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

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Chapter 5 Conclusions and Recommendations5.1 A SEAMLESS END-TO-END GEOGRAPHIC INTEGRATIONThe main scientific contribution of this research corresponds to theconnectivity of two independent and stand-alone modeling systems (HEC-HMSand HEC-RAS) under a map-centric framework for the purpose of delineatingflood inundation maps and streamlining the process to accomplish the integration.By facilitating integration of models and applications it is possible to takeadvantage of well-tested and approved design concepts, computer code and modelcomponents across multiple target-specific engineering models. This researchprovides a sound approach for “bringing the models together” under a mapcentricframework for automated and sequential hydrologic and hydraulicsimulations.GIS was employed in a dual fashion, for the spatial identification ofexchange points of information between the models and to automate the workflowof all involved processes. In contrast with the regular piecewise approach thisintegration avoids time-consuming, error prone, and more expensive flood studydevelopments under a comprehensive spatial framework. The spatial character ofthe needed points of information exchange between the involved models makesthis approach consistent and robust.The system facilitates the coupling of GIS and engineering models byimplementing a geographic integration based on existing and new relationshipclasses (spatial associations) on top of a standard data model, the Arc Hydro data186
model for water resources (Maidment, 2002). This spatially oriented system forthe linkage of hydrologic and hydraulic modeling systems is based on geographicrepresentations of the stream geometric network, schematic network, and modelcentricfeatures that have been proved feasible and extensible to even moreambitious implementations. By following the proposed integration methodology,other hydrologic information systems so defined may serve as a reference frameto link the operation of other supplemental engineering/environmental modelssuch as potential water quality components (e.g., QUAL2E, HSPF, SWAT, etc.).In linking HEC-HMS and HEC-RAS through the GIS-based Arc Hydrodata model (Maidment, 2002), the inherent expertise of each model is exploitedby allowing one model to determine streamflow hydrographs, and the second todetermine water surface elevations and flood extents as a function of given inputinherited from sequential simulations. By doing this, a traditionally tedious, timeconsuming, and error prone modeling task has been streamlined and can now beaccomplished under a more comprehensive and controlled environment that takesfull advantage of the spatial character of the study area undergoing the modelingexercise which executes in about four minutes what could normally take hours ofwork.The implementation of a standard data model for water resources, ArcHydro, the compliance of external and specialized stand-alone modeling systemswith standard interconnection protocols (COM technologies), and the higher levelof customization provided by the new ArcGIS 9 software provides all the187
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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
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By defining the three basic functio
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containing an inventory of damage s
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Data Models in charge of storing an
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Figure 3.1 Floodplain Modeling Sche
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either with Schematic Nodes (for Su
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channel cross sections, available H
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sequential data, called pathnames,
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Figure 3.5 NEXRAD square cells (873
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geodatabase formatted with the Arc
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The CrossSection feature class in A
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geodatabase (under Arc Hydro format
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3.4.4 External Execution of HEC-RAS
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analysis. In particular, GIS has be
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3.5.3 Model-Specific ElementsA geog
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Figure 3.11 Geographic and Hydrolog
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For HEC-RAS, the connectivity is ac
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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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Page 159 and 160: Figure 4.31 ProjectName Property in
Page 161 and 162: Figure 4.33 RunSteady Method in RAS
Page 163 and 164: Figure 4.34 ExportGIS Method in RAS
Page 165 and 166: data structures delivered by every
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Page 171 and 172: Once the water surface elevations f
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Page 175 and 176: Figure 4.42 2 Foot-Contour Lines fo
Page 177 and 178: Figure 4.43 Rosillo Creek’s terra
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Page 181 and 182: By doing this, the water surface el
Page 183 and 184: Figure 4.49 Create Flood Polygon Mo
Page 185 and 186: Int OperationThe Integer operation
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Page 193 and 194: Figure 4.55 Workflow for Extracting
Page 195: for it. Finally, the DigitalStorm2H
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Page 201 and 202: involved in the transformation of r
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Page 205 and 206: 5.6 A TRUE SPATIAL APPROACHAutomate
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Page 209 and 210: value of the entire runoff hydrogra
Page 211 and 212: case study. Bigger watersheds (abov
Page 213 and 214: The first step consists in installi
Page 215 and 216: 3.7 Map2Map UsageAll of the model b
Page 217 and 218: Congratulations! You have successfu
Page 219 and 220: Once the simplified version of Arc
Page 221 and 222: cells that cover your study area an
Page 223 and 224: Second, the user needs to modify th
Page 225 and 226: Appendix BMap2Map CD Content1 CD Da
Page 227 and 228: o hmsproj - contains folders with H
Page 229 and 230: 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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Converting a NEXRAD Rainfall Map into a Flood Inundation Map by ...

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