The participants were sharing interventions they had undertaken - or hoped to undertake in the future - to demonstrate pressing environmental issues to the public.
Although river flow demonstration tables are available to see (at Kingston University) or for hire (South East Rivers Trust) they are too heavy to move; or too expensive to hire for unfunded groups.
I really enjoyed seeing Tracey's model, which can be put together very easily as follows:
Helping People understand how rivers work by playing in the sand
A simple model river is easy to construct, and can show all kinds of river processes, like meandering, braiding, delta formation and erosion. It's also very valuable as a way of showing what really happens in flooding episodes and a great vehicle for introducing concepts and ideas in a non-threatening and easy to understand way.
All you need for playing in the sand - this is made from 3 drawers linked together, lined with a large plastic bag and filled with builder's sand. In this location, a brewer's bucket is a good way to run water down the "river".