The Storm Hydrograph Flashcards
What is peak discharge?
The highest discharge in the period of time you’re looking at
What is river discharge?
The volume of water flowing in a river
What is lag time?
The delay between peak rainfall and peak discharge
What is rising limb?
The increase in river discharge as rainwater flows into the river
What is falling limb?
The decrease in river discharge as the river returns to its normal level
Why does lag time happen?
Because most rainwater doesn’t land directly in the river channel
Name 3 factors that increase discharge?
High rainfall. Intense rainfall. Impermeable rock-can't infiltrate. Previously wet conditions. Steep slopes. Less vegetation.
Name 3 factors that decrease discharge?
Low rainfall. Light rainfall Permeable rock-can infiltrate. Previously dry conditions. Gentle slopes. More vegetation.
What causes flooding?
When the level of a river gets so high that it spills over its banks onto the flood plain
Name the physical factors that causes a river to flood?
Prolonged rainfall. Heavy rainfall. Snowmelt. Relief. Geology.
What is prolonged rainfall?
After a long period of rain, the soil becomes saturated. Any further rainfall can’t infiltrate, which increases runoff into rivers.
What is relief?
When a river is in a steep-sided valley, water will reach the river channel much faster because water flows more quickly
What is geology?
When a river is in an area of impermeable rock, water doesn’t percolate into the rock but flows on the surface
Name 2 human factors that causes rivers to flood?
Deforestation and urbanisation
