Hydrographs And River Regimes

Question 1

River regime

Answer 1

• changes in a rivers discharge over the course of a year in response to a number of factors

Question 2

River discharge

Answer 2

• volume of water that flows in a river per second
  River discharge = velocity x csa

Question 3

Flashy hydrograph

Answer 3

• has a short lag time and high peak discharge (has rapid in off and not much storage

Question 4

Peak discharge

Answer 4

• the highest point on the graph when river discharge is at its greatest

Question 5

Lag time

Answer 5

• delay between peak rainfall and peak discharge —> shorter lag time = increased peak discharge

Question 6

Rising limb

Answer 6

• part of the graph up to peak discharge = river discharge increases as rainwater flows into the river

Question 7

Falling limb

Answer 7

• after peak discharge = shows the river level as it falls

Question 8

What factors affect the run off and hydrographic shape?

Answer 8

• size of drainage basin = larger basins catch more precipitation, smaller basins —> shorter lag time
• shape of drainage basin = circular basins —> more flashy hydrographs compared to long narrow basins
• ground steepness = water flows more quickly downhill in steep sided basins
• rock and soil type = impermeable rocks don’t store water or let infiltration happen —> increases surface run off