Does anyone have a good reference for determination of BFE from the FIS, which I understand FEMA likes to see for LOMAs etc? The panels are driving me nuts.
In the area I am working is about 3/4 mile from a major river and between 2 cross sections, D and E about a mile apart, although one cross section only goes partway to the site. The Floodway Data shows a regulatory elevation of 199.3 ft at cross section D, downstream from my site. I assume that on the FIRM, this is the cross section line (of common elevation) depicted. I look at the Flood Profile, cross section D and come up with 199.0 ft. Not too bad.
Section E regulatory floodway data shows 201.1 ft. The flood profile crosses at 200.5 ft, definitely half way between 200 and 201 ft. However, the cross section E ends about 1/4 mile towards the river at some higher elevation (500 year flood) and I'm left with the squiggly lines at 1 foot elevations intervals in the site area. The State FEMA Coordinator says FEMA doesn't like to see these used as the basis for a BFE or LOMA.
Someone else is doing the LOMA (they missed the property being in the SFHA and have agreed to "fix it"). We'e definitely out of the Floodway.
Solutions for the BFE, anticipating a LOMA?
1. Project the site location parallel with the squiggly lines to the river and determine the river mile, then use the flood profile?
2. Project the site perpendicular to the base profile? The river curves significantly and the projection will cross the 200 foot elevation squiggle.
3. Interpolate between the squiggly lines to get the BFE?
Thanks.
#2
BFE from PROFILE
+1 for BFE from FIS
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Thanks for the Help Guide.
The situation is complicated by the fact that the house supposedly sits in an X zone island (out of flood plain), but with a basement and a tongue of the SHFZ (1%) which appears to touch the house. There are 2 X zones (0.2%) between the house and the river. The help guide says "the line to the profile baseline cannot intersect any Zone X or C areas". If I follow perpendicular to the flow (parallel with squiggly lines), it will intersect Zone X. Also, one cross section line downstream extends past the property, but the upstream cross section stops way towards the river.
I think I'll try a combination of proportioning between the cross sections, drawing a line perpendicular to the flow to the profile line and getting the BFE from the flood profile, and proportioning between the squiggly lines. Then pick the highest and see if the building is out.
Tyler Parsons, post: 382001, member: 139 wrote: Does anyone have a good reference for determination of BFE from the FIS, which I understand FEMA likes to see for LOMAs etc? The panels are driving me nuts.
In the area I am working is about 3/4 mile from a major river and between 2 cross sections, D and E about a mile apart, although one cross section only goes partway to the site. The Floodway Data shows a regulatory elevation of 199.3 ft at cross section D, downstream from my site. I assume that on the FIRM, this is the cross section line (of common elevation) depicted. I look at the Flood Profile, cross section D and come up with 199.0 ft. Not too bad.
Section E regulatory floodway data shows 201.1 ft. The flood profile crosses at 200.5 ft, definitely half way between 200 and 201 ft. However, the cross section E ends about 1/4 mile towards the river at some higher elevation (500 year flood) and I'm left with the squiggly lines at 1 foot elevations intervals in the site area. The State FEMA Coordinator says FEMA doesn't like to see these used as the basis for a BFE or LOMA.
Someone else is doing the LOMA (they missed the property being in the SFHA and have agreed to "fix it"). We'e definitely out of the Floodway.
Solutions for the BFE, anticipating a LOMA?
1. Project the site location parallel with the squiggly lines to the river and determine the river mile, then use the flood profile?
2. Project the site perpendicular to the base profile? The river curves significantly and the projection will cross the 200 foot elevation squiggle.
3. Interpolate between the squiggly lines to get the BFE?Thanks.
Step 1: Discuss with local flood plain administrator.
