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Presentation Outline
Hydrologic Cycle: Connecting the Land Surface with the Atmosphere
Connecting Hydrology and Meteorology
Regional flood analysis in Houston
Nexrad Rainfall for Storm of Oct 1994
Discharge in Buffalo Bayou at Katy October, 1994 storm
Calibrated Flow with HEC-HMS
Global Runoff (mm/yr)
GTOPO30 - 30” Digital Elevation Model of the Earth
Drainage in North America
Drainage Basins of North America
Streamflow Hydrographs for Large Basins
A Fundamental Dilemma
Geospatial Database: a set of compatible data layers or themes
Spatial Data: Vector format
Feature Attribute Table
Relational Linkages
Locations on the Stream Network
Watersheds defined using a Digital Elevation Model
Spatial Data: Raster format
Points as Cells
Line as a Sequence of Cells
Polygon as a Zone of Cells
Raster-Vector Data Model
Study Region in West Austin
Watershed Delineation by Hand Digitizing
30 Meter Mesh Standard for 1:24,000 Scale Maps
DEM Elevations
Austin West 30 Meter DEM Elevations in meters ftp://ftp.tnris.state.tx.us/tnris/demA.html
Flow Direction Grid
Stream Network for 5 cell Threshold Drainage Area
Streams with 200 cell Threshold (ᡊ hectares or 13.5 acres drainage area)
Watershed and Drainage Paths Delineated from 30m DEM
DEM Data Sources
Shape of the Earth
Geographic Coordinates (f, l, z)
Ellipse
Ellipsoid or Spheroid Rotate an ellipse around an axis
Representations of the Earth
Definition of Elevation
Coordinate System
Earth to Globe to Map
Conic Projections (Albers Equal Area, Lambert Conformal Conic)
Cylindrical Projections (Universal Transverse Mercator)
Azimuthal (Lambert Azimuthal Equal Area)
Presentation Summary
Email: maidment@mail.utexas.edu
Home Page: http://www.ce.utexas.edu/prof/maidment
Other information: AMS Meeting, Dallas, Jan 1999
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