LiDAR is very accurate, high resolution data typically captured from an aircraft. Light sensors are used to measure the distance between the sensor, located on the aircraft, and the target ground surface beneath. The distance to the surface below is derived by measuring the time it takes for the emitted light to reach the earth’s surface and reflect back to the instruments on board the aircraft.
The aircraft flies at a height of about 800 metres above ground level allowing a swathe width of about 600 metres to be surveyed during a flight, although this depends on factors such as the density of data required and weather conditions.
Large amounts of data can be captured quickly and safely making the data capture cost-effective and ideal for use in areas which are difficult or dangerous to survey such as mudflats or cliffs. It’s ideal for use in areas such as the Severn Estuary where the large, intertidal mudflats are too hazardous to survey on foot.
The Programme will capture LiDAR data for the entire South West coast once every five years, with more vulnerable or high priority sites being surveyed in intermediate years. Data is 1m resolution, with the exception of our LiDAR data for Chesil Beach and the Isles of Scilly which are flown to 0.5m resolution. All data is captured over low tide on a spring tide to ensure the data meets mean low water springs level and captures as much of the coast as possible. Data generally extends inland ~100m and covers the majority of the estuaries in the South West. Data capture takes place over the winter months, when vegetation is at its lowest, to ensure as accurate a dataset as possible.
The only drawback to this type of data collection is that it’s weather dependent; the sensors can’t see through cloud. This means that it’s unsuitable for use where the timing of the survey is crucial, such as for surveys required immediately post-storm.