[Code of Federal Regulations]

[Title 44, Volume 1]

[Revised as of October 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 44CFR65.13]



[Page 351-352]

 

              TITLE 44--EMERGENCY MANAGEMENT AND ASSISTANCE

 

 CHAPTER I--FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND 

                                SECURITY

 

PART 65_IDENTIFICATION AND MAPPING OF SPECIAL HAZARD AREAS--

able of Contents

 

Sec.  65.13  Mapping and map revisions for areas subject to alluvial fan flooding.



    This section describes the procedures to be followed and the types 

of information FEMA needs to recognize on a NFIP map that a structural 

flood control measure provides protection from the base flood in an area 

subject to alluvial fan flooding. This information must be supplied to 

FEMA by the community or other party seeking recognition of such a flood 

control measure at the time a flood risk study or restudy is conducted, 

when a map revision under the provisions of part 65 of this subchapter 

is sought, and upon request by the Administrator during the review of 

previously recognized flood control measures. The FEMA review will be 

for the sole purpose of establishing appropriate risk zone 

determinations for NFIP maps and shall not constitute a determination by 

FEMA as to how the flood control measure will perform in a flood event.

    (a) The applicable provisions of Sec.  Sec.  65.2, 65.3, 65.4, 65.6, 

65.8 and 65.10 shall also apply to FIRM revisions involving alluvial fan 

flooding.

    (b) The provisions of Sec.  65.5 regarding map revisions based on 

fill and the provisions of part 70 of this chapter shall not apply to 

FIRM revisions involving alluvial fan flooding. In general, elevations 

of a parcel of land or a structure by fill or other means, will not 

serve as a basis for removing areas subject to alluvial fan flooding 

from an area of special food hazards.

    (c) FEMA will credit on NFIP maps only major structural flood 

control measures whose design and construction are supported by sound 

engineering analyses which demonstrate that the measures will 

effectively eliminate alluvial fan flood hazards from the area



[[Page 352]]



protected by such measures. The provided analyses must include, but are 

not necessarily limited to, the following:

    (1) Engineering analyses that quantify the discharges and volumes of 

water, debris, and sediment movement associated with the flood that has 

a one-percent probability of being exceeded in any year at the apex 

under current watershed conditions and under potential adverse 

conditions (e.g., deforestation of the watershed by fire). The potential 

for debris flow and sediment movement must be assessed using an 

engineering method acceptable to FEMA. The assessment should consider 

the characteristics and availability of sediment in the drainage basin 

above the apex and on the alluvial fan.

    (2) Engineering analyses showing that the measures will accommodate 

the estimated peak discharges and volumes of water, debris, and 

sediment, as determined in accordance with paragraph (c)(1) of this 

section, and will withstand the associated hydrodynamic and hydrostatic 

forces.

    (3) Engineering analyses showing that the measures have been 

designed to withstand the potential erosion and scour associated with 

estimated discharges.

    (4) Engineering analyses or evidence showing that the measures will 

provide protection from hazards associated with the possible relocation 

of flow paths from other parts of the fan.

    (5) Engineering analyses that assess the effect of the project on 

flood hazards, including depth and velocity of floodwaters and scour and 

sediment deposition, on other areas of the fan.

    (6) Engineering analyses demonstrating that flooding from scources 

other than the fan apex, including local runoff, is either insignificant 

or has been accounted for in the design.

    (d) Coordination. FEMA will recognize measures that are adequately 

designed and constructed, provided that: evidence is submitted to show 

that the impact of the measures on flood hazards in all areas of the fan 

(including those not protected by the flood control measures), and the 

design and maintenance requirements of the measures, were reviewed and 

approved by the impacted communities, and also by State and local 

agencies that have jurisdiction over flood control activities.

    (e) Operation and maintenance plans and criteria. The requirements 

for operation and maintenance of flood control measures on areas subject 

to alluvial fan flooding shall be those specified under Sec.  65.10, 

paragraphs (c) and (d), when applicable.

    (f) Certification requirements. Data submitted to support that a 

given flood control measure complies with the requirements set forth in 

paragraphs (c) (1) through (6) of this section must be certified by a 

registered professional engineer. Also, certified as-built plans of the 

flood control measures must be submitted. Certifications are subject to 

the definition given at Sec.  65.2.



(Approved by the Office of Management and Budget under control number 

3067-0147)



[54 FR 33551, Aug. 15, 1989]