation. Such direct human intervention may not only affect single drought and flood characteristics in individual catchments but also the interplay between multivariate characteristics. This project aims to enhance our understanding of the statistical behavior of multivariate hydrologic extremes in a global change context where streamflow is increasingly regulated through reservoir operation or water abstraction. More specifically, it aims to (1) create a data set on hydrologic extremes and human flow-influences for the Central European Alps; (2) quantify the impact of reservoir operation and lake regulation on multivariate statistical flood and drought characteristics including multiple and regional characteristics, event types, the temporal clustering behavior of hydrologic extremes, and rapid drought-flood transitions; and (3) determine the effect of flow regulations on local and regional hazard estimates.These aims are addressed by a research team consisting of the PI, a PhD student, and a GIS specialist with support from student assistants. We will focus on the headwater regions of the four major rivers originating in the Central Alps, namely, the Rhine, Rhone, Danube, and Po, which provide essential water resources to dependent downstream regions and represent a highly regulated hydrological system. We will acquire and work with a data set of observed streamflow time series from the countries and regions within the study region. To quantify the impact of flow regulation on hydrologic extremes, we will compare flood and drought characteristics of natural and regulated catchments identified in observed and stochastically simulated streamflow time series. To estimate local and regional hazard estimates for natural and regulated catchments, we will develop classification and simulation approaches and rely on multivariate frequency analysis.This project will provide novel insights about the influence of human flow regulation on statistical drought and flood characteristics and their relationship and quantify to which degree drought and flood hazard in regulated catchments in the European Alps differs from the one in natural catchments. It will therefore provide information critical for decision making in a human-modified world.

• DFG Programme: Research Grants
• International Connection: Switzerland