Final answer:
The path of a river begins at the source water, usually in high elevations, and flows downhill due to gravity, carving a winding course through the landscape over time. The river erodes and transports soil and rocks, and as it widens and slows, it deposits sediments, reshaping its environment and creating new landforms.
Step-by-step explanation:
Describing the path of a river and how a river changes over time involves understanding the process of erosion, sediment transport, and deposition. Rivers usually begin at a point of origin, known as source water, which is typically cold, low in nutrients, and clear. The channel is narrowest here, causing the current to be relatively fast.
As a river flows downstream, it follows gravity's pull downhill, cutting through the landscape. This process not only carves out a path but also erodes soil and rocks. Over time, these actions lead to the river creating a winding course through valleys and plains. The relative contributions of surface runoff and groundwater seepage to a river's discharge depend on various factors like precipitation patterns and soil characteristics. After events like heavy rainstorms, river discharge increases markedly due to surface runoff, while the steady, normal flow is mainly maintained by groundwater contributions.
Throughout its journey, a river transports sediments it erodes from the land. As the river widens and the current slows, these sediments are deposited, which can lead to the formation of features such as flood plains, deltas, or estuarine areas. Over geologic time scales, these processes can significantly alter the landscape around the river, changing its course and creating new landforms.