Term
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Definition
| creates partially contributing areas. Infiltration occurs --> moves laterally --> rises the water table --> PCA |
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Term
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Definition
| The rate at which water moves through soil. Preferably higher conductivity creates lateral movement. As the soil density increases, hydraulic conductivity decreases, this is why there's low hydraulic conductivity at depth. |
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Term
| What influences hydraulic conductivity |
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Definition
-Different soil types and characteristics
- differences in hydraulic conductivity cause perched water tables. |
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Term
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Definition
| Water through fine pores or soil matrix |
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Term
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Definition
Q=Kia
Q=Discharge
K=Hydraulic conductivity
i = gradient (head distance/distance of two points)
a = area of the soil
This works best in the saturated zone. |
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Term
| Hydraulic conductivity in the unsaturated zone |
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Definition
| Hydraulic conductivity varies, it increases as the soil become wetter. There's a displacement effect as water displaces air within pore spaces. |
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Term
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Definition
| This takes into account varying hydraulic conductivity and soil moisture |
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Term
| Measuring hydraulic conductivity |
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Definition
Soil type (sand has a fire higher HC than clay)
Pedotransfer functions convert the characteristics of soil to hydraulic conductivity, this is empirically derived.
-Permeameter
-Guelph Permeameter
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Term
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Definition
Measures hydraulic conductivity/ permeability by obtaining soil samples.
However, these's aren't always done in situ and are often taken into the lab where conditions aren't homogenous with the natural conditions.
However, a Guelph permeameter allows you to do this in situ. |
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Term
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Definition
| rapid movement of water that bypasses the matrix |
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Term
| What creates macropore flow? |
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Definition
Desiccation cracks
-gaps in packing of aggregates
- burrowing, rooting, jointing, gaps in soil
- highly seasonal (in the UK it's far more autumnal and winter based) |
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Term
| How to measure macropores |
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Definition
| -Using food dye and cutting into the surface of the soil. The dye changes the colour of the matrix and leaves the macropores. |
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Term
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Definition
Macropores control a catchments rate of run-off as macropores can dramatically, and rapidly influence the height of the water table and subsequent run-off.
- As macropores end, matrix flow continues as normal
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Term
| Disadvantages of Macropores |
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Definition
| If pesticides are used in agricultural land, they can reach the water table, and even the water catchment very fast, contaminating drinking water for both animals and humans. |
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Term
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Definition
- Large network of micropores
- 3D microdrainage networks
These link different parts of the catchment to the channel/river and increase runoff |
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Term
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Definition
| Deep pipes are easily activated, shallow aren't |
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Term
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Definition
| An underground cave system with flowing water |
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Term
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Definition
Pipeflow: 300mms-1
Overland Flow: 50mms-1
Macropore flow: 3mms-1
Matrix Flow: 0.65mms-1
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