Appendix B
Definitions of Model Runs of the South Florida Water Management Model (SFWMM) and Natural System Model (NSM)
1995 Base (95 B or 95BSR in Figures 3 and 4) is a simulation of the South Florida Water Management system that represents the system infrastructure and operations as they were around 1995. The simulation is made using the South Florida Water Management Model (SFWMM). Water demands and land use are representative of those in 1995. The topography used was the best available at that time. A 31-year climatic record (1965–1995) was used in the simulation. The 1995 Base is also referred to as the current condition, or existing condition.
2050 Base (50BSR in Figure 4) is a simulation of the South Florida Water Management system that represents the likely system infrastructure and operations as they would be around 2050 without any of the Comprehensive Everglades Restoration Plan (CERP) projects in place. Non-CERP Projects assumed to be complete by 2050 include Kissimmee River Restoration, the Everglades Construction Project, Herbert Hoover Dyke improvements, the Modified Water Delivery to Everglades National Park and C-111 projects, and several critical projects in the Lower East Coast area. In the SFWMM simulation of the 2050 Base projected (2050) land use and water demands were used with the same 31-year climatic record (1965–1991) as in the 1995 Base. The 2050 Base is also referred to as the future without project condition or no action alternative.
D13R is the simulation of the South Florida Water Management system with completed Comprehensive Everglades Restoration Plan (CERP) projects in 2050, together with non-CERP projects as simulated in the 2050 Base. In the SFWMM simulation of D13R, the same projected land use and water demands as in the 2050 Base were used. Again the 31-year climatic record (1965–1991) was used. Benefits of D13R are determined by comparison with the current condition (1995 Base) and future without project condition (2050 Base). D13R4 (see Figures 3 and 4) is a scenario based on D13R that would enhance CERP performance by capturing additional water “lost” to tide.
NSM is the Natural System Model simulation that represents the hydrologic response to the pre-drainage Everglades using the same climatic inputs (1965–1995) as were used for the SFWMM. The NSM does not simulate the influences of any man-made features and uses estimates of pre-subsidence topography and historical vegetation cover. The Natural System Model has evolved as knowledge of the pre-drainage everglades has improved. The version of the NSM used to develop the CERP was NSM version 4.5F (NSM in Figure 3 and NSM45F in Figure 4). In the development of the CERP, the NSM pre-drained hydrologic response of the system was, in many cases, used as a target for hydrologic restoration under the assumption that restoration of the hydrologic response that existed prior to drainage of the system would lead to restoration of natural habitats, biota and species. . But whereas NSM water depths are typically used as CERP targets, NSM flow estimates are not necessarily used as targets because of high sensitivity of flow estimates to small changes in water depth estimates.
Source: Ken Tarboton, SFWMD, written commun., April 2002 and Richard Punnett, USACE, personal commun., July 2002. Additional information may be found at http://www.sfwmd.gov/org/pld/restudy/hpm/.