Rivers curve because as precipitation runoff comes down a slope, the shallowest or lowest part of a given area is where the water will run through, until it reaches its lowest point and becomes a lake, ocean, etc.
If one bank of a river is disturbed and begins to crumble, water fills the hole and sweeps away loose dirt. Over time, this creates a bigger and bigger hole in the river bank. As the water begins to rush faster through the new opening, it slows on the opposite river bank. Because slow-moving water can’t carry as much weight as fast-moving water, loose dirt and rocks build up on that side, making it more shallow. Eventually, the build-up creates new land and a new curve in the river’s watercourse.The new curve causes the water running against the outside bank to pick up enough momentum that it slams into the opposite bank further down the river, creating another curve. As more time passes, the rushing water creates more and more curves downstream
