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H&H Modeling
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
H&H Integration Overview
(HMS-RAS focus)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-2
Integration Approach

Mix of planning, GIS, and H&H modeling operations –
not a push button operation.

Types of integration
 Modeling
support (preparing data for model input)
 e.g. land use/soils/CN or rainfall processing – Arc Hydro or general
GIS data processing
 Linked
 GeoHMS
 GeoRAS
 Integrated
 DSS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-3
Integration Approach (2)

Key steps:

Plan (roughly) hydrologic and hydraulic model layouts – flow exchange
locations
 e.g. location of HMS modeling elements and RAS cross-sections

Identify sources of precipitation input into the hydrologic model and
techniques for their incorporation into the dataset
 e.g. Nexrad rainfall

Develop GeoHMS model (and precipitation sub model)

Finalize and run HMS model and generate results (DSS)

Develop GeoRAS model

Finalize and run RAS taking HMS results as input

Feedback between HMS and RAS is manual
 e.g. modification of time of concentration or routing parameters
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-4
Integration Planning

Identify where outputs from
one model (HMS) become
input to the second one
(RAS)
 Place
hydrologic elements
(subbasins, reaches, junctions)
to capture flows at points of
interest (confluences, structures)
 Place
hydraulic elements (crosssections) at points of interest
 Identify/specify
element naming
conventions between the two
models (persistent or transient
names)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-5
Precipitation Sources

Identify sources of
precipitation input into the
hydrologic model and
techniques for their
incorporation into the
dataset
 Point
(rain gage)
 Polygon
 Surface
(Nexrad cells)
(TIN/grid)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-6
Develop GeoHMS model

Follow all principles in development
of a hydrologic model

In addition, take into consideration
integration planning aspects
developed earlier
 Placement
 Naming

of flow exchange points
conventions
Incorporate precipitation submodel
 Develop
Arc Hydro time series for the
final subbasin delineation and export to
DSS

Export to HMS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-7
Meteorological Component

Current GeoHMS
approach is to
develop a custom
“gage” for each
subbasin that
carries the
precipitation input
for that subbasin
Arc Hydro
Arc Hydro to DSS transfer
 Export
the time
series for the
subbasin “gage”
from Arc Hydro time
series data structure
into DSS
DSS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-8
Finalize and Run HMS

Complete HMS
model with any
additional
parameters
including
meteorological
model and control
specifications

Follow all
principles in HMS
model
development
(calibration, etc.)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-9
Finalize and Run HMS (2)

Do the final run
and generate
results (DSS)
HMS View
DSS View
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-10
Develop GeoRAS model (pre-processing)

Follow all principles in
development of a hydraulic
model for element
placement (confluences,
structures, …)

In addition, take into
consideration integration
planning aspects developed
earlier
 Naming
conventions (add
name of the HMS element to
the cross-section that will get
the element’s flows)

Export to RAS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-11
Finalize and Run RAS

Complete RAS
model with any
additional
parameters
including initial
and boundary
conditions

Follow all
principles in RAS
model
development
(calibration, etc.)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-12
Finalize and Run RAS (2)

Do the final run
and generate
results (export
to sdf file)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-13
Process RAS results in GeoRAS

Construct the
floodplain based on the
results in the sdf

Review the results with
respect to spatial
integrity (extents of
cross-sections,
ineffective flow areas,
disconnected flood
areas, …)

Clean results

Revisit RAS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-14
GIS – HMS – RAS Feedback

At present it is manual and at discretion of modeler
 GIS
H

– H&H interaction
– H interaction
Visualization in both pre and post-processing – not just
a “pretty picture”
 Fly-over
in preprocessing (GeoHMS and GeoRAS)
 Identification of data problems
 Modeling element placement
 Post-processing
(GeoRAS)
 Validity of element placement
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-15
HEC-HMS Background
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-16
About HEC-HMS

HEC-HMS, NexGen
successor to HEC-1
 Precipitation-runoff
 Lumped-link
model
model (basin-
reaches)
 Some
pseudo-distributed
processes (ModClark)

Current release – version
2.2.2
Simplified HMS Watershed
Runoff Representation
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-17
HMS Components

Basin model
 Watershed
physical
description

Meteorologic model
 Precipitation
 Evapotranspiration
 Snowmelt

Control
specifications
 Time
control during
simulation
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-18
Hydrologic Elements

Subbasin: watershed catchments

Reach: rivers and streams

Reservoir: dams and lakes

Junction: confluence

Diversion: bifurcations and withdrawals

Source: springs and other model sinks

Sink: outlets and terminal lakes
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-19
Basin Model

Subbasin

Reach

Reservoir

Junction

Diversion

Source

Sink
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-20
Basin Model (cont.)

Transform editor
Many input
forms
Baseflow method editor
Loss rate editor
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-21
Mathematical Model Choices

Many characteristics needed to compute model
parameters are spatially based
 Area
 Lengths/slopes
 Average
properties over an area (e.g. CN)
 Precipitation
…
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-22
HMS Meteorologic Model

Grid-based precipitation

Specify DSS pathname parts
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-23
HMS Control Specifications Model

Time window

Time related specifications
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-24
HMS Model
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-25
Calibration Results
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-26
HMS Results

Hydrographs at points of interest (DSS)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-27
HEC-GeoHMS Overview
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-28
About GeoHMS

HEC-GeoHMS – companion product to HMS
 ArcGIS
 I/O
support through HMS (ASCII, XML)
 Beta

version (ESRI for HEC under CRADA)
expected in April
History
 HEC-PrePro
 Watershed
 ArcView

(UT, 1997), CRWR-PrePro, PrePro 2003, …
Delineator (ESRI, 1997)
3.* versions (ESRI for HEC, 2001-04)
Development philosophy
 Build
on top of Arc Hydro tools
 Automate
GIS feasible functionality
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-29
GeoHMS Functionality

HEC-GeoHMS
 DEM
preprocessing – “parent” definition (main view)
 Watershed
delineation – on “baby” models (project view)
 Topographic
 Hydrologic

characteristics extraction
parameter computations
 Model
schematization
 Model
input preparation (ASCII)
Other GIS processing
 Rainfall
distribution/interpolation
 LU/soils
Copyright © 2005 ESRI. All rights reserved.
runoff coefficient mapping
H&H Using ArcGIS
3-30
GeoHMS Functionality (cont.)

HEC-GeoHMS and Arc Hydro tools are tightly linked
 GeoHMS
computes as many Arc Hydro attributes as possible
(e.g. NextDownID, JunctionID, DrainID)
 DEM
preprocessing (main view) is done using Arc Hydro tools
 Topographic
characteristics extraction is based on Arc Hydro
tools
 Arc

Hydro tools operate on both main and project views
Option to change stream definition threshold when
extracting the project view (one threshold for the main
view and different thresholds for different project views)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-31
DEM Preprocessing (parent definition)

Hydrologically correct DEM

Flow direction (D8 method)

Flow accumulation

Stream definition and segmentation

Watershed pre-delineation

Project (“baby”) data extraction
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-32
DEM Preprocessing (cont.)

Stream definition and
segmentation
 Threshold
(performance)

Watershed predelineation
 At
stream confluences
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-33
DEM Preprocessing (cont.)

Project (“baby”) data
extraction
 Extract
specific area of
interest by defining the
outlet and inlets
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-34
Watershed Delineation

Flexible addition and removal of basin outlets
 Merge
 Split
existing basins
basin anywhere on the stream
 Add
an outlet anywhere (trace the outlet stream to an existing
stream)
 Profile

Interactive or batch processing

Understanding of basin character
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-35
Watershed Delineation (cont.)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-36
Topographic Characteristic Extraction

Well defined topographic descriptors
 Longest
flowpath, basin centroid, stream slope, centroidal
length, CN, etc. (others planned)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-37
Hydrologic (Model) Parameter Extraction

Loss rate method (SCS CN)
 Basin

Direct runoff method (SCS UH)
 Basin

CN
lag (TR55, SCS CN)
Reach routing
 Muskingum-Cunge

standard channel parameters
Precipitation
 Weighted
gage (standard SCS type II, 24 hour, 100 year design
distribution)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-38
Model Schematization

Upstream/downstream connectivity

Development of lumped-link schema
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-39
Model Input Preparation

Native HMS ASCII input files (hms, basin, geometry, met,
dss, gage, control)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-40
HEC-GeoHMS Details
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-41
HMS Project Setup

Define outlet and sources

Extract applicable GIS data for ProjView
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-42
GeoHMS: Project View
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-43
Basin and Reach Manipulation
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-44
Basin Merge

Rules
 The
subbasins must share a confluence OR
 The
subbasins must be adjacent in an upstream and
downstream manner
 More
than 2 subbasins are permitted.
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-45
Basin Merge

Select the two subbasins using the selection tool or any other selection
method
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-46
Basin Merge
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-47
Basin Subdivision

Method 1 - Subdivide an existing subbasin

Method 2 - Delineate a new subbasin

Method 3 - Delineate on a tributary branch where the
stream does not exist
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-48
Basin Subdivision - Method 1

Method 1 - An existing
basin can be subdivided
into two basins at an
existing stream.
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-49
River Merge

Reduce the number of routing reaches

Often simplify routing as single reach with less model
parameters requirements.

Select at least two rivers within the same subbasin and
run River Merge tool.
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-50
River Profile

Method 1 - Access through menu

Method 2 - Access through profile tool

Subdivide at grade break

click on the desired point on the profile, and that point is transferred
onto the map and the basin is subdivided at that point
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-51
Split Basin at Confluences

Rules
 Only
one basin can be selected for each
operation.
 This
menu item can be used with basin
having multiple confluences.
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-52
Batch Subbasin Delineation

Rule - The point should be located within the grid cell
that has an existing stream.

Import Batch Points
 Places
all selected points in the map into the batch point file. Id
source feature classes have “Name” and “Description”
attributes, they area assigned to the batch points

Delineate Batch Points
 Takes
points from batch point feature class and uses them to do
basin subdivision.
 BatchDone and SnapOn attributes to control snapping
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-53
Extraction of Physical
Characteristics
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-54
River Length and Slope

Z unit is obtained from the spatial reference of the data.
If that is not found, the spatial reference of the map is
used for unit conversion.
Added characteristics
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-55
Basin Centroid

Method 1 - Bounding Box

Method 2 - Flow Path

Method 3 - User specified location (out of box
ArcGIS)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-56
Longest Flow Path
From ArcHydro Tools
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-57
Centroidal Flow Path
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-58
Attributes of subbasin
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-59
Additional Subbasin Attributes

Utilize Arc Hydro characteristic extraction
 CN
 Impervious
 Basin
 User
area
slope
defineable
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-60
Assembling Data for HMS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-61
Outline

Develop HMS inputs from GeoHMS
 HMS
Schematic
 Basin
Model
 Background
 Grid

Map File
Cell Parameter File
Assemble an HMS model
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-62
Subbasin Naming

Basin AutoName menu

Editable to suit project needs
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-63
Reach Naming

Reach AutoName menu

Editable to suit project needs
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-64
Unit Conversion

Convert Map units to HMS units
(unit conversion defined in
configuration file)

Additional attributes can be
managed by editing the
configuration file
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-65
Development of HMS Schematic

Run HMS Schematic from HMS menu
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-66
Add Coordinates

Run Add Coordinates from HMS menu
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-67
Develop Background Map

Run Background Map
File from HMS menu
 ASCII
(.map) format as
well as XML format
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-68
Develop Lumped Basin Model

Run Lumped Basin File
from HMS menu
 ASCII
(.basin) format as
well as XML format
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-69
Developing HMS Model
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-70
Hydrologic Analysis (HEC-HMS)

Basin import

Geometry (background) import

Hydrologic (model) parameters – complete the model for the
parameters not defined through GeoHMS

Basin (precipitation-runoff transformation)

Reach (routing)

Precipitation

Calibration

Final run (hydrographs as results)

None of the results are sent back to GIS at this time

Use of DSS for time series storage and exchange with RAS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-71
Model Results (DSS)

Basin
Copyright © 2005 ESRI. All rights reserved.

Summary
H&H Using ArcGIS
3-72
HEC-RAS Background
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-73
About HEC-RAS

HEC-RAS, NexGen successor to HEC-2

1-Dimensional hydraulic program

Steady and Unsteady Flow

Compute water surface from channel geometry and flow

Current release – version 3.1.2
Flow
Water depth?
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-74
HEC-RAS Components

Graphical User Interface

Data storage/management

Graphics, Tabular Output & Reporting

GeoRAS – GIS pre and postprocessor
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-75
Geometric Data

Cross Sections

Detailed Bridge Analysis

Detailed Culvert Analysis (9 shapes)

Multiple openings (bridge, culverts, conveyance)

Inline Weirs/Spillways, Gated Structures

Lateral Weirs/Spillways, Gated Structures

Storage Areas and Hydraulic Connections

Rating Curves

Data importers: HEC-2, UNET, Mike11, GIS, Survey Data
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-76
RAS Schematic
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-77
Cross Sections
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-78
Flow Data and Boundary Conditions

Steady flow data - peak flows or time lines

Unsteady flow data - hydrographs

Boundary Conditions
 Stage
and/or flow hydrographs
 Rating
Curves
 Normal
or critical depth
 Lateral
and uniform lateral inflow hydrographs
 Groundwater
 Time
interflow
series of gate openings
 Elevation
controlled gates
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-79
Analyses Types

FEMA Floodway Analysis

Channel Modifications

Split Flow Optimization – steady flow

Bridge Scour Analysis

Detailed Flow Distribution

Mixed Flow Regime in Unsteady Flow

Subcritical and Supercritical flow, draw downs, and hydraulic jumps

Dam Break Analysis

Levee Breaching and Overtopping

Pump Stations – multiple pumps, on and off elevations

Navigation Dams – Dam and hinge point control
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-80
Viewing Results

Graphics

Cross sections

Water surface profiles

Stage and flow hydrographs


XYZ Plot

Rating Curves

Generic plots – Any variable in profile, rating

Animation – (cross section, profile, 3D plots)
Tabular Output

Pre-defined detailed and summary tables

User-define output tables
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-81
Cross Section Plot
.065
.04
.09
620
Legend
EG 22FEB1999 0500
Elevation (ft)
600
WS 22FEB1999 0500
Crit 22FEB1999 0500
580
Ground
Levee
560
Ineff
Bank Sta
540
520
0
200
400
600
800
1000
1200
1400
Station (ft)
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-82
Profile Plot
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-83
XYZ Plot
Legend
WS 22FEB1999 0500
Ground
Bank Sta
Ground
Levee
Ineff
Copyright © 2005 ESRI. All rights reserved.
Source: HEC
H&H Using ArcGIS
3-84
Stage and Flow Hydrographs
R iv er: Truc k ee
R each: Lower
RS: 11496. 09
4396
22000
Legend
20000
Stage
Flow
4394
18000
16000
14000
4390
12000
4388
Flow (cfs)
Stage (ft)
4392
10000
8000
4386
6000
4384
31
01
Dec96
Copyright © 2005 ESRI. All rights reserved.
02
03
Jan97
T ime
04
Source: HEC
05
4000
H&H Using ArcGIS
3-85
HEC-GeoRAS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-86
About HEC-GeoRAS

HEC-GeoRAS – companion product to RAS
 ArcGIS
 I/O
support through RAS (ASCII, XML)
 Beta

version (ESRI for HEC under CRADA)
released (in pre-beta for almost 2 years)
History
 ARC/HEC2
(UT, 1992)
 Philadelphia
 ArcView
version (ESRI) – AVRas 2.2
 ARC/INFO

COE (ARC/INFO solution)
and ArcView 3.* versions (HEC/ESRI)
Development philosophy
 Automate
 Provide
boring tasks
tools for “involved” tasks, otherwise standard ArcGIS
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-87
GeoRAS Functionality

HEC-GeoRAS
 Preprocessing
 Layer construction
 Data entry utilities
 Characteristics extraction (stream and cross-section properties)
 Model input preparation (ASCII)
 Postprocessing
 Import of RAS results into a geodatabase
 Generation of water depth and floodplain extent

Other GIS processing
 Mapping
 Visualization
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-88
HEC-GeoRAS
Preprocessing
Copyright © 2005 ESRI. All rights reserved.
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GeoRAS Data Layers - Required

Terrain Model – representation
of both the main channel and
adjacent floodplain area
TIN
or GRID
tiled
or monolith

Stream Centerline

Cross Section Cut Lines
Copyright © 2005 ESRI. All rights reserved.
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GeoRAS Data Layers – Optional

Flow paths

Stream banks

Land use

Ineffective areas

Levee alignments

Storage areas

Blocked obstructions

Bridge/culverts

…

Contours, images,
orthophotos, (visualization)
Copyright © 2005 ESRI. All rights reserved.
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GeoRAS Database Generation

Through code
 “Create
RAS Layers”
function in GeoRAS UI
 Each
function will generate
layers/attributes as needed

ArcCatalog
 From
geodatabase schema
 Careful with spatial reference

Careful with SDE
implementation (write
access)
Copyright © 2005 ESRI. All rights reserved.
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GIS Data Layer – Terrain

Terrain
 TIN
or GRID
 Used
to:
 Provide elevation values
 Georeference GIS layers !
 Contours
can be created and
used for visualization only
 Assists
in stream centerline
and cross section layout
Copyright © 2005 ESRI. All rights reserved.
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GIS Data Layer – Stream Centerline

Terrain

Stream Centerline
 Establishes
cross-sectional
river stationing
 Created
in the direction of flow from upstream to downstream
 Each
reach must have a unique
river-reach name
Copyright © 2005 ESRI. All rights reserved.
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GIS Data Layer – Stream Banks

Terrain

Stream Centerline

Stream Banks (Optional)
 Delineates
the main river
channel from the overbank
areas
Copyright © 2005 ESRI. All rights reserved.
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3-95
GIS Data Layer – Flow Paths

Contours

Stream Centerline

Stream Banks

Flow Paths (Optional)
 Created
in the direction of flow
 Located
at the center-of-mass
of flow
Copyright © 2005 ESRI. All rights reserved.
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GIS Data Layer – Cross Sections

Contours

Stream Centerline

Stream Banks

Flow Paths

Cross Sections
 XS
locations (cut lines) are
oriented from the left to right
bank
 Perpendicular
Copyright © 2005 ESRI. All rights reserved.
to flow
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River Stationing

Cross-sectional station
calculated from intersection
of Stream Centerline and XS
Cut Lines
Copyright © 2005 ESRI. All rights reserved.
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Bank Stations

Calculated at the intersection
of Cross-sectional Cut Lines
and Banks themes

Banks Stations are
calculated as a fraction of
the cut line
Copyright © 2005 ESRI. All rights reserved.
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Downstream Reach Lengths

Calculated at the
intersection of Crosssectional Cut Lines and
Flow Path Centerlines
themes

Reach lengths are
calculated as the length
between cut lines
Copyright © 2005 ESRI. All rights reserved.
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Station-elevation Data

Elevation data extracted
from intersection of Crosssectional Cut Line theme
with the terrain
Copyright © 2005 ESRI. All rights reserved.
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Station-elevation Data
Cross-sectional Cut Line
TIN
Resultant Cross Section
Copyright © 2005 ESRI. All rights reserved.
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GIS Data Layer – Manning’s n

Contours

Stream Centerline

Stream Banks

Flow Paths

Cross Sections

Land Use
 Estimate
n values
Copyright © 2005 ESRI. All rights reserved.
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Manning’s n Values

Intersection of Cross
Section Cut Lines and Land
Use themes

N value break points are
reported as a fraction of the
cut line
Copyright © 2005 ESRI. All rights reserved.
n2
n3
n4
n5
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GIS Data Layer – Other

Contours

Stream Centerline

Levees

Stream Banks

Ineffective flow areas

Flow Paths

Blocked obstructions

Cross Sections

Bridge/Culverts

Land Use

Inline structures

Lateral structures

Storage areas
Copyright © 2005 ESRI. All rights reserved.
Other
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GIS Data Layer – 3D Elements

Contours

Stream Centerline

Stream Banks

Flow Paths

Cross sections

Cross Sections

Stream centerline

Land Use

Bridge/Culverts

Other

Inline structures

Lateral structures

Storage areas
Copyright © 2005 ESRI. All rights reserved.
3D elements are
extracted from their
2D counterparts and
the terrain
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Geometric Import File (GIS

RAS)
Content
 Header
 River
Information
Network Definition
 Rivers, reaches, and
junctions
 Channel
and Floodplain
Geometry
 Station-elevation data
 Bank stations
 Downstream reach lengths
 Manning’s n values
 Other
 Storage areas
Copyright © 2005 ESRI. All rights reserved.
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Geometric Import File (cont.)

Format
 sdf
(RAS I/O ASCII
format)
 XML
Copyright © 2005 ESRI. All rights reserved.
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Completing HEC-RAS
and HEC-GeoRAS Postprocessing
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Analysis Process Overview

(GIS data Development completed)

Import GIS data into HEC-RAS

Complete data entry

Geometry
 Required information not covered by GIS

Modeling run
 Initial and boundary conditions


Perform the computations

QC of results

Calibration
Export results to GIS (GeoRAS postprocessing)

Floodplain delineation

Water depth determination
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Completing HEC-RAS
Input
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Imported Data

River system schematic
 River,

reach and junction labels
Cross-section data
 River,
reach, and river station labels
 Cross
section cut lines (x,y)
 Cross
section surface line (x,y,z)
 Main
channel banks stations (optional)
 Downstream
reach lengths (optional)
 Manning’s
n values (optional)
 Ineffective
flow areas (optional)
 Levees
(optional)
Copyright © 2005 ESRI. All rights reserved.
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Imported Data (cont.)

Storage areas

Structures (only 2 and 3D geometry and placement are
generated – detailed structure characteristics are
currently not – work in progress)
 Bridge/culverts
 Inline
structures
 Lateral
structures
Copyright © 2005 ESRI. All rights reserved.
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Data NOT Imported

Contraction and expansion coefficients

Optional cross-section properties
 Ice,

vertical n values, etc…
Hydraulic structure survey data
 Bridge

and culvert openings, weir characteristics, etc...
Flow characteristics
 Initial
conditions
 Boundary
conditions
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-114
Importing GIS Data into RAS

Extract the geometric
data from GIS

From the geometric
data editor, select
import geometry data
 GIS format
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-115
Importing GIS Data into RAS (cont.)

Imported river
system schematic

Save Geometric Data
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Completing the Data

GIS does not generate all required data. Some are
optional (e.g. Manning’s n or bank stations) and some
are not supported (e.g. structure characteristics or
flows).

In most cases, additional work will have to be done on
cross-sections
 “Banks”
 Manning’s
n
 Simplification
Copyright © 2005 ESRI. All rights reserved.
of cross-section points (weeding)
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Completing the Data – Flow Characteristics

Flow data

Boundary
conditions

Profile names
Copyright © 2005 ESRI. All rights reserved.
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Flow Data and Boundary Conditions

Steady flow data - peak flows or time lines

Unsteady flow data - hydrographs

Boundary Conditions
 Stage
and/or flow hydrographs
 Rating
Curves
 Normal
or critical depth
 Lateral
and uniform lateral inflow hydrographs
 Groundwater
 Time
interflow
series of gate openings
 Elevation
controlled gates
Copyright © 2005 ESRI. All rights reserved.
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Performing Computations and Viewing Results
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Viewing Results (RAS)

Graphics

Cross sections

Water surface profiles

Stage and flow hydrographs


XYZ Plot

Rating Curves

Generic plots – Any variable in profile, rating

Animation – (cross section, profile, 3D plots)
Tabular Output

Pre-defined detailed and summary tables

User-define output tables
Copyright © 2005 ESRI. All rights reserved.
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Water Surface Bounding Polygons

Cross section extents

Limited at Levees

Bridges, Culverts and
Weirs

FEMA Floodways
Copyright © 2005 ESRI. All rights reserved.
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Exporting Results to GIS

From HEC-RAS “File”
menu select “Export
GIS Data”

Many options

Make sure that the
result requested in
RAS is matching GIS
export requirements
(e.g. velocities)
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
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Exporting Results to GIS (cont.)

Cross section cut lines

Water surface elevations

Bounding polygon data

Stream centerline (optional)

Bank points (optional)

Storage areas (optional)

Velocity distribution information (optional)

Cross section properties (optional)

Cross section points (optional)

interpolated or not

channel or channel + floodplain area
Copyright © 2005 ESRI. All rights reserved.
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Post-processing in
HEC-GeoRAS
Copyright © 2005 ESRI. All rights reserved.
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Floodplain Delineation Methods

Import of model results into GIS
 Construction
of GIS coverage through water surface as defined
by the hydraulic model (e.g. HEC-RAS).
 fast, simple implementation
 limited to solution at the cross-section - non-terrain based
interpolation between the cross-sections
 Construction
of GIS coverage by construction of a water TIN and
then intersection of the water and terrain TINs to produce the
final floodplain outline.
 slow, complex implementation
 needs conversion of TIN into lattice (A/I)
 more precise interpolation
Copyright © 2005 ESRI. All rights reserved.
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Post-processing

Specify data and
output locations

Read the RAS output
and generate results
geodatabase

Process GIS data to
generate floodplain
polygons and depth
grids
Copyright © 2005 ESRI. All rights reserved.
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RAS GIS Export File

Cross-sectional Cut Lines

Water surface elevations

Bounding polygon data

Stream Centerline (optional)

Velocity points (optional)

Other elements planned (banks, …)
Copyright © 2005 ESRI. All rights reserved.
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RAS GIS Export File (cont.)
Copyright © 2005 ESRI. All rights reserved.
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Inundation Processing

Multiple steps
 Generate
water surface TIN
 Use cross-sections as breaklines with known water surface elevation
coming from RAS.
 Use bounding polygon as TIN extent (clip water surface extent)
 Convert
water surface TIN into a water surface GRID
 Rasterization cell is user defined (if terrain is in GRID format, it
should be terrain’s resolution)
 Positive
difference between the water surface and terrain GRID is
the water depth grid (negative values are discarded)
 The
perimeter of the water depth grid is the floodplain boundary
Copyright © 2005 ESRI. All rights reserved.
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Inundation Processing (cont.)

Line layer of cross-sectional
cut lines with water surface
elevations in attribute table
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Inundation Processing (cont.)

Water surface TIN is created
using cut lines as breaklines

WS TIN is created
irrespective of land surface
Copyright © 2005 ESRI. All rights reserved.
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Inundation Processing (cont.)

Water surface TIN is
clipped with a “bounding
polygon”

For a levee, bridges,
culvert, or floodway
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
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Inundation Processing (cont.)

TIN represents a continuous
water surface
 Water
surface interpolation
between cross sections is based
purely on geometry
 GeoRAS
performs no hydraulic
calculations
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
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Inundation Processing (cont.)

Terrain model and water
surface TIN are converted
to registered grids

Depth grid determined from
the difference of the water
surface and land surface
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
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Inundation Processing (cont.)

Floodplain boundaries at
the intersection of the
water surface and land
surface grids

Floodplain polygon is
created in GeoRAS by
vectorizing the depth grid
Copyright © 2005 ESRI. All rights reserved.
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Visualization
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Modeling Feedback

Visual inspection/interpretation of results (or sooner)
 Terrain
problems
 Ineffective
areas
 Problematic
cross-section location
 Floodplain discontinuity
 Short cross-sections
 Problematic
Copyright © 2005 ESRI. All rights reserved.
RAS auto cross-section interpolation
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Floodplain Discontinuity
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Floodplain Discontinuity (cont.)
“Dry”
Water surface profile
Terrain
Cross-sections
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H&H Using ArcGIS
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Cross-section Interpolation
TIN interpolated crosssections
RAS interpolated crosssections
RAS assumed terrain
Terrain
Original cross-sections
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
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Automating the
execution
Copyright © 2005 ESRI. All rights reserved.
H&H Using ArcGIS
3-142
Map2Map (rainfall to floodplain)
Flood map
as output
FLO
ODP
LAIN
MAP
Model for
flood flow
HMS
Nexrad rainfall map as input
Copyright © 2005 ESRI. All rights reserved.
Model
for flood
depth
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