South Florida Hydrology and Salinity Models

·     Evaluation of hydrology and salinity models for Everglades

·     Each model scored according to accepted model performance criteria

·     Complex numeric models were least portable and hardest to use, though they supply much greater detail

·     Empirical models were easiest to use and less-expensive to run with less detail in the output

ABSTRACT

This study evaluated the hydrology and salinity models being used for Everglades restoration. Each model that was reviewed was assigned a series of scores for achieving the modeling criteria, with 5 being the highest score (excellent).  The widest ranges of scores were for portability and ease-of-use reflecting the constraints of model sophistication.  The narrowest range of scores was associated with validity – most of these models have withstood the test of use and have been developed, reviewed, and updated to a point of application-ready acceptance. 

In general, the most complex models (SWMM, RSM, FTLOADDS, EFDC Florida Bay, Wang et al. (2003) Biscayne Bay, TABS MDS Biscayne Bay) are the least portable, are rated lowest for ease of use, and did not score as high on validity as did the models that are less complex (linear regression models for stage and flow, MLR salinity models, FATHOM, Four Box Model Florida Bay, Biscayne Bay Box Model). 

Temporal coverage was best for the regression models because they are daily time step models and can be run for the longest periods of time.  For spatial coverage, none of the models covers the full domain of the south Florida coastal system but most model domains cover the region(s) of focus. 

The least expensive models to employ are the least sophisticated statistical models and box models.  The use of grid-domain freshwater models covering a large region such as the spatial domain of the SFWMM and RSM will always require more budget than the freshwater ecosystem statistical and box models by a substantial amount.  However, there are important transport, exchange, and circulation questions in the connected Everglades freshwater and estuarine system that requires a very high level of resolution, justifying the use of more sophisticated models. 

Table ES-1: Summary of General Information on Hydrology and Salinity Models Currently in Use in South Florida.

Model Name	Model Type	Simulated Parameters	Spatial Domain	Grid Size	Simulation temporal domain	Relevant Time Step
Linear Regression Models	Statistical	Stage, Flow	Everglades	N/A	1965-2000	daily
PHAST	Wetland Basin	Flow	Everglades and Mangrove Zone	regional	1965-2000	monthly
SFWMM	Freshwater Hydrology	Stage, Flow	Everglades	3.2km X 3.2km	1965-2000	daily
RSM	Freshwater Hydrology	Stage, Flow	Everglades	variable	1965-2000	daily
ENPMod1	Freshwater Hydrology	Stage, Flow	Everglades	3.2km X 3.2km	1965-2000	daily
MLR	Statistical	Salinity	FL Bay, WW Bay, SW Gulf coast, Manatee Bay, Barnes Sound	N/A	1965-2000	daily
Four Box Florida Bay	Mass Balance	Salinity	Florida Bay	regional	1993-1998	monthly
Biscayne Bay Box Model	Mass Balance	Salinity, nutrients	Biscayne Bay	box, variable	1993-2007	monthly
FATHOM	Mass Balance	Salinity, nutrients	Florida Bay, Manatee Bay, Barnes Sound	open-water basins	1970-2000	monthly
FTLOADDS TIME/TTI	2D/3D Coupled surface and groundwater	Stage, Flow, Salinity	Everglades, northern Florida Bay, SW Gulf coast, TTI	0.5km X 0.5km		daily
EFDC	3-D Hydrodynamic	Salinity	Florida Bay	variable	1997-2000	daily
Wang et al., 2003 Biscayne Bay	3-D Hydrodynamic	Salinity	Biscayne Bay	variable	1995-1999	daily
TABS MDS Biscayne Bay	3-D Hydrodynamic	Salinity	Biscayne Bay	variable		daily

 

Model	Parameters simulated	Portability	Validity	Fidelity	Focus	Ease of Use	Temporal Coverage	Spatial Coverage
Linear regression models for stage	stage	3	4	2	-	5	5	3
PHAST	flow	2	4	2	-	5	4	2
SFWMM	stage, flow	3	4	4	-	4	4	4
RSM	stage, flow	1	5	4	-	1	5	4
MLR	salinity	5	5	2	-	5	5	3
Four Box Florida Bay	salinity	2	5	3	-	4	4	3
Biscayne Bay Box Model	salinity	3	5	3	-	4	4	3
FATHOM Florida Bay	salinity	4	5	4	-	4	4	3
FTLOADDS TIME / BISECT / TTI	stage, flow, salinity	3	4	5	-	3	3	4
EFDC Florida Bay	salinity	1	4	5	-	2	2.5	3
Wang et al., (2003) Biscayne Bay	salinity	3	4	4	-	3	2.5	3
TABS MDS Biscayne Bay	salinity	1	4	5	-	1	2.5	3