Use of ArcGIS 8.1 for Land Development Planning on Small Acreage Sites

1
Use of ArcGIS 8.1 for Land Development Planning
on Small Acreage Sites

• Tim Osting
• CE 394K.3 GISWR
• Fall 2001

2
Small Sites Background

• I would like to explore the possibility of
  applying GIS technology to a typical Land
  Development project
• I would like to determine if existing GIS
  resources have adequate resolution for a typical
  small-acreage project (lt100 acres)

3
Small Sites Overview

• OBJECTIVE Produce a PROJECT FEASIBILITY STUDY
  using readily-available GIS data without leaving
  my desk!
• Review General Development Planning Requirements
• Description of traditional methodology
• Description of GIS methodology
• Comparison of methods

4
Small Sites A Typical Project

• Location Map
• Property Boundary Map
• Drainage Area Map
• Existing and Proposed Runoff Calculations
• Floodplain Map
• Area Geology
• Area Wells

5
Small Sites Data Sources

• Traditional Methods
• Location Map from TxDOT CAD files
• Property Boundaries from plat (corners generated
  from ground and record information)
• Digitized Geologic Map from draft UT-BEG 7.5
  quads
• Soils Map from UT-BEG
• Wells

• GIS-based Methods
• Location Map from TxDOT CAD files
• Property Boundaries from same
• GIS Geologic Map from USGS
• GIS Soils Map from SSURGO/TNRIS
• GIS Wells from TWDB

6
Small Sites Drainage Calculations

• Traditional Methods
• Drainage Area digitized from 7.5 degree topo map
• Rainfall/Runoff HEC-1 or HEC-HMS
• Tc (or Tlag)
• Drainage Area
• CN
• Channel HEC-RAS
• Floodplain Map

• GIS-based Methods
• NED-generated Drainage Area
• OrRainfall/Runoff HEC-GeoHMS
• Tc (or Tlag)
• Drainage Area
• CN
• Channel HEC-RAS
• Floodplain Map not available

7
Small Sites Sample Project

• 2.6-acre residential resubdivision
• Located in ETJ near Hutto, TX, portions in both
  Williamson and Travis Counties
• Large up-gradient drainage area
• Existing drainage channel at front of lot

8
Small Sites Digitized Drainage Map
Site
Drainage Area
9
Small Sites Drainage Map by GIS
Site
Drainage Area
GIS Stream Network
10
Small Sites Tentative Conclusions

• GIS speeds up data gathering process (Goal
  Feasibility Study in 8 hours or less, lt600)
• HOWEVER, USE CAUTION!
• Most development occurs in areas that are
  changing, so GIS data is often out of date
• GIS data does not yet possess adequate resolution
  for a small-acreage site

11
Small Sites Tentative Conclusions

• GIS is well-suited for producing a Preliminary
  Project Feasibility Study for a small-acreage
  site (Drainage Areas lt250 acres)
• Current GIS is not well-suited to provide final
  design data
• Supplemental information is required for final
  project design