Final answer:
Rivers are dynamic systems influenced by precipitation and gravity, with river discharge being a key concept that describes the flow of water within a river system. Gravity directs the water downhill, and both surface runoff and groundwater seepage contribute to river discharge depending on various environmental factors.
Step-by-step explanation:
Rivers are dynamic systems driven by precipitation and gravity. Flowing water from rain and melted snow on land enters river channels by surface runoff and groundwater seepage.
discharge describes the volume of water moving through a river channel over time. Factors such as precipitation patterns, vegetation, topography, land use, and soil characteristics influence whether surface runoff or groundwater seepage contributes more to river discharge.
Soon after a heavy rainstorm, river discharge increases due to surface runoff, while the steady, normal flow of river water is mainly from groundwater that discharges into the river.
Gravity plays a key role, pulling river water downhill toward the ocean. During this journey, the moving water can erode soil particles and dissolve minerals, with groundwater contributing a significant amount of dissolved minerals to the river water.
The geographic area drained by a river and its tributaries, known as a drainage basin or watershed, can be vast, such as the Mississippi River drainage basin which encompasses approximately 40% of the U.S.