ABSTRACT EAR-9508031 Thorbjarnarson Two major categories of wetlands found in the coastal Southwestern United States are lagoonal fringe wetlands and riparian wetlands. The hydrology of these has been little studied, and direct quantification of the groundwater contribution to most wetlands is even less well understood. the goal of this Planning Grant is to assess the feasibility of particular field techniques in the evaluation of groundwater fluxes in these two major wetland categories. The ultimate goal is a full research proposal to quantify the various contributors, with a significant emphasis on groundwater, to the water budget of a semiarid wetland. The proposed preliminary research entails hydrogeologic and geochemical study of two field sites, the Tijuana estuary and the lower Santa Margarita River, and assessment of various hydraulic and tracer techniques to quantify the surface- and ground-water interactions. Proposed work during the planning phase includes evaluation of: (1) temporal variability of ground-water fluxes, (2) permeabilities in bottom sediments, (3) chemical differences among potential contributors to the water budget, (4) potential uses of various tracers in measurement of water fluxes, (5) effectiveness of seepage meters in the lagoonal wetlands.
