River Keeper / Alarm device

The river may look calm, but it might take your life in the next minute.Within a minute, the water level of the river can increase rapidly and flood a large area of land. This means that in most occasions people are unaware of the danger near the river until it is too late to evacuate.
But in fact, there are some signs of water level rise that can be observed from the river:
The temperature of water falling quickly
Water becoming more turbid.
public and increase chances of survival .