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Influences on Hydrographs - Coggle Diagram
Influences on Hydrographs
Drainage Basin Characteristics
Rock type
Impermeable rocks cause greater peak flow with flashy response
Slopes
Steeper slopes create more overland flow, shorter time lag adn higher peak flow
Porosity of rocks & soils
Impermeable surfaces cause higher overland flow- greater peak flow
Vegetation
Vegetation intercept rainfall-peak flows increase and time lags are reduced.
Density
Lower the drainage density- longer the time lag
Land use
Interception can be reduced with use of impermeable surfaces
Basin size & shape
Smaller and circular drainage basins respond to rainfall quickly
Takes longer for the lower part of the river to respond
Climate
Temperature
Higher temperatures leads to more evaporation therefore less water reaches the river channels
Increased vegetation soaks up more water- less water that reaches river channels peak of the hydrograph is reduced
Moisture
If the ground is already saturated there will be greater overland flow, high peak flow & short time lag
Precipitation
High intensity rainfall- overland flow, steep ring limb & high peak flow
Low-intensity rainfall- goes into the soil and slowly into the rock- increases the time lag and reduces the peak flow
When snow rapidly melts- can cause flooding, high overland flow and high peak flow