Implications of Groundwater-Surface Water Connectivity for Nitrogen Transformations in the Hyporheic Zone
Implications of Groundwater-Surface Water Connectivity for Nitrogen Transformations in the Hyporheic Zone.
Cost: £675k
Duration: 2009 - 2012
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Overview
The interaction of groundwater-surface water in the hyporheic zones of rivers during baseflow conditions, and its influence on nitrogen transport and transformations are poorly understood at a river reach scale. The predicted changes in precipitation and temperature linked to climate change may have further repercussions on the nature and extent of hydrologic exchanges in the hyporheic zones and biogeochemical processes.
This project seeks to elucidate both physical and chemical controls on nitrogen transport and transformations in the hyporheic zone of a groundwater fed river in Cumbria, UK. Preliminary research has revealed the spatial variability in the mineral N concentrations in the hyporheic zone of River Leith in Cumbria during baseflow conditions (Krause et al. 2009; Kaiser et al. (2009). The hypothesis is that the variability in mineral N concentrations is driven by (1) differences in geomorphology of the river bed, (2) the extent of ground water-surface water mixing and (3) the creation of zones of either denitrification or nitrification.
The project is using a multidisciplinary approach to explore the physical hydrology, hydrogeophysics and biogeochemistry controls on N transport in the hyporheic zone of River Leith at a reach scale. The project has the following objectives:
- 1. To identify how riverbed physical structure and permeability controls rates and magnitude of groundwater-surface water flux.
- 2. To establish if spatial heterogeneity in the hyporheic zone leads to redox-sensitive biogeochemical “hotspots” and “hot events” that determine the rate of N transport and transformations linked to variations in the riverbed connectivity.