2009 BES Annual Meeting Presentation and Poster Abstracts
Characterization of Vegetation-Shallow Groundwater Interactions Along an Urban Riparian Corridor
Co-Authors: Christiane Runyan, Claire Welty, Philip Larson
Abstract: Diurnal fluctuations in groundwater levels were observed during the summer of 2008 in eight shallow wells located along a 4-km stream reach in the Dead Run watershed. Previous studies (e.g. Loheide et al., 2005) have attributed such fluctuations to the extraction of groundwater by phreatophytic vegetation. The purpose of the analysis presented here was to calculate evapotranspiration (ET) along this urban riparian corridor from observed groundwater fluctuations using the White (1932) method. Mean ET values (mm/day) were found to be: 1.9 ±0.5 (Site 1), 1.1±0.5 (Site 9), 2.4±0.5 (Site 16), and 1.7±0.3 (Site 20). This presentation highlights sources of uncertainty that may be present when using the White method, including: data associated with precipitation events; net recharge; readily available specific yield; and change in storage. We suggest that site characteristics contributing to this uncertainty include: riparian well proximity to streams; percentage of grain sizes greater than 2 mm in soil horizons; well responses to precipitation events; and depth to water table being less than 1 m. Characterization of vegetation- groundwater interactions is important in urban areas because the removal or conversion of vegetation can raise shallow groundwater levels, thereby requiring infrastructure investments to maintain artificially lowered water tables.