Storm hydrographs - flashy or flat?

Short lag time, high peak, steep rising limb

• Flashy

• Flat

Intense storm which exceeds the infiltration capacity of the soil.

Rapid snow melt as temperatures suddenly rise above zero.

Low evaporation rates due to low temperatures

• Flashy

• Flat

Elongated basins tend to have delayed or attenuated hydrographs

• Flashy

• Flat

High drainage density means more streams and rivers per unit area, so water will move quickly to the measuring point.

• Flashy

• Flat

Permeable rocks, such as limestone, which allow percolation and so limit rapid surface run off

• Flashy

• Flat

High infiltration rate, such as sandy soils (3-12mm/h)

• Flashy

• Flat

High steep slopes that promote surface run-off

• Flashy

• Flat

Larger basin

• Flashy

• Flat

Vegetation is dense, deciduous in summer

• Flashy

• Flat

Basin already wet from previous rain, water table high, saturated soil so low infiltration/percolation

• Flashy

• Flat