Where do watershed boundaries typically occur?

Watershed boundaries are typically defined by the topography of the landscape, and the most common place for these boundaries to occur is along ridges that divide watersheds. These ridges, also known as watershed divides, are elevated areas that direct the flow of water towards different drainage basins. When precipitation falls, water flows downhill from the ridges into the surrounding valleys and water bodies, thereby delineating the outer edges of a watershed.

In contrast, transitional landforms like hills may be included within watersheds but do not inherently define the boundaries themselves. Urban development zones can exist within a watershed regardless of its boundaries, but they do not define them either. Significant water bodies can sometimes help identify where watersheds converge, but the actual boundaries are established by the highest points in the area, which are the ridges. Thus, the correct answer highlights a fundamental principle of watershed hydrology related to the topography that governs water flow and drainage patterns.