The Hydrologic Cycle STREAM SYSTEMS Earth Science Chapter 5 Reading pages 114 124 Earth s Water and the Hydrologic Cycle Oceans not filling up Evaporation precipitation System is balanced Earth s Water and the Hydrologic Cycle The Hydrologic Cycle Hydrologic Cycle The Hydrologic Cycle Precipitation Evaporation Infiltration Earth s Water and the Hydrologic Cycle Runoff Transpiration Running Water Comes from precipitation Transports sediment Erode channels 1 Drainage Basins Area that drains into a stream Separated by drainage divides The Work of Streams Erosion Transportation Deposition Running Water EROSION Depends on velocity Gradient Channel characteristics Discharge The Work of Streams EROSION Lifting loose particles Abrasion Dissolution Running Water CHANNEL CHARACTERISTICS Shape Size Roughness Gradient 2 Running Water Channel Shape GRADIENT Slope of channel Vertical drop channel length Same cross sectional area Channel perimeter about doubled 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 http waterdata usgs gov or nwis uv format gif period 31 site no 14191000 3 Longitunal Profile Longitunal Profile Cross section of length of stream Changes from head to mouth of stream Changes from head to mouth of stream Longitunal Profile Changes from head to mouth of stream Cross section of length of stream Gradient gradually decreases downstream Discharge increases downstream Channel gradient Channel size Discharge Velocity of flow Channel shape Discharge The Work of Streams TRANSPORTATION Three modes of moving material In solution Dissolved load Suspended load Sliding rolling bouncing Bed load The Work of Streams TRANSPORTATION Dissolved load From groundwater runoff and channel Supplies ocean with minerals in solution 4 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 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 Competence vs Capacity CAPACITY Amount of material Depends on discharge Ant has less competence Elephant has greater competence 5 Competence vs Capacity The Work of Streams Greatest competence with greatest velocity Greatest capacity with greatest discharge Maximum during floods Many ants is greater capacity The Work of Streams Erosion Transportation Deposition The Work of Streams DEPOSITION Slowing of velocity Largest particles deposited first ALLUVIUM Alluvial Channel Bedrock Channel High gradient Many rapids and waterfalls http www paul chesterfield btinternet co uk pages landscapes12 htm 6 High Velocity in Center Velocity displaced around meander curve Development of meanders Channel Pattern Natural progression to more meandering channel character http www ucpress edu books pages 6664 6664 ch04 html http www ucpress edu books pages 6664 6664 ch04 html Development of Meanders Stream Processes and Floodplain Development http www ucpress edu books pages 6664 6664 ch04 html Meandering Stream 7 Channel development Channel development Channel development Formation of Oxbow Lake http www ucpress edu books pages 6664 6664 ch04 html Well Established Meandering Stream Oxbow Lakes Oxbow Lake Formation http www ucpress edu books pages 6664 6664 ch04 html 8 Channel Pattern Braided Channel High Gradient Highly variable discharge High coarse sediment load Braided channel develops http www ucpress edu books pages 6664 6664 ch04 html Glacial Stream Dart River South Island New Zealand http www bartholmai com NZ2 WebPages 20NZ2 Pages Image51 html http www geology ucdavis edu gel109 SedStructures Lg AKRiverChannel jpg 9
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