Study of Impervious Surface in the Alum Creek Watershed

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Study of Impervious Surface in the Alum Creek
Watershed

• Luanne Hendricks
• GIS130 - Final Project
• 12/07/04

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Question

• How much impervious surface is there in the Alum
  Creek Watershed? What percent of total area?
• Scope study area down to portion of watershed in
  Franklin County

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Why Care?
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Alum Creek Watershed in Franklin County
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Planned Methodology

• Apply landuse estimate method described in
  Impervious Cover and Land Use in the Chesapeake
  Bay Watershed, by Cappiella Brown.
• Directly measure impervious surface of sample
  areas for different landuses
• Develop coefficients from samples
• Multiple total landuse areas by coefficents

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Source Data

• Alum Creek Watershed Boundary within Franklin
  County Shapefile
• MORPC, 2000
• Parcel Shapefile of Franklin County
• Franklin County Auditor, 10/2004
• Coefficient Data from study document

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Closeup of Parcel Data
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Impervious Cover Coefficient Data
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Analysis Mapping of Categories
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Analysis Geoprocessing Model
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Results
IC Sum_AREA X Coeff IC_Pct IC / Total
Watershed Area Pct_Area Sum_AREA / Total
Watershed Area Total Watershed Area
1514505863.18859 sq. ft.
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Results Sum of Percents
Impervious Cover 29.187
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Results - Map Document
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Are Results Reasonable?

• Impervious Surface 17
• Source Alum Creek Resource Sheet, FACT, Fall,
  2002
• Impervious Surface 44
• Source Alum Creek Action Plan Draft, FACT,
  January, 2004
• Impervious Surface 29
• Source my estimate

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Impervious Cover Estimate from FACT Inventory
Different Categories
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Possible Sources of Error

• Use of Chesapeake Bay coefficients
• Categorization of Parcels
• Use of Area Attribute values instead of
  calculated Area values
• How to factor in roads?