GEOG209 Lecture Notes - Lecture 7: Surface Runoff, Hydrograph, Water Table
13 Jun 2016
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Document Summary
Surface runoff two types: hortonian overland flow, saturated overland flow. Runoff (subsurface or surface) from land to ocean is the difference between precipitation and evaporation on land. Runoff: the portion of precipitation that reaches a natural channel after loss by evaporation, transpiration and soil moisture changes: can be on or below the surface, varying speeds, moves towards oceans via streams/channels. Streamflow (q, m3 s-1), runoff (q, m3 s-1, q or in mm) Regulated by such factors as landforms, soils and veg. , activities of human. Precipitation flows overland or through the soils to the streams. Basin morphology (size, orientation, land covers, slope) all influence hydrograph (stream flow) response. Occurs when infiltrated water encounters an impervious layer. Generates lateral flow above the water table. Roots, earthworms, voles/moles can create macropores that greatly increase water velocity. Runoff: infiltration capacity infiltration capacities of soil are higher with increasing grain size. Infiltration occurs when precipitation intensity < infiltration capacity.
