Colman, J. A., U. S. Geological Survey, Northborough, USA, jacolman@usgs.gov
Masterson, J. P., U. S. Geological Survey, Northborough, USA, jpmaster@usgs.gov
Lee, K. D., National Park Service, Wellfleet, USA, Krista_Lee@nps.gov
McCobb, T. D., U. S. Geological Survey, Northborough, USA, tmccobb@usgs.gov

SIMULATION OF FLOW AND NUTRIENT TRANSPORT FROM AN AQUIFER FLOW CELL TO A COASTAL EMBAYMENT

Transient 3-D modeling was used to simulate ground-water flow from the top of the ground-water flow cell to a coastal embayment at Cape Cod National Seashore, Massachusetts. Mixing in the subterranean estuary also was simulated by a finely discretized 2-D model. Simulations showed that freshwater discharge from the aquifer to the embayment varied from 500 m3/d when ground-water levels were low (November to December) to 2,500 m3/d when ground-water levels were high (May to June). Modeled freshwater fluxes agreed with those calculated from salinity and flow measurements made over multiple tidal cycles at a channel connecting the embayment to a larger estuary. Salinity measured in ground water in the intertidal zone using multilevel samplers detected movement of the salt/fresh interface on a tidal and seasonal basis that was consistent with simulation results. Fluctuations in simulated nitrogen loads corresponded with water flux variations. Little nitrogen loss occurred during transport in the aerobic subterranean estuary. Although most nitrogen discharging to the embayment was in the form of nitrate, most nitrogen leaving the embayment through the tidal channel was organic nitrogen.

Poster presentation

Presentation is given by student: No
Session #:089
Date: 03-06-2008
Time: 17:30 - 19:30