Author

Katja Haberland

Date

October 2007–April 2008

Project Type

Undergraduate dissertation

Subject

Geomatics

Datasets

OS County and National Grid Series

Sources: Historic Digimap; Aerial photography (from South Tyneside Council) for the period of 1999-2005

Dates/Editions: First Revision, First Revision, Third Revision, National Grid (NatSurvey)

Scales: 1:2,500

Related Subjects

Geomatics, GIS/Remote Sensing, Long-term Monitoring

Key Words

Geography; Aerial Photography

Publishing Institution

School of Civil Engineering and Geosciences, University of Newcastle upon Tyne

Summary

The project aims to measure coastal erosion rates at Marsden Bay, South Tyneside, Tyne and Wear, UK. The methodology has been chosen on the basis of previous studies in this or a similar study area. Marsden Bay consists of Magnesian Limestone, which is prone to erosion, especially on parts of the shore which are westwards-exposed. Mechanical wave erosion, wind and physical erosion are the main creators of the bizarre and unique shoreline. The focus is on estimating the coastal erosion rate by applying a remote sensing and GIS approach. The information on the shoreline was extracted from aerial imagery and historic map data and brought into a specially-designed GIS environment, which allows measurement of multi-temporal data simultaneously. Two different types of erosion rates were obtained, but the result used here, a major erosion rate of approximately 15 cm per year, underpins the general estimation for Marsden Bay.

Aims and Objectives

The main aim was to find out which changes can be recorded using different types of data - aerial imagery and historical maps. Additionally the quality of the maps and images was estimated due to the fact that these accuracy values are needed for the later calculations.

Methodology

After the data was collected it had to be processed and prepared for further analyses. The processing consisted of merging, georeferencing and digitising (digitising requires a huge amount of time and patience!).After these steps were successfully finished the digitised vector data (polyline) was brought into the GIS (ESRI ArcGIS 9.2) with a special extension called Digital Shoreline Analysis System (DSAS, provided by the USGS). The shorelines from all years were appended to one layer and a baseline, separately created and stored, and transects were calculated. The spacing and length of them need to be manually specified depending on the characteristics of the site. Due to the fact that the images and maps had been evaluated previously the accuracy was used in the calculations using linear weighted regression, i.e. less accurate data get a lower weight than high accuracy data with a low RMSE).

Results/Outcome

The results can be variously interpreted statistically, but the main differences of interest are those between oldest/youngest and closest/furthest shorelines. From these results annual average rates can be obtained. From these a maximum erosion rate of approximately 15 cm per year has been calculated.

References & Acknowledgements

Thanks to my supervisor for assistance, motivation and encouragement. Thanks also to the South Tyneside Council which supplied aerial imagery from 1999-2005.

Other Information

This graph shows the quality of the maps, taking control points from Digimap (OS MasterMap) to calculate the deviation from the real coordinates. The trend line shows the obvious trend that the older data is the less accurate it is (compared to present aerial photography), although the map from 1943 was very accurate.



There are major not correctable gaps and shifts. Re-georeferencing could help. Besides, there was a huge gap within one tile so that this map could not be used.