The study figure in Fig. 1 shows a steep island catchment before and after a cyclone. Before the storm, dense forest covered most slopes. Afterwards, severa...
Question 1 Report
The study figure in Fig. 1 shows a steep island catchment before and after a cyclone. Before the storm, dense forest covered most slopes. Afterwards, several slopes have lost trees and a river carries muddy water to the coast. Relief workers need to decide where to restore vegetation first. The resource booklet fig indicates that rainfall intensity was high, but it gives no numerical data table. Use the diagram to consider stores, transfers and the effects of vegetation removal.
(a) Name the water transfer from cloud to land during the cyclone. [1]
(b) Identify one change to a water store after trees are removed. [2]
(c) Describe how forest canopy affects rainfall before it reaches the ground. [3]
(d) Explain why deforestation can make river water muddier during a storm. [6]
(e) Which process carries water through soil towards the river after infiltration? [2]
(f) State two reasons why restoring trees may lower future flood risk. [3]
(g) What term describes water flowing over the surface towards the river? [2]
Answer Details
(a) Water moving from cloud to land is precipitation. [1]
(b) Tree removal decreases the interception store, because there are fewer leaves and branches holding rain. Water stored in vegetation also decreases. [2]
(c) The forest canopy intercepts rainfall, holds it temporarily on leaves and branches, and delays or reduces the amount striking the ground directly. [3]
(d) Removing trees leaves soil exposed and reduces interception. More rain becomes rapid surface runoff. Fast runoff has energy to erode loose soil, carrying sediment into streams. The sediment makes the river muddy or turbid. [6]
(e) Water moving through soil towards a river after infiltration is throughflow. [2]
(f) Restoring trees increases canopy interception and roots improve infiltration. Roots also bind soil, while vegetation slows runoff. Any two. [3]
(g) Water flowing over the land surface towards the river is surface runoff, or overland flow. [2]
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