 |
by
Joseph Young
Maine Floodplain Mapping Cordinator
Map Courtesy of Dan Walters NSDI Liaison, USGS
FEMA is considering the acquisition of LiDAR high resolution topography for about 20 square miles of the Fish River watershed.
More severe flooding occurred along the
downstream end of the Fish River than was expected given the existing values for the
base flood elevation (BFE) depicted on the Flood Insurance Rate Map (FIRM) for Fort Kent. There appears to be a hydraulic grade existing
at high flows near the downstream end of the Fish
River when the Saint
John River is at a high elevation at the confluence of the two
rivers. It is expected that high flows in the Fish River, combined with
a high water level in the St. John River, will produce a peak water surface
elevation for the one-percent chance annual flood at the downstream end of
the Fish River that is greater than the BFE depicted on the Fort Kent FIRM.
No current, detailed topographic mapping was
located for Fort Kent
in the vicinity of the downtown area, including all of Main Street on the landward side of the
levee, and including all land area at the downstream end of the Fish River
that was affected by flooding during the April 2008 event. Detailed topographic mapping is critical for correctly mapping the updated BFEs.
If you have any comments or would like to encourage FEMA to follow though with this study please contact David Knowles at 617-956-7570 or by e-mail. |
Remember This?
Do we have any grey beards who can identify this location?
We will publish the location in our next newsletter along with the names of anyone who can identify it.If you have any flooding pictures you would like to contribute to our archives please send them along either by e-mail or regular parcel post to: Joseph Young
Maine State Planning Office
184 State St.
38 State House Station
Augusta, ME 04333-0038.
We can scan the images and return your originals.
|
|
|
|
Courtesy of Oregon LiDAR Consortium and USDA Forest Service
National LiDAR Meeting
The Second National LiDAR Meeting was hosted by the USGS on May 21 and 22 of this year.
Ian Madin of the Oregon LiDAR Consortium gave a presentation explaining Oregon's approach of spending more money for higher resolution imagery in key sections of the state rather than doing the whole state with lower resolution. The above image shows the difference between point cloud returns of 8pts/m2 on the left and 2.5pts/m2 on the right.
Bob Brinkman from Ohio gave a presentation on Ohio's quest for Statewide collection of data. It is nearly complete and after a brief interruption is back on track to be completed within the next year or so. One of the largest beneficiaries of the statewide collection of data has been the Ohio Department of Transportation (ODOT). ODOT is using LiDAR information to reduce and sometimes eliminate traditional project preparation processes thereby substantially reducing planning costs. LiDAR is also being used for predictive landslide modeling, road crash analysis and improved planning and engineering studies.
Both of these presentations and nearly thirty others are available online. Many of them include both power point and audio of the speakers comments and are available for downloading. The effect of having both audio and power point available is almost as good as being there. It is worth a visit to the website just to see the range of information covered. (High Speed Internet service is a must for this the files are very large)
|
Floodplain Managers Corner
by: Sue Baker, CFM
Maine Floodplain Coordinator
What to do when you are stuck in the "Flood Zone"
The Federal
Emergency Management Agency (FEMA) has studied and mapped the floodplains of
the United States
and delineated them as 'Special Flood Hazard Areas' (commonly called 100-year
floodplains) on county/community Flood Insurance Rate Maps (FIRMs). In Maine,
these maps are published for each separate city and town except in areas where
FEMA deemed there was not enough risk or development to warrant the cost of
mapping. The maps, which show roads,
water bodies, and the shaded floodplains zones, are used by the local officials
of communities that participate in the National Flood Insurance Program for
land use and permitting purposes. They
are also used by lenders for making map determinations, and by insurance agents
for rating flood insurance policies.
Most FIRMs are based on a detailed flood study, however, there are a
number of Maine
communities where full studies have not been completed, and less technical data
has been used to map the floodplains.
The FIRMs are reasonably successful in showing the areas determined to
be within the 100-year floodplain, sometimes however, they contain inadvertent
errors. This is often caused by the lack
of availability of a highly detailed base map, map scale, and changes to the
landscape, not necessarily by the lack of quality of the actual flood
data. As with any mapping process,
occasionally there are errors. FEMA recognizes
this potential and has developed a process to deal with this issue.
The Flood Disaster
Protection Act of 1973 and the 1994 Reform Act made flood insurance mandatory
as a condition of a loan on any structure located within a 100-year
floodplain. The lender is responsible
for making a flood map determination on every loan for improved real estate
(unless the original loan balance is $5,000 or less and has a repayment term of
less than one year). Most lenders
contract with a private company to complete these determinations. Most of the companies are very large national
firms that do vast numbers of these determinations quickly, cheaply, and
without the benefit of local knowledge, i.e., information about where the
structure sits on the lot. The lenders
and map determination companies must use the current FEMA flood map and make a
purely horizontal determination on whether the structure is in, or out of the
mapped floodplain. (For the purpose of these determinations, ground and
house elevations at the site may not be taken into consideration.) The findings of these determinations are
sometimes not shared with the borrower until just days or hours before the
closing. Often, people are surprised to
learn that their property is in a flood zone and that they must purchase a
separate flood insurance policy before they can close and continue that
coverage for the term of the loan.
OK Fine!! I'm in the Flood Zone, but how do I get
No way, I'm not in a flood zone! How do I handle an inaccurate map
We
encourage the public and other professionals to seek assistance if they
question the flood hazard determination for their property. The staff of the Maine Floodplain Management
Program is available for providing information and resources regarding these
mapping and determination issues.
Please check out
our website for a wealth of information and links. The web site is very comprehensive and ever
changing. It contains a multitude of
data, forms, publications, and links to such things as: FEMA Forms (Elevation Certificate
and LOMA/LOMRs); Best Available Data; View and Print Flood Maps; Development in Approximate 'A' Zones; The Maine Floodplain Management Handbook; and a whole
lot more.
Visit
us at: www.maine.gov/spo/floodContact Sue Baker at 207-287-8063 or by email
|
|
(Caution large 5mb file)
Preliminary DFIRMS Issued for Kennebec County
by Joseph Young, Mapping Coordinator
Maine Floodplain Mapping Program
CDM floodplain mapping contractor for FEMA has completed and delivered the Kennebec County Flood Insurance Study and printed copies of the the preliminary digital flood insurance rate maps. If your community has not received it yet please contact us so that we can make sure they are delivered. They were mailed to the chief elected official in each Kennebec County community.
Local officials and citizens should review the maps for accuracy and make note of any errors. If you believe that the floodplains are not accurately portrayed and have technical supporting data that should be included in the flood study please contact either Tim Hillier at |
(Caution large 5 MB file)
Mapping Costs
by Joseph Young, Mapping Coordinator
Maine Floodplain Mapping Program
The process of creating completely new Floodplain maps is incredibly costly, time consuming and complex. Google Earth and other similar programs lure you into the impression that it is mere childs play to create simple easy to use maps.
Creating new digital floodplain maps is neither simple or easy. Even the shortened process of upgrading existing floodplain maps to overlay new ortho-photo base maps is an expensive time consuming process that requires a significant amount of time and effort. Even with the increased funding FEMA has received for upgrading the nations floodplain maps it is insufficient to correct all the known shortcomings.
This process requires building new maps with several layers of information and integrating huge databases of supporting documentation. Each layer must be registered to the new base map and go through a rigorous quality analysis and control process to ensure that the databases have been accurately compiled, before it is stored on the FEMA mapping information platform. In addition because the various layers of information are mapped at different scales each layer must be electronically manipulated to fit as closely as possible to the base map.
Just this relatively simple process will cost over $2,000 per floodplain panel and in Maine with over 1800 map panels the total cost of just converting to digital be over 3.5 million dollars. This does not include any additional funding for new topography, hydraulic, hydrological analysis or re-delineation of floodplain boundaries. Early estimates of costs for new high resolution topographical data come in at approximately 5 million dollars and completing new hydrological and hydraulic data to cover areas that have been mapped with only approximate studies have not been estimated with any degree of accuracy but would undoubtedly run into the millions of dollars also.
Sadly until we can obtain high resolution topography more accurate floodplain maps will be hard to come by.
If you would like to learn more about estimating mapping values FEMA publishes a Blue Book that establishes values of products provided by out side agencies that can be used in developing floodplain maps.
|
Chances Are.....
Contributed by: Robert Archilla,
Regional Manager,
Computer Sciences Corporation.
Bob can be reached at (781) 848-1908 or by email
Flooding is the most common natural disaster in America yet
homeowners insurance does not cover flood damage. Truth is, you can live miles away from water and
still be a victim of flooding. In fact,
nearly 1 in 4 flood insurance claims are paid on policies in
low-to-moderate-risk areas.
Where bodies of water have been studied as the source of high
flooding risk, the average chances of experiencing a flood over various time
periods is shown on the table below.
Bottom line, if your home is in a Special Flood Hazard Area
it has, on average, a 26% chance of being damaged by a flood over the life of a
30-year mortgage but only a 4% chance of having a fire during the same period. The closer and longer you live to the source
of flooding the higher above the average chances that you will experience a
damaging flood. To find your
flood risk visit FloodSmart.gov the official site of the National Flood Insurance Program.
This article was sugested by Richard St. John, CEO from Otisfield
|
Quote of the Day
"Never test the
depth of the water with both feet."
|
Newsletter Funding
This newsletter is funded with a grant provided by the Federal Emergency
Management Agency (FEMA)
EMB-2007-CA-0874
|
|
|
|
|
