TEXAS%20COASTAL%20WETLANDS

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TEXAS COASTAL WETLANDS

• Surface Water and its link
• to coastal wetlands loss
• Christine Otto

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BACKGROUND

• Texas wetlands
• 7.6 million acres of wetlands in Texas
• Between mid 1950s and 1979, 35 loss
• Link of wetland loss to population growth and
  density
• Between 1960 and 1990, population along coast
  more than doubled
• 187 persons/mile squared

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URBAN DEVELOPMENT
Alteration of wetland hydrology, topography, and
vegetation
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URBANIZATION
RUNOFF (more and faster)
EROSION
INCREASED IMPERVIOUS SURFACE
DECREASE GW RECHARGE
REDUCED FLOWS IN WETLANDS
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OBJECTIVE

• Incorporate the use of GIS in an analysis of the
  wetland loss along the Texas Coast
• Determine if a correlation exists between the
  decline in wetlands and the urban growth in the
  Texas Coastal Area

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DATA SOURCES

• Texas WetNet (General Land Office) Wetland
  Files, Texas Coastal Boundary
• Dr. David Maidments CE394K.3 class folder
• huc12 - polygon theme of Hydrologic Cataloging
  Units for Region 12 of the US
• rf1huc12 - EPA River Reach files for Region 12
• Texasppt - grid of mean and annual precipitation
  over Texas (mm)
• Texas USGS database Texas Discharge Data
• ESRI Urban development along coast

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METHODOLOGY

• Classify huc12.shp theme based on HUC codes (4
  subbasins)

120402 120904 121004 121102
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METHODOLOGY

• Classify huc12.shp theme based on HUC codes (4
  subbasins)
• Selected features of other themes within area of
  extent

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METHODOLOGY

• Classify huc12.shp theme based on HUC codes (4
  subbasins)
• Selected features of other themes within area of
  extent
• Calculate Precipitation, Runoff, and Flow Grids

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METHODOLOGY Precipitation
Balance of I and O water budget
Natural Water Level Fluctuations
Hydroperiod
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METHODOLOGY Runoff
R (mm/yr) 0.51 P (mm/yr) - 339
Change in water levels
Wetland Response Time
Change in detention time
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METHODOLOGY

• Classify huc12.shp theme based on HUC codes (4
  subbasins)
• Selected features of other themes within area of
  extent
• Calculate Precipitation, Runoff, and Flow Grids
• Discharge Data compiled and graphed

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FLOW
90 loss Submerged marine grasses in Galveston
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AREA OF INTEREST
9,563 acres lost along upper coast
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TIDAL INFLUENCES
Salt water intrusion
Erosion
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CONCLUSION

• Correlation between urban growth and wetlands
  loss along Texas Coastal Boundary
• Too early to determine long-term impacts
• Many factors affecting loss difficult to
  delineate exact causes

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FUTURE WORK

• Determine areas of loss versus areas of
  conversion
• Compare data found with USGS and Texas General
  Land Offices findings
• EPAs Dallas Office Trinity River Basin and
  Galveston Bay