Physical factors affecting hydrographs

Question 1

How do drainage basin characteristics affect hydrographs?

Answer 1

Large drainage basins catch more precipitation and have a higher peak discharge.
Steep-sided basins have short lag times. This can increase peak discharge
Circular basins have a flashy hydrograph, because all points on the watershed are roughly the same distance from the point of discharge measurement
Basins with lots of streams drain quickly and have shorter lag times

Question 2

How does amount of water in the drainage basin affect hydrographs?

Answer 2

Is the ground’s waterlogged, the infiltration is reduced and surface runoff increases. Rainwater reaches the river quicker

Question 3

How does rock type affect hydrographs?

Answer 3

Impermeable rocks reduce infiltration and increases surface runoff, reducing lag time. Peak discharge increases

Question 4

How does soil type affect hydrographs

Answer 4

Sandy soils allow lots of infiltration, but clay soils have low infiltration rates, which can increase surface runoff and peak discharge and reducing lag time

Question 5

How does vegetation affect hydrographs?

Answer 5

Vegetation intercepts precipitation, increasing lag time

The more vegetation, the more water is lost, reducing peak discharge

Question 6

How does precipitation affect hydrographs?

Answer 6

Intense storms will generate more precipitation, so greater peak discharge
Type of precipitation also affects lag time, snow that’s fallen melts in the spring, give a very long tag time

Question 7

How does temperature affect hydrographs?

Answer 7

Hot and freezing conditions result in hard ground, reducing infiltration and increases surface runoff.
High temperatures can increase evapotranspiration, so less water reaches the river channel, reducing peak discharge