Form 086-0-27E Alluvial Fan Flooding Form

DEPARTMENT OF HOMELAND SECURITY
FEDERAL EMERGENCY MANAGEMENT AGENCY

O.M.B. NO. 1660-0016
Expires December 31, 2010

ALLUVIAL FAN FLOODING FORM

PAPERWORK BURDEN DISCLOSURE NOTICE
response. The burden estimate includes the time for reviewing instructions,
Public reporting burden for this form is estimated to average 1 hour
searching existing data sources, gathering and maintaining the
data, and completing, reviewing, and submitting the form.
You are not required to respond to this collection of information unless a valid OMB control number appears in the upper right corner of this form.
Send comments regarding the accuracy of the burden estimate and any suggestions for reducing this burden to: Information Collections
Management, Department of Homeland Security, Federal Emergency Management Agency, 500 C Street, SW, Washington, DC. 20472, Paperwork
Reduction Project (1660-0016). Submission of the form is required to obtain or retain benefits under the National Flood Insurance Program. Please
do not send your completed survey to the above address,
Flooding Source: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Note Fill out one form for each flooding source studied.
A. THREE-STAGE ANALYSIS (Based on FEMA Guidelines dated February 23, 2000)
1.~~

a. The landform is composed of (check one)

alluvial

debris flow deposits

b. Source of data used to determine composition, morphology, and location of the landform:

Yes

c. Is there an NRCS soils survey and soil survey map available?

No

If Yes, please include a copy of the map and any pertinent sections of the soil survey
2. Stage 2 Analysis

a. The alluvial fan exhibits

active

inactive

b. Approximate age of inactive fan surfaces (thousands of years):

a combination of active and inactive alluvial fan flooding
_____yrs

c. Is there an opportunity for avulsions that could lead channels or sheetfloods across the older fan surfaces?
d. Is there evidence of headcutting that could lead to stream piracy?

Yes

No

e. Is there geomorphic evidence of past avulsions during the Holocene epoch?

Yes

No

Yes

D

No

f. The fan exhibits the following types of flooding (check one):
Flooding along stable channels

o Sheetflow
Debris flow
Unstable flow path flooding
3. Stage 3 Analysis
The boundaries of the 1%-annual-chance floodplain have been determined using (check one):
Risk-Based Analysis
FEMA Fan Program (if discharge at the apex is different than that given in the effective FIS, then attach MT-2, Form 2 along with a
area above the hydrographic apex, and the
plot of the flood frequency curve on long-normal probability paper and include the
mean, standard deviation, and skew coefficient of the curve)
Sheetflow Methods
Hydraulic Analytical Methods
Geomorphic Data, Post-Flood Hazard Verification, and Historical Information
Composite Methods

DHSIFEMA Form

AUG 2010

PREVIOUSLY FF81-89

MT·2 Form 6

Page 1 of 2

B. STRUCTURAL FLOOD CONTROL MEASURES

1. The following structural flood centrol measures are proposed or built (check one):
D

channelization

D

Levee/Floodwall

D

Dam

D

Sedimentation

2. Do the constructed or proposed structural measures affect flood hazards (including velocity, sceur, and sediment deposition), on other areas of
the fan?
DYes
No

D

3. Attach completed Form 3 (Riverine Structures Form)
4. Sediment Transport Considerations:
Was sediment transport considered?

DYes

D

No

If Yes, then fill out Form 3, Section F (Sediment Transport) . If No, then attach your explanation for why sediment transport was not
considered .

5. Please attach a copy of the formal Operations and Maintenance Plan .

C. MAPPING REQUIREMENTS
Attach a certified topographic work map showing the following :
- The boundaries of the alluvial fan including: toe , topographic and hydrologic apexes, and lateral boundaries
- The delineation of the active and inactive portions of the fan as determined by the Stage 2 Analysis
- The rev ised 1%-annual-chance floodplain boundaries , as determined by the Stage 3 Analysis, that tie into the effective floodplain
boundaries
- The correct alignment of all structural features
- The map scale

DHS/FEMA Form 086-0-27E, AUG 2010

PREVIOUSLY FF 81-89E

MT-2 Form 6

Page 20f 2