mathematics & science center

Virginia Watersheds

Mathematics & Science Center

What is a Watershed?

It’s the land that water flows across or under on it’s way to a

stream, river or lake.

A watershed with its small streams and larger river can be compared to a leaf with its sub-veins and main vein.

Watershed Movie

Courtesy of: Michigan EnvironmentalEducation Curriculum

We all live in a Watershed

• In the mountains or where the land is flat.• In cities, forests and on farms.• Even plants and animals live in a watershed.

Courtesy of DCR’s Soil & Water Conservation Programs

Watersheds Vary In Size

Hydrologic UnitsThe United States is divided and sub-divided into successively smaller hydrologic Units.

The Four Levels:• Region• Sub-Region• Account Unit• Cataloging Unit

What is a Divide?

A divide is the boundary that separates one watershed from another.

What is a Tributary?

A tributary is a stream or river that contributes its water to another stream, river or body of water.

Two Kinds of Water Pollution

• Point Source Pollution

• Nonpoint Source Pollution

Point Source Pollution

It’s usually easy to figure out where point source pollution comes from. If you see a pipe emptying into the water, that’s a point source. You can point to where it’s coming from.

Courtesy: The Scottish Agricultural College

Nonpoint Source Pollution

Nonpoint source pollution comes from places you can’t easily identify:

Rain washes loose soil off construction sitesRain washes oil and litter off parking lotsExtra fertilizer on lawns wash into our waterAcid rain exhaust from cars

Courtesy:www.deq.gov

Why Do We Study Watersheds?• Every place in Virginia belongs to a watershed. • The quality of water in each stream and river

depends in large part on the land use in the watershed.

• Land used for residential, agricultural, or commercial areas can either hurt or support water quality.

• Knowing where your water comes from is important, especially if any problems occur upstream.