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Variable-mesh ATLSS Models: Keeping Pace with the Future of Hydrologic Modeling for Everglades Restoration

Scott M. Duke-Sylvester, Eric A. Carr, Louis J. Gross and Jane Comiskey
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN

The Across Trophic-Level System Simulation (ATLSS) project has produced a set of Spatially Explicit Species Index (SESI) models, population demography models, and ecosystem process models. These models have been applied to provide a relative assessment of biotic responses to alternative water-management scenarios as part of the Comprehensive Everglades Restoration Plan (CERP). In the past, hydrologic data for these scenarios have been produced by the South Florida Water Management Model (SFWMM), which uses an underlying uniform spatial grid of square cells. Future scenarios will be produced by hydrologic models that employ variable spatial grids and meshes across the model area of southern Florida. ATLSS has undertaken a project to enable our models to process hydrologic data from these variable-mesh hydrologic models, including MODBRANCH, WASH123D, and the South Florida Regional Simulation Model (SFRSM), while maintaining compatibility with the SFWMM. We describe two main components of this project: (a) developing new Landscape v3.0 classes to handle hydrologic input in multiple underlying shapes and spatial resolutions; and (b) modification of the ATLSS SESI models to utilize the new Landscape classes.

We describe components of the conversion process and the basic tools we developed for input conversion, formatting, and data storage. Processing variable grids requires a mechanism for implementing geo-referencing and connectivity that is independent of cell shape and relative position. To accomplish these goals, the revised Landscape classes implement a separation of data storage, shape information, and interconnectivity. These three components are then wrapped to produce a unit called a Landscape Object. The new Landscape classes now provide ATLSS models with the flexibility to handle varying spatial resolutions and underlying shapes (e.g. points, triangles, squares, and rectangles). This functionality will allow hydrologic data from variable-mesh models to be stored, accessed, and processed within the Landscape v3.0 classes, enabling ATLSS models to maintain a single set of code and run a common set of algorithms for all proposed hydrology meshes. The SESI White-tailed Deer model was modified to use the new Landscape classes as a template for conversion of other ATLSS models. We present results of trial simulations of the mesh-based Deer model with available hydrologic data from SFRSM.

This project was undertaken in support of Critical Ecosystem Studies Initiatives (CESI) restoration goals that require a defensible scientific methodology to compare and contrast impacts to biota at the spatial and temporal scales of the alternative hydrologic plans being produced.

Contact Information: Eric A. Carr, Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37919-1610, Phone: 865-974-0223, Fax: 865-974-3067, Email:

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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