Watersheds & Water Pollution
Runoff What is runoff? Review: When rain or snow falls onto the earth, it just doesn't sit there, it starts moving according to the laws of gravity. A portion of the precipitation seeps into the ground to replenish Earth s groundwater. Most of it flows downhill as runoff.
More on Runoff Smaller creeks/streams flow into smaller rivers which flow into larger rivers or lakes.
What is a Watershed? A watershed is an area of land from which all runoff drains to the same body of water. Everyone lives in a watershed. What watershed do we live in?
Water Pollution Healthy watersheds are important for a healthy environment and economy because they provide water for drinking, irrigation, and industry. Many people also enjoy lakes and streams for recreational activities like swimming, boating, fishing, to watch wildlife, and to check out the beautiful scenery. Animal survival also depends on a healthy watershed, as it provides food and shelter. Contamination at any one place can affect the overall health of the watershed. Evaporation Condensation Ocean Storage Snowmelt Streams and rivers Lakes Groundwater flow to oceans Aquifers Springs Precipitation Infiltration into the ground How does this happen? Water continuously travels from one place to another due to the hydrologic cycle.
Types of Pollution Point source pollution- pollution that is directly dumped into a body of water Example: A factory dumps waste in a water This is not as much of a problem in the United States today. Why? Strict laws have been passed by the government
Types of Pollution Non-point source pollution- pollution that occurs when small amount of pollution from a variety of sources is picked up by runoff and carried into water bodies. Examples: Excess fertilizers, herbicides and insecticides Oil, grease, and other chemicals leaked onto the ground Bacteria and nutrients from livestock, pet wastes and faulty septic systems You can't point to the specific origin of the contamination; it comes from too many places and is difficult to trace.
Types of Pollution What activities are examples of point-source pollution and non-point source pollution? Point source pollution dumping oil into storm drain Non-Point source pollution fertilizer on yard litter thrown on ground oil leaking out of car
Water Treatment Watch the video clip How It s Made: Drinking Water to learn how water is treated.
Water Treatment 1. Coagulation- removes dirt and other particles suspended in water. Alum and other chemicals are added to water to form tiny sticky particles called "floc" which attract the dirt particles. The combined weight of the dirt and the alum (floc) become heavy enough to sink to the bottom during sedimentation. 2. Sedimentation- The heavy particles (floc) settle to the bottom and the clear water moves to filtration.
Water Treatment 3. Filtration- The water passes through filters, some made of layers of sand, gravel, and charcoal that help remove even smaller particles. 4. Disinfection- Water is placed in a closed tank or reservoir in order for disinfection to take place. A small amount of chlorine is added or some other disinfection method is used to kill any bacteria or microorganisims that may be in the water. 5. Storage- The water then flows through pipes to homes and businesses in the community.