The passage of water through the Drainage Basin

The Drainage Basin System:

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)

•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

Heavy Precipitation

And Interception

(Storage)

Interception Storage

http://uregina.ca/~sauchyn/geog327/intercept.html

Leaf cover / breaks fall

Conifers and deciduous trees

Interception slows water passage

Leaf drip / stem flowMore likely to infiltrate

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.

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 (1-acre +) properties, to 85% or more in commercial sites.

urbanisation

Channel flow (becomes an output)

Storm hydrograph

River run-off

output

Urbanisation affects shape of hydrograph

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.

Vegetation Storage

Evaporation (Output)

Transpiration (output)

Evapotranspiration