nigtrogen pollution change due to land use changes in the plano/allen area
TRANSCRIPT
GISC 6384 - Spring 2005 - Norris Stough
Land Use Change In Plano and Allen, Texas From 1990 to 2000
The Effect on Nitrogen Levels in Storm Water Run Off
GISC 6384 - Spring 2005 - Norris Stough
Project Objectives
General objectivesApplication of spatial analyst and modeling tools and methodology to data to achieve possible “real-world” applications.
Specific objectivesIdentify areas of land use change in the city of Plano and Allen, Texas and summarize their effect on nitrogen loading in storm water runoff.
GISC 6384 - Spring 2005 - Norris Stough
Data Sources
North Central Texas Council of GovernmentsLand use shape filesCity boundary shape files
Watershed boundary shape filesSource: www.dfwinfo.com
United States Geological Survey
NED (National Elevation Dataset) raster filesSource: http://seamless.usgs.Gov
GISC 6384 - Spring 2005 - Norris Stough
Steps:1. Conversion from feature data to raster data.2. Determining areas of change in land use type using
raster calculator.3. Reclassification of land use type by nitrogen
loading.4. Zonal sum of nitrogen loading by city and
watershed.5. Creation of drainage basin data for pollutant
summary.6. Zonal sum of nitrogen loading by predefined
drainage basin area.
GISC 6384 - Spring 2005 - Norris Stough
1990 Land Use RasterFeature to Raster Conversion
Source: North Central Texas Council of Governments
GISC 6384 - Spring 2005 - Norris Stough
2000 Land Use Raster Feature to Raster Conversion
Source: North Central Texas Council of Governments
GISC 6384 - Spring 2005 - Norris Stough
Determining Areas of Change Raster Calculator
Areas of change were determined by using Raster Calculator. The land use codes for 1990 were subtracted from the land use codes for 2000, resulting in a VAT of the differences.
[lu_00] – [lu_90]
Value of 0 = No Change
All other values = Change in land use
This only works when land use codes remain consistent from 1990 to 2000
Change
No change
GISC 6384 - Spring 2005 - Norris Stough
Reclassification for Areas of Change
Spatial Analyst Reclassify
The areas of change were then reclassified:– “NoData” for values of 0.– “1” for all other values.
The resulting raster layer could then be used as a filter to identify areas of change in the 2000 land use layer.
GISC 6384 - Spring 2005 - Norris Stough
Land Use Change Areas
GISC 6384 - Spring 2005 - Norris Stough
Land Use Change By 2000 Land Use Type
Raster Calculator was used to isolate areas of change from 1990 to 2000 by their 2000 land use codes.
[lu_change] * [lu_00]
GISC 6384 - Spring 2005 - Norris Stough
Reclassification By Nitrogen Loading Based On Land Use Type
Spatial Analyst Reclassify
Source: http://www.savethebay.org/land/environment/pollution/water.html
Conversion:
Cell Size2 = 2,500 sf
Acre = 43,560 sf
Conversion: 2,500 / 43,560 = 0.057
Pounds (acre) * 0.057 = Pounds (cell)
GISC 6384 - Spring 2005 - Norris Stough
Nitrogen Load by Land Use After Reclassification
GISC 6384 - Spring 2005 - Norris Stough
Plano and Allen, Texas Raster File Feature to Raster Conversion
Source: North Central Texas Council of Governments
GISC 6384 - Spring 2005 - Norris Stough
Watershed Raster File Feature to Raster Conversion
Source: North Central Texas Council of Governments
GISC 6384 - Spring 2005 - Norris Stough
Basin GenerationHydrology Watershed
Generating a watershed through the use of elevation data is a common task in GIS.
Watersheds can be generated using pour points to define total upstream area from a point.
However, they can also be generated for local areas of study within a larger watershed by defining basins using a minimum number of cells to determine area.
The process is much the same as used in class, but instead of selecting the “points” options, use “threshold” size.
GISC 6384 - Spring 2005 - Norris Stough
Original NED Elevation
GISC 6384 - Spring 2005 - Norris Stough
Allen Land Use Change Overlay on NED Elevation
GISC 6384 - Spring 2005 - Norris Stough
NED DataHydrology Fill Sinks
2,447 Sinks were Identified and filled.
GISC 6384 - Spring 2005 - Norris Stough
Flow DirectionHydrology Flow Direction
Drainage channels are easy to identify even at this point.
GISC 6384 - Spring 2005 - Norris Stough
Flow AccumulationHydrology Flow Accumulation
GISC 6384 - Spring 2005 - Norris Stough
Basins with Land Use OverlayHydrology Watershed
Basins generated using threshold to generate area.
GISC 6384 - Spring 2005 - Norris Stough
Zonal Sum By City
Lbs.
GISC 6384 - Spring 2005 - Norris Stough
Zonal Sum By Watershed
Lbs.
GISC 6384 - Spring 2005 - Norris Stough
Zonal Sum By Basin