Final answer:
Water does not travel uphill, so watersheds are determined by: A. topography & geology.
Step-by-step explanation:
Watersheds, which are areas of land where all the water drains to a common point such as a river or lake, are determined by a combination of topography and geology. Topography refers to the physical features of the land, such as slopes, hills, and valleys, which influence the movement of water. Geology refers to the type of rocks and soil in the area, which can affect how water is absorbed or flows over the surface.
Topography plays a key role in determining the direction and speed of water flow. Water naturally moves downhill due to gravity, so the slopes and contours of the land determine the pathways of water and the formation of watersheds. For example, water will flow more quickly and directly down a steep slope, while it may pool or move more slowly in a flat or gently sloping area.
Geology also influences watersheds by affecting how water is absorbed into the ground or flows over the surface. Different types of rocks and soil have varying permeability, or ability to allow water to pass through. For example, clay soils can be more compact and less porous, leading to increased runoff and the formation of smaller watersheds. On the other hand, sandy soils are more porous and allow water to infiltrate more easily, leading to larger watersheds with greater groundwater recharge.
In conclusion, topography and geology work together to determine the boundaries and characteristics of watersheds. The physical features of the land and the composition of rocks and soil influence how water moves and is stored, ultimately shaping the flow and distribution of water in a particular area. The correct answer is A. topography & geology.