Ladd, C.J.T.; Duggan-Edwards, M.F.; Bouma, T.J.; Pagès, J.F.; Skov, M.W.

Change in saltmarsh extent for six regions across Great Britain (1846-2016)

Data are presented showing change in saltmarsh extent along 25 estuaries/embayments in 6 regions across Great Britain, between 1846 and 2016. Data were captured from maps and aerial photographs. Marsh extent was delineated a scale of 1:7,500 by placing vertices every 5 m along the marsh edge. Error introduced from: (i) inaccuracies in the basemap used to georeference maps and aerial photographs; (ii) the georeferencing procedure itself; (iii) the interpreter when placing vertices on the marsh edge; and (iv) map and photo distortions that occurred prior to digitisation were calculated and used to estimate the root mean square error (RMSE) in areal extent of each marsh complex. Measures of marsh extent were only recorded if maps and aerial photographs were available for the entire estuary/embayment. Data was collected as part of a study on the large-scale, long-term trends and causes of lateral saltmarsh change. The data was used in the analysis for Ladd et al. (2019). C. Ladd and M.F. Duggan-Edwards carried out the collection and processing of the saltmarsh extent data. All authors contributed to the interpretation of the data. The work was carried out under the NERC programme - Carbon Storage in Intertidal Environment (C-SIDE), NERC grant reference NE/R010846/1.

Publication date: 2019-09-18

Get the data

This dataset is available under the terms of the Open Government Licence

Format of the dataset : Shapefile

You must cite: Ladd, C.J.T.; Duggan-Edwards, M.F.; Bouma, T.J.; Pagès, J.F.; Skov, M.W. (2019). Change in saltmarsh extent for six regions across Great Britain (1846-2016). NERC Environmental Information Data Centre. https://doi.org/10.5285/03b62fd0-41e2-4355-9a06-1697117f0717

 

© Bangor University

© Royal Netherlands Institute for Sea Research

© Centre d’Estudis Avançats de Blanes

Where/When

Study area
Temporal extent
1846-06-01    to    2016-05-26

Provenance & quality

The aerial extent change in saltmarsh extent across Great Britain came into existence by using Ordnance Survey (OS) maps and aerial photographs to delineate marsh extent for each estuary.. Marsh extent was delineated in ArcGIS 10.6 at a scale of 1:7,500 by placing vertices every 5 m along the marsh edge. A Root Mean Square Error (RMSE) term (in meters) was calculated for each marsh complex by assessing error introduced by: (i) inaccuracies in the basemap used to georeference maps and aerial photographs; (ii) the georeferencing procedure itself; (iii) the interpreter when placing vertices on the marsh edge; and (iv) map and photo distortions that occurred prior to digitisation. To qualitatively assess whether the vectorised layer could be considered accurate, the most recent digitised marsh extent was compared against national marsh extent layers to ensure general agreement. Literature searches were also done to verify whether observations of significant change in marsh extent were reliable, or whether errors introduced by map surveyors on the location of the marsh edge likely explain the differences.
Data were exported from ArcGIS as a shapefile for ingestion into the Environmental Information Data Centre.

Correspondence/contact details

Ladd, C.J.T.
Bangor University
 c.ladd@bangor.ac.uk

Authors

Ladd, C.J.T.
Bangor University
Duggan-Edwards, M.F.
Bangor University
Bouma, T.J.
Royal Netherlands Institute for Sea Research
Pagès, J.F.
Centre d’Estudis Avançats de Blanes
Skov, M.W.
Bangor University

Other contacts

Custodian
Environmental Information Data Centre
 eidc@ceh.ac.uk
Publisher
NERC Environmental Information Data Centre
 eidc@ceh.ac.uk

Additional metadata

Topic categories
Biota , Environment
Keywords
areal extent,  Historical,  Saltmarsh,  Salt Marsh
INSPIRE Theme
Habitats and Biotopes
Funding
Natural Environment Research Council Award: NE/R010846/1
Spatial representation type
Vector
Spatial reference system
OSGB 1936 / British National Grid
Last updated
2019-09-18