Bit late in the day, but each time there is a flooding incident, this blog will mention the open-source plan for a low-cost, effective, high-volume, low-head pump ideally suited to shifting flood waters.
For any DIY enthusiasts, garden shed engineers and entrepreneurs out there, if you click here you can find out how to build a pump using an outboard motor and few intermediate technology skills.
I made one myself and tested it in the Congresbury Yeo. It worked very well.
It would prove ideal for use in Cornwall where 50% of houses have an outboard motor (I just made that up, but the rest is true).