Understanding the role of the dynamics impacts of hyporheic zone processes on water balance and nutrient dynamis at the groundwater - surface water Interface of floodplains
Final Report Abstract
The results of this project proof that redox conditions and groundwater – surface water mixing in the streambed can have a substantial impact on the groundwater nitrate delivery to freshwater environments. It was possible to show that the streambed control on groundwater fluxes and nitrate concentrations reaches significantly deeper structures of the streambed sediments than usually anticipated and is not necessarily limited to the surface water infiltration zone into the streambed. Nitrate changes along the upwelling groundwater flowpath were not only found to be characterized by strong spatial pattern, the results of this study also indicate significant temporal variability of groundwater nitrate concentration changes. A seasonal dynamic of groundwater nitrate contributions to the stream nitrate loads has been observed, indicating that during baseflow conditions at summer the streambed is representing a source of nitrate whereas during high flow events other sources seem to dominate the in stream nitrate concentrations and groundwater fluxes through the streambed have a rather diluting effect. These results are of great importance for river management and regulation as they support the argument that, depending on the redox conditions, flow and mixing of groundwater and surface water the streambed has a strong potential to change the nutrient load in freshwater ecosystems. Events as the flooding occurring between both field seasons significantly altered the streambed structure what lead to a substantial alteration of the streambed behavior in terms of fluxes, uptake and delivery of nitrate. This random events impressively demonstrated the effects of disturbances on the streambed hydrological and biogeochemical processes and thus, can be interpreted as important scenario cases for potential management impacts.
Publications
- 2008. Groundwater-dependent wetlands in the UK and Ireland: controls, ecohydrological functions and assessing the likelihood of damage from human activities. Journal of Water Resources and Management. 21 (12), 2015-2025
Krause S., Heathwaite A.L., Miller F., Hulme P., Crowe A.
- 2008. Why can't we do better than Topmodel? Hydrological Processes. 22 (20), 4175-4179
Buytaert, W., Reusser, D., Krause, S., Renaud, J-P
