In this recent case, the system has been closed for over 8 months under hot, dry conditions. This has caused shallow water temperatures to increase triggering algal blooms which have intensified causing oxygen levels to decline, approaching hypoxic stress.

At the same time, upstream infrastructure posed a flood risk should rainfall increase rapidly after drought conditions break.

These trade-offs are familiar to many of us:

• Ecological stress if left closed
• Flood risk if rainfall spikes
• Potential habitat disruption if breached artificially
• Environmental impact costs involved
• Financial costs involved

Using modern tools such as drones, GIS and ground data capture tools we are able to monitor

• Optimal breach points
• Flood lines
• Algal bloom intensity
• Sediment volumes
• Breakout thresholds
• Habitat exposure zones
• Impacts on fauna and flora

However, in this case, no detailed survey was conducted prior to breaching assistance using heavy machinery. The outcome was significantly more costly, environmentally and financially, than necessary.

I’m interested to find out how others would have approached this situation with regards to:

• Trigger thresholds for intervention?
• Monitoring protocols?
• Use of drone-derived DSMs and 3D models in decision support?
• Breaching methods?