Article Review: Use of Unmanned Aerial Systems for Environmental Monitoring

A recently published pre-print article details the usage of Unmanned Aerial Systems (UAS) for environmental monitoring. While the article was written within the specific armpit of a project, it raises interesting issues on the use of drones for data collection, ecosystems and river monitoring.

The usage of drones, UAVs or Unmanned Aerial Systems (UAS) continues to be widespread within agriculture. Drones are used in cropping, monitoring plants, pests control and many other areas including forest and environmental monitoring. 

A recently published pre-print article by a group of scholars reviews the use of Unmanned Aerial Systems (UAS) for environmental monitoring. Drones are proving very popular from the traditional field observations and air and space-borne remote sensing as they provide high spatial detail over relatively large area.

The major aim of the article is to provide a common shared knowledge framework useful to guide and address the future activities curried under the auspicies of HARMONIOUS COST Action – a project funded by the European Cooperation in Science and Technology (COST)

• Article Title: On the use of Unmanned Aerial Systems for Environmental Monitoring
• Authors : Manfreda, S., et al
• DOI : 10.20944/preprints201803.0097.v1
• Publication date: 2018/03/14

The article begins by reviewing the use of UAS in environmental monitoring and notes that these present an alternative monitoring platform that is low-cost opportunity to capture spatial data as compared to airborne systems or satelites. The cost goes down with choice of drones, for example a high resolution natural colour image at 50 cm/pixel from a satellite can cost USD$3,000, while on the other hand a UAS with a natural colour camera can be purchased for less than USD$1,000.

The current work on UAS-based environment monitoring cited in the paper focused on:-

• Land mapping
• Vegetation state, phenology and health
• Precision farming or agriculture
• Monitoring crop growth, and invasive species infestation
• Atmospheric observations
• Disaster mapping
• Soil erosion
• Mapping soil surface characteristics, and
• Change detection

Aspects of UAS-based environmental monitoring

Within environment monitoring they are a number of areas where UAS can be applied. The paper focuses on, 1) data collection and processing, 2) monitoring natural and agricultural ecosystems, 3) monitoring river systems.

With regards to data collection, the pre-data collection plans are very essential to collecting relevant data and the paper cites a number of issues to focus on. There are still many workflow and complexity issues brought about by UAS. There is also the element of cameras and their resolutions and software considerations which are a necessary contributor to good data quality.

UAS has proven to be useful in monitoring natural and agricultural ecosystems, and has managed to provide high accuracy in species-level vegetation classification, ability to monitor weed infestations and detecting crop water stress. Examples where UAS have been used in these areas are then given.

On monitoring river system, the paper notes that UAS allow data to be interpreted looking at water body observation and hydrological modelling. For example the article states that, “USA can describe river dynamics, but with a level of detail that is several orders of magnitude greater and can enable distributed flow measurements over any river system and in difficult-to-access environments” (p.12).

However, there is still a huge need to standardize the workflow for operational use of UAS and also high spatial resolution of UAS data generates high demands on data storage and processing capacity.

Challenges in using UAS

There are still legal constraints restricting the collection of data in most countries. There are also technical limits related to weather that can affect the operation of the devices. The following challenges are discussed in detail:-

• The flight time (due also to device battery), it affects the area to be investigated. Most devices are also now equipped with a solar panel on board that allows battery recharging and thereby extending the typical flight time.
• Impact of Ground Sample Distance (GSD) on the quality of the surveys – only 3D enabled devices are better in offsetting this.
• The image registration, correction and calibration due to weather conditions.

Citation of the article, Manfreda, S.,Mccabe, M.,Miller, P.,Lucas, R.,Pajuelo, V.,Madrigal,.Mallinis, G.,Ben-Dor, E.,Helman, D,. Estes, L.,Ciraolo, G., Müllerová,J.,Tauro, F.,Isabel De Lima, M.,Pedroso de Lima, J., Francés,F.,Caylor, K., Kohv, M.,Maltese, A.,Tóth,B. 2018. On the Use of Unmanned Aerial Systems for Environmental Monitoring. Avaliable Online. DOI: 10.20944/preprints201803.0097.v1