GIS Modeling

1. GIS Modeling Venkatesh Merwade, University of Texas at Austin Interdisciplinary aquatic modeling workshop, July 21, 2005

2. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

3. 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

4. Data Model based on Inventory of data layers

5. Vector Data (x2, y2) (x2, y2) (x1, y1) (x1, y1) (x1, y1) (x1, y1) (x4, y4) (x1, y1) (x3, y3) (x1, y1) Point – pair of (x,y) coordinates Line – a sequence of points Polygon – a closed set of lines All vector shapes (2D and 3D) are made from a set of points.

6. Vector Data for Guadalupe Basin in Texas Monitoring Points – USGS gaging stations Stream Network – Low resolution NHD Flowlines Watershed – 8 digit HUC units

7. Measure in ArcGIS A PolylineMZ can store m and z at each vertex along with x and y coordinates. 64.0056 112.3213 0

8. Raster Data Number of columns Cell Size Number of rows Cell Cell Value Example, Digital Elevation Model

9. Raster  Vector Vector Raster Point Line Zone of cells Polygon

10. Edge Node Face Triangulated Irregular Network

11. How do we combine these data? Digital Elevation Models Streams Watersheds Waterbodies

12. An integrated raster-vector database

13. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

14. Geodatabase Design GeoDatabase (stores geographic data organized into datasets and feature classes ) Feature Dataset (collection of feature classes and relationship classes) Raster Catalog (a collection of raster datasets) Polyline Feature class Point Feature class Polygon Feature class Relationship class Object class

15. 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

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

17. Arc Hydro Data Model • A geospatial and temporal data model for water resources Arc Hydro framework HydroEdge Personal Geodatabase Watershed HydroJunction Feature Dataset Network Hydro Edge Hydro Junction Watershed Relationships

18. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

19. Vector Analysis • Attribute tools • Join/relate, calculations • Topology and Network analysis • geometric networks and solvers • Geo-processing • Batch processing of geometries

20. Attribute Relationships ReachHasCrossSections

21. Calculations using vector attributes 2 1 3 Wshed 1 Area = 2.47 CN = 71.64 PR = 32.20 Wshed 2 Area = 3.49 CN = 65.01 PR = 32.66 Wshed 3 Area = 23.30 CN = 68.70 PR = 32.51

22. Geometric Network Geometric Network for Streams in Upper Guadalupe Trace Downstream Network Flag Trace Upstream Find Path

23. Geo-processing

24. Surface analysis • Raster Models • Perform simple algebraic calculations on raster cells • Drainage Analysis using DEM • Flow direction, flow accumulation, watershed delineation

25. Runoff, Q (mm/yr) Q Precipitation, P (mm/yr) P Runoff calculations Cell by cell evaluations of mathematical functions

26. Runoff Load Pollutant Loading Estimation Load Mass = EMC * Runoff Computation of pollutant load (fecal coliform) to Galveston Bay in Texas.

27. 32 64 128 16 1 8 4 2 72 95 76 90 75 85 90 80 81 73 83 89 83 85 80 72 82 89 70 87 Drainage Analysis 75 77 79 85 92 DEM Flow Direction Grid Contributing areas and stream definition Stream Cell Eight direction pour point model

28. Zonal Stats: Area, CN and PR

29. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

30. 3D Representation of MODFLOW Control volume for the model domain Vertical dimension ~ 75 meters Each cell in the 2D representation is transformed into a 3D object (Multipatch) Example from Savannah River in Georgia

31. 3D HydroElement

32. Rainfall and Streamflow Variations 29 hour duration, 15-minute interval

33. Tracking Fecal Bacteria in Galveston Bay

34. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

35. GIS and Modeling • Loose coupling • Use GIS to extract input data and display output • Model runs independent of GIS • Tight coupling • GIS and model are integrated in one system (eg. EPA Basins) • Hydrologic Information Systems • Framework for coupling

36. Loose Coupling • HEC-GeoRAS • GIS interface for HEC-RAS • cross-sections, reaches, bank-lines in GIS • Creates geometry files • Display Results in GIS

37. Tight Coupling • GIS and model are integrated within one system (eg. EPA Basins) • Tool development in GIS to simulate hydrologic processes • Dynamic Link Libraries • Code development • Must keep up with technology and model development

38. Modeling Geodatabase Hydrologic Information System A hydrologic information system is a combination of geospatial and temporal hydrologic data with hydrologic models that supports hydrologic practice, science and education

39. Connecting Arc Hydro and Hydrologic Models GIS Interfacedata models HMS HMS IDM Geo Database Arc Hydro data model RAS RAS IDM

40. Model Process Process Derived Data Project Data Tool Derived Data Tool Process Project Data Derived Data Tool (a) (b) (c) Project Data ArcGIS Model Builder

41. Overview • GIS and data representation • Geodatabase design • Vector and surface analysis • 3D and visualization in GIS • GIS and Modeling • Case studies

42. FLOODPLAIN MAP From a NEXRAD Map to a Floodplain Map Center for Research in Water Resources Component 3: Creating a Flood Inundation Map Component 1: Importing NEXRAD data into Geodatabase and Mapping to Watersheds Component 2: Hydrologic & Hydraulic Integration based on common geographic framework Hydrologic Model HEC-HMS Hydraulic Model HEC-RAS NEXRAD Data Salado Creek, San Antonio Rosillo Creek Watersheds NEXRAD Rainfall Geographic Integration using Arc Hydro Component 3 Process Operations using Arc 9 Model Builder Component 1 Component 4 Component 4 Component 2 Component 4 Component 3: Floodmapping from HEC-RAS GIS SDF File Component 4: Geodatabase to HEC-DSS to Geodatabase Flood Inundation Polygon DEM Cross Sections with Water Surface Elevations Water Surface Raster Time Series in HEC-DSS Time Series in Geodatabase HEC Data Storage System for Time Series Research funded by The San Antonio River Authority

43. Criterion Depth & velocity Species groups Habitat Hydrodynamic Habitat Model Model Descriptions RMA2 Biological Sampling GIS Instream Flow DecisionMaking Fish Habitat Modeling

44. Hydraulic and Biological Data Attribute Table Bathymetry Points Habitat Descriptions

46. Summary • GIS can be used to store and visualize any type of data (geospatial and temporal) • Geodatabase Model for storing Data • Vector and surface analysis in GIS help accomplish data processing, parameter extraction and simple calculations • Hydrologic Information Systems provides a way to integrate simulation models with GIS using a standard protocol

47. Courtesy: Texas Water Development Board Questions Thank you • David R. Maidment • Tim Whiteaker