Ch 2.4a How do humans influence and manage the river environment?

Question 1

Name the characteristics of the rivers in Hong Kong.

Answer 1

Most of the rivers are short and small. The few large rivers are found in the north-west. All rivers in Hong Kong have a steep upper course and very gentle lower course. The middle course is not distinctive.

Question 2

List the examples of river in Hong Kong?

Answer 2

1. Tuen Mun River
2. Sham Pui River ( Tin Shui Wai )
3. Kam Tin River ( Yuen Long )
4. Shenzhen River
5. Sheung Yue River
6. Ng Tung River ( Ku Tung )
7. Lam Tsuen River ( Tai Po )
8. Shing Mun River
9. Tung Chung River

Question 3

What are the human activities that influence the river environment?

Answer 3

Construction of reservoirs and catchwaters.
Farming and fisheries
Development of new towns and infrastructure

Question 4

Describe the construction of reservoirs and catchwaters.

Answer 4

Large rivers at the upper course are dammed to build reservoirs. Catchwaters are built to divert water from streams at the upper course to the reservoirs.

Question 5

What are the positive impacts of the construction of reservoirs and catchwaters?

Answer 5

Provide freshwater fro consumption and farming at the lower course.

Question 6

What are the negative impacts of the construction of reservoirs and catchwaters?

Answer 6

1. Amount of channel water at the lower course decrease -> worsens water pollution at the lower course.
2. Reduces amount of silt and nutrients that move downstream -> Degrades farmland downstream.

Question 7

Describe farming and fisheries.

Answer 7

Wetlands on the floodplains are converted into fish ponds and farmland.

Question 8

What are the positive impacts of farming and fisheries?

Answer 8

1. Boosted farming and freshwater fisheries in the past.
2. Attracts many migratory birds.

Question 9

What are the negative impacts of farming and fisheries?

Answer 9

1. Reduces the ability of wetlands to absorb flood water. -> Increasing the risk of flooding.
2. Increase of the water level.

Question 10

Describe the development of new towns and infrastructure.

Answer 10

River mouth and floodplains are reclaimed and rivers are paved or modified for urban development.

Question 11

What are the positive impacts of the development of new towns and infrastructure?

Answer 11

1. Provide flatland for development.
2. Reduces the over-concentration of population and economic activities in old urban areas.

Question 12

What are the negative impacts of the development of new towns and infrastructure?

Answer 12

1. Impermeable land surfaces reduces infiltration -> Increases overland flow -> Increases the risk of flooding.
2. Destroy natural habitat.

Question 13

When does flooding occur?

Answer 13

When river discharge is greater than the water carrying capacity, flooding occurs.

Question 14

Why is flooding common in Hong Kong? Explain with natural factors.

Answer 14

1. Relief.
   Steep slopes in upper course
   Less infiltration
   More overland flow.
2. Rainfall
   High annual rainfall
   Heavy rain in summer
   Less infiltration as soil is saturated
   More overland flow

Question 15

Why is flooding common in Hong Kong? Explain with human factors?

Answer 15

1. Deforestation
   Fewer roots bind soil
   More soil erosion
   Silting occurs
   Decrease water holding capacity.
   Decrease infiltration
   Increase overland flow.
2. Farming and fisheries
   Convert wetland to farmland and fish ponds
   Decrease the amount of flood water absorbed by the wetlands
   Decrease water holding capacity
3. Development of new towns and infrastructure
   Built-up areas are paved
   Land surface becomes impermeable
   Increase overland flow
4. Cutting slope
   Steeper slopes
   Less infiltration
   More overland flow