Colleagues-
I would appreciate your experiential comments on this:
We do have Regulatory Flood Elevation Contours in certain Conservation Authorities but it is not universal in Ontario.
There are some areas where there are questionable contours too.
Is the mapping and processing of flood zone certification an area only open to professional USA surveyors ?
Is it a viable enterprise ?
What are the pitfalls other than the impression that the certification is very minimal in cost ?
I understand in Canada there is a rejigging of the bench mark system that will affect/change elevations thereof.
Thank you,
Derek
Derek, it sounds as though the system is considerably different in Canada, so comparisons may not be meaningful.
It's not surprising to hear that private-sector insurers in Canada don't want to write flood insurance without much better maps than are now available. In the US, private insurors have never been willing to write flood insurance at all, whether with good maps, poor maps or no maps. All flood insurance comes from FEMA, a Federal agency, and they also prepare all the maps.
Surveyors in the US mainly deal with elevation certificates and with applications for map changes. An elevation certificate is typically used to show that the critical parts of a building are above the established flood elevation, thus enabling the building to qualify for a lower flood-insurance rate. I have only done a few of these, but from postings on this board it appears they are a streamlined, low-budget product and not very profitable.
Map-change applications, showing that the official flood map needs to be changed with regard to a particular building or site, are more individualized and more complex, and thus somewhat more profitable.
Flood mapping is, of course, necessarily done by government due to its cost. As you no doubt are aware, topography of the entire watershed is combined with statistics about rainfall and snow-melt, and hydrologic formulas are used to calculate how much water will turn up at a given location, and how often.
The original FEMA flood maps, in the 1970s and 1980s, were prepared based on photogrammetric maps, and the hydrologic calculations were no doubt done using hand drafting, mechanical calculators, and such early computers as were then available. They are gradually being upgraded, although the process is very slow. LIDAR topos are beginning to be used, and of course computers are much more powerful. But the limitations of the remaining early maps continue to require work by surveyors in preparing map-change applications, and elevation certificates are needed for many new buildings.
I'm sure that Canadian property owners would benefit from a national (or provincial) system of flood maps and flood insurance if government decided to create one. Most likely they would use LIDAR, and there would be some work for surveyors in processing that data. There would be a good deal of work for hydrologists, computer modelers, and CAD technicians.
The datum change you mention shouldn't cause any trouble, except on paper. The numbers might change, but the physical, on-the-ground elevations of structures and the calculated flood would remain the same.