Development and Testing of an Automated, In-Situ Groundwater Seepage Meter

Hydrologic studies of lakes tend to not include groundwater inputs as they are seen as a negligible amount to the water budget. However, there are certain environments such as Geographically Isolated Wetlands (GIW) in which groundwater dynamics are essential to understanding the periodic wet and dry periods of these environments. This drying and wetting cycle plays a large role in the breeding period of a number of amphibians and in the role that GIWs play in removing nutrients from water systems. While there are a number of methods to measure and estimate groundwater seepage in lakes, they are not very accurate on the whole. The purpose of this project is to develop and test a new seepage meter. The design of the seepage meter a PVC tube inserted into lake sediment where the head within the tube is drawn down and the recovery curve is recorded. Through laboratory and numerical experiments, it was shown that preforming a linear regression on derivative values of the recovery curve against the hydraulic gradient provides a more accurate seepage estimate than the traditional method of analysis. While the seepage meter is not as accurate as hoped, there are positive signs that it can be improved with increasing experimental sampling size, using a more reliable on-board pump, and improving the design of the seepage meter body. The seepage meter has shown that it can work within a field environment and produced optimistic data from preliminary field tests.