Discharge relationships within drainage basins

Question 1

Storm Hydrographs

Answer 1

Shows how the discharge of a river varies over a short period of time

Question 2

Drainage Density

Answer 2

Relates to the efficiency by which water is carries over the landscape
Low drainage density comes as a result of lower peak discharge and longer lag time

Question 3

Rock Type

Answer 3

Permeable rock keeps the peak discharge low and lag time longer and so results in a lower drainage density
Impermeable rock therefore results in a higher drainage density

Question 4

Soil Type

Answer 4

Thin soil has a very short lag time and a very high peak discharge as it can’t absorb as much water so it moves quickly into rivers via throughflow therefore resulting in a higher drainage density
Thicker soil therefore has a lower drainage density

Question 5

Natural Vegetation

Answer 5

Forests store more water via interception and so have huge interception stores
This means they have a lower peak discharge and higher lag time
Moorland has low levels of interception and so water moves quickly into the ground through stemflow
This means they have a higher peak discharge and a lower lag time

Question 6

Land Use

Answer 6

Urban areas have high levels of surface runoff due to more impermeable surfaces like tarmac
The lag time is shorter and the peak discharge is higher as cities are built to not flood so water enters the rivers quickly
Rural areas have longer lag times as water has to travel through the soil by groundflow

Question 7

Use of River

Answer 7

Limited use of rivers results in a higher discharge as there are no dams blocking the flow of water
Rivers with dams have lower peak discharge as dams restrict water flow and disrupt the natural flow of water