Contributions to estuarine eutrophication modeling: Watershed population estimation methodology, estuarine flushing model, and eutrophication model

This dissertation advances the development of sub-basin level estuarine eutrophication modeling by providing the means to produce: sub-watershed nitrogen loading surrogates; sub-basin flushing estimates; and operational estuarine eutrophication models. The dissertation presents the following to accomplish the above: an estuarine watershed human-population estimation method; an estuarine flushing model; and an estuarine eutrophication model.; The watershed-population estimation methodology reaggregates county population data to hydrologic cataloging units. These reaggregations are useful nitrogen loading surrogates in eutrophication models. Comparison of the reaggregations to census block/track compilations, finds they agree 85%, with increased error in smaller watersheds. As census block/track compilations are not available for sub-watersheds, the reaggregations can be used instead.; The flushing model uses dynamic modeling to track the flushing of a single tidal cycles worth of freshwater as it is subsequently removed from the estuary over a series of tides. Simultaneously, it sums the freshwater residuals and uses that information to determine the freshwater fraction of the estuary, which is used to calculate the salinity of the estuary. Therefore, the model combines the functionality of freshwater flushing with tidal flushing while using the estuarine volumetrics and estuary salinity to calibrate the model runs. Comparisons of the model's freshwater input vs. empirically derived freshwater inputs, finds them to be highly correlated {dollar}rm(rsp2=0.97),{dollar} which verifies the model's internal logic. Pending the development of oligo-mesohaline volume estimates, the model can be scaled down produce zone-level (i.e., sub-basin) flushing estimates. These sub-basin flushing estimates should be more useful than the estuary-level estimates, they should be of use to sub-basin eutrophication modeling efforts.; The estuary-level eutrophication model uses nitrogen loadings, nutrient ratios, and salinity stratification in a multinominal logistic regression that produces probabilities predicting the estuaries trophic status. The eutrophication model is the first of its type to actually work, it has an 80% correct prediction rate. This eutrophication model is not considered to be a management tool, yet. However, it provides the platform from which sub-basin eutrophication models could be produced. These yet to be produced sub-basin models are considered to be the estuarine eutrophication management tool.