{"id":525,"date":"2024-12-05T10:04:38","date_gmt":"2024-12-05T10:04:38","guid":{"rendered":"https:\/\/southwest-environmental.co.uk\/blog\/?p=525"},"modified":"2024-12-05T10:04:38","modified_gmt":"2024-12-05T10:04:38","slug":"incorrect-flood-zone-3b-on-flood-mapping","status":"publish","type":"post","link":"https:\/\/southwest-environmental.co.uk\/blog\/2024\/12\/05\/incorrect-flood-zone-3b-on-flood-mapping\/","title":{"rendered":"Incorrect Flood Zone 3b on Flood Mapping"},"content":{"rendered":"

Incorrect Flood Zone 3b on Flood Mapping<\/h1>\n

This is about as niche as it gets . . . . but here we go!<\/p>\n

We have recently seen a couple of examples where Cornwall Council’s flood mapping<\/a> (which is different to flood map for planning<\/a>) gives some very strange results for Flood Zone 3b.<\/p>\n

How Flood Zones Normally Appear<\/h2>\n

Perhaps the most familiar flood mapping for those “in the trade” is the flood map for planning. Typically we see the darker blue (more often flooding)\u00a0 Flood Zone 3, fringed with lighter blue (less often flooding) Flood Zone 2.<\/p>\n

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Screen shot from flood map for planning.<\/p><\/div>\n

In flood mapping it is always the cases that a “more often” flood outline (shaded area) never go outside of the “less often” flood outline. Look:<\/p>\n

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Flood Zones from Some Older Mapping<\/p><\/div>\n

In the above slide the dark blue areas do not extend beyond the light blue areas. They can extend up to the edge, but not beyond.<\/p>\n

Flood Zone 3b on Cornwall Council Flood Mapping<\/h1>\n

So when we first saw the mapping from Cornwall Councils’ own mapping service below we knew something was wrong with it. Apart from the strange colour scheme, you can see Flood Zone 3b Extends well beyond Flood Zones 2 and Flood Zone 3a.<\/p>\n

So there is something wrong with the modelling of Flood Zone 3b at this site.<\/p>\n

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Incorrect Flood Zone 3b – Cornwall Mapping<\/p><\/div>\n

The image below shows the beginning of our investigations in to the error. We made a detailed study of elevations in the vicinity for starters and then wrote a report to explain why the site in this instance should not be included in Flood Zone 3b.<\/p>\n

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Detailed Contour Zones on Google Satellite Images<\/p><\/div>\n

And we are happy to say that the argument we politely put forward worked well, and the permissions was granted.<\/p>\n

If you have issues with a site that appears to be included in FLood Zone 3b, when maybe you think it shouldn’t be then please do contact us<\/a> and we will be glad to help. We can deal with this issue as part of a flood risk assessment<\/a> or as a bolt on.<\/p>\n

We have seen strange behaviour like this in Cornwall Council’s flood mapping, and also in Bristol City Council’s Flood Mapping.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Incorrect Flood Zone 3b on Flood Mapping This is about as niche as it gets . . . . but here we go! We have recently seen a couple of examples where Cornwall Council’s flood mapping (which is different to flood map for planning) gives some very strange results for Flood Zone 3b. How Flood […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10,9],"tags":[95,106],"class_list":["post-525","post","type-post","status-publish","format-standard","hentry","category-flood-risk","category-flood-risk-assessment","tag-flood-risk","tag-flood-zones"],"_links":{"self":[{"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/posts\/525","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=525"}],"version-history":[{"count":1,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/posts\/525\/revisions"}],"predecessor-version":[{"id":530,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/posts\/525\/revisions\/530"}],"wp:attachment":[{"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=525"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/southwest-environmental.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}