Physical stream quality measured by drones and image analysis versus the traditional manual method.

Information on the physical and ecological state of streams along with an overview of the need for maintenance is traditionally a time-consuming manual field task with subsequent limitations in area coverage. Here we propose a novel approach to stream monitoring and management using a low-cost Unmanned Aerial Vehicle (UAV) platform to collect data comparable to that from traditional monitoring schemes. This technology provides high-resolution imagery while being easy to implement at a low cost along with providing data that represent the stream in both fine-scale and at landscape scale. The results show a significant correlation between results obtained by the two methods, with the largest difference in DFI values being 10, but in many cases being <5. The UAV-method is especially strong in supporting geographical measurements of stream width and course along with certain stream parameters such as physical variation, water flow and gravel coverage. The results indicate that UAV mapping of streams is a feasible alternative or support to the traditional mapping of certain open stream types with the possibility of covering more area with the same time-use.