ENVIRONMENTAL SCIENCE AND ENGINEERING

TOPICS

• Renewable energy resources

• Floods and drought

• Agriculture and over grazing

• Water resources

Renewable energy resources

• Solar energy

• Wind energy

• Water energy

• Geo thermal energy

Solar energy

At focal point = heat liquid – steam to turn turbine

Solar electricity generation

Solar water heating solar air heating

Solar house problems

• The Los Angeles air = smog

• Retrofitting- very expensive

• Hard for big hotels, Wal-Mart's, etc.

Wind energy

Banning Pass

Wind Power Generation

Netherlands = coastal development

England = off shore

Wind energy problems

• Location – near population center

• Bird migration –

• Visual

• Must be coupled with other sources of electricity (intermittent supply)

Hydropower

Problems with hydroelectric

• Location = unused rivers are in extreme north or low population areas

• Competition with recreational uses (U.S.) and environmental concerns

• Hard to build dams in populated river valleys

• Siltation of dams – limited life.

Tidal power

1.In areas of large tides

2.Anywhere – build offshore dam

Tidal power anywhere

1.No dam – but a turbine.

Problems:

1. Corrosion

2. Navigation

3.Amount of energy available is low

4.Best tides are near poles – away from people.

Geo thermal energy

Heat near surface of the earth = geysers, volcanoes, etc,,.

Use heat to make steam to turn turbine for electrical generation

Note: deep hot waters are corrosive to best to inject clean water in a closed system and bring it back to the surface as steam.

Geothermal Energy

Floods and Droughts

Causes OF Floods

• Floods are an excess of water that covers land that is normally dry.

• This can be due dam or level failures, more rain than the landscape can dispose of, torrential rains caused by storms, rapid snow melts, or a blocked river.

Causes OF Droughts

• it is caused by a lack of precipitation in an area resulting from weak or less frequent storms and other weather systems than normal.

• Most major droughts last for months or years.

• What is considered a drought in a rainy location may be enough precipitation for another region.

When Do They Occur?

• Floods can occur any time of the year.

• Floods occur primarily in the spring season due to ice and snow melting and frequent storms.

• In some countries, there are monsoon seasons, a time of great rain, when floods often occur, then a dry season, when drought conditions occur.

• Droughts can occur any time of the year.

• In North America, droughts occur most often between March and September, when it is often dry and hot.

Major River Floods

The areas in red are where river floods have occurred this year.

Other Facts

• Floods account for 40% of all deaths caused by natural disasters.

• In an average year, floods account for about 200 deaths and $2 billion of damage in the U.S. alone.

• In 1937 floods removed 300 million tons of topsoil in the Ohio Valley.

• The world’s longest drought occurred in Arica, Chile, from October 1903 to January 1918. No rain fell for over 14 years.

AGRICULTURE

Crop rotation• Alternating the crop planted (e.g., between corn and

soybeans) can restore nutrients to soil and fight pests and disease.

Contour farming

• Planting along contour lines of slopes helps reduce erosion on hillsides.

Intercropping

• Mixing crops such as in strip cropping can provide nutrients and reduce erosion.

Alley cropping

Terracing• Cutting stair steps or terraces is the only way to farm

extremely steep hillsides without causing massive erosion. It is labor-intensive to create, but has been a mainstay for centuries in the Himalayas and the Andes.

Shelterbelts• Rows of fast-growing trees around crop plantings

provide windbreaks, reducing erosion by wind.

Overgrazing

• When livestock eat too much plant cover on rangelands, impeding plant regret

• The contrast between ungrazed and overgrazed land on either side of a fence line can be striking.

Overgrazing

• Overgrazing can set in motion a series of positive feedback loops.

Effects of overgrazing

Land degradation Soil erosion

Water resources• Hydrologic Cycle

• Water Reservoirs

Hydrological cycle

Hydrological cycle

Freshwater Reservoirs

• Rivers and Streams

• Lakes

• Groundwater

Freshwater Reservoirs

River and streams lakes

Groundwater• Much greater in volume than either lakes or

streams

• renewable in our lifetime

AQUIFER

• Geologic formation that possesses porosity and permeability

Confined and unconfined aquifers

THANKYOU

• BY

– K.V. VARUN

KARTHIKEYAN