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This book page provides an overview of river systems, including rivers, tributaries, watersheds, and lakes. It also explores various types of freshwater ecosystems such as ponds, swamps, and wetlands. Discover the importance of wetlands and how they contribute to the environment.
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What is a river system? A river system includes a river in addition to any streams or tributaries that flow into that river.
Tributary A stream or smaller river that feeds into a main river.
Tributaries • Flow downward toward the main river. • What force causes this? • Pulled down by the force of Gravity!
Watershed The land area that supplies water to a river system.
Amazon River Basin Largest watershed in the world.
Divide A ridge of land that separates one watershed from another.
The Continental Divide, the longest divide in North America, follows the line of Rocky Mountains
Lakes and Ponds • Bodies of fresh water • Contain still or standing water • Lakes and ponds form when water collects in hollows and low-lying areas of land.
Ponds Ponds are thriving habitats for various plants and animals. Algae serves as food for many animals. Ponds are typically very shallow and sunlight can reach plants on the bottom.
Lakes Lakes are bigger and deeper than ponds. Sunlight does not reach the bottom in a deep lake. Lake bottoms consist of sand, pebbles and rock.
Lakes Lakes can form from: • Cut-off meandering rivers (Oxbow lakes) • Erosion by ice (eg. The Great Lakes) • Extinct volcano craters (eg.Crater Lake, Mount Mazama – Oregon, USA) • Movements of Earth’s crust (eg. Lake Tanganyika and Lake Victoria in Central Africa) • Manmade lakes are formed by river dams.
Crater Lake, Mount Mazama – Oregon, USA • Crater Lake, Mount Mazama – Oregon, USA
Lakes- Human Uses • Drinking water • Irrigation • Boating • Fishing Reservoir- A lake that stores water for human use.
Lake Turnover When the water in a lake mixes due to temperature change causing minerals, plant matter, and other nutrients to rise to the surface. This refreshes the nutrients of the lake.
Eutrophication When nutrients build up in a lake over many years. Algae forms a thick green scum on the surface of the water.
Icebergs Large chunks of ice that break off of a glacier and float away into the ocean. Made of frozen FRESHWATER.
Wetland A land area that is covered with a shallow layer of water during some or all of the year.
Three types of freshwater wetlands 1. Marshes • Are usually grassy areas covered by a shallow water or a stream. • Team with cattails and other tall, grasslike plants.
Three types of freshwater wetlands 2. Swamps • Look more like flooded forests, with trees and shrubs sprouting from the water. • Located in warm, humid climates, where trees grows quickly.
Three types of freshwater wetlands 3. Bogs • More common in cool, Northern areas. • Often form in depression left by melting ice sheets thousands of years ago. • The water in bogs tends to be acidic, and mosses thrive in these conditions.
Importance of Wetlands • Because of their sheltered waters and rich supply of nutrients, wetlands provide habitats for many living things. • They act as natural water filters (eg. Pickerel weed filter pollutants from water). • Help control floods by absorbing extra runoff from heavy rains.
