Spatial and temporal mapping of shallow groundwater tables in the riparian zone of a Swedish headwater catchment

• Main Author: Hellstrand, Eva
• Format: Others
• Language: English
• Published: Uppsala universitet, Luft-, vatten och landskapslära 2012
• Subjects: Riparian zone; recharge area; shallow groundwater tables; GIS; terrain analysis
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182816

Understanding the hydrology of the riparian zone in a catchment can be an important prerequisite for determining solute loads and concentrations in streams. The riparian zone is the transition zone between surrounding landscape and an open water stream. This study focuses on the spatial and temporal variations of shallow groundwater levels in a forested headwater catchment in the Bergslagen area of central Sweden. Three snapshot campaigns were conducted during dry, humid and wet conditions to map the spatial variability of the groundwater levels. Piezometers giving the total hydraulic head were placed in the riparian zone along a stream network consisting of three first order streams and one second order stream. To asses temporal variations five groundwater wells were installed with automatic loggers to record continuous data during the wet period. Historical streamflow records from a permanent field station were collected and related to the groundwater levels in order to assess the relationship between groundwater levels and streamflow. Additionally a landscape analysis using GIS methods was conducted in order to identify potential drivers of spatial variation of groundwater levels in the riparian zone. The results showed that the slope could partially explain the observed spatial variability of riparian groundwater levels. The results from the spatially distributed piezometers and the continuously monitored groundwater wells with loggers were contradicting. Where the piezometers showed increasing depth to the groundwater table with increasing slope the loggers indicated the opposite. However, because the piezometers outnumbered the loggers the piezometer results can be considered more representative of the spatial variation of groundwater levels. There could be no general result concluded on the catchment scale but when looking at specific subcatchments it could be found that the variations in the riparian groundwater levels could be better explained where the stream had a more distinct channel. This indicates the importance to evaluate not only slope but the profile curvature as well for groundwater predictions.