1(a) Using well-labelled diagrams only, explain how a waterfall and plunge pool is formed. [6]




(b) In managing river discharge, many countries have built dams, like the one in Fig. 1. Discuss the threats they pose to the human and physical environment
in employing such methods. [6]






(c) With reference to Fig. 2B which shows a sketch of the photo in Fig. 2A, explain how features Y and Z are formed by marine processes.[5]



(d) Study Fig. 2B, identify and evaluate suitable measures at the respective
places to protect tourists’ beach at X and the area at Z. [8]








Suggested answers


1 (a) Using well-labelled diagrams only, explain how a waterfall and plungepool is formed. [6]

Diagrams- 2m…..

4-5 diagram s— must show development of waterfall and the deepening of plunge pool

DRAW DIAGS

Waterfall
-sill, More Resistant rocks
-Less Resistant rocks lies downstream
-as river flows downstream
-dominant erosional processes- abrasion
-pebbles and rocks chiseled into the bed of the river
-causes the Less Resistant to erode more than the More Resistant
-changes in gradient of river channel
-steeper after prolong erosion, river flows over the steeper gradient that develop on the river bed
-As the water plunges over the steep gradient formed to the river bed below
-A waterfall is formed
-the sheer force of the water plunging [hydraulic action] over a steep gradient
-and the grinding action from eroded rocks and pebbles that are carried by the river
-leads to the formation of a plunge pool
-abrasion- widens and deepens the pool
-hydraulic action-deepens also
-so at base of waterfall a deep plunge pool forms

(b) In managing river discharge, many countries have built dams, like the one in Fig. 2. Discuss the threats they pose to the human and physical environment in employing such methods. [6]

Human environment

· Financial costs that must be incurred in
o construction of those structure.
o Maintenance of these structures, if not
· Poor maintenance will lead to cracks, which will lead to degeneration due to heavy rainfall and so structures will give way which will lead to the flooding of the lower course of the river
· Recent Earthquake in China, close to 300 dams inspected had cracks
o Huge financial strain to repair all affected dams.
o Dams collapsed, massive number of human deaths, destruction of settlements, farms downstream
· Sediments trapped behind dams
o Decrease in depth, leading to smaller capaityc of reservoir and river.
o Increase chance of flooding during heavy rainfall upstream
· Less food for riverine ecosystem
o Decrease in amount fish, shellfish etc
o Affect fishermen and farmers

Physical ENVIRONMENT
· Downstream deprived of sediments ,and less opportunity for flooding
· Formation of Depositional features such as floodplain, delta would be affected
· Decrease fertility of soil as there is less alluvium
· River dynamics after dam as the downstream is changed
· River has less sediments, therefore greater energy to erode

(c) With reference to Fig. 2b which shows a sketch of the photo in Fig. 2a, explain how features Y and Z are formed by marine processes? [5]

Z - Headland
Y - Bay

· alternating resistant and less resistant rocks
· Adjacent to the coast
· Less Resistant rocks - most erosion which gives rise to bays
· leaving more Resistant rock outcrops as headlands
· now as headlands receives highest energy waves – refraction
· so vulnerable to erosion more than the sheltered bays because wave energy dissipated at the bays which experience low energy waves- accumulation of sand
·
(d) Study Fig. 3b, identify and evaluate suitable measures to protect tourists’ beach at X and the area at Z. [8]

L1 0-3
Describes the suitable measures of breakwater, groynes and beach nourishment.

L2 4-6
Describe effectiveness OR ineffectiveness of 1 measure
Describe effectiveness OR ineffectiveness of 2 measures structures
Assess 3 effectiveness OR 3 ineffectiveness of 3 measures
OR
Assess all effectiveness AND ineffectiveness 3 measures with no refernce to
corresponding places—max 4

L3 7-8
Assess all effectiveness AND ineffectiveness of 1 measure and briefly for 2nd .
Assess all effectiveness AND ineffectiveness of 2 measures and briefly for 3rd
structure.
Assess all effectiveness AND ineffectiveness 3 measures

At Z…. Breakwater
- an artificial reef mage of cement or rocks
- built // to coast at some distance from the sea
- just in front of the headland

Function/Advantages
• Break force of waves at some distance from coast
• Creating a zone of quiet water, energy, deposition of materials behind break-water is slack

Disadvantages
1. costly to build and maintain
2. costly US$1m
3. breakwater can be unsightly, spoil scenery of beach. adds to the cost.


At X… Groynes and beach nourishment

Groynes
• Built perpendicular to coast

Function/advantages
• Stop movement of material from coast
• Interrupts Long Shore Drift
• Deposition on side of groyne facing Long Shore Drift -updrift side
• Widens the beach

BUT/disadvatages

• Erosion on the other side-downdrift side
Without regular maintenance of groyne systems they degrade and can become dysfunctional
· Spoils the natural beauty of the area
Tourists activities can be disrupted as this is a tourist beach


Beach nourishment

Advantages
• Simply means sand / beach replenishment
• i.e. rebuilding beaches
• Instant beaches
• Overnight beach

Disadvantages
• Very nice in the beginning
• Very expensive too
• US$1m to 6m per mile
• Temporary measure
• Erodes 10 time faster than natural beach
Lifespan of 10 years to 2 months