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

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Figure 4.1 Map2Map Workflow in ModelBuilder for Historic Event Use Case4.1.1 The Radar2GDB Script ToolThe first step in the Map2Map application (first yellow box above) dealswith the access and transfer of precipitation time series data (to drive thehydrologic simulation in HEC-HMS) from the available NEXRAD format andinto an extended Arc Hydro format for time series. For the currentimplementation of the Map2Map application, the rainfall data is provided by thenetwork of NEXRAD radars along the U.S. The mappable format of this datacorresponds to the rectangular grid termed Hydrologic Rainfall Analysis Project(HRAP) grid having a nominal grid spacing of 4 km x 4 km. Each of therectangular grid cells is identified by a PixelID with which a time series of rainfalldata is associated.70
A subset of NEXRAD time series data for Texas was provided by theGuadalupe Blanco River Authority in Texas as a series of ASCII files. The subsetwas comprised of 552 hourly text files for a storm event in late August of 2002and for the entire state of Texas. Thus, for the current format being used, therainfall data are stored in individual ASCII data files named after the hourly timestamp they contain.A snippet of the file content of one of the text files is shown below for afilename “0701200204.” The filename contains the time stamp embedded in itwith the date format MMDDYYYYHH. Thus, the filename “0701200204”contains a rainfall data for an event occurring on July 01, 2002 at hour 04. Figure3.4 shows a snippet for this data text file. The text file contains a header definingthe first columns as a pixel id (P_ID) and the second column as the precipitationvalue in inches (PRECIP_IN). At the end of the data records, the text file endswith an END statement.The precipitation values on the above Figure are associated with a PixelIDpointing to a NEXRAD cell in the mappable HRAP format. The layer containingthe HydroResponse feature class with the NEXRAD cell definition was providedby the Brazos River Authority in Texas. This layer is a statewide NEXRADHRAP grid in which the “Rfcthsn_ID” field in the grid layer corresponds to theP_ID field (first column Pixel ID) in the above data text file.Given that each of the hourly text files of precipitation contains data for allof the NEXRAD cells in Texas (50,150 cells), the NEXRAD cells covering thespecific study area must be extracted and a new NEXRAD layer for the watershed71
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Table of ContentsList of Figures ..
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4.1.12 The XML2GDB Script Tool ....
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Figure 3.24 Components of a Steady
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Figure 4.50 Create Flood Inundation
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Chapter 1 Introduction1.1 BACKGROUN
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for undeveloped or natural conditio
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All the previous statements favor t
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science, and engineering models as
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Different approaches have been used
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generic and self-described formats,
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externally executed from a central
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though GIS-based, the system does n
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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
Page 63 and 64: Section line for a RAS cross-sectio
Page 65 and 66: from the geodatabase back into the
Page 67 and 68: Figure 3.19 Relationship Classes fo
Page 69 and 70: Figure 3.20 DSS Time Series content
Page 71 and 72: Figure 3.22 Extended Time Series Co
Page 73 and 74: Figure 3.23 Creating a Flow File fr
Page 75 and 76: etween the HEC-DSS file system and
Page 77 and 78: The more specific steps for the pos
Page 79: Chapter 4 Map2Map Components4.1 MOD
Page 83 and 84: A folder location is also provided
Page 85 and 86: Figure 4.4 Radar2GDB Model Componen
Page 87 and 88: ecords. Figure 4.6 illustrates the
Page 89 and 90: Figure 4.8 Time Series Tables and R
Page 91 and 92: having different formats and that a
Page 93 and 94: Part E: Time Interval of stored dat
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Page 97 and 98: on the steps needed to transfer the
Page 99 and 100: Len_sBTime (I): The length of the s
Page 101 and 102: 52: Invalid precision exponent spec
Page 103 and 104: methods: user hyetograph, user gage
Page 105 and 106: Once the hyetograph is defined (for
Page 107 and 108: The resulting runoff hydrograph is
Page 109 and 110: Thus, the time period for the entir
Page 111 and 112: After the ZSRTS subroutine is execu
Page 113 and 114: Figure 4.12 HMSCaller Model Compone
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Page 117 and 118: These simple command line statement
Page 119 and 120: To programmatically accomplish this
Page 121 and 122: to provide the hydraulic input for
Page 123 and 124: information into the extended Arc H
Page 125 and 126: The HydroJunction, used for connect
Page 127 and 128: Once the identification of flow cha
Page 129 and 130: 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
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Olsen R. J., Beling, P. A., Lambert
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Werner, M. G. F. 2001. Impact of gr
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Converting a NEXRAD Rainfall Map into a Flood Inundation Map by ...

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