Drones for River AssessmentProfessor Ian Maddock and Sophie Pearce
River Science Research GroupSchool of Science and the Environment, University of Worcester
Outline1. Introduction: Who we are and what we work on
2. Traditional mapping and monitoring methods
3. Drones for water velocity measurement: Sophie Pearce
4. Drones for surveying topography and river morphology
5. Drones for monitoring channel change
6. Final thoughts
7. Discussion
Research Focus:
Hydromorphology & Physical HabitatThe interaction of hydrology and channel morphology and its
influence on aquatic biota (esp. macroinvertebrates & fish)
e.g. the flow
regime, drought
& floods, depth
& velocity
e.g. channel
shape, river bed
morphology,
substrate size
e.g. aquatic species,
macroinvertebrates,
plants, fish, etc.
How can we measure, survey & quantify hydraulics, morphology & physical habitat?
San Pedro River, Chile: The influence of channel marginal
habitats on native fish at a planned hydropower site
Lead Collaborator: Prof Evelyn Habit Funders: University of Concepcion, FONDECYT, Chile; UW (studentship)
Publications: Wilkes, Maddock, Link & Habit (2016), Woodget, Austrums, Maddock & Habit (2017)
Endangered Native Fish
Galaxiids
Megan Klaar, PhD (2010). Learning from unimpacted sites: Glacier
Bay, Alaska: The relationship between stream age, channel
morphology, trees in the river (large wood), native fish
Funders: UW & Uni Birmingham (PhD studentship), Prof Sandy Milner (UB)
Publications: Klaar, Maddock & Milner (2009), Klaar, Hill, Maddock & Milner (2011)
Setting environmental flows to
improve habitat availability for
fish (trout and grayling) and four
species of macroinvertebrates
Image:
https://twitter.com/envagencymids/status/966339060766711808
Upper River Derwent, Derbyshire: Assessing the impact of dam
releases on fish and macroinvertebrates
Lead Collaborators: Rachel Spence, Tim Pickering (EA), Dr Melanie Bickerton (UB)Funders: Environment Agency
Publication: Maddock, Bickerton, Spence & Pickering (2001)
Chris Greensmith (MRes in River Science): New Project;
Environmental DNA (eDNA) for detection of otter, water vole and mink
With the kind support of a BHS, JBA & EA Masters studentship award
The need for Physical Habitat Assessment?
Environmental Flows
River Restoration
Weir Removal
What do traditional surveys entail?• 1-10s kms
• Walking the river bank
or in-channel
• Mapping ‘key’ habitat
features
Pool
Pool
Pool
Glide
RiffleRun
• Using established
survey / classification
systems
Surveying, mapping and measuring rivers and their habitats at two scales:
1. Long reach habitat (‘walkover’) survey
2: Traditional mapping and monitoring methods
1. Long reach habitat (‘walkover’) survey
Scale: 1 – >10kms
Surveying, mapping and measuring rivers and their habitats at two scales:
2. Short reach hydraulic & river habitat modelling
• Reach lengths typically 50-500m
• Hundreds of measurements of topography,
velocity and depth across cross-sections
Most surveying methods:
Time consuming
Sparse point data
Low resolution of topography / bathymetry data
You need access to all parts of the site
▪ 2010 purchased our first drone
▪ 2011 CAA permission for drone flying, four ‘licenced’ pilots, with one
more next year
▪ Used in the UK and overseas: Chile, Slovenia & Switzerland
▪ Two international conferences (2013 and 2016)
▪ Three different rotary-winged, one fixed-wing UAV
Drones at the University of Worcester (UW)
Most common commercial drone usage:
Oblique aerial photos for a site overview
Most common commercial drone usage:
Video for marketing (River Teme)
Drones and Surface Flow Velocity measurement?
Using drone video for image velocimetry
3: Drones for velocity measurement
Background• Rivers need to be monitored during flood to inform prediction,
management and mitigation
• Flood conditions often pose a threat to traditional monitoring
instruments or people.
• Need to be measured for both Discharge readings and point
measurements (mainly for applications of flow to other studies,
such as calibrating hydraulic models for habitat studies)
Problems…- Time consuming with current meters
- High flows…ADCPs struggle…Gauging stations unreliable
Photo courtesy of Nick Everard
(EA)
Unreliable at high flow…• Flood warning systems rely on accurate hydrographs
• Hydrographs often based on measurements at ‘normal’ flow
conditions, and extrapolated to represent extreme flow
conditions = high errors for prediction, mitigation and
management.
Jodeau et al (2017)
Using remote technologies for river
monitoring
- Image-VelocimetryNon contact & safe, quick, direct, but errors remain
Lots of different algorithms but theoretically
very similar concepts
Three main ones to know are:
Large Scale Particle Image Velocimetry (LSPIV)
Space Time Image Velocimetry (STIV)
Particle Tracking Velocimetry (PTV)
Image-Velocimetry 1. Video recorded of the flow
(with surface features)
2. Image rectification
3. Image processing
– Calculation of
surface
velocity
Image-Velocimetry…requires surface
features
River Bow,
Canada
Bow Falls,
Canada
River Arrow,
Warwickshire
Broom monitoring
Station
Application…
Instantaneous surface velocity results
Average surface velocity results
Research and Development…
Currently lots of error sources regarding…
a) Visualisation of the water surface – features required…seeding
densities?
b) Which is more accurate drone or bankside camera?
c) Towards a completely remote technique – currently, ground truthing
still required
d) To allow a simple and effective technique…currently predominantly
restricted to expert research use…tools are not necessarily user
friendly.
Potential…
• Currently image-velocimetry is being
researched and adopted into hydrological
practises in many other countries including
Japan, France, Australia and the USA.
• EA very interested in the use of image-
velocimetry for gauging high flow events
• Has the potential to provide us with an
accurate, quick and safe method for
collecting data during events whereby access
to the river would be too dangerous….
• As well as exploring its application for during
a range of river flows (including low
flows…applications for calibrating hydraulic
models for example.
• Create topographic
maps
• Survey river beds
• Repeat flights: compare
surveys, measure and
map channel change
Drones and Structure-from-Motion (SfM) photogrammetry:
take measurements from photographs
How does it work?
4: Drones for topography and river morphology
Process the photos using
photogrammetry software:
Agisoft Photoscan
• Stitch them together.
• Remove distortions.
• Create a point cloud. Millions
of survey points…
River Teme: Point cloud >55 million survey points
River Teme: Orthophoto – high resolution, no distortion
River Teme: Orthophoto
– usable for long reach habitat mapping
Can’t we just use Google Maps / Earth satellite image?
Can’t we just use Google Maps / Earth satellite image?
Can’t we just use Google Maps / Earth satellite image?
• Image resolution is too coarse
Date of imagery is fixed.
• Drones give us bespoke flights
• Present day data on habitat
features, morphology etc
• Repeat flights for monitoring
change
River Teme: Digital Elevation Model (DEM):create cross profiles, long profile, export to hydraulic and habitat models
Any project where you need ultra-high resolution topographich survey
Detailed bathymetry maps if the conditions are suitable
Woodget
(2015)
Technological Developments for Monitoring Channel Change
• Understand natural river processes
• Identify sources of erosion and deposition
• Excessive sediment inputs leads to ecological decline
5: Drones for geomorphic change detection
Using repeat drone surveys to monitor channel migration
Geomorphic Change Detection
Before and after surveys
Map and measure erosion,
deposition, channel change,
bank erosion
(Tamminga et al 2015)
Potential for assessing
changes in morphology (and
velocities) around weir
removals
Megan Robertson (MRes in River Science): New Project; Natural Flood
Management and assessing sediment delivery to rivers using drones
Funder: Environment Agency
Final thoughts…
• These are important new tools in the river scientists toolbox
• Ultra High Resolution Data: Understand geomorphic and
hydraulic processes, map and monitor habitats and measure
flow velocity in ways not possible previously
New technology has and is transforming how we measure, map and
monitor rivers including the depth of shallow sites, velocities, habitats and
channel change
• Drone video for surface velocity measurement: Image Velocimetry
• Drone photos for topographic surveys: SfM Photogrammetry
• Repeat surveys for geomorphic change detection and soil erosion
Thank you
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