Arc Hydro is a set of data models and tools that operates within ArcGIS to support geospatial and temporal data analyses. Use Arc Hydro to delineate and characterize watersheds in raster and vector formats, define and analyze hydro geometric networks, manage time series data, and configure and export data to numerical models.

1. Arc Hydro: GIS for Water Resources
• Arc Hydro
– Hydronetwork
– Drainage systems
– Channels
– Time Series
– Modeling
– Hydrologic integration
The Arc Hydro data model and
application tools are in the public
domain

2. GIS in Water Resources
Consortium
Bringing together these two communities by using a
common geospatial data model
Arc Hydro design took 3 years from 1999 - 2002
GIS
CRWR
CRWR
Water
Resources

3. Hydrologic Information System
Analysis, Modeling,
Decision Making
Arc Hydro
Geodatabase

4. 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 equations
• Data Model – a conceptual model expressed in a
data structure
• Geographic Data Model – a data model for
describing and reasoning about the world

5. What is Arc Hydro?
• A geographic data model for storing
geospatial and temporal water resources
data in ArcGIS
– A set of hydro objects built on top of
ArcObjects
– A set of standardized attributes
– A vocabulary for describing data (glossary)
– A toolset for implementing the data model

6. Flow
Time
Time Series
Hydrography
Hydro Network
Channel System
Drainage System
Arc Hydro Data Model

8. ArcGIS Hydro Data Model
Hydrography Hydrology

9. Streams
Drainage Areas
Hydrography
Channels
Terrain Surfaces
Rainfall Response
Digital Orthophotos
Data Model
Based on
Inventory

10. 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.

11. Integrating Data Inventory using
a Behavioral Model
Relationships between
objects linked by tracing path
of water movement

12. Streams
Watersheds Waterbody
Monitoring Points
Arc Hydro Framework Input Data

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Feature
Waterbody
HydroID
HydroCode
FType
Name
AreaSqKm
JunctionID
HydroPoint
HydroID
HydroCode
FType
Name
JunctionID
Watershed
HydroID
HydroCode
DrainID
AreaSqKm
JunctionID
NextDownID
ComplexEdgeFeature
EdgeType
Flow line
Shoreline
HydroEdge
HydroID
HydroCode
ReachCode
Name
LengthKm
LengthDown
FlowDir
FType
EdgeType
Enabled
SimpleJunctionFeature
1
HydroJunction
HydroID
HydroCode
NextDownID
LengthDown
DrainArea
FType
Enabled
AncillaryRole
*
1
*
HydroNetw ork
*
HydroJunction
HydroID
HydroCode
NextDownID
LengthDown
DrainArea
FType
Enabled
AncillaryRole
HydroJunction
HydroID
HydroCode
NextDownID
LengthDown
DrainArea
FType
Enabled
AncillaryRole
Arc Hydro Framework

14. National Hydro Data Programs
http://www.crwr.utexas.edu/giswr/nhdconf/nationalhydro.html
National Elevation Dataset
(NED)
National Hydrography Dataset
(NHD)
Watershed Boundary DatasetElevation Derivatives for
National Application (EDNA)

15. Arc Hydro Framework Dataset
for the Guadalupe Basin

16. HydroNetwork through Canyon Lake
Generic Junction
(for topological
connection of edges)
Flowlines through water body

17. Network Tracing
Upstream Tracing Downstream Tracing

18. HydroJunction has Waterbody Relationship

19. NWS forecast
Watersheds
(flooding)
EPA TMDL
Segments
(water quality)
TNRCC water
availability points
(water supply)
Guadalupe
HydroNetwork
Watersheds of the Guadalupe Basin

20. Scales of representation of Drainage Systems
Basins – drainage areas for water
resources management
Catchments – subdivision of
Basin into elementary drainage
areas by physical rules
Digital Elevation Model –
land surface terrain grid cells
Watersheds – subdivision of Basin
for a particular hydrologic purpose

22. Channel Cross-Section
Direction of Flow
Cross-Section
Channel

23. Channel ProfileLines

24. Guadalupe Network
Study area only
1.4 km!

25. 1/2 meter Digital Ortho Photography
Study Area (Guadalupe river near Seguin, TX)

26. Boat setup for data collection

27. The electronic depth sounder operates in a similar way to radar It sends out an
electronic pulse which echoes back from the bed. The echo is timed electronically
and transposed into a reading of the depth of water.
Depth Sounder (Echo Sounder)

28. Differential GPS: Bank to Boat
GPS gives the location of each point collected in terms of
latitude and longitude. Two locations for differential GPS.

29. Channel Data
Each point has (x,y,z)

30. Interpolation
Points are interpolated
in ArcMap to produce a
continuous surface.

31. Centerline
Define the centerline along
the thalweg of the channel

32. Measure in ArcGIS
0
54.37 154.41
281.36
A PolylineM can store
m-values at each vertex
along with x and y
coordinates.
Measures are assigned in
meters

33. Coordinate Transformation
m is measure along
the centerline
r is distance across the
river from the
centerline
Sinuous river becomes
straight when
transformed into (m,r)
co-ordinates.

34. Coordinate Transformation
Sinuous river
Profile line and cross-sections
Straightened river

35. Straightened River in 3D

36. Data back to x,y coordinates
Original river in X,Y Profile lines and cross-sections in (x,y)
created using FishNet in (m,r).

37. Profile Lines and Cross Sections in 3D
Bird’s eye view!

38. TSDateTime
FeatureID
TSType
TSValue
Arc Hydro Time Series Object

39. National Water Information System
Web access to USGS
water resources data
Arc Hydro NWIS data
retrieval tool

40. Retrieving NWIS Data
• Select Gage
Layer
• Enter Period of
Record

41. Streamflow Time Series
Arc Hydro Time Series Table

42. Time Series Extracted to Excel
(In Excel, use Data/Get External Data to query Geodatabase)
Geodatabase
view
Excel
view

50. Nexrad Data for Florida
• Real-time Nexrad data
supplied every 15
minutes on a 2km grid
• Data from 14 radars
calibrated with 435
rain gages
• At end of month more
careful calibration is
done for historical rain
map archive

51. HRAP Cells for Nexrad Data
Average area = 14.5 km2

53. GIS and Hydrologic Modeling:
Where are we now?
• All the major hydrologic models have GIS data
support systems
– HEC-GeoHMS, HEC-GeoRAS, GIS-Weasel for MMS,
Mike-11GIS, WMS, ….
• An extensive body of experience in terrain
processing for hydrology has been built up
• Standardized national geospatial datasets for
hydrology
– National Elevation Dataset, EDNA, National
Hydrography Dataset, Watershed Boundary Dataset

54. GIS and Hydrologic Modeling:
Where are we going to?
• Integrated data and modeling systems e.g. Corps
Water Management System, EPA Basins, DHI Mike
Objects, …..
– Integration of observational (time series) data, geospatial
data, model-derived data
• Integration of vector, raster and time series data in a
database management system
• A language (vocabulary and grammar) for
communicating between databases and models e.g.
XML

55. Arc Hydro and Modeling
• Intrinsic Modeling – within a particular
application eg Excel, ArcGIS, custom
objects
• Dynamic Linked Library – tightly coupled
package of functions (e.g. LibHydro from
HEC)
• Independent Modeling – separate
hydrologic model with data exchange

56. Dynamic Linked Library
Can have
Fortran
subroutines
in a DLL
Muskingum
flow routing

57. Independent Hydrologic Model
VB progam reads and writes
text files

58. Analysis, Modeling,
Decision Making
Arc Hydro
Geodatabase
Visual Basic
ArcGIS
Relational Database
(Access)
Excel
Interfaces to Arc Hydro Data and Models

59. Atmospheric Water
Soil Water Surface Water
Groundwater
Vertical and Horizontal
Water Balance

60. Decoupling
and
connecting
hydrologic
systems

61. Model Building in ArcGIS 9

63. What software do you need?
• ArcView 8.2
– Viewing, querying existing geodatabases
– Editing feature classes and adding data
• Spatial Analyst for ArcGIS
– To operate the raster tools in Arc Hydro
• ArcInfo 8.2
– To build geometric networks and create new
relationships
Arc Hydro tools and data model are on CD at back of
Arc Hydro book and available on web at
http://archydro.crwr.utexas.edu

64. Learning Arc Hydro
• “Arc Hydro—GIS for Water Resources” book
from ESRI Press
• Tutorial on tools and sample dataset on CD at
back of book
• Exercises in Fall 2002 GIS in Water Resources
class http://www.ce.utexas.edu/prof/maidment
• GISWR website
http://www.crwr.utexas.edu/giswr
• ESRI’s Arc Online (discussion forum)