Watershed is the area of land that contributes water to a particular watercourse.
Divide marks the high point of land that separate one watershed from another.
Headwaters are the upper limits of the watershed.
Tributaries are smaller branches of watercourse that join together to make larger sections of the river.
Wetlands are permanently or seasonally inundated lands.
Channel is the normal area that the river occupies.
Floodplain is the area on either side of the watercourse that may be covered by water in times of high flow.
Confluence is where a branch of the watercourse joins the main channel.
Mouth marks the end of the watercourse at a body of water, usually a lake or the sea.
Groundwater exists in the spaces of bedrock or loose material, such as sand and gravel.