CASE STUDY CLIFF EROSION PICTURED FROM THE SKIES Last month, a small drone flew in the skies on behalf of East Devon District Council to photograph Sidmouth* beach and cliffs to provide evidence of coastal erosion for its Beach Management Plan Project. The drone – weighing just ½ kg and fitted with a compact computer and camera – flew for 45 minute periods at speeds of around 45 km/h, surveying 3 km of the coast over two days. On each programmed flight, the drone captured 250 high-resolution images of the beach and cliffs taken at different angles. The 1500 photographs that were taken have been 'stitched' together electronically to produce a detailed contour survey of the coast, which can be used to see and measure changes to the coastline. The drone was capable of avoiding aggressive seagulls and was fitted with a wind sensor, which tells it to come home if the weather gets too bad. Mark Elliott, assistant Project Manager, said: "Existing photogrammetric aerial imagery of the coastline is for 1946, 1950, 1988, 2006, 2009 and 2012. We decided it was important to update our data with this survey and fill in the gaps with other information, so we have the best possible evidence of how the beach and cliffs have changed over time". The Beach Management Plan will look at maintaining and improving the town’s costal defences in the long-term. Sidmouth Clifs *Sidmouth (Devon, UK) is a beautiful coastal town which lies on the Jurassic Coast (World Heritage site) whose coastline is dominated by the vivid red sandstone cliffs which date back to the Triassic period. 10. Answer the following questions. What was the goal of the aerial surveying over Sidmouth? What were the technical features of the drone? How long did each flight last and what speed did the drone fly at? What kind of images did the drone capture? How have the images taken by the drone been used? What was the drone fitted with? When were previous surveys of the coastline made? Why was this survey so important, according to Mark Elliott? What was the final result of the survey? What is the future purpose of the plan?