CEE%20795%20Water%20Resources%20Modeling%20and%20GIS

1
CEE 795Water Resources Modeling and GIS
Lecture 6 Flow Networks in GIS (ArcHydro) (some
material from Dr. David Maidment, University of
Texas, Dr. David Tarboton, Utah State
University, and Dr. Franciso Olivera) February
22, 2006

• Learning Objectives
• Describe a Network model
• Identify Flow in a network model
• Develop a hydrologic network
• Perform linear referencing on networks

Handouts
Assignments Exercise 5
2
Hydro 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
3
National Hydrography Dataset
Key feature classes
Five feature classes with NHDFLowline built
into A geometric network
NHDPoint, NHDLine, NHDArea are point, line and
area water features on map apart from
flowlines and waterbodies
4
National Hydrography Dataset
5
NHD Waterbody
6
NHD Geometric Network
7
Arc Hydro Framework Input Data
Watersheds
Waterbody
Streams
Hydro Points
8
Arc Hydro Framework Data Model
9
Arc Hydro Framework For South Florida
Basins
Waterbody (NHD)
Hydro Points
Hydro Network (NHD)
10
Network Definition

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

11
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

12
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!!
13
Polylines and Edges
14
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

15
Connectivity Table
p. 132 of Modeling our World
J125
Junction
Adjacent Junction and Edge
J123 J124, E1
J124 J123, E1 J125, E2 J126, E3
J125 J124, E2
J126 J124, E3
E2
J124
E3
E1
J123
J126
This is the Logical Network
16
Build Network Tables

• Establishes connectivity of Edge and Junction
  features
• Enables tracing
• Generates Generic Junctions

Geometric Network Wizard in ArcCatalog
17
Snapping Features
18
Network Sources and Sinks
Each junction feature class in a network can
have junctions which are sources or sinks for
flow
19
Flow to a sink
20
Flags
21
Trace Solvers
22
Upstream Trace Solvers
23
Flow Line
Traces movement of water in a one-dimensional
flow system
24
Location of the Flowline
25
Introduction to the Hydro Network

• Hydro Edge think of Arc
• Hydro Junction think of Node
• Waterbody think of Polygon

26
Flow Network
A connected set of flow edges
27
Hydro Network for Holland
28
Guadalupe Basin Framework Dataset
29
Network Tracing on the Guadalupe Basin
30
Schematic Network
31
Connecting Waterbodies using Relationships
32
Hydro Network through Canyon Lake
33
Linking Canyon Lake to the Network
34
Connecting Drainage Areas using Relationships
35
Connecting Drainage Areas to the Network
Area goes to point on line
36
Linear Referencing
Where are we on a line?
37
My Streams are really long
Use ReachID to link many Hydro Edges together
into one River
38
Addressing
39
Coordinates of a 2-D Polyline
40
Coordinates of a 2-D Polyline M
41
Setting Line Measure
42
Proportional Aliasing
Distance is measured Relative to the length of
the line as a percentage 0 100
43
Setting Percent Measure
pMSeg.SetAndInterpolate MsBetween 0, 100
pMSeg.SetAndInterpolate MsBetween 100, 0
0 100 going downstream
0 100 going upstream
44
Distances from Upper End in Meters
45
0
Percent distance from bottom end of reach
100
46
Measure in kilometers
Measure in km from bottom end of line (like river
miles or Kilometers)
pMSeg.SetAndInterpolateMsBetween 0,
(Shape_Length /1000)
47
Point and Line Events
48
Displaying Events