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  1. Hydrosphere Surface Water and the Water Cycle

  2. Goals for This Unit Explain the structure and processes within the hydrosphere • Explain how water is an energy agent (currents and heat transfer) • understand the role of water in weather and atmospheric change • use concepts of fluid density to describe global water movement and ocean currents and their effect in distributing heat around the globe • Explain how ground water and surface water interact • understand the concepts and dynamics of river systems with emphasis and examples drawn from NC river systems • list and describe common methods used to conserve both water quantity and quality

  3. How Do You Use Water?

  4. The Water Cycle • A never-ending natural circulation of water through Earth’s systems powered by the Sun

  5. Steps of the Water Cycle • Precipitation – rain, snow, hail, sleet • Runoff or ground seep • Reservoir – living things, snowfields, glaciers, lakes, oceans • Evaporation – from land or bodies of water • Transpiration • Condensation

  6. Runoff V/S Ground Seep • Vegetation • more vegetation = more ground seep • less vegetation = more runoff • Rate of Precipitation • lighter rainfall = more ground seep • harder rainfall = more runoff • Soil composition • high humus, coarse particles = more ground seep • low humus, fine particles = more runoff • Slope • flatter slope = more ground seep • steep slope = more runoff

  7. Stream Systems • Some runoff flows into brooks, creeks, streams and rivers that eventually empty into lakes and oceans • Watershed – all the land area whose water drains into a stream system • Stream load – all the materials (living and non-living) that the water in a stream carries • Carried in three ways – solution, suspension, bed load

  8. Solution • When material has dissolved in a stream’s water • Dependent upon the material a stream has passed through • High amounts of calcium carbonate and magnesium • Groundwater provides most of the dissolved load to streams • Expressed in parts per million (ppm)

  9. Suspension • Particles small enough to be held up by the turbulence of a stream’s moving water • Dependent upon volume and velocity of the stream • Faster moving water = larger particles

  10. Bed Load • Sediments too large or heavy to be held up by turbulent water • Consists of sand, pebbles, cobbles that are rolled and pushed along the stream bed • Abrasion – particles rubbing and scraping against one another as they tumble in the water • Erodes not only sediments in water but also sides and bottom of stream itself

  11. Stream Carrying Capacity • Amount of material a stream can transport • Depends upon velocity and amount of water moving in the stream • Affected by channel slope, depth and width • Discharge – measure of the volume of stream water that flows over a particular area within a given period of time • Discharge(m3/s) = width(m) X depth(m) X velocity(m/s) • As discharge increases carrying capacity increases • Impacted by heavy rain, flooding, rapid melting of snow

  12. Floods • Floodplain – broad, flat area extending out from a stream’s bank that is covered by excess water during times of flooding • As flood water recedes it deposits sediments in the floodplain that develop highly fertile soil • Upstream flooding – local • Downstream flooding - widespread • Monitoring of streams is provided by the National Weather Service, weather satellites and the US Geological Survey (USGS)

  13. Water Cycle Project • Please draw the water cycle • Criteria • Must be accurate • Must be neat • Must be on plain paper • Must be colored • DUE Tuesday 25 September

  14. Hydrosphere Stream Development

  15. A Stream is Born • Precipitation provides the water for the beginnings of stream formation • Headwater – region where water first accumulates to supply a stream • Stream channel – narrow pathway carved into sediment or rock by stream waters • Stream capture – when a stream erodes the area separating two drainage basins, joins another stream and then draws away its water

  16. Stream Valleys • V-shaped channels caused by erosion from streams • Grand Canyon, Colorado River • Streams continue to erode until they reach their base level, the point where they enter another stream or body of water • Lowest possible base level is the ocean • Eventually v-shaped valleys erode into broader valleys with gentle slopes

  17. Meandering Streams • Meander – bend or curve in a stream channel • Velocity differences • Straight stream: fastest in the center, slower on the sides and bottom • Meander: fastest along the outside of a curve, deposition occurs on inside of curve where water slows • Over time meanders become more accentuated • Mouth – area of a stream that empties into another body of water

  18. Sediment Deposition • Occurs as streams slow (lose velocity) • Alluvial fan – occur when mountain streams flow into broad, flat valleys • Usually found in dry, mountainous regions • Usually composed mostly of sand and gravel • Delta – occur when streams join larger bodies of quiet water • Usually form a triangle shaped deposit • Usually composed of silt and clay particles

  19. Alluvial Fan

  20. Deltas

  21. Stream Rejuvenation • Downcutting – wearing away of a streambed • Stops when a stream reaches its base level • Rejuvenation – occurs when downcutting resumes due to land uplift of the stream bed or lowering of the base level • Creates v-shaped valleys • In meanders, creates deep sided canyons

  22. Hydrosphere Lakes and Freshwater Wetlands

  23. Lakes • Form from many sources • Streams, runoff, local precipitation, springs, etc • Created two ways • Man Made • Ponds – livestock, fish supplies, attract wildlife • Reservoirs – stores water for human use • Naturally Formed • Oxbow • Landslides • Remnants of prehistoric lakes • Glaciers • Dissolved limestone

  24. Glacier Lakes • Moraine-dammed • Form when glacial moraines dam some depressions and restrict outward flow of water • Cirque • Form when cirques that are carved out by high valley glaciers fill with water • Kettle • Form when water fills depressions left by blocks of ice from melting glaciers

  25. Changing Lakes • Exist for long periods of time as long as the supply of water is more than what is removed by evaporation and human use • Some only exist during times of heavy rains • Over time (100,000+ years) will eventually fill with sediment and become part of the landscape

  26. Eutrophication • Process by which lakes become rich in nutrients from the surrounding watershed, which results in a change in the kinds of organisms in the lake • Photosynthesis (plants) add oxygen and waste products to the lake • Animals in the lake use the oxygen and add their waste to the lake • Decay of dead animals and plants also uses dissolved oxygen supplies • Amount of dissolved oxygen helps determine the health of a lake and if it can support life

  27. Rates of Eutrophication • Increases with addition of nutrients • Nitrogen and phosphorus from fertilizer • Animal wastes • Phosphate detergents • Release of toxins from industry and untreated sewage • Additional nutrients causes excessive algae to grow • Causes organisms that eat the algae to multiply • Overpopulation and decay of large numbers of plant and animals consumes the oxygen supply • The lake eventually dies

  28. Freshwater Wetlands • Land area covered with water most of the year • Include bogs, marshes, swamps • Have certain soil types that support specific plant species

  29. Bogs • Receive water only from precipitation • Soil is waterlogged • Rich in sphagnum (peat moss) • Peat moss breakdown produces acid • Acidic soil supports unusual plant species • Pitcher plants • Sundew • Venus flytrap

  30. Marshes • Common along the mouths of streams and in areas with large deltas • Constant supply of water • Shallow roots of marsh grasses allow for capture of silt and mud that slows water flow and expands the marsh • Diverse wildlifeand plants • Birds, fish, reeds, grasses, sedges and rushes

  31. Swamps • Low-lying areas often near streams • May develop from marshes as they fill-in • Support the growth of larger plants such as trees and bushes • Because of increased shade, marsh grasses begin to die • Present day coal reserves were once swamps 250 million years ago

  32. Importance of Wetlands • Help improve water quality • Trap pollutants, sediments, pathogenic bacteria • Provide vital habitat for migratory water birds and other wildlife • Between 1700 to 1985 the US lost 50% of its wetlands • Wetlands are often filled-in to make space for people • New York City (Queens, Brooklyn) • New Oreleans • Washington, DC