The ATLSS High Resolution Topography/Hydrology Model

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The ATLSS High Resolution Topography/Hydrology
Model

• Scott M. Duke-Sylvester
• ATLSS Project University of Tennessee

Project web-site www.atlss.org E-mail
sylv_at_tiem.utk.edu
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Overview of Presentation

• Purpose of the High Resolution Topography
  (HRT)/High Resolution Hydrology (HRH) models
• HRT/HRH creation
• Verification, calibration and validation
• Versions and availability

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Purpose of the HRT/HRH

• To provide an estimate of finer scale spatial
  variation in hydrology for the ATLSS models
• Resolution 500x500 meters
• Used by all ATLSS models including
• SESI models
• Fish model (ALFISH)
• Deer/panther model

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Why 500x500 meters?

• Plants and animals respond to local variations in
  hydrology at a spatial resolution finer than the
  2x2 mile SFWMM blocks
• Tree islands
• Transition from slough to prairie
• Permanent ponds vs. marsh with transient water
  depths

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Tree Island Skinners Camp
4 miles
HRT
SFWMM
4 miles
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Slough to prairie transitionVariation in water
depths
SFWMM
HRH
Wet
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Dry
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HRT Features

• Common resolution 500x500 meters
• Available 30x30 meters
• Coverage Most of the natural areas of SF

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HRH features

• Common resolution 500x500 meters
• Common time step 5 days
• Time span Jan 1 1965 - Dec 31 1995
• Adaptable to longer SFWMM runs
• Spatial coverage SFWMM region
• Adaptable to use with other data sets

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HRT Creation

• Basic premise Plants are present in locations
  where local topography and hydrology combine to
  create favorable hydroperiods
• Topography Hydrology gt Vegetation
• Vegetation Hydrology gt Topography

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Inputs

• Hydrology SFWMM Calibration/verification run
• Vegetation FGAP
• Hydroperiod ranges Literature, expert opinion
• Adaptable to other data sets

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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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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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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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Processes
Ep
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HRH Creation

• 2x2 mile SFWMM hydrology data is distributed over
  a 500x500 meter HRT
• Redistribution takes place on a 2x2 mile cell
  basis
• Total daily water volume is preserved in each
  cell
• Resulting hydrology has a 500x500 meter resolution

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Verification

• Simple visual inspection
• e.g. tree islands are higher than surrounding
  slough
• Comparison to independently computed values
• Function testing

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Calibration

• The main features of the HRT that can be
  calibrated are the hydroperiod ranges for each
  vegetation type.
• Hydroperiod ranges estimated from published
  literature
• Expert opinion

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HRH Validation

• Comparison of HRH water depths to measured water
  depths
• Time series Feb, Apr, Jul, Oct, Dec 1995
• Region WCA-3 and Shark River Slough
• 16 sites, 3 plots at each site
• r2 for HRH to field data 0.289
• r2 for SFWMM to field data 0.236
• Gaff, H. 1999. Spatial heterogeneity in
  ecological models two case studies. PhD.
  Dissertation, University of Tennessee.

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HRT Validation

• Comparison to USGS HAED
• Compared the mean elevation and variance between
  the HRT, USGS High Accuracy Elevation Data (HAED)
  and SFWMM data.

• HRT variance is more similar to HAED variance
• HRT mean is lower than either SFWMM or HAED mean

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Conclusion

• HRT is not an exact fit to measured elevations.
• HRT is generating a level of topographic
  variation consistent with the HAED data in many
  instances.
• Further calibration of model will improve the fit
  between the HRT output and HAED.

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Application to Restoration Planning

• Provides an estimate of topography and hydrology
  to other models at a spatial resolution relevant
  to ecological modeling

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Versions

• Version 1.0
• Available for use today
• Has been used in the past
• 1997-1998 hydrology scenario evaluation
• Based on
• FGAP 2.1
• Hydroperiod values from Michael Huston
• SFWMM 3.4, Calibration/verification run
• Version 2.0
• Available by June 30 2002
• Based on
• FGAP 6.6
• Hydroperiod values from Paul Wetzel
• SFWMM 3.5, Calibration/verification run
• Calibrated with latest USGS HAED

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Availability

• HRT maps
• Created at UT
• Maps are available to collaborating agencies
• ENP, SFWMD
• High Resolution Hydrology
• Created as part of the ATLSS SESI package
• Sun/Solaris Workstations
• ENP

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Collaborators/Contributors

• FGAP Leonard Pearlstine
• SFWMM Ken C. Tarboton, SFWMD
• ATLSS
• Paul Wetzel, ATLSS
• Charley Comiskey, ATLSS
• Michael Huston, ORNL

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• E-mail sylv_at_tiem.utk.edu
• Web site www.atlss.org/sylv