By

Babcock, Kenneth P听1听;听Ge, Shemin听2

1听University of Colorado at Boulder
2听University of Colorado at Boulder

The purpose of this study is to gain a scientific understanding of the groundwater-surface water interactions occurring between Boulder Creek and an alluvial aquifer. The study area is located at the Sawhill and Walden Ponds in Boulder, Colorado. This area is the property of the City of Boulder and Boulder County who reclaimed the area after gravel mining operations ceased in the 1970鈥檚. Consequently, groundwater has filled in the gravel pits and riparian vegetation has re-grown.

An integrated approach is used to examine the study area through field measurements and numerical modeling. Collected field data suggests alluvial conductivities of 3.5-7 ft/day. Groundwater level monitoring from August to present has indicated decreasing baseflow conditions with sporadic stage increases correlated to precipitation events. Field data is used in numerical simulations to predict the extent that the stream influences the hydraulic gradient of the alluvial aquifer. It is hypothesized that the patterns of groundwater-surface water interaction will be a function of high or low flows in, and distance from Boulder Creek.

Anticipated benefits of this study include an increased understanding of the hydrologic processes occurring in the riparian ecosystem and insight into future methods of maintaining the health of this and other riparian ecosystems. An applied understanding of these interactions will contribute to both the local community and to the broad scientific community.