Environmental Modeling - PowerPoint PPT Presentation

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Environmental Modeling

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Environmental Modeling Integration of GIS with Env Models 1. Issue Predict fire potential in San Jacinto Mountain, Southern California using GIS data and ... – PowerPoint PPT presentation

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Title: Environmental Modeling


1
  • Environmental Modeling
  • Integration of GIS with Env Models

2
1. Issue
  • Predict fire potential in San Jacinto Mountain,
    Southern California
  • using GIS data and meteorological data and
  • meteorological models
  • Zack, J.A. and R.A. Minnich, 1991. Integration of
    geographic information systems with a diagnostic
    wind field model for fire management. Forest
    Science, 37(2) 560-573.

3
1. Causal factors of wildfire
  • Hot and dry weather
  • - high temperature and low humidity
  • Windy
  • - high wind speed and certain wind direction
  • Fuels
  • - dry grasses and shrubs

4
2. Tasks
  • Create topographic and weather databases
  • Use GIS and weather data as input for a
    diagnostic wind model to estimate surface wind
    field
  • Combine output of the wind model and slope as
    input for a slope-wind interaction fire model to
    estimate fire potential
  • Use GIS to display model results

5
3. Model I
  • A diagnostic wind field model KRISSY
  • Input
  • (1) 3D topography,
  • (2) vertical profile of horizontal wind speed
    and direction,
  • (3) synoptic-scale pressure gradient, and
  • (4) inverse distance squared interpolation
  • To estimate
  • wind direction and speed for surface grids and
    above surface grids

6
4. Data
  • Surface
  • wind speed
  • wind direction
  • temperature (21 sites)
  • 124,000 DEM
  • Upper air
  • 1 vertical profile of wind and temperature

7
5. GIS Processes
  • Re-sample DEM to 150m resolution
  • Attach locations to elevation and weather data
    for KRISSY

8
6. Model I Again
  • Model constraints
  • - Concordance with surface and
  • upper air observations
  • - Laws of physics

9
6. Model I ..
  • Output
  • Convert model output in GIS
  • elevation, wind direction, wind speed,
  • E-W, N-S, and vertical component of wind
  • Prepare slope angle and aspect for the second
    model

10
7. Model II
  • Slope-Wind Interaction Fire Model (SWIF)
  • Fire spread rates increase up-slopes and change
    with slope aspect
  • SWIFi,j Vi,j 1(sin Si,j)0.5 (cos
    (?i,j-?i,j))
  • Vi,j - wind speed (estimated by KRISSY)
  • Si,j - slope angle (degree)
  • ?i,j - wind direction (estimated by KRISSY)
  • ?i,j - slope aspect

11
7. Model II..

451350(e) vs. 22503150(w) -450450(n)
vs.13502250(s)
Sin0 0 Cos0 1
Sin270 -1 Cos270 0
Sin90 1 Cos90 0
3. 4. Aspect is a circular variable. To
differentiate its circular values, divide it into
e-wn-s, or use sin or cos.
Sin180 0 Cos180 -1
12
7. GIS Process II
  • Display fire potential using a set of graduated
    point symbols

13
8. Possible Error Sources
  • Resampling terrain data
  • Surface wind observation
  • Spatial distribution of the wind observation
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