Arc Hydro: An Introduction

Michael N. DeMersDepartment of Geography

New Mexico State University

Arc Hydro

• Extension of geodatabase model for support of water resources applications (template data model)–Surface and groundwater

• Collection of tools for support of Arc Hydro geodatabase design and basic water resources functions

• Starting point for water resources database and application development

Arc Hydro Data Model

Data Model Purpose

• Target audience: Water resources community interested in quick start in ArcGIS implementation

• Starting point for project model design• Not a “do all” design• Not implementation/application specific, but provides the key components upon which to develop your implementation

• Not a numerical but a DATA model–Allows support for many models

Describing the Hydrologic Cycle

Arc Hydro Framework Data Model

Surface water featuresGroundwater features

Time Series

Arc Hydro Data Model Details

Time Series Components

Basic Concepts

• Define core feature classes for water resources analyses– Inventory of relevant spatial elements

• Establish relationships between core feature classes– So we know what is connected to what

• Use geometric network for tying pieces together– So we can trace upstream/downstream

• Mobilization of standard ArcGIS functionality

• Custom tools for some of the attribute management• Custom tools for advanced “water resources”

functionality

Application and use of Arc Hydro for a Water Geofabric

1. Build and compile key GIS

Databases

2. Build and serve key Digital

Basemaps

3. Build and serve Operational

Layers

4. Build and serve

Tasks

5. Build and serve key

GIS Applications

GIS Application

Operational layers

Digital Basemap (2D or 3D)

Tasks that operate against . . .

. . . a fully operational GIS database(a Geofabric)

Scalability

1:17,000,000

1:5,000,000

1:2,500,000

1:500,000

1:175,000

1:40,000

1:24,000

1:5,000

Arc Hydro Tools

Key Concepts

• Transitions between the raster and vector worlds – integrated operations

• “Relationships between objects linked by tracing path of water movement”

Raster NetworkVector

Logical SchemaExtended Network

Terrain Processing

• Start with the terrain model

• Identify drainage patterns

• Identify catchments

Network Generation

• Start with the drainage pattern

• Define hydro edges from drainage lines

• Generate junctions at confluences

• Build the geometric network

Connecting Catchments to Junctions

• Start with the catchments

• Identify drainage points

• Link drainage points to junctions

Extended (Hydrologic) Network

• Combination of hydro network and drainage areas connected through junctions.

• Allows tracing through network and selection on drainage areas

Node-Link Schematization

• Start with the catchments

• Find centroids• Continue with drainge

lines• Find confluences• Connect nodes

• Transition from geo representation to logical representation

Node-Link Schematization

• Support for various modeling efforts

Arc Hydro Tools

• 70 + functions currently available –Watershed Delineation–Batch Terrain Preprocessing–Schema Creation–Parameters Accumulation–Parameters Computation (e.g. mean elevation, 10-

85 slope, etc.)–Time Series

Arc Hydro Tools• Functions developed during projects are integrated

into the Arc Hydro tools (needs driven development)–Batch Terrain Preprocessing–Parameters Computation –Terrain Morphology–and others…

Process Automation in Model Builder Arc Hydro Model For Hydro Landscape Characterization

Many Aspects of Arc Hydro

Saxe, John Godfrey, 1963, “The Blind Man and the elephant”, New York: Whittlesley House

Database design

Application

“Standard”

Tools

Marketing

Development environment

Elephant illustration ©2002 Jason Hunt www.naturalchild.org/jason

“Why Should I Care” about Arc Hydro ?• Economy of development

–Why reinvent the wheel?–Established configuration methodology–Established development framework

• Industry “standard”–Fundamental geodatabase design principles implemented for water resources theme

–Established techniques rolled into a publicly available utility

–Tested and accepted• Training and support• Free maintenance – ESRI’s commitment to the water resources community

Where To Begin

Where to Learn More

Alternative to ArcHydro