ArcGIS Hydro Data Model Data Dictionary - Center for Research in ...

ArcGIS Hydro Data Model Data Dictionary 

By David R. Maidment 

Center for Research in Water Resources 

University of Texas at Austin 

May 24, 2001 

This document lists the classes and attributes of the May 24, 2001, version of the ArcGIS Hydro 

data model and describes what they represent. It is organized according to the feature classes in 

each of the four feature datasets in the model: Hydro Features, Drainage, Channels, and Hydro 

Network. Time Series are stored in an object class within the geodatabase but outside the 

feature datasets. 

The data model contains a total of 27 feature and object classes within which objects can be 

created. It also contains 6 abstract classes (in italics) whose purpose is to gather attributes to be 

inherited by the classes below them in the class hierarchy. One classes (HydroEdge) has 

explicitly defined subtypes, which create new classes specific to each subtype so that different 

attribute values and behaviors can be attached to the subtypes if necessary. 

Hydrography: 12 feature classes and 2 abstract classes 

Network: 4 feature classes 

Drainage: 5 feature classes and 2 abstract classes 

Channel: 2 feature classes and 1 abstract class.

Objects: 4 object classes and 1 abstract class 

Hydrography DataSet Classes 

2

Class 

(Type) 

Hydro 

Feature 

(Abstract) 

Hydrograpy 

(Abstract) 

Inherits 

From 

Feature 


Feature 

HydroPoint Hydrography 

(Point) 

HydroLine 

HydroArea 

Waterbody 

Hydrography 

(Polyline) 

Hydrography 

(Polygon) 

HydroArea 

(Polygon) 

Attribute Attribute 

Type 

Description 

Abstract class holding common 

attributes and methods for 

HydroFeatures 

HydroID Integer Unique feature identifier within a 

geodatabase 

HydroCode String Unique feature identifier within a 

set of geodatabases 

Abstract class holding common 

attributes and methods for 

Hydrography features 

Ftype String Descriptor for feature type. Can be 

expanded using Subtypes 

Name String Geographic name 

Point features from map 

hydrography and inventory sources 

JunctionID Integer HydroID of the HydroJunction 

with which this point is associated 

HasZ = False 

HasM = False 

Area features from map 

hydrography 

A merging of HydroAreas that 

constitute a single waterbody 

AreaSqKm Double Area independent of map units 

JunctionID Integer HydroID of the HydroJunction 

which is outlet of this waterbody 

3

Class 

(Type) 

Dam 

Bridge 

Structure 

Monitoring 

Point 

Water 

Withdrawal 

Water 

Discharge 

UserPoint 


ResponseUnit 

Inherits 

From 

HydroPoint 















Feature 

(Polygon) 

Attribute 

Attribute 

Type 

Description 

A structure creating a pond or 

reservoir storing water 

A structure carrying a road across 

a stream 

Any other kind of water resources 

structure 

A permanent measurement station 

or the location of a sampling point 

Point of withdrawal of water, 

usually with a pipe and pump 

system 

Point of discharge of water, e.g. 

wastewater discharge, irrigation 

return flow 

Any other point of interest 

Any subdivision of the landscape 

used for surface water balance 

accounting (e.g. climate cells, soil 

& land use polygons,…) 

AreaSqKm Double Area independent of map units 

4

Hydro Network Feature Dataset Classes 

Class 

(Type) 

HydroEdge 

Inherits 

From 

Complex 

Edge 

Feature 

Attribute 

HasZ = False 

HasM = True 

Attribute 

Type 

Description 

The lines connected by junctions 

in the HydroNetwork 


geodatabase 

HydroCode String Unique feature identifier in a set 

of geodatabases 

ReachCode String Reach identifier 

Name String Geographic name 

LengthKm Double Stores HydroEdge length 

independently of map units 

LengthDown Double Length along shortest path to a 

downstream reference location 

FlowDir 

HydroFlow 

Directions 

CVD 

Labels flow direction: 

Uninitialized = 0, WithDigitized 

= 1, AgainstDigitized = 2, 

Indeterminate = 3; initial value = 

1 

5


Junction 

Schematic 

Node 

Schematic 

Link 

Simple 

Junction 

Feature 


Feature 



Feature 


FType String Descriptor for feature type. Can 

be expanded using Subtypes 

EdgeType Subtype 

CV 

Domain 

Flowline = 1, Shoreline = 2, intial 

= 1 

Enabled 

Coded 

Value 


0 = Disabled, 1 = Enabled 

(inherited attribute from 

ComplexNetworkFeature) 

HasZ = False 

HasM = True 

Junctions between HydroEdges 

marking outflow points from 

Waterbodies, or for other 

purposes, such as a Sink 


geodatabase 

HydroCode String Unique feature identifier in a set 

of geodatabases 

NextDownID Integer HydroID of next downstream 

HydroJunction 

LengthDown Double Length along shortest path to a 

downstream reference location 

DrainArea Double Upstream drainage area 

FType String Descriptor for feature type. Can 

be expanded using Subtypes 

Enabled 

Ancillary 

Role 

Coded 

Value 


Coded 

Value 


0 = Disabled, 1 = Enabled 

(inherited attribute from Simple 

Junction Feature) 

0 = None 

1= Source 

2 = Sink 

(inherited attribute from Simple 

Junction Feature) 

Points in a schematic network 

connecting Hydro Features 

FeatureID Integer HydroID of the associated Hydro 

Feature 

Lines in a schematic network 

connecting Hydro Features 

FromNode Integer HydroID of the SchematicNode 

at from end of link 

ToNode Integer HydroID of the SchematicNode 

at to end of link 

6

Drainage Feature Dataset Classes 

7

Class 

(type) 

Drainage 

Feature 

(Abstract) 





Line 



Area 

(Abstract) 

Catchment 

(Polygon) 

Watershed 

(Polygon) 

Basin 

(Polygon) 

Inherits 

from 


Feature 

(Abstract) 


Feature 


Feature 


Feature 


Area 


Area 


Area 

Attribute 

Attribute 

Type 

Description 

Abstract class for Drainage 

System features 

DrainID Integer Link between point, line and area 

features of a drainage system (e.g. 

GridCode, Pfaffstetter number, 

HUC number) 

Point at the center of a DEM cell 

on a drainage path, usually seed 

point location for drainage area 

delineation 

JunctionID Integer HydroID of the associated 


Line through the centers of the 

DEM cells on a drainage path 

Abstract class for common 

drainage area attributes 

AreaSqKm Double Drainage area independent of map 

units 


HydroJunction, which is the 

drainage area outlet location 

NextDownID Integer HydroID of the next downstream 

area in this drainage area class 

An elementary drainage area 

produced by a uniform process of 

landscape subdivision 

Any subdivision of the landscape 

into drainage areas 

A set of standardized watersheds 

for data archiving and delivery 

8

Channel Feature Dataset Classes 

9

Class 

(Type) 

Channel 

Feature 

(Abstract 

class) 

ProfileLine 

(3D 

PolylineM) 

CrossSection 

(3D 

PolylineM) 

Inherits 

From 


Feature 

Channel 

Feature 

Attribute 

Attribute 

Type 

Description 

Abstract class for gathering common 

channel attributes 

ReachCode String Reach identifier 

RiverCode String River identifier 

HasZ=True 

Longitudinal profile of the channel 

HasM=True 

FType String Descriptor for types of ProfileLines 

(Thalweg, Bankline, Streamline) 

ProfOrigin String Descriptor of the origin of the data 

used to form the ProfileLine 

CSCode String CrossSection identifier 



ProfileM Double Location of the CrossSection using 

ProfileLine measure 

CSOrigin String Descriptor of the construction 

method of CrossSection. Possible 

subtpes: 

3Dtype = 0 

PolylineType = 1 

LineType = 2 

PointType = 3 

LocationType = 4 

10

Object Classes 

CrossSectionPoint Object class: 

Class 

(Type) 

CrossSection 


Inherits 

From 

Object 

Attribute 

Attribute 

Type 

Description 

CSCode String CrossSection identifier 

CrossM Double CrossSection measure point location 

Elevation Double Elevation of CrossSection point 

above mean sea level 

HydroEvent Object classes: 

Class 

(Type) 

HydroEvent 

(Abstract) 


Event 

HydroLine 

Event 

Inherits 

From 

Object 



Attribute Attribute 

Type 

Description 

Abstract class to store attributes 

and methods for events 

ReachCode String Attribute identifier for the line on 

which measure is defined (could 

be changed to RiverCode if 

measure is in river miles or km 

A point event 

Measure Double Measure location of the event 

A line event 

FMeasure Double Measure location of the start of 

the line event 

TMeasure Double Measure location of the end of 

the line event 

Offset Double Offset distance of event from line 

11

Time Series Object class 

Class 

(Type) 

TimeSeries 

Inherits From Attribute Attribute 

Type 

Description 

Object 

FeatureID Integer HydroID of the Hydro 

Feature described by a 

time series 

TSType String Type of time series data 

TSDateTime Date Time at which TSValue 

applies 

TSValue Double Time series data value 

Relationships 

Origin Class Primary Destination Primary Multiplicity Name 

Key Field Class Key Field 

Hydro HydroID Watershed JunctionID 1 to 1 WatershedhasJunction 

Junction 

Hydro HydroID Waterbody JunctionID 1 to 1 WaterbodyhasJunction 

Junction 

CrossSection CSCode CrossSection 


CSCode 1 to 1..* CrossSectionhasPoints 

12

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