From fast-moving rivers to trickling creeks, scientists around the world work to measure discharge, or the volume of water flowing past a point per second. Discharge is the number that turns "the river is high" into "this could flood downstream," and it underpins everything from reservoir operations to crop planning.
The problem is that gauges are unevenly distributed across the planet, and some of the places where better monitoring matters most — remote regions, fast-changing watersheds, politically complex borders — are often the hardest to measure consistently. That's where Earth-observing satellites come in.
