Why do rivers flow down?

Question

muzzack · Answer

Rivers always flow downhill, of course! A stream, or a river, is formed whenever water moves downhill from one place to another. This means that most rivers begin high up in the mountains, where snow from the winter, or ancient glaciers, is melting. On their way down to the sea, they collect water from rain, and from other streams. There is another place where rivers rise up: from springs. Where groundwater seeps up onto the surface, it may form a lake or pool or it may start running downhill right away, but one way or another, it is a river's beginning.
     In lower places where there are no lofty mountain peaks covered with snow, rivers often begin this way, springing up--well, from springs!

     What you see when you look at a river, though, is not the whole story. For the river is flowing even where you can't see it. It flows deep beneath the bottom of the river (the substrate), and it flows underneath the ground on both sides of it. If you are standing on the bank of a river, the river may well be flowing under your feet. This area underground where the river flows is called the hyporheic zone (hy-po-ree-ik). In the hyporheic zone, many forms of life can be found. In fact, a lot of the mayflies and other insects and crustaceans that we've been talking about can move down into the hyporheic zone. Hiding down there between the rocks protects them from predators, yet the water still flows to them, bringing them nutrients.

     Depending on how gravelly or rocky the ground is, a river's hyporheic zone has been found to extend far away from the part of the river you can see, far into the river's floodplain. In fact, wells drilled into the earth for houses near rivers will sometimes yield up tiny little animals! The more gravelly the ground, the farther the hyporheic zone will extend. In reality, a stream, its underground hyporheic zone, and its aquifer beneath the hyporheic zone are all part of a single system.

anonymous · Answer

because people like you are imbarrised that i am straighter than you