Introduction

The North Norfolk village of Happisburgh lies one of the fastest eroding coastlines in the UK and indeed the world with historic records indicating an average erosion rate of 1m per annum since at least 1600 (British Geological Survey, no date). About 1400 people live in the 600 houses in the village.

The challenge is to visualize coastal retreat through time and its impact on the village.

Coastal retreat at Happisburgh has been visualized in several ways.

1. As a set of small multiples.
2. Cliff lines from historical maps.
3. A 3D composite rendering.

Small multiples

Small multiples are a simple way of revealing change in space and time. Each slice shows state at a particular time with digitized cliff lines of all times overlain for comparison.

Cliff Retreat 1886 – 2012

Cliff Retreat 1886 – 2012 attempts to communicate change on a single map.

Historic cliff lines (top of coastal slope) were obtained from three sources:

1. 1886, 1906, 1938, and 1970 digitised from 1:2500 scale OS general purpose maps.
2. 1800 and 1700 cliff lines are interpolated from the 1886 cliff line with an erosion rate of 1m/year retreat.
3. 1999 and later cliff lines are digitised from Environment Agency LIDAR models .

‘Observed’ cliff lines are solid, and ‘estimated’ lines dashed. Retreat between observed coastlines is displayed as a semi-transparent brown fill lightening with increasing age with the intention of evoking a vertical geological section or seismic profile. Retreat is displayed over a ‘time-composite’ of OS basemaps of different ages:

1. The 2017 basmap is displayed inland of the 2017 cliffline.
2. The 1970 basemap is displayed between the 1970 and 2017 coastlines.
3. The 1938 basemap is displayed between the 1938 and 1970 coastlines.
4. The 1876 basmap displayed is seaward of the 1938 coastline.

The change from the most recent colour base map in colour (2017) to black and white historic maps is clear but the transition between 1938 and 1970 map is less effective as the transition is less distinct between pairs of black and white basemaps. One of these might be removed.

The Ghost of Happisburgh

The Ghost of Happisburgh is a 3D visualisation of change between 1930 and 2022 that aims to communicate the human loss by focusing of the streets and houses lost rather than physical change.

A 2020 25-cm resolution aerial photograph is overlain onto a 2022 1-meter resolution LIDAR DTM. The 1930 OS basemap is clipped to the 2022 cliff line to reveal the ‘ghost’ of past streets and buildings. Modern buildings are 3D models created from the LIDAR point cloud and OS building outlines.