Question about the discharge of streams?

Question

The discharge in most streams and rivers increases downstream, but in a few discharges actually decreases and then the stream finally disappears...why does this happen?

Answer 1

There are three reasons why this can happen: (1) the surface water sinks into a cave system or large underground aquifer; (2) evaporation rates exceed the amount of water gained from tributaries; and (3) wells and water diversions remove the water from the system. An example of the first situation is Idaho's Lost River, where a large river disappears entirely, and re-emerges as a spring several hundred miles away. Other examples are common in the vicinity of Mammoth Cave.