The passage of water through the Drainage Basin

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The passage of water through the Drainage Basin
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The Drainage Basin System
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Heavy Precipitation Input
Compacts the ground Blocks pores with
dust Reduced infiltration More overland flow
(which is rapid (more soil erosion)
Heavy rain passes through drainage basin
quickly Gradual rain infiltrates more (and
passage is therefore slowed)
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Heavy Precipitation
And Interception (Storage)

• water can be delivered too quickly for the plants
  to accommodate
• a larger proportion of low intensity
  precipitation will be intercepted as the storage
  capacity is created by drippage and stemflow

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Interception Storage
Leaf cover / breaks fall Conifers and deciduous
trees Interception slows water passage
Leaf drip / stem flow More likely to infiltrate
http//uregina.ca/sauchyn/geog327/intercept.html
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Interception storage
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Surface storage
Puddles fill up when it rains (slows passage) Can
infiltrate if ground porous/permeable Can run-off
as overland flow if too much rain or if ground
impermeable Can evaporate if weather improves
Here the puddle is frozen
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Infiltration rates (flow)
Infiltration into the soil Rate may change over
time Rate may vary according to type of
vegetation If infiltration capacity exceeded
Then overland flow occurs
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Emerging from an underground research facility
for studying interflow during storms.
Throughflow (interflow)
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Groundwater (storage) in aquifers
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Groundwater Flow
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Overland flow (Flow)
Impervious surfaces include any surface, paved or
compacted, that does not allow infiltration of
water.
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Overland flow on pavement
Water flows over the surface of the compacted
soil or pavement, picking up pollutants as it
moves. The contaminated water will enter a
natural drainage, a man-made drainage, or a storm
drain. In all three cases, the water ends up in
a water body with no treatment for pollutants.
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Urbanisation
Many people think of parking lots when they think
of impervious surfaces.
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urbanisation
Most of the land in this photo could be
considered to be impervious surface. Impervious
cover ranges from 20 or less on single family
large-lot (1-acre ) properties, to 85 or more
in commercial sites.
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Channel flow (becomes an output)
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Storm hydrograph
River run-off output
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Urbanisation affects shape of hydrograph
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Vegetation Storage
GREEN GARDENING advice from WESSEX WATER Certain
plants are particularly well suited to dry
conditions, such as succulents, sedums and cacti
which have thick waxy leaves to store
water.Some plants and grasses have fleshy roots
and others such as poppies, reach deep into moist
areas in the soil.
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Evaporation (Output)
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Transpiration (output)
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Evapotranspiration
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