The SLEUTH model, also known as the Clarke Cellular Automata Urban Growth Model or as the Clarke Urban Growth Model, is intended to simulate urban growth in order to aid in understanding of how expanding urban areas consume their surrounding land, and the environmental impact this has on the local environment. SLEUTH derives its name from the six types of data inputs: slope, land use, urban, exclusion, transportation, and hillshading. SLEUTH is calibrated using these types of historical data. It produces forecasts of land use change from a local to regional scale.
This model simulates the transition from non-urban to urban land-use using cellular automata. This body of methods generates dynamic spatial patterns by applying growth rules to a grid of cells, each of whose land-use state is dependent upon local factors (e.g. roads, existing urban areas, topography), temporal factors, and random factors. Additionally other, non-urban land use transitions (such as range land to agricultural land) can be simulated assuming urbanization is the driver. Annual maps of forecasted change are generated allowing for animated display of forecasts over time as well as integration in GIS data bases for further spatial analysis.
General Info
Developers:
Keith C. Clarke, Jeannette T. Candau
Website:
www.ncgia.ucsb.edu/projects/gig
Strengths:
ï Concurrently simulates four types of growth (spontaneous, diffusive, organic, and road-influenced)
ï Provides both graphical and statistical outputs.
ï Incorporates momentum of booms and busts using threshold multiplier with subsequent temporal decay.
ï Allows for relatively simple alternative scenario projection.
Outputs:
The model provides outputs as a set of GIF image files that can be merged into an animation or brought into a GIS as data layers. Resolution of output images depends on the resolution of the input data. ACSII files contain statistical data for the simulations.
Resources
User Input Requirements:
In GIF format:
ï Slope: Derived from a DEM (Digital Elevation Model)
ï Excluded areas: Water bodies and other land where urbanization cannot occur.
ï Roads/transportation network
ï Seed or urban layer
ï Background
An ASCII "scenario" file contains all input information (path names, file names, coefficient values, etc.) and execution variables (preferences for output colortables, classification of images, etc.)
Time Commitment:
-Calibration of the model can be involved and take from several hours to several days depending upon the size of the data set. Once calibration has been completed forcasting is relatively quick taking several minutes to hours to complete. Any number of forecast scenarios may be generated from the single calibration.
Equipment Needs:
The SLEUTH model requires a PC, workstation, or mainframe with a UNIX or Linux operating system and a C compiler (e.g.; gcc or cc).
Limitations:
ï The model does not explicitly deal with population, policies and economic impacts on land use change, except in terms of growth around roads or those that can be expressed in permissive/controlled growth zoning.
Staff Requirements:
Installation and calibration of the model requires experience in UNIX operating system, C programming, and gnu C compiler (gcc), as well as GIS and land-use modeling expertise.
Software Cost:
None - may be downloaded for free at http://www.ncgia.ucsb.edu/projects/gig/download.htm
Preview:
The SLEUTH Model can be downloaded from http://www.ncgia.ucsb.edu/projects/gig/download.htm
