full geography secondary 3 express- floods and droughts 2

Arman Alluwie TP2 SHSS

+

3 Express Pure Geog:Floods and Droughts19h April 2012Causes of Floods and Droughts


2+Lesson Objectives

By the end of the lesson, we would have discussed the impact of floods and droughts on

human lives and the environments evaluate the effectiveness of management strategies

taken to mitigate and respond to floods and droughts


3+Lesson Recap: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


4+Lesson Recap:Causes of Floods Natural Causes

1. 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


5+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


6+Lesson Recap:Storm surges

http://www.nhc.noaa.gov/surge/animations/hurricane_stormsurge.swf


7+

Indonesia/Australia

Peru,South America

Droughts Heavy Rains


8+

Indonesia/Australia

Peru,South America

Heavy Rain Droughts


9+Human causes of floods:Clearing of forests Title

Legend


10+Feedback

Reducing Impact of Climate Change Pg 125 Not important

Answers to Worksheet 8.1 Student Handout


11+

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. 138- 147 of textbook

Today


12+Impacts of Floods:Fertile Soil / Loss of Lives Provides fertile alluvium

Floodplains around coastal areas and rivers attractive places for cultivation of crops/ farming many people continue to live on low-lying plains near

rivers despite risk of floods

BUT when flooding occurs, lots of lives are lost Based on location and predictability Eg. 2003, north-central Huai River Basin

298 lives

positive impact

negative impact


13+Impacts of Floods:Damage to Property and Infrastructure Disrupts power supply and phone lines, cutting off

communication Making relief efforts and emergency evacuations

difficult


14+Impacts of Floods:Spread of diseases Overcrowded makeshift shelters

Lack of sanitation and clean drinking water Especially in countries where sewage is not piped Floating debris / Dead bodies


15+


16+Impacts of Floods:Damage to Environment Destroys plant life and natural habitats of animals

eg. Tsunami that struck Java on 17 July 2006 severe damage to the coastal ecology nature reserve near Pangandaran Beach


17+Impact of Droughts:Shortage of Water and Food People and animals die from dehydration and

crops destroyed

Especially crops which are dependent on seasonal cycles eg. monsoon rain

Leads to famine


18+Impact of Droughts:Forest fires and haze Vegetation becomes very dry and catches fire

easily Note that a drought is defined as “prolonged period

with little or no rainfall” An area may be experiencing drought but still have

vegetation around.

Smoke from forest fires lead to haze in neighboring countries

Affects environment and health of people


19+Impacts of Droughts:Damage to the environment Desertification

spread of deserts into areas where there is little or no rain

Arid and Semi- Arid Regions places with 250- 500 mm of rainfall per year

Soil becomes very dry and unable to support vegetation

Soil blown away by wind, leaving a barren piece of land

Deserts around the world are expanding at a rate of about 80 000 square kilometres per year.

(desertification vulnerability)


20+Checkpoint 1:Impacts of Floods and Droughts

Floods Droughts

Impact on people and the environment

1. Loss of lives2. Damage to

property and infrastructure

3. Spread of diseases4. Damage to the

environment5. Fertile Soil for

agriculture

1. Shortage of water and food

2. Damage to the environment

3. Forest fires and haze

pg 138- 142

am I able to discuss the impacts of floods and droughts on human lives and the environments?


21+Flood Management Strategies:Building artificial levees/ dykes walls of sand, stone and concrete

increases holding capacity of river

BUT must be paired with other strategies Yellow River, China not successful in preventing

floods because of constant deposition of sediment river bed becomes raised, making river shallower water levels rise higher than the dykes higher dykes have to be built constantly


22+

23+Flood Management Strategies:Construction of Dams Control the amount of water flowing into rivers

Gates which hold back or release water from the man-made reservoir behind it reservoir increases holding capacity

Controls the amount of water that flows downstream

BUT slowing down the speed of water increases the accumulation of sediments

not enough energy to carry sediments raise reservoir bed and cause flooding in the future


24+Flood Management Strategies:Construction of Dam Three Gorges Damn, Yangtze River


2:49- 5:55 of http://www.youtube.com/watch?v=3z9K82ZVdMA


25+Flood Management Strategies:Building Control providing information for developers in flood prone

areas

construction of good network of drainage canals eg. flood prone areas in Singapore have dropped from

3200 ha in 1970 to 238 ha in 2006


26+


27+


28+Flood Management Strategies:Watershed Management Watershed

boundary which is marked by crests of hill rides and mountains

separates on drainage basin from the next


29+


30+Flood Management Strategies:Watershed Management Eg. Royal Forest Department (RFD) in Thailand

detailed plans on conserving natural vegetation in watersheds

re-planting tress in areas which were previously cut down

reducing surface runoff and amount of sediments


31+Flood Management Strategies:Flood Insurance Financial resources to rebuild property if a flood

strikes

Depending on trends and history of floods

eg. UK, national flood insurance programmme helps reduce financial burden


32+Flood management strategies:Monitoring and education modern technology allows us to monitor weather

patterns and issue warnings

Educating citizens on what to do in the event of a flood Evacuation plans

Safest route to the nearest food shelter Public announcements

Flood warning signs


33+Flood Management Strategies:Post-flood management measures Evacuation plans

boats / helicopter to temporary shelters

Opening public areas for humanitarian and rescue operations Louis Armstrong New Orleans International Airport

during Hurricane Katrina

Foreign Aid in the form of food, water, blankets, medical teams


34+Checkpoint 2:Flood Management Strategies

pg 142- 145

am I able to evaluate the effectiveness of management strategies taken to mitigate and respond to floods?

1. Building Artificial Levees/ Dykes

2. Construction of Dams

3. Building Control

4. Watershed Management

5. Flood Insurance

6. Monitoring and Education

7. Post- Flood Management Measures


35+Drought Management Strategies:Management of watershed and agricultural practices Agenda 21 Report

Eg. Mongolia hundreds of thousands of seedlings planted to

increase vegetation in drought-affected regions laws to limit the number of trees

only local community allowed to cut down trees for firewood


36+Drought Management Strategies:Management of watershed and agricultural practices Growing crops to suit the dry climate of regions

Changing staple diet or importing food


37+Drought Management Strategies:Using proper irrigation techniques brings water to areas which receive little or no

rainfall

eg. Turkey, precision sprinklers drip small amounts of water directly onto crops


38+Drought Management Strategies:Cloud Seeding induces formation of rain

disperse substances like silver iodide or dry ic

enable water droplets/ ice crystals to form more easily nucleus for water droplets in the air to adhere to

over time clouds form and rain falls

dispersed by aeroplanes or machines on the ground

eg. Thailand, 2005, ease drought by 80% but cost of seeding very high and no guaranteed

success


39+Drought management strategies:Post- Drought U.S. Agency for International Development

(USAID) donations of money, food and water to Ethiopia 2006

Food for Hungry Relief brought in water in tanker trucks and used

“dewatering” pumps to transfer the water into school cisterns


40+Checkpoint 2:Flood Management Strategies

pg 146- 147

am I able to evaluate the effectiveness of management strategies taken to mitigate and respond to droughts?

1. Management of watershed and agricultural practices

2. Using proper irrigation techniques

3. Cloud seeding

4. Post-drought management measures

full geography secondary 3 express- floods and droughts 2

Education

faminearman alluwie

droughtsarman alluwie

peryeararman alluwie

textbookarman alluwie

impacts of floods

impact of floods

human causes of floods

impacts of droughts