Final Exam Running Water Erosion and Deposition Earth Science Chapter 5 Pages 120 135 Scheduled for 8 AM March 21 2006 Bring A scantron form A calculator Your 3 x 5 paper card of formulas Review questions due next time March 16 2006 will not be accepted late because key will be posted on website Running Water Discharge Calculation DISCHARGE Volume of water flowing past a point in a certain amount of time Cross sectional area x velocity Gaging station Running Water http www waterwatch org au library module 4 flow html 10 Willamette Discharge Data 2006 March 9 http waterdata usgs gov or nwis uv format gif period 31 site no 14191000 1 Willamette Discharge Longitunal Profile Cross section of length of stream Changes from head to mouth of stream Data 2006 March 14 http waterdata usgs gov or nwis uv format gif period 31 site no 14191000 Longitunal Profile Longitunal Profile Changes from head to mouth of stream Channel gradient Channel size Discharge Velocity of flow Channel shape Discharge Changes from head to mouth of stream Cross section of length of stream Gradient gradually decreases downstream Discharge increases downstream The Work of Streams TRANSPORTATION Three modes of moving material In solution Dissolved load Suspended load Sliding rolling bouncing Bed load 2 The Work of Streams TRANSPORTATION Dissolved load From groundwater runoff and channel Supplies ocean with minerals in solution The Work of Streams TRANSPORTATION Bed load Too large to keep suspended Grinds channel and downcuts TRANSPORTATION COMPETENCE Size of particles Depends on velocity V competence 2 The Work of Streams TRANSPORTATION Suspended load Most of material transported Sand silt clay Larger particles in flood The Work of Streams TRANSPORTATION Competence Capacity TRANSPORTATION CAPACITY Amount of material Depends on discharge 3 Competence vs Capacity Ant has less competence Elephant has greater competence The Work of Streams Greatest competence with greatest velocity Greatest capacity with greatest discharge Maximum during floods Stream Valleys Competence vs Capacity Many ants is greater capacity The Work of Streams Erosion Transportation Deposition Channel development V shaped Wide with flat floors 4 Stream Valleys Bedrock Channel V shaped Wide with flat floors High gradient Many rapids and waterfalls http www paul chesterfield btinternet co uk pages landscapes12 htm Broad flat bottomed Valley Channel Pattern Low gradient Stream cuts into valley walls Mass wasting delivers sediment to stream Natural progression to more meandering channel character http www ucpress edu books pages 6664 6664 ch04 html The Work of Streams High Velocity in Center DEPOSITION Slowing of velocity Largest particles deposited first ALLUVIUM 5 Alluvial Channel Velocity displaced around meander curve Channel development Stream Processes and Floodplain Development Meandering Stream Development of meanders Development of Meanders http www ucpress edu books pages 6664 6664 ch04 html http www ucpress edu books pages 6664 6664 ch04 html 6 Channel development Oxbow Lakes Oxbow Lake Formation Formation of Oxbow Lake Oxbow Lakes Oxbow Lake Formation Well Established Meandering Stream http www ucpress edu books pages 6664 6664 ch04 html Channel Pattern High Gradient Highly variable discharge High coarse sediment load Braided channel develops http www ucpress edu books pages 6664 6664 ch04 html 7 Braided Channel Glacial Stream Dart River South Island New Zealand http www ucpress edu books pages 6664 6664 ch04 html http www bartholmai com NZ2 WebPages 20NZ2 Pages Image51 html Base Level Resistant bed creates a local base level http www geology ucdavis edu gel109 SedStructures Lg AKRiverChannel jpg Base Level Base Level Over time the resistant bed is eroded Local base level becomes closer to ultimate base level 8 Base Level Base Level Ultimate profile is idealized graded stream Gradual decrease in gradient from head to mouth Eventually resistant rock is eroded to ultimate base level Erosion by Streams Headward Erosion Erode to BASE LEVEL Ultimate base level Local base level temporary Cannot erode below base level http www lib utexas edu maps new mexico html http www lib utexas edu maps national atlas 1970 ca000043 large jpg Headward Erosion Stream Valleys V shaped Wide with flat floors http www lib utexas edu maps colorado html 9 Broad flat bottomed Valley Low gradient Stream cuts into valley walls Mass wasting delivers sediment to stream Deposition SLOWING OF VELOCITY Decrease in gradient Decrease in discharge Loss of channelization Flood stage Body of water Deposition Flows into a body of water Creates delta Delta Formation Flood stage gets out of its deposit Forms set of DISTRIBUTARIES Delta Formation Deposition decreases gradient Flood stage gets out of its deposit Delta Formation Forms set of DISTRIBUTARIES 10 Mississippi Delta Deposition SLOWING OF VELOCITY Loss of channelization Body of water Flood stage Stream Processes and Floodplain Development Natural Levee Creation Competence lost when stream leaves its channel Deposits largest particles first http www ucpress edu books pages 6664 6664 ch04 html Natural Levee Formation Natural Levees Natural Levees 11 Yazoo River Alluvial Fan http wiseman brandonu ca earthscience newpage35 htm http www mvk usace army mil offices pp yazoobackwater basics asp category basics Alluvial Fan Drainage Patterns Channel layout within a drainage basin Described by overall shape formed Dentritic Radial Rectangular Trellis Badwater Fan Death Valley California http www windows ucar edu earth geology images alluvial fan lg jpeg 12 13
View Full Document
Unlocking...