Rivers- Physical Factors that affect the Storm Hydrograph

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How does a Larger Drainage Basin affect Lag Time and Peak Discharge?
Larger drainage basins catch more precipitation, so have higher peak discharge compared to smaller basins. But smaller basins generally have shorter lag times because precipitation has less distance to travel, so reaches the main channel quicker.
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How does having a Steep-Sided drainage basin affect Lag Time and Peak Discharge?
Steep-Sided drainage basins have shorter Lag Times than shallower basins- water flows more quickly downhill into the river on steep slopes. This can also increase peak discharge.
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How do Circular basins affect Lag Time and Peak Discharge?
Circular basins are more likely to have a flashy hydrograph than long, narrow basins- as all points on the watershed are roughly the same distance from t point of discharge measurement- so lots of water will reach the measuring point together- inc.PD
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How do basins with High Drainage Density affect Lag Time and Peak Discharge?
Basins with lots of streams (HDD) drain quickly, so have shorter Lag Times.
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How does the amount of water already present in the drainage basin (antecedent moisture) affect Lag Time?
If the ground's already waterlogged then infiltration is reduced and surface run-off increases. Surface run off is much faster then throughflow or baseflow, so rainwater reaches the river more quickly, reducing Lag Time.
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How does Rock Type affect Lag Time and Peak Discharge?
Impermeable rocks don't store water or let water flow through them. This reduces infiltration and increases surface run off, reducing Lag Time. Peak Discharge also increases as more water reaches the river in a shorter period.
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How does Soil Type affect Lag Time and Peak Discharge?
Sandy soils allow a lot of infiltration, but clay soils have very low infiltration rates. Low infiltration rates increases surface run-off, reducing Lag Time and increasing Peak Discharge
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How does Vegetation affect Lag Time and Peak Discharge?
Veg intercepts precipitation and slows its movement to the river channel, increasing Lag Time. As well as this, the more veg there is in a basin, the more water is lost (evapo+transp) before it reaches the river channel, reducing Peak Discharge.
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How does Precipitation affect Peak Discharge?
Intense storms will create more precipitation and so greater Peak Discharges than light rain showers. The type of precipitation also affects Lag Time e.g snow that's fallen in a winter storm can melt and flow into the river in spring= v.long Lag Time
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How does Temperature affect Lag Time and Peak Discharge?
Hot, dry conditions and cold, freezing conditions both result in hard ground. This reduces infiltration and increases surface runoff- reducing Lag Time and increasing Peak Discharge.
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Other cards in this set

Card 2

Front

How does having a Steep-Sided drainage basin affect Lag Time and Peak Discharge?

Back

Steep-Sided drainage basins have shorter Lag Times than shallower basins- water flows more quickly downhill into the river on steep slopes. This can also increase peak discharge.

Card 3

Front

How do Circular basins affect Lag Time and Peak Discharge?

Back

Preview of the front of card 3

Card 4

Front

How do basins with High Drainage Density affect Lag Time and Peak Discharge?

Back

Preview of the front of card 4

Card 5

Front

How does the amount of water already present in the drainage basin (antecedent moisture) affect Lag Time?

Back

Preview of the front of card 5
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