Shields parameter

The shields parameter is like a big, invisible force field that can tell us if a river or stream is strong enough to move big particles like sand or gravel. Imagine you're in a river and you try to push a big rock. The river water is also trying to push the rock. The shields parameter is the balance between how strong the water force is and how heavy the rock is. If the water is too weak to move the rock, it won't move. If it's too strong, the rock will move easily. Scientists use this parameter to help understand how rivers and streams shape the land around them, and to help protect people and property from flood hazards.