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Flashcards in the trouble with water Deck (33)
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1
Q

Evaporation

A

When the sun heats the earth’ s surface,the water in the seas, rivers,lakes and soil evaporates and becomes water vapour.It passes into the air.

2
Q

Transpiration

A

Leaves of plants release water as water vapour.

3
Q

Condensation

A

When water vapour rises,it cools and condenses into water droplets.These water droplets group together to form clouds.

4
Q

Precipitation

A

Water falls from clouds to the earth’ s surface as rain or snow.

5
Q

Overland flow

A

Water flows down the slopes.

6
Q

Infiltration

A

Water seeps into the ground and becomes groundwater.

7
Q

We mainly found water in

A
  1. the air/atmosphere
  2. ocean and seas
  3. the land:lakes,rivers,plants,groundwater,glaciers and ice caps
8
Q

Three major rivers in China

A

The Chang Jiang , the Huang He , the Zhu Jiang

9
Q

Describe the flow of major rivers in China.How is it related to the relief of China?

A

The river flow of the major rivers in China is from west to east.In China, the height of land decreases from the highland in the west towards the coast in the east.Since water flows from high levels to low levels, most rivers in China flow towards the east.

10
Q

Describe the summer monsoons

A
  1. In summer, the land is heated by the sun.Air becomes hot and it rises.Air pressure over the land is low.
  2. Water absorbs heat more slowly than land.Therefore, air over the sea is relatively cooler than air over the land.Cool air sinks.Air pressure over the sea is higher than over the land.
  3. Air moves from high-pressure to low-pressure areas.Therefore winds blow from the sea towards the land(the southern and eastern parts in Asia).
    * Winds blowing from the sea to the land are onshore winds.They carry a lot of moisture to the coastal regions.Therefore, coastal China receives much rainfall in summer.
11
Q

Why the coastal areas in China receive more precipitaion than inland areas?

A

As the wet summer monsoon travels inland, it loses much moisture.Therefore inland areas generally have less precipitaion.

12
Q

The amount of water resources decreases from ? to ?

A

The amount of water resources decreases from south-east to north-west.

13
Q

Four main activities cause changes to the water cycle

A

1.Cutting trees on a large scale
↓Infiltration ↑Overland flow
↓Transpiration ↑River flow
↓Precipitaion ↑Evaporation from land

2.Building dams
↓River flow downstream

3.Reclaiming lakes
↑River flow downstream

4.Overdrawing groundwater for human activities
↓Groundwater storage
↓River flow

14
Q

Impacts of overdrawing groundwater(3)

A
  • Without groundwater, rivers dry up and the size of lakes is also reduced.This threatens the eater ecosystems in these areas.
  • In coastal area, overdrawing groundwater may cause the saltwater to intrude into rivers and groundwater storage. This will contaminate the freshwater supply.
  • Without the groundwater to give support to the land above it,the soil collapses and the land sinks.Land subsidence(地陷) occurs.
15
Q

Harmful effects of flooding in China

A
  • Loss of life and injuries
  • Crop failure
  • Damaging buildings, roads, rail lines, bridges and engineered structures
  • Disrupting transport services
  • Disrupting utility services such as gas and electricity supplies
  • Polluting drinking water
  • Spreading diseases
16
Q

Causes of flooding(physical factors)

A

-Heavy rainfall and typhoons
In some regions in China,the summer moonsoon and typhoons brings heavy rainstorms.If large amounts of rainwater reach the river channel in a very short period of time,this will lead to flooding.(太大riverflow)
-Relief
when the slope is gentle,the water flow is slow,the sand and soil will deposited on the river bed,causes silting,the river bed becomes shallow,and the holding capacity of river channel will redused.(容水量不足)

17
Q

Cause of flooding - Human factors

A

-Deforestation
Tree roots help hold the soil,without trees may cause soil erosion,the rain will washed away the loose soil.It may causes silting,thus the holding capacity of water will decrease.
Tree roots also help infiltration,without trees,the infilttation decreases and more water will flow over the land as overland .River flow increases.
-Poor farming practices
The grass was eaten up by the livestocks as overgrazing,the grass protect the soil,overgrazing leads to soil erosion,when the soil is washed into the river channel,silting occurs.The holding capacity of river flow decrease.
Over-cultivation will cause the soil become poor as the crops take up the nutrients from soil,it leads to soil erosion,it causes silting,the holding capacity of river flow decreases.
-Reclaiming lakes for different uses
Lakes can store water and help regulate the flow of rivers,if people reclaiming lakes ,there are less water can store in lakes,thus the excess rainwater will flow into rivers,the amount of river flow increase.
-Urban development
Through the urban development,the land may cover with concrete.When rain falls,it cannot infiltrate underground,so it becomes overland flow,the amount of river flow increase.
Sewers and drains help divert rainwater quickly,but it makes water reach the river channels within a short period of time,the amount of river flow increase.

18
Q

How can the flooding problem in China be eased?

A

1.Regulating the river flow
-building dams and reservoirs
-restricting the reclamation of land from lakes
-giving up farmland and fish ponds reclaimed from lakes
-planting trees on valley slopes(↑infiltration
)(help reduce overland flow and river flow)

2.Increasing the holding capacity of river channels
-planting trees
-terracing 起梯田
-stopping grazing on steep slope
(↓soil erosion and ↓silting)
-straightening river channels(help increase the speed of flow,and drain water quickly)將河拉直之後,水流動快了,就能處理更多水,不會積在一個地方造成flooding
-dredging river channels 清理river的淤泥(help lower the river bed,↓silting)

19
Q

State a large-scale flood control project

A

Three Gorges Dam (Sanxia) Project (1993-2009)
It involved the building of the largest dam in the region,the Sanxia Dam.It is the largest flood control project in China.

The building of the Sanxia Dam has created a big reservoir which can store water from the upstream areas.When there is heavy rain in the upper course,the dam can hold and slow down the river water flowing downstream.This can regulates the flow,and thus lowers the danger of flooding.

20
Q

Disadvantages of the Three Gorges Dam Project

A

Upstream area:
-Large areas of farmland and many historical sites behind the dam are flooded
-People have to move
-The natural habitat of wildlife is damaged
-Sediment is trapped behind the dam
Downstream area:
-If the dam collapses,it will flood the downstream area
-With less sediment,the farmland in the downstream area become infertile
-It is very expensive

21
Q

What is drought?

A

When rainfall in an area is much lower than normal,or there is a long period without rainfall,the area does not have enough water for usual water consumption,it causeswater shortages and drought occurs.

22
Q

Where does drought usually occurs?

A

Droughts are mainly found in northern,southern and south-western parts of China.

23
Q

The harmful effects of drought in China

A

Effects on the environment
-lakes and rivers may dry up,cut-off of rivers occurs 斷流
-the sediment in a river will stay on the river bed,it causes silting,it increase the risk of flooding when rainstorms come.增加flooding風險
-the topsoil may be blown away,it causes soil erosion,intensify the desertification,sandstorms will also become more common,thus vegetation cant grow.無法種植
-plants and animals cant live,the ecosystem is affected
Effects on people
-drought may lead to crop failure,food shortages may occur
-industries need water for production,their production may fall
-low water levels in reservoirs may negatively affect HEP generation
-affect water transport
-people will nit have enough water for drinking and other uses,it may affect their health

24
Q

What are the causes of drought?(physical factors)

A

When wet summer monsoons come late,or dry winter monsoons come earlier than normal,the rainfall received in a place may fall below the average amount.Drought may occur.

25
Q

The causes of drought (human factors)

A
-Increasing demand for water
  population growth
  changing rural into urban
  higher consume if meat
  living standard increase  
  consume more electricity
-Deforestation
  ↓transpiration
  ↓infiltration
  ↓evaporation
  ↓precipitation
-Misuse of water 
  price of water is low 水太便宜
  farmers 用 flood irrigation等
  leakage occurs in some irrigation channels 漏水
  building dams cause water shortage in                 downstreams下游唔夠水
-Overdrawing groundwater
  In northern China,(Beijing,Tianjin),there are less precipitation and high population,therefore they draw groundwater .
-Water pollution
  industries produce sewage
26
Q

How is drought eased in China?

A
1.Reducing the demand of water 減少需求
☞Saving water on farms
   -drip irrigation
   -leakage prevention work
   -reduce evaporation of soil water by plastic film
   -grow drought-resistant crops 抗旱作物
☞Reducing water wastage
   -Education
   -increasing water charges
   -passing laws(for factories)
      (comply with water-saving regulations)
2.Increasing the supply of clean water 增加供應
-collect rainwater for use
-save floodwater through pipelines
-increase rainfall through cloud seeding播雲
-treat sewage
-use recycled water
-desalination 海水化淡
27
Q

State a large-scale water projects of drought

A

The South-North Water Transfer Project 南水北調工程.
It is the largest water transfer project in China.It transfer water from Chang Jiang to the north.
It provide clean water for northern China.
-it improves water transport on the Grand Canal
(水上交通on Grand Canal)
-with more water,more farmland can be opened up (農地增加)
-help maintain the wetland and river ecosystems
(鞏固濕地及河的運作)

28
Q

Disadvantages of the South-North Water Transfer Project

A
  • The Danjiangkou Dam is heightened,it caused flooding in upsteam
  • The HEP generatiob in the Chang Jiang basin will be affected
  • Water that is diverted may be polluted
  • Natural habitat along the Chang Jiang is threatened.
29
Q

Where does water pollution usually found?

A
  • rivers
  • lakes
  • groundwater
30
Q

What is the impact of water pollution?

A
  • a great threat to public health
  • may leads to water shortages
  • affects water ecosystem
    eg: algal bloom used up the oxygen in the water.Fish died.
31
Q

The causes of water pollution in China

A

-population growth
-increase in water usage,as well as sewage
人越來越多,工廠製造污水
-Poor discharge of sewage
-toxic materials may infiltrate and pollute the groundwater 滲透到地底,污染地下水

32
Q

How is water pollution in China eased?

A
☞Reduce the discharge of sewage
  -close polluting factories
  -encourage public particiption in reporting polluters 舉報污染者
  -education
  -increase water charges
☞Treat the sewage before discharged
  -build new sewage treatment plants
  -improve sewage management
☞Clean up polluted rivers and lakes
  -pass laws abd provide money to take action for the clean-up
33
Q

Sponge cities海綿城市

A

Store up water during rain,release the stored water for use during water shortages.At the same time,the soil and vegetation acts as a filter to help improve water quality.