Watersheds, Flooding and Pollution

Look around you, right now - you are in a watershed. The water in your watershed quenches thirst, grows food, washes clothes, and powers industry. However, too much water can cause raging floods and flush pollutants and soil into rivers and streams. How do we interact with the water in our watershed?

Mountain streams quickly over flow in flash floods due to rainfall or snowmelt. Source: NOAA National Weather Service - Hazardous Weather Awareness Week

Water Forecasts and Management

Cities, utilities, reservoir operators, agriculture, and other industries depend on accurate forecasts of water availability. Hydrologists, water-system scientists, use snow data, river gauges, evaporation rates, precipitation forecasts, radar and other data to produce forecasts that allow water managers and others to plan efficient and safe use of this natural resource.
Water managers use this information to make decisions about water allocation. For instance, how much water should they release from a reservoir during spring run-off and how much should they hold for later consumer, agricultural and industrial needs. These decisions can reduce flooding threats, limit the impact of droughts, and influence fish migrations. Cargo ship and barge captains on large rivers use information on the current and forecasted depth, river level, and the volume of water, flow rate, information for navigation planning. Hydroelectric dam operators use similar information to most efficiently produce electricity. And, recreationist such as fishermen, whitewater paddlers, and other boaters use these river predictions to plan safe outings.

Watersheds and Flooding

When water enters the watershed too quickly for the land to absorb it flooding can occur. Floods result from rapid melting of winter snows, severe thunderstorms, tropical storms, and other high precipitation events. Annually in the U.S., flooding causes billions of dollars in damages and takes dozens of lives.
Accurate prediction of the amount of water flowing down rivers and the time of its arrival has saved countless lives and dollars. Hydrologists, the forecasters who predict these events, consider the condition of the watershed and its relationship to the rest of the water cycle. Watersheds in urban areas with lots of concrete, pavement, and roofs, shed water quickly while forested and grassy rural areas absorb more water. Knowledge of land use, geology, and hydrology of an area, combined with weather predictions are essential to accurate flooding forecasts.

Runoff and Pollution

Storm-water runoff is one of the most significant threats to ecosystems along the coastal areas of the U.S. As the water runs over and through the watershed it picks up and carries contaminants and soil. The blotches of leaked motor oil on parking lots, plastic grocery bags, pesticides, fertilizers, detergents, and sediments are known as non-point source pollutants. If untreated, these pollutants wash directly into waterways carried by runoff from rain and snow melt. These contaminants can infiltrate groundwater and concentrate in streams and rivers and can be carried down the watershed and into the ocean. Non-point source pollution is linked to the creation of large dead-zones (areas with minimal oxygen) in the ocean and also threatens coral reef ecosystem health around the world.

Education Connection
Learning about the water in the watersheds can help develop respect, understanding, and appreciation for the symbiotic relationship that we have with watersheds. Some resources in this collection encourage educators to get students outside. Others provide real-world data, hands-on activities and examples to help students understand the positive and negative interactions between them and their watershed. stewardship skills can help protect water resources and the environment for our future use..

Last updated: 6/7/2011

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