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CEE 795 Water Resources Modeling and GIS 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 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

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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

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National Hydrography Dataset 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 Key feature classes

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National Hydrography Dataset

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NHD Waterbody

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NHD Geometric Network

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Streams WatershedsWaterbody Hydro Points Arc Hydro Framework Input Data

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Arc Hydro Framework Data Model

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Hydro Network (NHD) Basins Waterbody (NHD) Arc Hydro Framework For South Florida Hydro Points

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

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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

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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!!

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Polylines and Edges

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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

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Connectivity Table J124 J125 J123 J126 E1 E3 E2 J123J124, E1 J124J123, E1J125, E2J126, E3 J125J124, E2 J126J124, E3 JunctionAdjacent Junction and Edge This is the “Logical Network” p. 132 of Modeling our World

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

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Snapping Features

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

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Flow to a sink

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Flags

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Trace Solvers

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Upstream Trace Solvers

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

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Location of the Flowline

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Introduction to the Hydro Network Hydro Edge – think of Arc Hydro Junction – think of Node Waterbody – think of Polygon

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Flow Network A connected set of flow edges Edge Junction

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Hydro Network for Holland

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Guadalupe Basin Framework Dataset

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Network Tracing on the Guadalupe Basin

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Schematic Network

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Connecting Waterbodies using Relationships

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Hydro Network through Canyon Lake

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Linking Canyon Lake to the Network

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Connecting Drainage Areas using Relationships

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

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Linear Referencing Where are we on a line?

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

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Addressing

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Coordinates of a 2-D Polyline

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Coordinates of a 2-D Polyline M

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Setting Line Measure

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

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

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Distances from Upper End in Meters

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0% 100% Percent distance from bottom end of reach

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Measure in kilometers pMSeg.SetAndInterpolateMsBetween 0, ([Shape_Length] /1000) Measure in km from bottom end of line (like river miles or Kilometers)

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Point and Line Events

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Displaying Events

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