454 lecture 5 DRAINAGE BASINS A drainage basin or watershed is defined from a downstream point, working upstream, to include all of the hillslope & channel areas which drain to that point Each basin is surrounded & defined by a drainage divide (high point from which water flows away) Channel initiation Type of downslope movement of precipitation depends on 1) infiltration capacity of surface, which is controlled by soil texture & structure antecedent moisture vegetation other surface conditions 2) intensity and duration of precipitation
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DRAINAGE BASINS - Sites · The morphology of a drainage basin can be viewed as the connection between the way water moves into the basin, & the way it moves out. 454 lecture 5 Water
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454 lecture 5
DRAINAGE BASINS
A drainage basin or watershed is defined from a downstream
point, working upstream, to include all of the hillslope &
channel areas which drain to that point
Each basin is surrounded & defined by a drainage divide
(high point from which water flows away)
Channel initiation
Type of downslope movement of precipitation depends on
1) infiltration capacity of surface, which is controlled by
soil texture & structure antecedent moisture
vegetation other surface conditions
2) intensity and duration of precipitation
454 lecture 5
water moving downslope as runoff moves rapidly & has erosive
ability:
precipitation
soil
profile
zone of
percolation
water tableground water
Hortonian overland flowsaturation overland flow
throughflow
groundwater flow
runoff
channels begin to develop when the erosive force, F
(function of slope angle, water depth) of the overland flow
exceeds the resistance, R (function of vegetation, nature of
surface) of the surface being eroded
454 lecture 5
Stages of overland flow
• rainbeat – impact cratering
• thread flow – integration of raindrops, flow around surface grains
• sheet flow – integration of thread flow, water level rises above