Floodplain Restoration Petronell - Increasing Multifunctionality for Ecosystem Integrity & Drinking Water Supply

The renaturation of river floodplains offers nature-based solutions for promoting biodiversity, ecosystem functions, and water quality. This project investigates how the multifunctionality of the Petronell Danube floodplains changes after reconnection measures. The focus is on how changes in lateral and vertical connectivity influence ecological properties, biogeochemical processes, and self-purification capacity, which are relevant for drinking water production. We quantify (1) changes in ecological organization, including nutrient cycles, food webs, and habitat functions. (2) We analyze how different hydrological conditions—from throughflow to isolated residual waters—shape the input and transformation of nutrients and organic matter, as well as the responses of green and brown food webs. (3) We investigate how side arm reconnection supports biogeochemical properties, trophic relationships, and the development of juvenile fish stages. (4) Along the gradient from the Danube to the groundwater, we record changes in water quality, including nutrients, anthropogenic substances, microorganisms, and organic matter, in order to assess effects on drinking water wells. The investigations are conducted using a BACI design with a before-and-after survey and control sites. Event-based sampling records flood, low water, and dry periods. The results provide an integrated assessment of the ecological, biogeochemical, and water management effects of floodplain renaturation and highlight its potential and limitations as a nature-based solution for drinking water extraction.