CGF3M Dynamics of Moving Water CGF3M

Dynamics of Moving Water  The Hydrosphere  Hydrologic Cycle Infiltration Runoff  Stream Flow Velocity Discharge Flow

CGF3M Hydrologic Cycle Condensation Precipitation Infiltration Runoff Evaporation

CGF3M Hydrologic Cycle  Infiltration: precipitation that seeps into the ground.  Factors affecting infiltration:  Interparticle size – the size and connectedness of the particles in the ground, eg., sand vs clay  Vegetation (associated organisms) – loosen the soil.  Rainfall intensity  Seasonal factors, eg., freezing of the ground  Permafrost – is there any, its depth  Urban landscape - paving, buildings, etc.

CGF3M Hydrologic Cycle  Infiltration con’t:  When rain falls, the first type of erosion is splash erosion.  Raindrop impacts reduce infiltration rate because the soil particles become more compacted movement of material downhill.

CGF3M

Hydrologic Cycle  Runoff: flow of water from the land as both surface and subsurface discharge.  Occurs when rate of precipitation is greater than rate of infiltration.  Usefulness: recreational, sewage disposal, domestic, irrigation, food source, hydroelectric power, etc.

CGF3M Hydrologic Cycle  Runoff Categories:  Surface Runoff/Overland flow:  excessive overland flow can lead to sheet erosion forming small rills or tiny rivers.  can include Channel Flow (water traveling in a river or stream).  Subsurface Runoff/Ground Water:  travels beneath the surface towards a body of water.

CGF3M Stream Flow  The velocity (speed) of flow in a river is controlled by:  Gradient  Friction due to resistance of water on the bed of the channel.  Volume

CGF3M Stream Flow  Discharge: volume of water that flows past a given point can be determined by the following factors:  Q = A x V Q is discharge A is cross-sectional area of stream V is mean velocity (in m3/sec usually)

CGF3M Stream Flow  Load: ability of a stream to carry load of solid material varies with discharge, velocity and particle size.

CGF3M