1. Hydrologic Model Integration
Francisco Olivera, Ph.D., P.E. Texas A&M University Department of Civil Engineering

2. Model Integration
Sharing of information between models is necessary to capture the complexity of natural hydrologic processes.
This sharing of information between models in a systematic fashion is called here model integration.

3. Model Integration Connection on a two-model basis.
Depends on the already connected models.

4. Model Integration HUB Connection on a hub basis.
Independent of the already connected models

5. Arc Hydro
Arc Hydro can be used as the hub for connecting hydrologic models.

6. What it is and what it is not …
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Arc Hydro is a standard data model for spatial and temporal hydrologic data.
A data model is a template for organizing data, so that it can be found and retrieved easily.
Arc Hydro is a geodatabase, that is, a relational database that contains geographic information.
River network
Watersheds
Waterbodies
Points

7. PrePro2002 HEC-HMS HUB HUB Arc Hydro
PrePro2002 is an ArcGIS pre-processor for the HEC Hydrologic Modeling System (HMS) developed by Texas A&M University – Civil Engineering and Dodson and Associates, Inc.
HEC-HMS “is a new generation software for precipitation-runoff simulation that supersedes the HEC-1 Flood Hydrograph Package.” (HEC-HMS User’s Manual)
HEC-HMS
HUB
HUB
Arc Hydro

8. PrePro2002
PrePro2002 uses the ArcGIS hydrologic functions to analyze the terrain.

9. PrePro2002 1 2 4 8 16 32 64
128
The eight-direction pour point algorithm (D-8) assigns a flow direction code to each cell, based on the steepest downhill slope as defined by the DEM.
Flow direction codes 1 1 67 56 49 53 44 37 58 55 22 67 56 49 53 44 37 58 55 22

10. PrePro2002 Flow direction grid Flow network DEM Flow accumulation grid78 72 69 71 58 2 2 2 4 4 74 67 56 49 46 2 2 2 4 4 69 53 44 37 38 1 1 2 4 8 64 58 55 22 31
128
128 1 2 4 68 61 47 21 16
128
128 1 1 4
DEM
Flow direction grid
Flow network 1 1 2 1 3 8 5 2 1 1 20 1 24
Flow accumulation grid
Flow accumulation
(> 2 cells)
Watersheds

11. PrePro2002
Flow direction grid
Flow accumulation grid

12. PrePro2002
Reaches
Outlets

13. PrePro2002
Reaches and watersheds
HMS basin file

14. PrePro2003
PrePro2003 will store the hydrologic elements in seven feature classes:
HMSSubbasin
HMSReach
HMSJunction
HMSSource
HMSReservoir
HMSDiversion
HMSSink

15. PrePro2003
PrePro2003 will calculate the parameters of the hydrologic elements and store them as attributes of the seven feature classes.

16. PrePro2003
PrePro2003 will store the hydrologic time series in one object class:
DSSTimeSeries

17. PrePro2003
Using XML files, PrePro2003 will prepare a HEC-HMS input file.

18. Conclusions
Using an standard data model, it is possible to analyze complex hydrologic processes that require the use of multiple models and participation of multiple modeling teams.

19. The Future