Converting a NEXRAD Rainfall Map into a Flood Inundation Map by ...

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and River Hydraulics is normally modeled with the HEC-RAS (USACE, 1997)river analysis system (for simulation of one-dimensional and usually steady flowconditions). Each of these independent simulation models is normally executed ina separate and non-integrated fashion and manually exchanging informationbetween them in a loose, tedious, error-prone, and non-systematic fashion. Ingeneral, the flow of information between data acquisition systems like radar data,hydrologic and hydraulic modeling systems, and flood mapping utilities areindividually and independently accomplished.To straighten out the traditional step-wise approach this research dealswith the development a Flood Simulation System on top of the Arc Hydro DataModel that will streamline the simulation process, manipulation and generation ofmodeling outputs needed for flood inundation mapping in flood assessmentstudies and mitigation plan evaluation. That is, a seamless, end-to-end integratedRegional Watershed Modeling System for flood information support termed the“Map2Map” application.1.2 MOTIVATIONThe need to update flood inundation maps and to obtain realistic flooddischarge hydrographs in response to specific storm events is clear. In particular,the herein developed Map2Map integrated approach should allow for straightforward evaluations to properly take into account the following modeling issuesand limitations:• Ability to consider Land-use changes that could alter the response of awatershed to rainfall, since flood discharges determined with outdated data2
for undeveloped or natural conditions may not reflect discharges expectedwith developed conditions.• Overcome that fact that few streams are gauged, and those that are, do nothave a record long enough for accurate flood impact analysis and forstatistical models to be fitted accurately in flood frequency analysis studies(Haan, 1977, Chow et al., 1988, Bedient et al., 1992).• Provide complete flood related information beyond the statistical-analysisapproach (e.g., USGS StreamStats) that does not provide informationabout runoff volume and timing.Rapid evaluation of flood events provides for a clear visualization of areasin need of flood protection or the need for new floodplain policies andregulations. In some cases, “after-the-fact” projects are normally proposed basedon the most recent history of flood damages. An end-to-end, integrated, anddynamic system will help the evaluation of a whole range of potential events(Wurbs, et al., 2001) to better identify flood abatement measures.Floodplain boundaries used for management and regulating purposes areusually outdated. The shape and water elevations of the floodplain have adynamic character governed by multiple regional and local factors. This dynamiccharacter of the watersheds poses a constant need for remapping the floodplainboundaries due to:• New planning criteria defined by updated storm frequency analysis thatprovides more realistic design storms obtained from longer records of dataand the inclusion of new extreme events.3
Page 3 and 4: Table of ContentsList of Figures ..
Page 5 and 6: 4.1.12 The XML2GDB Script Tool ....
Page 7 and 8: Figure 3.24 Components of a Steady
Page 9 and 10: Figure 4.50 Create Flood Inundation
Page 11: Chapter 1 Introduction1.1 BACKGROUN
Page 15 and 16: All the previous statements favor t
Page 17 and 18: science, and engineering models as
Page 19 and 20: Different approaches have been used
Page 21 and 22: generic and self-described formats,
Page 23 and 24: externally executed from a central
Page 25 and 26: though GIS-based, the system does n
Page 27 and 28: Geographic Information Systems, Arc
Page 29 and 30: By defining the three basic functio
Page 31 and 32: containing an inventory of damage s
Page 33 and 34: Data Models in charge of storing an
Page 35 and 36: Figure 3.1 Floodplain Modeling Sche
Page 37 and 38: either with Schematic Nodes (for Su
Page 39 and 40: channel cross sections, available H
Page 41 and 42: sequential data, called pathnames,
Page 43 and 44: Figure 3.5 NEXRAD square cells (873
Page 45 and 46: geodatabase formatted with the Arc
Page 47 and 48: The CrossSection feature class in A
Page 49 and 50: geodatabase (under Arc Hydro format
Page 51 and 52: 3.4.4 External Execution of HEC-RAS
Page 53 and 54: analysis. In particular, GIS has be
Page 55 and 56: 3.5.3 Model-Specific ElementsA geog
Page 57 and 58: Figure 3.11 Geographic and Hydrolog
Page 59 and 60: For HEC-RAS, the connectivity is ac
Page 61 and 62: cross sections in the hydraulic mod
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Section line for a RAS cross-sectio
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from the geodatabase back into the
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Figure 3.19 Relationship Classes fo
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Figure 3.20 DSS Time Series content
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Figure 3.22 Extended Time Series Co
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Figure 3.23 Creating a Flow File fr
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etween the HEC-DSS file system and
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The more specific steps for the pos
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Chapter 4 Map2Map Components4.1 MOD
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A subset of NEXRAD time series data
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A folder location is also provided
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Figure 4.4 Radar2GDB Model Componen
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ecords. Figure 4.6 illustrates the
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Figure 4.8 Time Series Tables and R
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having different formats and that a
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Part E: Time Interval of stored dat
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execution time and for their corres
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on the steps needed to transfer the
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Len_sBTime (I): The length of the s
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52: Invalid precision exponent spec
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methods: user hyetograph, user gage
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Once the hyetograph is defined (for
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The resulting runoff hydrograph is
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Thus, the time period for the entir
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After the ZSRTS subroutine is execu
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Figure 4.12 HMSCaller Model Compone
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ased on a process handle (a program
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These simple command line statement
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To programmatically accomplish this
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to provide the hydraulic input for
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information into the extended Arc H
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The HydroJunction, used for connect
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Once the identification of flow cha
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As with the GDB2HMSDSS, the first t
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4.1.7 Time Series ExtractionOnce th
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accomplish this have been developed
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straight forward for all time stamp
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As opposed to HEC-DSS, the Arc Hydr
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Table 4.4: Variable Type Equivalenc
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ZCAT DSS subroutines) and stored in
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Table 4.5: Time Interval Equivalenc
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There are not specific valid values
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catalog list. For the DSS2GDB appli
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4.1.9.1 Opening the HEC-DSS fileThe
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channel (the hydraulic representati
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the model if the new configuration
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the main program as a public module
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Then, the RASCaller application acc
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Figure 4.31 ProjectName Property in
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Figure 4.33 RunSteady Method in RAS
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Figure 4.34 ExportGIS Method in RAS
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data structures delivered by every
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The two most well-known models for
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The water surface elevations obtain
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Once the water surface elevations f
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Generate a suitable water surface m
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Figure 4.42 2 Foot-Contour Lines fo
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Figure 4.43 Rosillo Creek’s terra
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standard ArcGIS tool), is used in M
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By doing this, the water surface el
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Figure 4.49 Create Flood Polygon Mo
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Int OperationThe Integer operation
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case that was developed for Map2Map
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contours (isohyetals) or by interpo
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design storm input given its possib
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Figure 4.55 Workflow for Extracting
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for it. Finally, the DigitalStorm2H
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model for water resources (Maidment
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Hydro, the HydroJunctionHasCrossSec
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involved in the transformation of r
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process model in sequence. For the
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5.6 A TRUE SPATIAL APPROACHAutomate
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time series between NEXRAD, the HEC
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value of the entire runoff hydrogra
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case study. Bigger watersheds (abov
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The first step consists in installi
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3.7 Map2Map UsageAll of the model b
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Congratulations! You have successfu
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Once the simplified version of Arc
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cells that cover your study area an
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Second, the user needs to modify th
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Appendix BMap2Map CD Content1 CD Da
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o hmsproj - contains folders with H
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Goodchild, M.F., Steyaert, L.T., an
Page 231 and 232:
Olsen R. J., Beling, P. A., Lambert
Page 233 and 234:
Werner, M. G. F. 2001. Impact of gr
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