Overland flow is the portion of water which cannot infiltrate the surface so has to travel over the ground surface towards a stream channel. Water (from the Old English word wæter) is a colorless, tasteless, and odorless substance that is essential to all known forms of life and is known also as the most universal solvent. ...
This is further split into 2 categories
Infiltration excess overland flow - occurs when water cannot infiltrate the surface because the maximum rate of infiltration has been exceeded.
Saturation excess overland flow - occurs when the surface is saturated preventing soil from infiltrating.
High rates of overland flow are found in urban areas as concrete and asphalt surfaces do not allow for infiltration of water. This article is about the construction material. ... Asphalt is a highly viscous liquid that occurs naturally in most crude petroleums. ...
Overlandflow, then, is directly related to Precipitation intensity and inversely related to Infiltration capacity and Evaporation: O = P - I - E d.
Normally, the rate of overland erosion in humid climates is slow enough to allow a chemically profiled true soil to develop and maintain itself and the plant communities dependent on it.
Steep slopes subjected to heavy precipitation may form rills, small gouges in the slope, as tiny irregularities in the surface begin to channel overlandflow (this is sort of the transition to channeled or stream flow, actually).
Normalized total flow to the stream from the flowpath is shown in Figure 1, along with normalized stream flow from the W-9 watershed as a whole.
Figure 2 also shows that during low-recharge conditions, saturation overlandflow comes to a halt and all of the flow reaching the stream is as base flow.
For the period simulated (which represents the highest recharge rates of the year) the primary factors controlling flow to the stream were the hydraulic conductivity of the stream and the hydraulic head generated by recharge throughout the watershed.
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