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M.7 Hydraulics Submittal Standards

Summary of questions/comments received for the Hydraulics section on DHS Interactive and responses provided through October 3, 2008.

Topic Comment Response
List of Hydraulics Comments Here's a list of some of the errors/issues we have run into:

The XS_SRC field in S_XS is listed as being a short type, length 4. However, it references a domain table with values that are all much longer than 4, without ID number which would be required if we were to use the short field type

WSEL_PT2PCT in S_XS is too long for a shapefile field name

Pg. 59, last line, there is a typo (lists S_Pofil_Basln instead of S_Profil_Basln).

Figure M-10 is referenced as showing the difference between a profile baseline and a streamline, yet only a streamline is shown in the image.

It would be helpful to new users if domain tables referenced from Appendix L are also included, or if Appendix L is referenced when it requires use of Appendix L tables.

The WTR_NM field in S_Profile baseline is 254 characters, in the S_XS it is only 100. Might eliminate some problems if the field length was the same in both.		 We agree with these comments. The revised version of Appendix M posted in September 2008 addressed these comments. The updated document also made an effort to make the field length for fields that exist in more than one layer/table match. Additionally, at this time all domain tables referenced by the attribute fields in Appendix M will be listed in the document for ease of use.

The image shown in Figure M-10, which shows the stream centerline and the profile baseline, does show both features, but due to the map scale, the stream centerline located under the profile baseline is difficult to detect. However, this image is no longer applicable and was removed as a result of the recent update to the document.
Deliverables Are DXF files acceptable for profiles? The Floodplain Mapping section lists both DWG and DXF as acceptable file formats. This section should be consistent. Yes, DXF file format is acceptable and is the recommended format. The revised version of Appendix M posted in September 2008 clarified this.
Data Files Are S_BFE and hydraulic stream centerlines no longer required for the hydraulics submittal? They don't seem to be listed in the hydraulics section.

Recommend adding Future Conditions as an "if applicable" feature so users know how those data would be submitted.		 Yes, the S_BFE Spatial file is required but it was inadvertently omitted from Section M.7 on Hydraulics. It is included in the version posted in September 2008.

The stream centerline will be the same as the profile baseline if the path of the flood flow follows the main channel of the stream.

We will consider the suggestion to add Future Conditions to Appendix M.
Directory Structure Problem: Supplemental and other data formats.
Proposed Resolution: Provide a folder for this type of data.		 The supplemental data analyses and backup files are to be placed in Hydraulic Databases folder which will be re-named as \Hydraulic Models\"Stream Name"\Hydraulic Supplemental Data. The acceptable data formats are described in Section M.7.2.4, which were revised in the revised document posted in late September 2008.
Approximate Studies Submittal requirements for Approximate Studies should be limited to a project description and narrative. Publishing or distributing water surface elevations based on approximate methods could lead to appeals. There is no intent to publish water surface elevations on the FIRM for approximate studies. The requirement is for the Mapping Partner to provide the backup data for the computations of the elevations used in defining the flood boundaries. The water surface elevations could have significant uncertainty but the concept is to have some documentation for the flood boundaries. Since the water surface elevations (base flood elevations) will not be published on the FIRM, there is no basis for an appeal (may be only a protest).

Last Modified: Thursday, 04-Jun-2009 13:41:00 EDT