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Title: PRELIMINARY HYDROGEOLOGIC CHARACTERIZATION OF A RIPARIAN MANAGEMENT SYSTEM IN CENTRAL IOWA

Author
item SPEAR, B - IOWA STATE UNIVERSITY
item TWEDT, T - IOWA STATE UNIVERSITY
item JOHNSTON, D - IOWA STATE UNIVERSITY
item ANDRESS, R - IOWA STATE UNIVERSITY
item SIMPKINS, W - IOWA STATE UNIVERSITY
item ISENHART, T - IOWA STATE UNIVERSITY
item SCHULTZ, R - IOWA STATE UNIVERSITY
item Parkin, Timothy

Submitted to: Geological Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Three Riparian Management Systems (RiMS) consisting of 20 m wide by 90 m long rows of grasses, shrubs, and trees have been constructed adjacent to Bear Creek near Roland, Iowa, in order to study the hydrological and geochemical effects of re-establishing riparian areas in agricultural areas. The Risdal North RiMS consists of cool season grasses and the Risdal South and Strum RiMS consist of rows of switchgrass, shrubs, and trees. For the hydrogeological investigation, 41 water table monitoring wells, 108 tensiometers, and 176 porous-cup lysimeters have been installed along ground water flow paths from the crop field to the creek. Hydraulic head data recorded since June 1996 suggests that ground water flows laterally from the adjacent crop field, through the buffer strip, and into Bear Creek during most of the year. K values range from 10**-/5 to 10**-/4 m/s based on pumping and slug tests. Upward-directed hydraulic gradients have dominated in the unsaturated zone during the summer months of 1997 and have precluded significant vertical recharge. NO3-N concentrations at the water table generally decrease from 15 mg/L at the field edge to 0 mg/L at the creek. They are accompanied by a general increase in N2O concentrations from 0 to 5 umol/L and constant Cl concentrations. In summary, our preliminary data suggest that NO3-N enters the ground water mostly beneath the crop field and moves laterally beneath the RiMS within a 7 month period. NO3-N is lost, perhaps to denitrification, during transport. Current research focuses on the processes and rates of NO3-N loss within the RiMS.