Final answer:
The amount of runoff in a watershed increases with higher rainfall, influenced by various factors such as vegetation, soil characteristics, and land use. Some rainfall infiltrates the ground to become groundwater, while the remainder becomes surface runoff, affecting river discharge volumes.
Step-by-step explanation:
The amount of runoff in a watershed is closely related to the amount of rainfall it receives. Runoff occurs when precipitation that falls on land flows over the surface, potentially entering into bodies of water such as rivers, lakes, or oceans. However, not all precipitation becomes runoff; some water will infiltrate or soak into the ground, becoming groundwater. Groundwater can also move to bodies of water, be taken up by plants, or percolate deeper into aquifers.
Factors such as vegetation, topography, land use, and soil characteristics influence how much rain becomes runoff versus groundwater. Vegetation can absorb some rainfall, leading to a process called evapotranspiration. Soil's water retention capacity also plays a critical role; well-structured soils with high organic matter can absorb and slowly release significant amounts of water, reducing runoff. Conversely, compacted soils with low organic content have reduced absorption capabilities, which can lead to increased runoff, erosion, and even flooding.