Potential Applications for Unmanned Aerial Vehicles in River Hydrography

Daniel Sinnott - WaterNSW , 20 December, 2016

Unmanned Aerial Vehicles (UAVs), also commonly called drones are a relatively low cost aerial sensing platform that allows a number of tasks to be performed at a much lower cost to conventional aerial methods or in such a way that potentially enhances or simplifies current methodologies used by field hydrographers.

UAVs take many forms and each configuration has inherent benefits and deficiencies related to their flight capabilities. In the field of river hydrography due to the topographies experienced, the ease of operation and the scale of areas being considered, an assessment of the available technology shows that the multi-copter configuration to be best suited to potential applications.

Potentials for UAV use include site mapping, 3D modelling of micro-catchments, remote installation inspection, safety applications in high risk work such as flood gauging, temporal recording of site condition such as vegetation cover and geomorphology, payload carrying, marketing, new site selection and site condition monitoring.

Certain limitations must be considered in UAV application, regulations controlling the use of private and commercial drones are about to be updated in Australia, with the aim to both enhance public safety and reduce red-tape, potentially simplifying both private and commercial drone use.

Many other factors also need to be taken into consideration such as Occupational Health and Safety, privacy and no-fly zones outside of those in CASA regulations. Drone use must also take into account possible negative effects to native wildlife which may have their life-cycles disturbed through UAV interference.

Currently advanced remote sensing devices available for UAVs tend to be expensive, and there are technological limitations which can make it quite costly to enhance drone use with a selection of different camera types and other sensing equipment. With the current popularity of UAVs it is expected that this will change, with both commercially available affordable options, and with the growing popularity of amateur technology hacking making more sensing options available at a competitive price point.

A practical test of deploying a UAV in the field was conducted using a DJI Phantom 3 quad-copter and an assortment of software applications tested to enable the mapping of an operational NSW site (Mann River at Jackadgery). Utilising android apps, a cloud-based system and a windows software application, field aerial photography was collected at the site which allowed the construction of orthorectified photogrammetry in high definition.

This was further processed into a 3 dimensional map of the micro catchment and a digital elevation model constructed which could, with further work, serve as a reasonably accurate basis for establishing site cross sections, longitudinal sections and development of high-stage rating tables in a much more time-efficient manner than using current ground-based survey methods.