Maharashtra Board Class 7 Science Chapter 10 Disaster Management PDF Download

Disaster Management

Is it possible to prevent the loss of life caused by lightning?

What should be done to prevent the bunds on a farm from getting washed away in the rainy season?

Why do we experience water-scarcity?

We have studied two types of disasters, namely, manmade and natural disasters. Into which categories do the disasters shown in the news items above, fall?

We can prevent certain disasters, while it is necessary to take precautions in the case of some other disasters. Natural and manmade disasters are related to each other.

Natural disasters such as famine, lightning strikes, cloudbursts, storms, etc. occur due to changes in the weather. There is the possibility of loss of life and damage to property in such natural calamities. Who is to be held responsible for that? What can we do to deal with these losses?

Famine

The condition that arises due to long term and severe scarcity of foodgrains and water is called famine. Famines can be very severe. Although the main cause of famine is natural phenomena, yet a famine condition is created by some human activities besides some natural events.

What would happen if no food were grown during one whole year?

Teacher's Note

Famine happens when there is no food or water for a long time. In India, during droughts, many farmers face famine when rains do not come.

Exam Trick

Remember: Famine = No food + No water for long time. If no rains come, crops die, and then famine comes.

Points to Remember

Famine is caused by severe scarcity of food and water.
Natural events like drought and floods cause famine.
Human activities like war and poor planning also cause famine.
Famine can cause loss of life and big problems in a place.

Causes Of Famine

Drought, heavy rains and flood, crops getting washed away or damaged in the flood, environmental changes such as temperature change, storms, cold waves or fog, damage of crops by animals like mice and rats, attack of pests, locusts or diseases of crops, a natural calamity like earthquake, etc. are some of the causes of famine. Of these, drought is the main cause. Man-made causes of famine include war, internal unrest, absence of transport routes, uncontrolled population growth, etc.

There are records of loss of life caused by severe famines in various parts of the world. Asia has turned out to be the most famine affected continent of the world. A majority of the famines occurred in drought prone and flood affected regions. Among the most dreadful famines that have occurred in the world, are the famines that affected India and China.

Are We Responsible For Famine?

Water shortage is increasing as the balance between rainfall and population is disturbed.

Though there has been a very high rise in the production of foodgrains as a result of the green revolution, the balance of the environment has been lost due to use of chemical fertilizers, pesticides and weedicides.

Unlimited lifting of water.

Erosion of land.

Misuse of water.

In The Past...

Famines are not a new phenomenon. The problems of drinking water, food, and fodder for animals date back to historic times. Chhatrapati Shivaji Maharaj and Chhatrapati Shahuji Maharaj implemented many schemes to overcome the famines of their time. Their water supply and water storage schemes are ideal even in today's circumstances. You too can make schemes like these to face future crises and disasters, which will be of use not only in your own life in the future, but also for society at large.

Malik Ambar implemented a canal scheme for drinking water in Aurangabad. It exists even today. Collect more information about it.

What Can We Do To Ease The Severity Of A Famine?

Planned usage of water and reuse of water.

Proper planning of water conservation and harvesting at the local level.

Large scale plantation of trees and prevention of deforestation.

Making appropriate changes in plans, taking into account the weather forecasts.

Large scale tree plantation – No famine, no land erosion!

Compose a variety of such slogans and use them during Environment Awareness Rallies.

Teacher's Note

In villages around us, we see farmers worry about water during dry season. Planning like tree planting and water saving helps them.

Exam Trick

Remember: To stop famine, plant trees, save water, and plan well. Think of it like a recipe - without these three things, famine happens.

Points to Remember

Drought and floods are the main causes of famine.
Using too much water and cutting down trees makes famine worse.
We can stop famine by planting trees and saving water.
Planning ahead for bad weather helps prevent famine.
The government and people must work together to stop famine.

Cloudburst

Sometimes the water coming down from rain clouds does not reach the land in the form of rain. Instead, due to very high temperature near the land, it vapourizes and goes back into the same clouds. As a result the amount of vapour in those clouds becomes very high. Due to rapid condensation, it rains suddenly over a specific and small region at a rate of 100 mm per hour or more. This is known as a cloudburst.

What causes rain?

Do You Know?

A cloudburst occurred at Leh (Ladakh) on 6th August 2010. The cloudburst that occurred in Mumbai on 26th August 2005 was extraordinary and unforgettable. On that day it rained about 950 mm, that is, 37 inches, in 8 to 10 hours, and the entire city of Mumbai was waterlogged and flooded.

Why shouldn't we wait at the foothill while it is raining heavily?

Teacher's Note

When heavy rain falls suddenly in one small area, it is called a cloudburst. In 2005, Mumbai had a cloudburst that flooded the whole city.

Exam Trick

Remember: Cloudburst = Sudden heavy rain in one small area only. Like if you pour all water from a bucket at once instead of slowly, that is a cloudburst.

Points to Remember

A cloudburst is very heavy rain in a small area.
It happens when water drops suddenly form in clouds.
Cloudbursts can cause floods and damage homes.
The 2005 Mumbai cloudburst was very bad and flooded the city.

Flood

What is meant by flood? What are the effects of flood?

We have already learnt about floods and the effects of floods. Collect information about the floods that have occurred at various places in Maharashtra in the last few years.

Protective Measures In View Of Floods

Construction of small dams in mountainous regions

Construction of percolation tanks

Making river beds flat

Cultivation of new forests

Connecting rivers

Government of India established the National Flood Commission in 1976. The Commission has made special efforts towards the control of floods. A plan regarding flood control is kept ready from national level to village level. Large scale damage of property and loss of life can be avoided because of this plan.

Teacher's Note

Floods happen when water overflows from rivers and dams. In Maharashtra, we see floods almost every year in the rainy season in some areas.

Exam Trick

Remember: Flood = Too much water in one place. The government builds dams and plants trees to stop floods, like a fence stops an animal.

Points to Remember

Floods happen when water overflows from rivers.
Building dams and planting forests stops floods.
We must follow government warnings about floods.
Moving to high ground quickly saves lives during floods.

Lightning

Have you seen a flash of lightning in the sky? When?

What causes lightning?

You have learnt about generation of electric charge and lightning strikes in the lesson on static electricity. In this lesson we shall learn something more about lighting and the measures for protection from it.

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