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Networks in GIS

Networks in GIS. Network model Flow on Networks Hydrologic networks Linear referencing on networks. Some slides in this presentation were prepared by Dr Francisco Olivera. Network Definition. A network is a set of edges and junctions that are topologically connected to each other.

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Networks in GIS

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  1. Networks in GIS • Network model • Flow on Networks • Hydrologic networks • Linear referencing on networks Some slides in this presentation were prepared by Dr Francisco Olivera

  2. Network Definition • A network is a set of edges and junctions that are topologically connected to each other.

  3. Network Model in GIS • Three components • Geometric model: (x,y,z,m) coordinates of edges and junctions • Logical model: which edges are connected to what junctions • Addressing model: location on the network using measure

  4. Edges and Junctions • Simple feature classes: points and lines • Network feature classes: junctions and edges • Edges can be • Simple: one attribute record for a single edge • Complex: one attribute record for several edges in a linear sequence • A single edge cannot be branched No!!

  5. Polylines and Edges

  6. Junctions • Junctions exist at all points where edges join • If necessary they are added during network building (generic junctions) • Junctions can be placed on the interior of an edge e.g. stream gage • Any number of point feature classes can be built into junctions on a single network

  7. Connectivity Table p. 132 of Modeling our World J125 Junction Adjacent Junction and Edge E2 J124 E3 E1 J123 J126 This is the “Logical Network”

  8. Build Network Tables • Establishes connectivity of Edge and Junction features • Enables tracing • Generates Generic Junctions Geometric Network Wizard in ArcCatalog

  9. Snapping Features

  10. Network Sources and Sinks Each junction feature class in a network can have junctions which are sources or sinks for flow

  11. Ancillary Role of Sink

  12. Flow to a sink

  13. Flags

  14. Trace Solvers

  15. Upstream Trace Solvers

  16. Hydrologic Networks • Hydrologic data includes: • Single-line streams • Double-line streams • Braided streams • Manmade channel systems • Waterbodies

  17. Flow Line Traces movement of water in a one-dimensional flow system

  18. Location of the Flowline

  19. Introduction to the Hydro Network • Hydro Edge – think of Arc • HydroJunction – think of Node • Waterbody – think of Polygon

  20. Edge Junction Flow Network A connected set of flow edges

  21. Flowlines and Shorelines

  22. Network Building • Define flow-paths within double-line streams and waterbodies. • Define network sinks and sources.

  23. Network Connectivity Find connected Find loops

  24. Network Flow Direction • Enable flow in flow-paths. • Disable flow in shorelines Sink Flow direction is unknown

  25. Network Flow Direction • Enable flow in flow-paths. • Disable flow in shorelines Sink Flow direction is known

  26. Uninitialized Flow Direction

  27. Assigned Flow Direction

  28. Network Tracing Trace Upstream Trace Downstream

  29. Trace Path Find the shortest path between two points on the network

  30. Hydro Network for Holland

  31. Hydro Network for Colorado River Basin around Lake Travis

  32. Guadalupe Basin Framework Dataset

  33. Network Tracing on the Guadalupe Basin

  34. Schematic Network

  35. Hydro Network Junctions

  36. Connecting Waterbodies using Relationships

  37. Hydro Network through Canyon Lake

  38. Linking Canyon Lake to the Network

  39. Connecting Drainage Areas using Relationships

  40. Connecting Drainage Areas to the Network Area goes to point on line

  41. Linear Referencing(Requires ArcInfo 8.1) Where are we on a line?

  42. My Streams are really long… Use ReachID to link many Hydro Edges together into one River

  43. Addressing

  44. Coordinates of a 2-D Polyline

  45. Coordinates of a 2-D Polyline M

  46. Setting Line Measure

  47. Proportional Aliasing Distance is measured Relative to the length of the line as a percentage 0% – 100%

  48. Setting Percent Measure pMSeg.SetAndInterpolate MsBetween 0, 100 pMSeg.SetAndInterpolate MsBetween 100, 0 0 – 100 going downstream 0 – 100 going upstream

  49. Distances from Upper End in Meters

  50. 0% Percent distance from bottom end of reach 100%

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