The ATLSS High Resolution Topography HRT and High Resolution Hydrology HRH Models

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The ATLSS High Resolution Topography (HRT) and
High Resolution Hydrology (HRH) Models
Scott M. Duke-Sylvester The Institute for
Environmental Modeling University of
Tennessee sylv_at_tiem.utk.edu www.atlss.org/sylv L
ouis J. Gross University of Tennessee
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Original idea and direction for the High
Resolution Topography and High Resolution
Hydrology came from Michael Huston at ORNL in
Oak Ridge, TN.
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ATLSS Across Trophic Level System Simulation

• Panther
• Deer
• Vegetation
• Cape Sable Sea Side Sparrow
• Wading Birds
• Fresh Water Fish
• Alligator
• Snail Kite
• High Resolution Topography
• High Resolution Hydrology

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Overview

• Model Motivation and Goals
• Model Design and Implementation
• Inputs
• Processes
• Outputs
• Results
• Comparison to SFWMD elevation
• Comparison to USGS High Accuracy Elevation Data
• Discussion

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ATLSS Philosophy

• Fauna and flora of an area respond to local
  variation in the environment.
• Differences between locations can have a strong
  influence upon dynamics at higher levels of
  organization.
• Population
• Community
• Ecosystem

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Motivation for ATLSS

• Recently the motivation has been to provide an
  assessment of the relative impacts of different
  hydrology scenarios upon various biotic
  components of the South Florida Everglades.
• Panthers
• Sparrows

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Motivation for the HRT and HRH

• To model the responses of fauna and flora to
  differences in local conditions we need
  topography and hydrology with spatial variation.
• We need to cover an area which is relevant for
  both the species in question and our need to
  understand the system.
• Current elevation maps and hydrology data sets do
  not include the resolution and extent appropriate
  for modeling detailed biotic response to changing
  hydrology.

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Extent

• The area for which we need elevation data is
  described by the SFWMD Hydrology modeling area.

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Resolution used by current ATLSS models

• Deer 100x100 meter cells
• Panther 100x100 meter cells
• Fresh Water Fish 500x500 meters
• Vegetation 100x100 meters

The HRT model is capable of generating elevation
data at a 30x30 meter resolution.
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Elevation data sets currently available.
USGS High Accuracy Elevation Data
South Florida Water Management Districts
Elevation Map
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Question

• How do we generate topography and hydrology at
  the scale and extent relevant to the species of
  SF?
• We combine data sets which are available to
  extrapolate small scale elevation for SF.

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Model Design and Implementation

• Model combines three primary inputs to compute
  elevation
• Hydrology data
• Vegetation type map
• Vegetation hydroperiod values
• The vegetation types are assumed to be at
  locations and elevations with appropriate
  hydroperiods for the species within them.

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Input Hydrology Data

• Spatial scale
• most of SF
• 2x2 mile resolution
• Temporal scale
• 1979-1995
• daily time step
• SFWMM Cal/Val

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Hydrology Data

• Transform the Stage Height data into hydroperiod
  histograms.
• Describes the number of days at or above each
  elevation.
• We use an average of values from 1986 to 1995.
• Currently based on the Calibration/Validation
  (Cal/Val) run of the SFWMM.

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Vegetation Map

• Raster Map
• high spatial resolution
• high spatial heterogeneity
• Each cell contains an index value which
  represents one vegetation type.
• Currently based on the Florida GAP Map.

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Spatial scale of inputs

• It is important to note that the hydrology data
  and the vegetation data are provided at
  difference spatial scales.
• Veg 30x30 meters
• Hydro 2x2 miles
• We need to preserve each resolution.
• Veg resolution is needed for topography
• Hydro resolution is needed to preserve water
  volume.

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Hydroperiod values for vegetation types.

• For each vegetation type in the FGAP map we
  estimate a range of hydroperiods.
• The hydroperiod used for any particular cell in
  the FGAP map is interpolated as follows

• Hydroperiod values are drawn from the literature.

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Processes
Ep
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Result High Resolution Topography (HRT)
4 miles
4 miles
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4 miles
4 miles
4 miles
4 miles
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High Resolution Hydrology

• Created by combining the ATLSS HRT map and the
  SFWMD hydrology data.
• Preserves water volume in each of the 2x2 mile
  cells of the SFWMD hydrology data.

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High Resolution Hydrology
4 miles
4 miles
4 miles
4 miles
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Comparison to the USGS High Accuracy Elevation
Data (HAED)

• Compared the HRT, the SFWMD and the HAED.
• Point-wise for each HAED region
• Regional elevation means for each HAED region.

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Comparison Results

• Compared regional elevation means between the
  SFWMD, HAED and HRT (ANOVA)
• Inconclusive, some means differ, some do not. No
  discernable pattern.
• HRT has regional variance in elevation greater
  than SFWMD data.
• The results indicate a need to refine the
  hydroperiod parameters

• A more complete analysis of the differences
  between the HRT and HAED data can be found at
  www.atlss.org/sylv

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Important outcome

• At a regional scale the HRT is generating more
  spatial variability in elevations than the SFWMD
  elevation data.
• HRT is capable of producing spatial variability
  which is more appropriate for modeling detailed
  biotic responses to changing hydrology.

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Future Directions

• Update to the Florida GAP v6.6
• Implementing hydroperiod parameters.
• Implement new algorithm
• Genetic algorithm
• Optimal search algorithm
• Seek new input parameters
• Make additional comparisons

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Open problems

• Scale of hydrology data
• small areas represented by few cells.
• How to handle water control structures
• canals
• levees
• How to deal with SFWMM cell boundaries.
• How to incorporate the HRT methodology and new
  elevation data sets.
• How to use the HRT and the NSM together
• Estuarine areas

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Movie
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Goals

• To provide hydrology data with spatial
  heterogeneity at a scale which is meaningful to
  the plants and animals of South Florida.