Presentation on theme: "Running Water and Groundwater"— Presentation transcript:
1 Running Water and Groundwater Oceans – 97 %Glaciers/ice – 2 %Freshwater - < 1 %Water cycle = the continuous circulation of earth’s water supplyIt is powered by the sun
2 Evaporation = liquid to gas Condensation = gas to liquid (forms clouds)Precipitation = water (s,l ) returns to earthInfiltration = water that soaks into groundRunoff = water that flows across the groundTranspiration = water that plants release into the atmosphere (gas to liquid)
3 Earth’s water cycle is balanced…if it wasn’t balanced, the earth would tip over and fall out of orbit and crash into the sun.Balanced = earth’s annual precipitation = the amount that evaporatesLocal imbalances do exist like droughts and floods.
4 Stream FlowVelocity is the distance that water travels in a period of time. (some slow some fast)Highest velocities in the center of channelVelocity fastest on the outside bank/bend when a steam bends/curvesThe ability of a stream to erode & transport materials depends largely on its velocity
5 5 Stream Velocity Factors Gradient = slope (how steep or flat)Shape = crooked vs straightSize = wide vs narrow & deep vs shallowRoughness = smooth vs roughDischarge = the volume of water flowing past a certain point per unit of time (m3/s)
6 Stream Profile Changes Profile - a cross-sectional stream viewGradient and roughness decrease as you go downstreamDischarge, velocity, depth, and width increases as you move downstreamThe ability of a stream to erode increases as the discharge increases.
7 Stream Terms Tributary – anything that empties into another stream Base level – the lowest point to which a stream can erode its channelMeander – bends/curves in a river/streamOxbow lake – a meander that gets cut off from the main stream and form a small lake.
8 Stream ErosionThe ability of stream to carry a load is dependent upon 2 factors:Competence - the largest particles the stream is transportingCapacity – the maximum load it can carrySteams generally erode “V” shaped valleys & channels in three waysAbrasionGrindingDissolving soluble materials
9 Stream DepositionAs the stream slows down material/alluvium begins to settle outLarger materials settle out firstDelta – a triangular accumulation of sediment formed where a stream enters a lake/oceanLevee – accumulation of sediment along the river banksRivers carve
10 3 Stages of Stream Development 1 Young – fast, straight, narrow, rapids2 Mature – slower, meanders, wider3 Old – slowest, meanders/oxbows, widest
11 Flooding Flood plain – flat areas along rivers that occasionally flood Flood contribution factors:PavingExcess precipitationMethods of controlDams and leveesLimiting development
12 Drainage basin - the land area that contributes water to a stream Divide – imaginary line that separates one drainage basin of one stream from anotherDrainage patternsDendriticRadialBraidedTrellis/rectangular
13 GroundwaterZone of saturation – area below ground where all the pore spaces are completely filled with waterZone of aeration – all the pore spaces are not completely filled with waterWater table – the line that divides the two
14 Groundwater – It’s Underground Porosity – the percentage of the total volume of rock (or sediment) that consists of pore spacesPermeability – how well water moves through the rock/sedimentWell rounded and well sorted grains = high porosityAquifer – rock layers or sediment that allow groundwater to flow freely (sandstone)Aquitard – does not allow groundwater freely to flow freely (shale)
15 Hot springs – water is heated from magma just below the surface Springs – form whenever the water table intersects the surface of the groundHot springs – water is heated from magma just below the surfaceGeysers – intermittent hot spring/fountain that periodically erupts (Old Faithful)Wells – a hole bored into the zone of saturationA pump is neededCone of depressionArtesian wells – groundwater rises on its own under pressure and no pump is neededRead pages 175/176 (env probs)
16 Caverns A naturally formed underground chamber Usually forms in limestone from carbonic acid dissolving the rockTravertine – Calcium carbonate depositsStalactites, stalagmites, soda straws, curtains/ribbons, flowstone, etcKarst topography – limestone areas with many caves and sinkholes (collapsed caves)