Hi I live beside a river in a very low lying house. I have been flooded twice. I would like to build a devive that monitors the water level out side my house when we are in a flood threat time. I need this device to sense a rise or fall over time of say 2m in depth and have an accuracy of 1mm scale. The average rise and or fall in flood times is approx. 1-2cm per hour. The idea would be to see if the water is tending to rise or fall over time and to set alarm points. It would be good to log the data but not esential. Has anyone got any ideas please? Phil