The calculation of estuarine turnover times using freshwater fraction and tidal prism models: A critical evaluation |
| |
| Authors: | Joan E Sheldon Merryl Alber |
| |
| Institution: | (1) Ocean Monitoring and Prediction Laboratory, College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA |
| |
| Abstract: | Freshwater fraction and tidal prism models are simple methods for estimating the turnover time of estuarine water. The freshwater
fraction method prominently features flushing by freshwater inflow and has sometimes been criticized because it appears not
to include flushing by seawater, but this is accounted for implicitly because the average estuary salinity used in the calculation
reflects all the processes that bring seawater into the estuary, including gravitational circulation and tidal processes.
The model relies on measurable salinity differences among water masses and so must be used for estuaries with substantial
freshwater inflow. Tidal prism models are based on flushing by flood tide inflow and ignore seawater inflow due to gravitational
circulation. These models should only be applied to estuaries with weak or nonexistent gravitational circulation, which are
generally those with little freshwater inflow. Using a framework that is less ambioguous and more directly applicable to the
estimation of turnover times than those used previously, this paper critically examines the application of tidal prism models
in well-mixed estuaries with complete tidal exchange, partial ebb return, or incomplete flood mixing and in partially mixed
estuaries. Problems with self-consistency in earlier versions of these models also apply to the budgeting procedure used by
the LOICZ (Land-Ocean Interactions in the Coastal Zone) program. Although freshwater fraction and tidal prism models are different
approaches to estimating turnover times in systems with very different characteristics, consistent derivation shows that these
models have much in common with each other and that they yield equivalent values that can be used to make comparisons across
systems. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
