

flood warning systems are often simple networks of rain gauges or stream gauges that are triggered when rain or floodwaters exceed a certain level.
The gauges can then be used to warn those at risk of flooding, whether by text message, which may not be effective in areas with spotty cellphone service; notifications broadcast on TV and radio; or sometimes through a series of sirens.
It doesn’t seem like a basic solution should even cost nearly that much.
Even then I don’t see why something like this wouldn’t work. If not, you could spend 100x more money and still be nowhere close to a million.