Tuesday 10 August 2021

"With a little help from my friends", Part II

New how-to 

Part I showed how a map of DEFRA open data can help situational awareness for a West Midlands XR event. Having done a sea level rise and risk of flooding map for the Thames River valley near London last year, I redid one now with the lessons learned in the interval. The previous Sea Level Rise map from Open Data was rather onerous: I streamlined the process to simply load free & open data with only GIS styling; the resulting Build your own can be replicated on other GIS with listed data sources.

A few display tricks are used in Esri, the resulting maps are pleasing and you can access web maps from the end of the notes:

(original map at left, new rendition at right) click to enlarge

Great London Area

As before DEFRA 10 m. resolution elevation data is amply sufficient for this. There are some gaps in the data, which is focused on river courses and thus don't impede our display of encroaching flood risk or sea level rise. The trick is to leave below-sea-level clear so that no data also shows transparent.

While I modelled in the first manual and my last post on East Anglia flood defenses using sea level rise with incremental elevations and timelines acc. to scientific consensus, I simply modelled here the DEFRA elevation at the same incremental cut-offs: it's a mapmaking shortcut that mirrors the model that's a whole lot easier for citizen scientists to carry out.

DEFRA Risk of Flooding from River and Sea is simply added as a web mapping service. Its advantage is that as their ground mapping and risk assessments change, they're reflected on the web maps directly.

Catchment Area

After posting the area within the M25 orbital extending beyond the Thames Barrier, I was asked: "How about the Thames River catchment area?". Well I found two answers from DEFRA and EUROPA.

DEFRA Water Body Catchment Cycles (download) delineate the catchment areas, which I aggregated into the Thames River one. EEA Integrated Data Platform (web service) displays European river network, incl. the UK in the EU when the project was carried on based on Copernicus satellite imagery.

(DEFRA at left + EEA at right) click to enlarge

You can see that the sea level rise for the entire catchment area only affects the Greater London Area, which makes sense but had to be seen on a map. That in turn helped improve the GLA map somewhat:

(DEFRA at left + EEA at right) click to enlarge

See the web map with printing and the lighter web app or the data sources.


The upshot of this whole story, is user-driven requests to document sea level rise and risk of flooding not only in my home area of East Anglia, but also for other XR actions in London and West Midlands. That was also  driven by lessons learned in the interval, which helped simplify the playbook. And last but not least, further request on a broader ecological context were easily met with the new learnings. And all this is very à-propos...

The IPCC Report released just yesterday stated the following here (underline mine):

GENEVA, Aug 9 – Scientists are observing changes in the Earth’s climate in every region and across the whole climate system, according to the latest Intergovernmental Panel on Climate Change (IPCC) Report, released today. Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years.

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