source of a river; headwaters; water source area
Refers to the geographical area where a river or water supply originates, often used in environmental or geographical contexts.
The source of this river is inside the national park.
Protecting the forests in the water source area is important for maintaining clean water.
Compound of 水源 (water source) and 地 (land, area). The exact historical derivation is straightforward; the spelling is conventionally associated with the meaning.