Effects of desiccation on the self-purification capacity of headwater streams: Consequences for the stream management
Water scarcity and drought are among the most pressing environmental challenges of the 21st century. Over the past thirty years, the frequency and duration of droughts has increased dramatically across Europe, causing perennial streams to shift to intermittency even in temperate regions like Austria. Already now, a large number of streams in Carinthia, Burgendland and Styria fall dry during summer.
Drought impairs the self-purification capacity of streams and may result in water quality deterioration. The project PURIFY aims to
- investigate the effects of drought on the self-purification capacity and the water quality of temperate streams,
- identify factors which determine the resilience of stream processes to drought,
- model potential consequences of drought for selected reaches, and
- develop a guideline for Austrian water management authorities to assess the risks of water quality deterioration due to drought.
We will investigate drought effects on the water quality and the self-purification of streams via both field sampling and lab experiments. In 2018-19, intermittent streams in Carinthia, Styria and Burgenland will be sampled before, during, and after the drought for nutrient and organic matter concentrations in the stream water, and for the biomass and activity of biofilms in the sediments. We will perform nutrient addition experiments to calculate nutrient uptake during different phases of drying. In the lab, we will determine the effects of drying on the nutrient uptake via experimental flumes and sediment perfusion cores (2019-20).
For three reaches, we will combine uptake rates with the results of 2D hydrodynamic models (RSim-2D) to estimate the potential consequences of drought in dependence of discharge.
In addition, we will identify factors which determine the vulnerability of streams to drought and we will develop a guideline which supports stream managers in the management of intermittent streams.
This project is funded by Klima- und Energiefond (Austrian Federal Government) through the “Austrian Climate Research Programme ACRP 2017” (GZ B769828 „ACRP10 – PURIFY – KR17AC0K13643”).