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The passage of water through the Drainage Basin

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Presentation on theme: "The passage of water through the Drainage Basin"— Presentation transcript:

1 The passage of water through the Drainage Basin

2 The Drainage Basin System:

3 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)

4 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

5 Interception Storage Leaf cover / breaks fall Conifers and deciduous trees Interception slows water passage Leaf drip / stem flow More likely to infiltrate

6 Interception storage

7 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

8 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

9 Emerging from an underground research facility for studying interflow during storms.
Throughflow (interflow)

10 Groundwater (storage) in aquifers

11 Groundwater Flow

12 Overland flow (Flow) Impervious surfaces include any surface, paved or compacted, that does not allow infiltration of water.

13 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.

14 Urbanisation Many people think of parking lots when they think of impervious surfaces.

15 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.

16 Channel flow (becomes an output)

17 Storm hydrograph River run-off output

18 Urbanisation affects shape of hydrograph

19 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.

20 Evaporation (Output)

21 Transpiration (output)

22 Evapotranspiration


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