Evaluating the use of Conceptual Models to explain surface water and groundwater interactions at meadows restored with the pond and plug technuque
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Authors
Wagner, Karly
Issue Date
2015
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Thesis
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Abstract
The pond and plug incised meadow restoration method, used for meadows in the Sierra Nevada Range, takes available sediments on site to fully dam the incised channel in several places. Each dam, or plug, creates a pond as the water table rises closer to the meadow surface. Groundwater storage gained from restoration may alter flow paths and water availability. Water flowing through the meadow is elevated and slowed by floodplain spreading, meanders, and roughness from vegetation. Expanded riparian vegetation and slowed water transport increase evapotranspiration (ET) following restoration. Using Landsat derived NDVI (Normalized Difference Vegetation Index) as a proxy for ET in thirty meadows; we found a significant increase in average NDVI of 0.07 following restoration (p-value < 0.05). NDVI decreased following restoration at only one site. Conceptually meadows may act as: A) a sponge, storing abundant water from snowmelt or precipitation and releasing water in dry periods; B) a valve, regulating water outflow from springs recharging the meadow; and/or C) a drain, draining water from the meadow to a regional aquifer. Areas in eight meadows were classified into these three conceptual models using ET (meadow and pond), summer pond and groundwater elevations, stream flow data, and climate data. Evaporation from open pond water made up 1-7% of total meadow ET. Meadow ET estimates ranged from 0.32 m to 0.40 m. In ponds, 20-80% of the summer decline (-0.11m to 1.78 m) was attributed to ET. This study was conducted in a dry period and the data reflect effects of below average precipitation.
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In Copyright(All Rights Reserved)