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CEE 795Water Resources Modeling and GIS

Session #1(some material from Dr. David Maidment, University of Texas)

January 18, 2006Learning Objectives:• Outline the various types of models that can be integrated with GIS• Describe the geospatial database of hydrologic features • Outline the Arc Hydro data model• Demonstrate the use of curved earth and a flat map projections

Handouts: Assignments:Get SCR login accounts

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Water Resources Modeling and GIS: Session 1

• Water Resource Models and GIS

• Geospatial database of hydrologic features

• Arc Hydro data model

• Curved earth and a flat map

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GIS and Hydraulic Models

• HEC Geo-RAS• Used for Pre and Post

processing of data from HEC-River Analysis System (RAS)

• Open Channel flow model

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GIS and Hydrologic Models• Automated

Geospatial Watershed AssessmentTool (AGWA)

1992 NALC Hillshade DEM STATSGO

ForestOak WoodlandsMesquite WoodlandsGrasslandsDesertscrubRiparianAgricultureUrbanWaterBarren / Clouds

Land CoverForestOak WoodlandsMesquite WoodlandsGrasslandsDesertscrubRiparianAgricultureUrbanWaterBarren / Clouds

Land Cover

0 5 10 km0 5 10 km

NN

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GIS and Water Distribution Models

• Haestad WaterGEMS

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Water Resources Modeling and GIS: Session 1

• Water Resource Models and GIS

• Geospatial database of hydrologic features

• Arc Hydro data model

• Curved earth and a flat map

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Geographic Data Model

• Conceptual Model – a set of concepts that describe a subject and allow reasoning about it

• Mathematical Model – a conceptual model expressed in symbols and equations

• Data Model – a conceptual model expressed in a data structure (e.g. ascii files, Excel tables, …..)

• Geographic Data Model – a conceptual model for describing and reasoning about the world expressed in a GIS database

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Data Model Data Model based on based on Inventory of Inventory of data layersdata layers

Spatial Data: Vector format

PointPoint - a pair of x and y coordinates(x1,y1)

LineLine - a sequence of points

PolygonPolygon - a closed set of lines

Node

vertex

Vector data are defined spatially:

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Themes or Data Layers

Vector data: point, line or polygon features

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Kissimmee watershed, Florida

Themes

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Attributes of a Selected Feature

Raster and Vector Data

PointPoint

LineLine

PolygonPolygon

VectorVector RasterRaster

Raster data are described by a cell grid, one value per cell

Zone of cells

14http://srtm.usgs.gov/srtmimagegallery/index.html

Santa Barbara, California

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How do we combine these data?

Digital ElevationModels

Watersheds Streams Waterbodies

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An integrated raster-vector

database

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Data Model Based on Behavior

“Follow a drop of water from where it falls on the land, to the stream, and all the way to the ocean.”

R.M. Hirsch, USGS

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Integrating Data Inventory using a Behavioral Model

Relationships betweenobjects linked by tracing pathof water movement

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Water Resources Modeling and GIS: Session 1

• Water Resource Models and GIS

• Geospatial database of hydrologic features

• Arc Hydro data model

• Curved earth and a flat map

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Arc Hydro: GIS for Water ResourcesPublished by ESRI Press

The Arc Hydro data model andapplication tools are in the publicdomain

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Arc Hydro — Hydrography

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Arc Hydro — Hydrology

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Flow

Time

Time Series

Hydrography

Hydro Network

Channel System

Drainage System

Arc Hydro Components

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Hydrologic Information System

Analysis, Modeling, Decision Making

Arc Hydro Geodatabase

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Nexrad Radar Rainfall Map

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Nexrad Map to Flood Map in Model Builder

FLOODPLAIN MAP

Flood map as output

Nexrad map as input

Model for flood flow

Model for flood

depth

HMS

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Water Resources Modeling and GIS: Session 1

• Water Resource Models and GIS

• Geospatial database of hydrologic features

• Arc Hydro data model

• Curved earth and a flat map

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Origin of Geographic Coordinates

(0,0)Equator

Prime Meridian

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Latitude and Longitude

Longitude line (Meridian)N

S

W E

Range: 180ºW - 0º - 180ºE

Latitude line (Parallel)N

S

W E

Range: 90ºS - 0º - 90ºN(0ºN, 0ºE)

Equator, Prime Meridian

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Latitude and Longitude in North America

90 W120 W 60 W

30 N

0 N

60 N

Austin: (30°N, 98°W)

Logan:(42°N, 112°W)

Map Projection

Curved EarthGeographic coordinates: ,

(Latitude & Longitude)

Flat Map Cartesian coordinates: x,y

(Easting & Northing)

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Earth to Globe to Map

Representative Fraction

Globe distanceEarth distance

=

Map Scale: Map Projection:

Scale Factor

Map distanceGlobe distance

=

(e.g. 1:24,000) (e.g. 0.9996)

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Coordinate Systems

(o,o)(xo,yo)

X

Y

Origin

A planar coordinate system is defined by a pairof orthogonal (x,y) axes drawn through an origin