Transcript Water_Unit2
Chapter 5: Water Section 1.1: The Blue Planet Water Facts 70-75% of the Earth is covered by water. About 97% of the water on Earth is salt water found in the oceans. The remaining 3% is freshwater. Of the Earth’s freshwater, 70% is frozen in glaciers or polar caps. Water is continually recycled by the water cycle. Groundwater Some rain and melting snow seeps into the ground and becomes groundwater. About 22% of the Earth’s freshwater is groundwater, which is accessed through wells and supplies most of the daily household, agricultural, and industrial needs. Water Wells Groundwater Contamination Because groundwater supplies much of the Earth’s drinking water, its quality in many countries is closely monitored for contamination. Hard Water Hard water is a natural contamination. As groundwater flows down through the soil and rocks, it dissolves certain minerals. Minerals that are commonly dissolved are calcium, iron and hydrogen sulfide. Human sources of groundwater pollution Septic tank systems that are not properly installed. Human sources of groundwater pollution Septic tank systems that are not properly installed. Pesticides often used on farms and lawns. Landfills. Landfills Human sources of groundwater pollution Septic tank systems that are not properly installed. Pesticides often used on farms and lawns. Landfills. Chemical spills (including oil from cars) Leaking storage tanks Salt used for deicing roadways In Pennsylvania, our groundwater’s overall quality is considered good! How do rivers Begin? They begin when runoff flows along tiny channels known as rills. How do rivers Begin? They begin when runoff flows along tiny channels known as rills. Rills merge to form larger bodies of water called creeks and streams. Creeks and streams merge to form rivers! Stream Characteristics The place where any river or stream begins is known as the source or headwaters. The place where the river empties into another body of water is called the mouth. Rivers of Western Pennsylvania Two Types of Water Flow Laminar flow occurs when water moves in straight paths that are parallel to the streams channel. Thus very little mixing of stream contents occurs. Turbulent flow occurs when water moves in tiny circular paths as it flows downstream. Other Stream Characteristics 1. Velocity – is the distance water flows during a period of time (ie: feet per second) – typically determines if the stream is laminar or turbulent. Determines the kind and amount of sediment, or load, that the water can carry. Other Stream Characteristics 2. Sediment Load – streams are capable of carrying sediment in one of three ways: Dissolved load: the amount of dissolved sediment carried in the water. * Enters the water as it flows over rocks and soil. * Much of the dissolved load comes from groundwater that returns to the Earth’s surface. Other Stream Characteristics Suspended Load – is sediment such as silt and clay that is in suspension. * Most of the streams load is typically suspended. Bed Load – is the sediment that is carried along the bottom of the channel (includes sand, gravel, pebbles) Other Stream Characteristics 3. River Deposits – Sediment that is dropped by the river as the river slows down. Deposits called bars are made from sand and gravel and are found on the inside of a river bed. Stream Bars Other Stream Characteristics 3. River Deposits – Sediment that is dropped by the river as the river slows down. Deposits called bars are made from sand and gravel and are found on the inside of a river bed. Rivers also deposit sediment when they overflow or flood – these areas that commonly are covered during a flood are called flood plains. Flood plains Flood plains are very fertile areas of land often used for farming. Pennsylvania has more miles of streams and rivers per square mile than most states. Major rivers of Pennsylvania 1. 2. 3. 4. 5. Ohio Allegheny Monongahela Genesee Susquehanna 6. 7. 8. 9. Juniata Delaware Lackawaxen Lackawanna Major drainage patterns of Pennsylvania 1. Dendritic Most rivers have this drainage pattern – tends to resemble mature trees. Dendritic drainage patterns are the function of the slope of the land over which the river or stream flows. Dendritic river pattern Major drainage patterns of Pennsylvania 2. Radial Typically form when streams flow from a high central point such as a plateau or volcanic mountain. Radial River Pattern Major drainage patterns of Pennsylvania 3. Rectangular Form when bodies of rock are broken by a series of faults and other fractures in the earth surface. Bends in this type of river pattern are right angles. Rectangular river patterns Rectangular river patterns Major drainage patterns of Pennsylvania 4. Trellis This pattern is a special rectangular river pattern in which the tributary streams are nearly parallel to each other. Form in softer, nonresistant rocks alternating with harder, resistant rocks. Trellis River Pattern The drainage patterns in western Pennsylvania is typically Dendritic.