Rhodamine WT dye-tracer injections in rivers of the Willamette River Basin (northwestern Oregon) yield concentration-time curves with the characteristically long times of recession suggestive of active transient storage processes. Hyporheic linkage between the surface stream and sub-surface flows is one of the possible physical mechanisms contributing to long concentration recessions. In both the Willamette and Santiam Rivers, hyporheic linkages are further suggested by detailed measurements of river discharge with an Accoustic Doppler Current Profiler, delineating zones in which water enters and leaves the surface channel. A transient storage assessment of the tracer studies has been completed using the USGS OTIS code package. In this analysis, a dimensionless parameter expresses the spatial extent of storage relative to river cross-section. In the basin-scale context of the Willamette River Basin National Water-Quality Assessment study, we conclude that the transient storage assessment is not definitative in itself, but is an additional indication of likely hyporheic linkages throughout the basin.
1US Geological Survey Portland, OR 97216,
2US Geological Survey
Menlo Park, CA 94025
Tracer-dilution experiments and associated solute-transport simulations provided estimates of discharge and time of travel along several reaches of Saint Kevin Gulch, a stream receiving acidic effluent from mine tailings in Lake County, Colorado. Profiles of time-varying tracer (lithium chloride) concentration were simulated with a transport model depicting advection, dispersion, lateral inflow, and the transient storage of solutes in immobile zones along the stream channel. Simulated profiles were sensitive to variations in the model's transient-storage parameters, including the cross-sectional area of the storage zone and the stream-storage exchange coefficient. Although similar to values calibrated in simulations of tracer profiles in other mountain streams, these transient-storage parameters were specific to individual reaches and could not be predicted from linear combinations of simple hydraulic variables. Parameters that were calibrated for the simulation of lithium concentrations could be used without adjustment to simulate measured concentrations of chloride. This result increased confidence in the ability of the model to simulate the nonreactive behavior of any solute. The steady- state profile of lithium concentrations during the plateau stage of the experiment also was simulated successfully. Assumptions underlying tracer-dilution methods are violated in losing reaches of streams. Injection of a second tracer (sodium bromide) and a direct measurement of discharge provided an improved estimate of the flow rate downstream from a losing reach of Saint Kevin Gulch.
1US Geological Survey Denver, CO 80225
full citation: Broshears, R.E., K.E. Bencala, B.A. Kimball, and D.M. McKnight, 1993, Tracer-dilution experiments and solute-transport simulations for a mountain stream, Saint Kevin Gulch, Colorado, U.S. Geological Survey, Water Resource Invest., 92-4081.
A 1.19 hour NaCl injection was done in the pool and riffle Big Chico Creek located about 3 hours North of San Francisco, California in the Sacramento Valley. The study area is 315 meters long, through the California State University at Chico Campus. Although the accuracy of the tracer run was lowered due to a leaky tank and flow being above its base the experiment achieved its purpose of a good first run. Rough parameters were generated for the OTIS model that will prove beneficial for other investigations. Examples of how a calibrated OTIS might be used are included.
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