A Case Study on Long-Term Erosion Mapping in Northeast England

In the UK alone, the British Geological Survey states that across England and Wales 113 000 residential properties, 9000 commercial properties and 5000 hectares of agricultural land are within areas potentially at risk of coastal erosion.

Mitigating the effects of climate change requires coastal protection studies and coastal protection measures. As every planner knows, though, this increases the burden of allocating ever-reducing financial resources.

Accurate studies of the changes, gleaned from historical studies, combined with best practice from current studies and environmental factors allow the most effective and efficient decisions to be taken in coastal protection anywhere in the world.

Drones or Unmanned Aerial Vehicles (UAVs) are a great asset for monitoring the stability of a coastline and for carrying out a rapid initial survey after a storm event.

UAVs can quickly survey potentially difficult and dangerous large sites with a very high level of detail.

Erosion monitoring, assessing cliff stability, monitoring coastal vegetation and changes in land volume or coastline state are only a few examples of the applications of UAVs in coastal areas.

QUESTUAV’S SPECIAL RELATION TO COASTAL APPLICATIONS

QuestUAV has always had a special interest in using drones for coastal applications. Our company is located in a port town in North-East England on the shore of the North Sea.

The environment here is harsh – wind and weather re-shapes the coast every day.

The conditions in which our UAVs have to perform are challenging, but have greatly helped create one of the most stable fixed-wing UAV platform on the market.

HIGH SPATIAL ACCURACY AND GIMBALLED SENSORS

QuestUAV airframe design and sensor gimbals ensure data quality even in turbulent conditions with wind speeds up to 65 km/h.

Latest PPK (Post Processing Kinematic) technology on board QuestUAV drones allows survey mapping of an area down to 2cm spatial accuracy without the need of Ground Control Points (GCPs).

GCPs are normally not easy to place along the cliffs and dunes of a coastline, so the use of our PPK technology makes surveying quicker and less expensive.

Our UAVs have been used for a variety of coastal surveys across the world, such as:

• Rapid pre- and post-storm assessment to quantify forecasted storm impacts
• Large industry environmental monitoring: nuclear power stations / mining sites
• Coastal property monitoring (insurance)
• Monitoring coastal sand digging activities (cement)
• Habitat monitoring / sea colour surveys
• Breakwater inspections
• Geological cliff and rock surveys / baseline surveys

QUESTUAV IS KEEPING AN EYE ON THE LOCAL COAST…

The Northumberland coastline is designated as an Area of Outstanding Natural Beauty (AONB) and conservation area due to its significant landscape and wildlife values.

QuestUAV started monitoring the local coast of Northumberland between Alnmouth and Cresswell back in 2008.

Since 2008 the local coast has been hit by two exceptionally strong flood events - one in November 2013 and one recently on the 13th of January 2017.

Immediately after the latest storm a QuestUAV crew flew the local coast, assessing the impact of the floods on the basis of the long-term image series. Our workflow involves a correlation of information from historic sources, satellite imagery and 3d-modelling.

We concentrated our survey on the less protected dune land, especially to see how much property owners have lost from erosion.

Our crew flew the site with a Q-200 PPK drone which has the great advantage of surveying an area with centimetre-level accuracy without the need for GCPs. The UAV provides images with a spatial resolution of 2.9cm at 400ft.

TIME-SERIES TO DETECT STORM IMPACTS

The time series shows that the latest flood changed the frontline of the dunes by 1 – 2 metres. Rocks and previous coastal erosion measures became exposed. Large volumes of sand and grass were removed and slumps occurred within hours of high tides.

Our calculations show that approximately 850 tonnes of dune and dunefoot was lost along an 80 metre stretch of coastline and the high water mark receded by up to 2.2 metres at the most critical point. The expected slumps that will happen as a result of erosion at the toe are expected to carry a further 300 tonne loss within 12 months.

To see the long-term development of the coastline we also included a flight from January 2013 in our analysis.

The good news is that the coastline recovers over time!

The storm event in November 2013 had comparable impact as the latest flood. Fortunately, sand, stones and organic matter deposits along existing structures and the coastline recovers over the years.

As long as the big storms do not increase in frequency, we do not see the local coast particularly endangered by coastal erosion. We will stay alert though.

SUMMARY
Climate change can cause unpredictable events and it is more important than ever to keep an eye on the development of the coastline.

Drones will continue to take an ever increasing role in the monitoring and assessment of coastal erosion and assist in effective decision making for local planners and environmental bodies.

QuestUAV endeavours to build drones which are able to fly in harsh and difficult environments. The conditions we have to test our UAVs in help us create the most stable fixed-wing UAV platform on the market.

Our drones are flown across the world and clients count on the stability of the system, especially in difficult conditions as it is often the case in coastal regions.

We also provide the workflows that allow accurate mapping and timely interpretation of processed results.