Testing drones to help monitor water quality

Technologies that allow scientists to remotely observe what is happening in bodies of water have been advancing rapidly in recent years. Between innovations in satellite technology, lower-cost sensors and access to satellite data in cloud environments, scientists are able to provide information on water conditions in higher detail than ever before.

However, there are areas that still require improvement before these technologies are fully operational. It is particularly challenging to observe water conditions by satellite in small water bodies with nearby land, and this includes most lakes in the UK as well as rivers and coastal bays. The challenges are mainly due to atmospheric interference and reflections from the water surface, lake beds and shores.

With this in mind, a small team from PML working with colleagues at UKCEH are exploring how to optimize the use of drones to help monitor the water quality of lake and river environments, collecting data to validate the accuracy of satellite observations as a way to complement direct water sampling.

The drone cameras record the full spectrum of sunlight reflected in the water and these measurements can then be compared to the water colour observed from satellite and analysed samples back in the laboratory to help determine the qualities of the water. The ultimate aim is for drone water monitoring to become a standard capability within the water monitoring toolkit, especially alongside existing direct water monitoring efforts.

Equipped with a test drone carrying a full payload of high-specification camera sensors, the multi-disciplinary team flew over sections of Windermere that are already regularly sampled by the UKCEH water monitoring team. Having a good existing dataset with which to compare the drone data helps corroborate accuracy and highlights matters that require attention.

The test flight proved successful and the prototype drone payload is showing promise for wider introduction to field campaigns. However, the scientists note that dedicated investment will be required to make the payload smaller and lighter, to lower the cost of the system and hence, make the system more ‘plug and play’.

Prof. Stefan Simis, Earth Observation Scientist for Inland & Coastal Waters at Plymouth Marine Laboratory, said:

“We are excited to be undertaking innovative research that we hope will result in an exciting and useful product for anyone managing water quality around the world.”

“For these pilot flights at sites around Windermere and Esthwaite we were lucky with the weather, with fairly clear skies and little rain. It’s great to see that the work that went into designing and balancing the payload paid off – the drone was very stable even during some gusty winds. The good weather probably helped calm the nerves of the scientists involved!”

Dr Stephen Thackeray, Lake Ecologist at the UK Centre for Ecology & Hydrology, added:

“We have been sampling Windermere for many years and have developed an excellent understanding of its dynamics. Conventional sampling methods using boats will continue to bring a wealth of information, helping us understand how these lakes respond to gradually changing pressures, such as climate change. But we are also aware of the need of water management authorities to respond rapidly to concerns of pollution. Our focus on lake functioning, combined with PML’s expertise in remote optical water quality detection from lakes to the ocean, brings a lot of overlapping interest and these collaborations are needed to address pressures on water quality from pollution and climate change.”

So far, the work has been supported as a small component of the UK EOCIS (Earth Observation Climate Information Service) and internal funds from PML and UKCEH, so the next step is to find additional funding to take this project to the next level. In particular, our scientists are keen to make the sensor payload smaller and lighter, lower the cost of the system and make the device more user-friendly so those without specific Earth observation expertise could use it easily.