Getting to the right place at the right time to monitor coastal pollution isn’t always easy and innovative solutions to the problem need to be developed. A cost effective and time efficient aerial device has been purchased by our Marine Ecology section to help monitor nutrient run off, or diffuse pollution, at some of our estuaries.
Problems and solutions
The Marine Ecology section has been trialling the use of aerial imagery to help monitor nutrient run off from macroalgal (opportunistic seaweed) mats in various estuaries. The mats are an indicator of a disturbed ecosystem and could smother the natural habitat of fish and other animals that live in the estuary, taking away a food source for birds. The mats are one indicator that we use to monitor the water quality status of estuaries under the Water Framework Directive and other legislation.
We usually carry out surveys at low tide by walking onto mud flats, but some areas are too dangerous to be accessed on foot, such as the middle of Montrose Basin and some areas of the Eden estuary at St Andrews. This is where aerial imagery is essential; unfortunately traditional aerial imagery is not reliable enough. Combining low tides with good weather is not always easy in summer either, with no imagery taken in 2010 due to the poor conditions. This is why we decided to purchase our own unmanned aerial vehicle (UAV). The UAV will allow us to obtain our own digital images. It will give us greater flexibility, letting us take advantage of small good weather windows quickly. It will also capture the detail we need to monitor the environment.
Traditional aerial imagery combined with hand held global positioning system (GPS) technology has already transformed our surveys. Now we do not have to physically walk around the weed mats using handheld GPS to monitor them, as the weed mat extent can be digitised from the aerial imagery. We have also been able to plan our surveys more accurately. All this saves time and money, as we’ve been able to reduce the surveys from five days to two days, with a minimum of two teams of two people, compared to three or four teams in the past. With the UAV we will also be able to run multiple flights to check the progress of the algal mats throughout the season at no extra cost. Having the post processing side of things taken care of by an online service will make a big difference to us, as no extra staff will need to do the time consuming manual processing.
The UAV was trialled this year, along side field surveys, helping us survey areas we have been unable to get to on foot before. Using the UAV, we will replace other more expensive forms of remote sensing that we’ve used in the past, e.g. commissioning the Environment Agency’s plane and purchasing satellite images.
Aerial monitoring allows our results to be more accurate too, as a complete snapshot of the environment can be captured. The data provided will mean we will be better informed of the state of the environment, enabling us to be smarter and better at protecting it.
Future uses of the UAV include mapping sea grass beds in inter-tidal areas. As an operational service it will have many uses e.g. capturing aerial imagery of estuaries, wetlands and riverbanks and to provide a snapshot of the environment before and after development work. The most exciting benefit of the equipment is that it will not cost us anything, other than time, to pilot new projects. So this new technology will allow us to continue with sampling innovation throughout SEPA to protect the environment, while providing excellent value for the public purse.
Case study: UAV in action at the Rottal Burn restoration project
The Rottal Burn, in upper Glen Clova (Angus, north of Kirriemuir) is part of the South Esk Special Area of Conservation. In the eighteenth century, around 1.2km of the Rottal Burn river channel was straightened to improve agriculture, this resulted in degraded habitats and has required regular dredging since then. The lost habitats would have included pools, bars and riffles, forming excellent spawning and juvenile habitat for salmon and other animals.
The River Esk Fisheries Trust, with support from the Water Environment Fund administered by SEPA, is restoring the habitats in the Rottal Burn. Construction began in April 2012 and by mid June the new channel had been completed. A natural channel form has been created. The channel contains pools, riffles, bars. The banks have been lowered so there will be much better connection to the floodplain. Wood jams, a natural build up of wood and other debris to locally divert flow, are being trialled to see how they can offer a more natural approach to bank protection in vulnerable areas. The scheme was fully connected to the main river in October. The restored channel was surveyed by the UAV end of July 2012. The resulting images show the precise location and form of the restored channel (it is even possible to pick out the saplings planted on the banks, and individual cobbles in the channel), and will be used as a benchmark against which to measure future changes.
The alternatives to gathering this data would have been much more expensive. The UAV is a rapid, flexible and efficient way to collect very precise data for environmental monitoring.