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Drifter Studies in Open Shallow Water Habitats of the San Francisco Bay and Delta
Jay I. Cuetara and Jon R. Burau, USGS, Sacramento, CA

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View enlargements of figures: 5A (107 KB) and 5B (110 KB).

See study area mapFigure 5. The difference between the flood and ebb drifter path lengths shown in this Figure is a clear demonstration of "tidal pumping". Even though the flood and ebb tides are of similar magnitude, as shown by tidal flows at Jersey Point (see tidal discharge subplots on each map), drifters deployed on the Sacramento River side of Sherman Lake travel 3.6 miles farther than those deployed on the San Joaquin River. This occurs because the currents change about 60 minutes later on the San Joaquin River side of Sherman Lake. A drifter released as Sherman Lake begins to flood from the Sacramento River reaches the San Joaquin River almost precisely when the San Joaquin is beginning to flood. This adds to the length of the tidal excursion. The reverse occurs for releases into Sherman Lake from the San Joaquin River.

Drifters released as water began to flow into Mayberry Slough from the San Joaquin River river traversed Sherman Lake but did not exit into the Sacramento River Drifters released as water began to flow from the Sacramento River through the northern breach of Sherman Lake traversed Sherman Lake in roughly an hour and continued to travel 3 miles up the San Joaquin River
Figure 5A. Drifters released as water began to flow into Mayberry Slough from the San Joaquin River river traversed Sherman Lake but did not exit into the Sacramento River. Figure 5B. Drifters released as water began to flow from the Sacramento River through the northern breach of Sherman Lake traversed Sherman Lake in roughly an hour and continued to travel 3 miles up the San Joaquin River.

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