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Watersheds and Wetlands CHAPTER 1 Lesson 1.1 The Blue Planet Groundwater Surface Water Stream Characteristics Major Drainage Patterns Pennsylvania’s Drainage Patterns PA Academic Standards for Environment & Ecology Standard 4.1.10.B Explain the relationship among landforms, vegetation and the amount and speed of water. Lesson Objectives. Students will be able to … • • • • • • • Analyze a stream’s physical characteristics. Describe how topography influences streams. Explain the influence of mountains on precipitation. Explain how vegetation affects storm water runoff. Delineate the boundaries of a watershed. Describe factors that affect the quality of groundwater. Explain how the speed of water and vegetation cover relates to erosion. The Blue Planet • Water is the most common substance on Earth. 97% of the Earth’s water is saltwater. Example: oceans 3% of the Earth’s water is freshwater. Example: lakes, rivers, streams, and glaciers • There are three main forms (states) in which water exists as it circulates through the water cycle. Solid • Example: ice Liquid • Example: water Gas • Example: water vapor • The three forms of water move water through the environment via the water cycle --- an unending circulation process powered by the sun. Major Processes Evaporation – changing from a liquid to a gas (heating) Condensation – changing from a gas to a liquid (cooling) Precipitation – when water returns to the Earth Transpiration – when plants release water vapor from their leaves (stomata) Percolation/Infiltration – when surface water seeps into the ground Groundwater • Some precipitation runs off the surface of the ground into near-by surface water sources. However, some water seeps into the ground and becomes groundwater. • Definition: Groundwater – water from rain and melting snow that seeps into the ground and is stored beneath Earth’s surface Groundwater Where is the groundwater supply? • About 22% of the Earth’s freshwater supply is groundwater. • Groundwater can be accessed by private and public wells. • How is groundwater used in PA? • People and industry use more than 1 billion gallons of groundwater each day. • Major source of drinking water for residents. • Major source of water for mining and agricultural operations throughout the state. Overdrawing Groundwater Intro: To increase supplies of high quality freshwater, groundwater is being used • Groundwater is not an unlimited resource • Balance should be: Groundwater withdrawal = recharge • The truth: Withdrawals exceed recharge! The Biggest Problem with overdrawing groundwater: Falling Water Tables The affects of this would be: 1. Irrigation • Uses up by far the most groundwater • In the Midwest, Ogallala Aquifer • Over the past 40 years, the water table has dropped 100 feet • It continues to fall at a rate of 6 feet per year 2. Diminishing Surface Water: • Springs and seeps dry up (lakes and ponds are affected) • Wetlands dry up 3. Land Subsidence: • Water pressure underground acts as a support • When that water is lost, the earth may settle or suddenly sink (sinkhole) • Very typical in the southeast U.S. 4. Saltwater Intrusion: • Coastal regions have springs that empty into the ocean • As long as the water table is high, the pressure of the groundwater exiting the spring results in freshwater entering the ocean • If the water table diminishes, then saltwater flows back into the freshwater Groundwater Quality • Groundwater supplies much of the Earth’s drinking water supply. • Therefore, the quality of the groundwater in many countries is closely monitored for contamination. • Major causes of contamination Natural sources Human activities Video Clip – Water Contamination Contamination: Natural Sources • As water flows through and around soils and rocks, it dissolves certain minerals, which contaminate the water. • If the water is acidic, it can leach out metals from the ground. Example: hard water (Ca & Mg) Example: overall reduced water quality (Fe,Zn,Cu and S) Contamination: Human Activities • Groundwater quality can also be adversely affected by human activities that occur above ground. Examples: septic tanks, pesticides and fertilizers, storage tanks, chemical spills, landfills, and roadway salts. How does my septic system & well work? PA’s Groundwater Quality • Overall quality of groundwater in Pennsylvania is generally good. The decrease in the amount of nitrates in some Pennsylvania groundwater supplies could be a result of a combination of changes in agricultural practices and better installation and maintenance of septic systems. The increases in the amount of other contaminants in some parts of the state have been attributed to a rise in the amount of road salt applied to roadways as well as urban development. The #1 source of pollution along the Susquehanna is agriculture. What can farmers do? Terracing Stream Bank Fencing Riparian Zone Proper Manure Management Reduce Fertilizers & Pesticides No-till farming Surface Water • Common freshwater sources – Lakes – Ponds – Rivers – Soils – Air Stream Characteristics • Velocity • Sediment Load • River Deposits Stream Characteristics (1) Velocity Definition: The distance water flows during some period of time, such as meters per second or feet per second As a stream flows from its source to its mouth, the water flows in one of two ways. • Laminar flow – Water moves parallel to the stream channel • Turbulent flow – Water moves in tiny circular paths as it flows downstream • The velocity of a stream or river determines the type of flow observed in a system. Slow moving waters tend to have a laminar flow. Fast moving waters tend to have a turbulent flow. • The velocity of the stream or river determines the kind and amount of sediment that the water can carry. (2) Sediment Load As streams and rivers flow they carry sediment in three major ways. • Dissolved load – Sediment carried in solution • Suspended load – Silts and clays • Bed load – Sand, gravel, pebbles, and boulders (carried along the bottom) (3) River Deposits Rivers deposit sediment as the velocity of the water decreases. • Example: bars, or river deposits, form when a river slows down as it travels around a bend in the channel. • A flood plain is the part of a river valley that is covered during a flood. River deposits and agriculture • Why are river deposits important to agriculture? Rivers deposit sediment when they overflow their banks into floodplains, or low lying portions of land next to rivers that fill with water as river levels rise. These areas are fertile areas for farming, as the soils are rich with sediments carried from upstream. Major Drainage Patterns • Pennsylvania has more square miles of streams and rivers per square mile than most states. • The drainage patterns of these rivers and their tributaries, or feeder steams, depends largely on topography, or the physical characteristics of the land. • All drainage patterns are controlled by the types of rocks over which rivers and streams flow, as well as the presence or lack of folds and faults in the rocks. Topographic Maps Major Drainage Patterns • Four major types of drainage patterns Dendritic Drainage Patterns Radial Drainage Patterns Rectangular Drainage Patterns Trellis Drainage Patterns Major Drainage Patterns Dendritic Drainage Patterns • Most common type of drainage pattern. • Form where bedrock is uniform and massive, such as in a plains region. • Mainly a function of the slope of the land over which the stream or river flows. • Resembles the shape of a mature tree. • Common in western Pennsylvania because of a massive formation of sedimentary rock. Radial Drainage Patterns • Form where streams flow from a high, central area such as a plateau or other uplifted feature. • Resemble the spokes of a bicycle. Rectangular Drainage Patterns • Form when bodies of rock are broken by a series of faults of other fractures. • Resembles a series of lines, all of which turn at right angles. • Common in South-central Pennsylvania because of fractures and faults in the Earth’s surface. Trellis Drainage Patterns • Form when sections of softer, nonresistant rocks alternate with sections of harder, resistant rocks. • Resembles rectangular drainage patterns but tributaries run parallel to one another. • Common in southeastern Pennsylvania which has river systems which run parallel to each other yet perpendicular to the main stream or river. Theme Vocabulary Lesson 1.1 • • • • • • • • • • • • bed load condensation evaporation groundwater mouth precipitation runoff source topography transpiration tributaries velocity