Coastal Services Center

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Impervious Surface Analysis Tool

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The Impervious Surface Analysis Tool (ISAT) is used to calculate the percentage of impervious surface area of user-selected geographic areas (e.g., watersheds, municipalities, subdivisions). The National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center and the University of Connecticut Nonpoint Education for Municipal Officials (NEMO) Program developed this tool for coastal and natural resource managers. ISAT is available as an ArcView^® 3.x, ArcGIS 8.x or an ArcGIS 9.x extension.

The Impervious Surface Analysis Tool

• Requires the Spatial Analyst^® extension and the following inputs:
  • Land cover grid
  • Polygon data set for which percentage of impervious surface is to be calculated
  • Set of land cover impervious surface coefficients calibrated for low, medium, and high population densities
  • Optional population density theme
• Creates the following outputs:
  • Shapefile that includes green, yellow, and red polygons to represent conditions of good, fair, and poor water quality
  • Attribute table that includes a calculated value for the percent impervious area and total impervious surface area of each selected polygon
• Incorporates land cover change scenarios to examine how changes influence impervious surfaces
• Includes Web-based help files that describe ISAT's functions

Download Instructions

Before you download ISAT, create a C:\isat directory. Select the link below and save the file to the C:\isat directory.

Unzip the file within C:\isat. Freeware and shareware programs for ZIP archives are available for both UNIX^® and PC. The file contains setup.exe, Microsoft^® XML Parser (msxl3.exe in ArcView 3.x and msxml.msi in ArcGIS 8.x/9.x), and the files required to walk through the tutorial. Run the setup.exe program by double-clicking on it. The installation process for the ArcView 3.x extension will place a copy of the extension in the ArcView extensions folder, typically located at C:\Esri\Av_gis30\Arcview\Ext32. The installation process for the ArcGIS 8.x/9.x extension for ArcMap will create a directory in C:\Program Files\ called isat_ext. The coefficient files, help files, and any temporary files are saved under this directory. Consult the tutorial ( Adobe^® Reader^® is needed to view and print PDF files) for further instruction.

Instructions for ArcGIS 9.2 Users: In addition to installing the ISAT extension for ArcGIS 9.x available below, you must also install the ISAT patch for ArcGIS 9.2. The patch addresses several issues discovered with ArcGIS 9.2.

Download the ISAT extension for ArcView 3.x

Download the ISAT extension for ArcGIS 8.x

Download the ISAT extension for ArcGIS 9.x

Download the ISAT patch for ArcGIS 9.2 Users

Download only the ISAT tutorial and data

If you have difficulty accessing this file or if you need more information, contact the NOAA Coastal Services Center's Clearinghouse at (843) 740-1210, or through our contact form.