Upload
arman-alluwie
View
2.186
Download
7
Tags:
Embed Size (px)
Citation preview
Arman Alluwie TP2 SHSS
+
3 Express Pure Geog:Floods and Droughts19h April 2012Causes of Floods and Droughts
Arman Alluwie TP2 SHSS
2+Administration
Class Tests will be returned latest on Tuesday 24th April
Floods and Droughts Causes (Today) Impact and Adaptation (Monday 23rd April)
Revision Lectures Bring your own Questions Tuesday 24th April, Wednesday 25th April
Arman Alluwie TP2 SHSS
3+What did we learn last lesson?
Impact on Plants and Animals
Wrapped up on Climate Change with a “Hot Planet?” alternative technology current concerns of climate change
Class Test
Arman Alluwie TP2 SHSS
4+Lesson Objectives
By the end of the lesson, I would have described the natural and human causes of floods
and droughts
Arman Alluwie TP2 SHSS
5+
Natural Hazards
Floods Droughts
Causes Natural causesEg. Excessive rainfall
Natural causesEg. Delayed or insufficient rainfall
Human causesEg. Clearing of forests
Human causesEg. Reduced forest cover
Impact on people and the
environment
Eg. Loss of lives Eg. Shortage of water and food
How people have adapted to floods
and droughts
Eg. Building artificial levees or dykes
Eg. Management of watershd and agricultural practices
pg. 149 of textbook
Today
Arman Alluwie TP2 SHSS
6+Past O Level Questions (2000- 2009) Select one of the climatic disasters shown on Fig.
2, either droughts or tropical storms State the climatic disaster selected and name an area
where it occurs [1] Explain the reasons for its occurrence in that area [4] Describe how it affects people living in the named
area [5] Describe some of the measures taken to reduce its
effects on the loves of people in this area [5]
N2001 P2 Q3c
Arman Alluwie TP2 SHSS
7+Past O Level Questions (2000- 2009) What is a drought? Describe the effects of drought
on the lives of people living in areas such as the Sahel or Southern Africa [5]
N2006 P2 Q1b,c
Describe the effects of either floods or droughts upon the lives of people in areas where they are experienced. [5]
N2007 P2 Q1b,c
Arman Alluwie TP2 SHSS
8+Past O Level Questions (2000- 2009) Severe weather conditions may also cause human
disasters. Using examples, discuss the impact of droughts on human lives and the environment. [8]
N2008 P1 Q1c
Arman Alluwie TP2 SHSS
9+
Natural Hazards
Floods Droughts
Causes Natural causesEg. Excessive rainfall
Natural causesEg. Delayed or insufficient rainfall
Human causesEg. Clearing of forests
Human causesEg. Reduced forest cover
Impact on people and the
environment
Eg. Loss of lives Eg. Shortage of water and food
How people have adapted to floods
and droughts
Eg. Building artificial levees or dykes
Eg. Management of watershd and agricultural practices
Arman Alluwie TP2 SHSS
10+Floods and Droughts
Hazard Definition: can endanger lives and destroy property
Flood Definition: occurs when land that is usually dry is
submerged by large amounts of water
Drought Definition: prolonged period with little or no rainfall normally occurs in regions which receive 250- 500
mm per year
Arman Alluwie TP2 SHSS
11+Causes of Floods
Natural Causes1. Excessive rainfall
2. Storm surges
3. Melting snow
4. Global atmospheric processes
5. Movements of the Earth’s surface
Human Causes1. Clearing of forests
2. Urban development
3. Impacts of enhanced greenhouse effect
Arman Alluwie TP2 SHSS
12+Natural causes of floods:Excessive rainfall Areas experiencing Tropical Monsoon
Climate
Excess rainwater is unable to seep into the ground
When rivers overflow their banks because river channels can no longer contain excess water
amount (more than usual) frequency (prolonged rain)
Arman Alluwie TP2 SHSS
13+Natural causes of floods:Excessive rainfall Eg. Yangtze River and Yellow River, China
rain washes large amounts of sediments into rivers sediments deposited on the river beds rivers become shallower
Arman Alluwie TP2 SHSS
14+Natural causes of floods:Storm surges strong winds raise the waves in the ocean to
exceptionally high levels
tropical storms blow strong winds over the ocean creating gigantic waves, which crash onto the coast
and flood the land
Arman Alluwie TP2 SHSS
15+Natural causes of floods:Storm surges
http://www.nhc.noaa.gov/surge/animations/hurricane_stormsurge.swf
Arman Alluwie TP2 SHSS
16+Natural causes of floods:Storm surges Eg. Bangladesh
low-lying relief 80% sits on low-lying
floodplains of Brahmaputra and Ganges Rivers
35% is less than 6 meters above sea level
pg 132 of textbook
Arman Alluwie TP2 SHSS
17+Natural causes of floods:Storm surges
shallow shelf deep shelf
not all coastal areas would be affected
Arman Alluwie TP2 SHSS
18+Natural causes of floods:Melting snow Areas experiencing cool temperate climate
Melting snow in spring releases large amounts of water intro rivers
eg. 1986 St. John River, Canada
19+Natural causes of floods:Global Atmospheric Processes El Nino/ La Nina
Alternate patterns of heating and cooling between eastern and western parts of South Pacific Ocean
For a specific place, floods during El Nino, Droughts during La Nina
Eg. ‘97- ’98: flooding of Piura River, Peru Intense El- Nino brought heavy and prolonged rains to
Peru for several months
Arman Alluwie TP2 SHSS
pg. 133 of textbook
Arman Alluwie TP2 SHSS
20+
Indonesia/Australia
Peru,South America
http://www.mygeoscienceplace.com/ElNinoLaNina.html
Arman Alluwie TP2 SHSS
21+
Indonesia/Australia
Peru,South America
Arman Alluwie TP2 SHSS
22+
Indonesia/Australia
Peru,South America
Arman Alluwie TP2 SHSS
23+
Indonesia/Australia
Peru,South America
http://www.mygeoscienceplace.com/ElNinoLaNina.html
Arman Alluwie TP2 SHSS
24+Natural causes of floods:Global Atmospheric Processes El Nino/ La Nina
Alternate patterns of heating and cooling between eastern and western parts of South Pacific Ocean
For a specific place, floods during El Nino, Droughts during La Nina
Eg. ‘97- ’98: flooding of Piura River, Peru Intense El- Nino brought heavy and prolonged rains to
Peru for several months
Arman Alluwie TP2 SHSS
25+Natural causes of floods:Movements of the Earth’s surface earthquakes cause landslides
soil along hill or mountain slopes loosen up deposited into a river and may cause the water to
overflow
earthquakes triggering off tsunamis undersea earthquake 2004 Indian Ocean Tsunami affecting Banda Aceh,
Indonesia
Arman Alluwie TP2 SHSS
26+Human causes of floods:Clearing of forests Areas with extensive clearing of forests
Eg. China and Bangladesh (Ganges and Brahmaputra Rivers)
Arman Alluwie TP2 SHSS
27+Human causes of floods:Clearing of forests Title
Legend
Arman Alluwie TP2 SHSS
28+
Arman Alluwie TP2 SHSS
29+
30+Human causes of floods:Urban development Land is cleared to meet needs of urban population
Built-up areas increase Concrete pavements and tarred roads prevent
rainwater from seeping into the ground Less natural vegetation to intercept rain Increase in surface runoff
eg. Areas around River Thames, London
Arman Alluwie TP2 SHSS
Arman Alluwie TP2 SHSS
31+Human causes of floods:Impacts of Enhanced Greenhouse Effect Global warming
Higher rainfall in wetter regions
Reduction of ice cover in the polar regions rising sea levels affecting low-lying coastal regions
Arman Alluwie TP2 SHSS
32+Causes of Droughts
Natural causes of droughts1. Delayed rain or insufficient rainfal
2. Global atmospheric processes
Human causes of droughts1. Reduced forest cover
2. Impact of enhanced greenhouse effect
3. Overuse of water
Arman Alluwie TP2 SHSS
33+Natural causes of Droughts:Delayed rain or insufficient rainfall Areas with little rainfall
250- 500 mm per year
or Tropical Monsoon Regions Bangladesh/ India Delay of monsoon winds
Prolonged dry season
Arman Alluwie TP2 SHSS
34+
Indonesia/Australia
Peru,South America
Natural causes of droughts:Global atmospheric processes
Arman Alluwie TP2 SHSS
35+
Indonesia/Australia
Peru,South America
Natural causes of droughts:Global atmospheric processes
Arman Alluwie TP2 SHSS
36+Human causes of droughts:Reduced forest cover lower rates of transpiration, leading to less water
vapour fewer clouds formed
ground exposed to direct heating by the Sun soil dries up quickly
load Google Maps (Brazil)
Arman Alluwie TP2 SHSS
37+Human causes of droughts:Impact of enhanced greenhouse effect Droughts in places with drier climates
Sahel in Africa
Rapid evaporation, which dries up land, rivers and lakes
More imminent with increase in emission of greenhouse gases
Arman Alluwie TP2 SHSS
38+Human causes of droughts:Overuse of water population, more water is needed for homes,
industry and agriculture
eg. Kothariya, India drought in 2001 population of 4000 get their water from five water
holes dug into floors of ponds
Arman Alluwie TP2 SHSS
39+Lesson Objectives
Am I able to describe the natural and human causes of floods and
droughts?