In response to the storms which hit the River Mole in winter 2013/14, we were employed by Royal Haskoning DHV, on behalf of the Environment Agency, to conduct a range of low level aerial surveys of the area. The purpose of this was to locate and identify any issues in the channel, particularly those which could negate flood risk management, such as significant build-up of debris or damage to the river bank.
For these surveys, we collected HD video, 360° video and photogrammetric elevation models. UAVs were particularly suited to this job for three main reasons.
- Firstly, the low levels which UAVs can fly at means they can capture very high resolution aerial imagery, translating into incredibly detailed and accurate elevation models.
- Secondly, UAVs can conduct surveys far more quickly than those being undertaken on the ground. This was crucial for project as the survey had to be undertaken whilst the level of the river was dropped,which could only be done for a limited amount of time due to the river’s fish population.
- Thirdly, the vast majority the river channel was not visible from the ground due to steep banks which were largely inaccessible. The use of a UAV allowed for an unobstructed view of the entire river channel without requiring personnel to actually climb into the channel, potentially putting them at risk.