For the salmon/seatrout fisherman it is desirable to know when a spate is occurring and when it is finished; as there is a strong correlation between runs of fish and changes in water height.
To determine whether a fishing trip is worth it and once fishing, how the river is behaving; rising or falling.
...and if you are a River Fisherman....Why? Because there is no point even turning up at a fishing venue if the river is a raging torrent and conversely the same might apply if its on its bare bones. It may save a drive of 200mls+. But how do you know the state of a river 200 mls away? With these:
The fisherman receives raw height data on his Handheld unit and trend data on the Receive Unit.