Project Details
Projekt
Analysis of the mechanisms and impacts of a regime shift towards spatially increasing and more frequent intermittent runoff regimes in German river landscapes
Subject Area
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Term
since 2026
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 577008456
In a pilot study using the 1575 runoff stations of the CAMELS-DE dataset, we found a surprisingly large fraction of river gauges (16 % in the investigation period 1981-2020) with intermittent behaviour spread over entire Germany. Even though a large part of the intermittent stations falls dry rarely, we saw a clear increase of zero flow periods for a significant proportion of stations in the recent past. Most stations showed intermittent behaviour for the first time in the last three years of the series. This project will shed light on the underlying dynamics and causes of this sharp and widespread increase of zero flow periods over the last years and will address the potential impacts on riverine vegetation and bank stability. For this purpose, the hysteretic responses of discharge intermittency will be assessed to identify and categorise the speed of drying and re-filling for different prevailing runoff conditions for the entire CAMELS-DE dataset. For a detailed process analysis of changing catchment water budgets and river network connectivity, three experimental catchments in the drier north-east of Germany will be equipped with groundwater levels and photo-point sensors to monitor onset and extent of drying in the riparian zone for three years. To enable a thorough analysis of all potential processes and interactions contributing to intermittency, the catchments will be modelled using the ecohydrological tool SWAT+. Model calibration and validation will be targeted to represent intermittent behaviour. Modelled water balance components will be analysed to understand which processes are dominant at the onsets and conclusions of zero flow periods. Moreover, the effects of climate and land use change on intermittent runoff behaviour and groundwater dynamics in the river network and on all water balance components will be simulated to understand the combined effects and the interplay of climate and land use change on intermittent behaviour. Finally, degradation of greenline vegetation and resulting riverbank stability due to water stress will be quantified as a function of intermittency frequency using high-resolution remote sensing imagery, field sampling data and model information on the temporal-spatial extents of zero flow periods in river stretches. A comparative study of stream stretches from river stretches across north-east Germany with frequent and non-frequent intermittency regimes, as derived from the CAMELS-DE data set, will inform on the on-sets of vegetation deterioration and potentially increased lateral connectivity thus reducing the positive effects of greenline vegetation in the riparian zone. To the end, this project will generate new insights into the timing and severity of ecohydrological shifts in runoff regime, riparian zone and network connectivity. It will provide essential knowledge for the development of adaption measures to mitigate the negative impacts of emerging and potentially persistent intermittency regimes.
DFG Programme
Research Grants
International Connection
Brazil, France, Spain
