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USE OF CONTINUOUS DATALOGGERS TO ASSESS THE TEMPORAL AND SPATIAL VARIATION OF GROUND WATER/SURFACE WATER INTERACTION BEFORE AND AFTER STREAM RESTORATION
Citation:
Striz*, E. USE OF CONTINUOUS DATALOGGERS TO ASSESS THE TEMPORAL AND SPATIAL VARIATION OF GROUND WATER/SURFACE WATER INTERACTION BEFORE AND AFTER STREAM RESTORATION. Presented at 2002 Ground Water Expo, Las Vegas, NV, 12/9-11/02.
Description:
Minebank Run is a degraded second-order flashy urban stream in Baltimore County which is slated to undergo restoration in August 2003 to re-establish geomorphic stability. We are currently conducting an intensive investigation of surface water/ground water interaction and nutrient fate and transport before and after restoration of Minebank Run. One initial objective of this study is to determine the level of site characterization necessary to characterize spatial and temporal variations in near-stream hydrology as a function of stream flow and stream morphology. To accomplish this goal, it was necessary to set up a stream and floodplain monitoring network that would capture the spatial and temporal hydrodynamics of the flow field around the stream. The study design consists of three monitoring transects located across specific stream morphologic structures (pools, riffles, etc.) that will be significantly altered after the restoration. Each transect is composed of nests of stream bed and stream bank piezometers along with flood plain deep/shallow monitoring well pairs. The stream bed piezometer nest is composed of three one inch stainless steel piezometers driven into the cobble bed to depths of two, four and six feet. Nests of three piezometers were installed on both banks and driven to match the stream bed piezometer mean sea-level depths. Finally, two sets of shallow/deep two-inch monitoring wells were installed at 50 and 100 ft distances from the stream centerline on both banks. A continuous stream gage and precipitation gage were also installed near the transects. All of the piezometers and some of the monitoring wells were equipped with continuous dataloggers set to record water level measurements every five minutes. The first few months of continuous water level measurements from the site will be presented. These data demonstrate the true spatial and temporal nature of the surface water/ground water interaction and its response to rainfall events. In particular, the temporal response of the stream and bank water levels is significantly different from the stream flow hydrograph in terms of both the rate and time of progression/recession. The curves also suggest that capillary hysteresis may exert significant control on the response in the water table aquifer. Overall, it is apparent that the use of continuous dataloggers is necessary to capture both the temporal and spatial variation of near-stream hydrology in a flashy urban stream like Minebank Run.