Diagram of Watershed No Labels – Blank Sheet to Print

All 11 parts on the diagram

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Start here: 5 main parts 5

Watershed All the land whose streams and rain drain to one outlet. It is also called a drainage basin or catchment.
Drainage divide The ridges and hills that separate one watershed from the next. Rain on one side drains into this watershed, rain on the other into its neighbour.
Main river The largest stream in the watershed. Every other stream flows into it on its way to the outlet.
Tributaries The smaller streams that flow into the main river.
Outlet The one point all the watershed's water leaves by. For example, a river mouth or the outflow of a reservoir.

On the land: 3 3

Smaller watershed The land drained by one tributary. Larger watersheds are made of many smaller ones.
Reservoir A lake held back on the main river. Lakes and reservoirs are part of the watershed's surface water.
Wetland Marshy ground by a stream, part of the watershed's surface water.

Where the water comes from: 3 3

Precipitation Rain and snow falling on the watershed. It is where the watershed's water comes from.
Runoff Rain that runs over the ground instead of soaking in. It goes down the slopes to the stream.
Groundwater Water that has soaked into the ground. It seeps slowly to the stream, which is why a stream can keep flowing when it has not rained.

How this list was compiled: Read 2026-09-27. U.S. Geological Survey, Water Science School, Watersheds and Drainage Basins, https://www.usgs.gov/water-science-school/science/watersheds-and-drainage-basins : a watershed is an area of land that drains all the streams and rainfall to a common outlet, such as the outflow of a reservoir, the mouth of a bay or any point along a stream channel; also called a drainage basin or catchment; the ridges and hills that separate two watersheds are the drainage divide; it takes in surface water (lakes, streams, reservoirs and wetlands) and the underlying groundwater; larger watersheds contain many smaller watersheds; precipitation, runoff and infiltration; a stream often keeps flowing where there is no direct runoff from recent rain. Licence: own work

The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work

How it works

A diagram of a watershed with no labels, to fill in by hand. Eleven lines run out from the drawing with nothing written at their ends: eight on the map from above, three on the slice across the valley.

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Word bank for the eleven lines

In alphabetical order: drainage divide, groundwater, main river, outlet, precipitation, reservoir, runoff, smaller watershed, tributaries, watershed, wetland. Write it on the board, or leave it off for a harder sheet. The key shortens three of them: Divide, River and Sub-watershed.

Where the names go

On the map, the thick dashed line is the drainage divide and all the land inside it is the watershed. The lake on the river is the reservoir, and the patch with an edge of its own is the smaller watershed. On the slice, the arrows down both slopes are runoff.

Fold the sheet under the map and a younger class has eight names to write instead of eleven.

Questions and answers

How big is a watershed?

Any size. The US Geological Survey says a watershed can be as small as a footprint, or large enough to take in all the land that drains into the rivers reaching Chesapeake Bay. It depends on the outlet you choose.

Does all the rain that falls in a watershed flow out?

No. Some evaporates, some is taken up by plants and some soaks deep enough to refill aquifers. The amount of rain and snow is still, by far, the greatest factor in how much water a stream carries.

Why do floods get bigger in a paved watershed?

Parking lots, roads, sidewalks and rooftops do not let rain soak in. They send it straight into storm drains and on to streams, so floods become larger in watersheds where such surfaces are spreading.

Is the watershed on the diagram a real place?

No. It is drawn for this sheet and is not to scale: one main river, a reservoir, a wetland and one smaller watershed inside the divide. The key names all eleven parts.