River channels represent a quasi-equilibrium condition between the river discharge, flow regime (whether laminar or turbulent), amount of sediment being transported, and slope of the river channel. The river can respond to these variables by finding an equilibrium or quasi-equilibrium condition by adjusting the channel shape (width and depth), the velocity of the flow, the roughness of the bed and bank, and the slope of the bed. The slope of a riverbed can be adjusted by the river by increasing or decreasing the number of its bends, or meanders. If the river needs to lower the slope to maintain a quasi-equilibrium condition, then it can increase the number of bends and flow more parallel to the contours. If the river needs to increase the slope, it can cut through the banks and flow straight downhill, attaining a slope equal to the regional gradient. This is one of the reasons rivers have so many different forms, from straight to wildly meandering channels.
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