Hydrographs and Discharge Flashcards
What is discharge?
The volume of water passing a gauging station in a river at a particular time
What is discharge measured in?
Cumecs (cubic metres per second) (m3/5)
Name the 6 different things that affect the discharge
- Basin size (shape and relief)
- rock type
- soil type
- temperature
- precipitation
- land use
How does the basin size(shape and relief) affect the amount of discharge?
Small basin- water takes longer to reach the rivers
Large basin- high peak discharge (catch more precipitation)
How does soil type affect the amount of discharge?
Rural(farmland)- water gets absorbed- increases peak discharge
Urban(city)- impermeable
How does temperature affect the amount of discharge?
Hot and cold- ground will be hard
Dry(summer) - water will be absorbed
Cold- encouraged overland flow
How does precipitation affect the amount of discharge?
Rain- increases discharge
Snow + frost - when frozen, reduces discharge until it melts= increasing discharge
What does a hydrograph show?
Discharge
Amount of rainfall
Lag time
What does the X & Y axis show on a hydrograph?
X - time
Y - increase rainfall & discharge
What does a rising limb (steep or shallow) show?
The rising flood water in the river (water building up)
What does a falling/receding limb show?
Falling flood water in the river
What is the lag time?
difference between peak rainfall and peak discharge
What is peak discharge?
Most amount of discharge through the storm (when the river flows quickest)
What is peak rainfall?
Most amount of rain at a certain point/time
What is base flow?
Normal flow rate of water in the river
