Transcript The passage of water through a drainage basin

The passage of water through the Drainage Basin
The Drainage Basin System:
Heavy Precipitation Input
Compacts the
ground
Blocks pores with
dust
Reduced
infiltration
Heavy rain passes through
drainage basin quickly
Gradual rain infiltrates more (and
passage is therefore slowed)
More overland
flow (which is
rapid
(more soil erosion)
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
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
Interception storage
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
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
Emerging from an
underground research
facility for studying
interflow during storms.
Throughflow (interflow)
Groundwater (storage)
in aquifers
Groundwater Flow
Overland flow (Flow)
Impervious
surfaces
include any
surface,
paved or
compacted,
that does not
allow
infiltration of
water.
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.
Urbanisation
Many
people think
of parking
lots when
they think of
impervious
surfaces.
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 (1acre +) properties,
to 85% or more in
commercial sites.
Channel flow (becomes
an output)
Storm hydrograph
River run-off
output
Urbanisation
affects shape of
hydrograph
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.
Evaporation (Output)
Transpiration
(output)
Evapotranspiration