describe the flow of essential elements from the environment through

living organisms and back into the environment.

Biogeochemical Cycles

Hydrologic Cycle

How come we never run out of water?

ECOWLECJuvena May Alegre

After four and a half million years you’d think the

water would be all used up! It’s not, though,

because of one special process: the

hydrologic cycle, more commonly called

“the Water Cycle.”

ECOWLECJuvena May Alegre

The Hydrological Cycle

(also known as the water cycle) is the journey, water

takes as it circulates from air, the land , subsurface waters, and organism to the sky, and back again. 

ECOWLECJuvena May Alegre

Water is Ubiquitous!

Biosphere- Water Cycle

Hydrosphere• Liquid waters of

earth.

1. Oceans2. Lakes3. Streams4. Glaciers

Atmosphere• Layer of gases

surrounding earth.

1. Clouds

2. Vapor

Earth is a closed system:

The water available on Earth , today, is the same water that has always been available and the only water that ever will be available!

How much Water do We Have?

Fresh Water

≤ 1 % of Earth’s water is available for the following:

• Support organisms such as: plants, bacteria, humans

• Support industry, agriculture• Provide a source of recreation • Hydropower plants- energy• Transportation• Habitats • Waste processing

Earth’s Water Budget

How the water is divided among:

• Ocean• Land• Atmosphere

Proportions of waterremains relatively

stable on Earth. Only the distribution

differs (tropical vs desert).

Baby water cycle concept

The elementary water cycle:

Better…

EVEN BETTER, but still lacks time and amount information!(like 90% of clouds are

from ocean evaporation)

Water Cycle

The actual path any given water molecule follows

in a complete water cycle can be varied and

complex and may not follow the

exact path shown by a diagram.

Water is Always on the Move

From Atmosphere to Surface

1. Condensation2. Precipitation

From Surface to Atmosphere

1. Evaporation2. Transpiration3. Sublimation

Sublimation: from solid to gas without melting.

Snow or ice vapor

What happens to 100 drops of rain fall?

2 make it into our faucets2 Goes into “ground water”

29 of them go into creeks and rivers

67 drops go back into the skyWithin a week

2 make it into our faucets2 Goes into “ground water”

29 of them go into creeks and rivers

67 drops go back into the skyWithin a week

But… how do those 67 drops make it back? IN TEXAS..

But… how do those 67 drops make it back? IN TEXAS..

2 make it into our faucets2 Goes into “ground water”

29 of them go into creeks and rivers

33 drops evaporate directly

34 drops make it viaTRANSPRIATION

Evaporation

From liquid to vapor

• 80% of all water entering the atmosphere originates from the ocean.

• Transfers energy from the earth’s surface to the air above.

Latent energy: hidden heat energy

Latere- (Lat.) to lie hidden

Transpiration:

The process of transferring water from the roots up to the leaves of the plant to facilitate nutrient transfer. The water is evaporated at the leaves.

Water Vapor

• Odorless, colorless gas that mixes with other gases in the atmosphere like N2 and O2. These gases make up 99% of the atmosphere.

• The amount of water vapor varies from less than 1% to 4% in the atmosphere.

Condensation

• Water vapor cools in the upper atmosphere to form drops or ice.

• Releases latent heat warming the air.

• The released heat may trigger storms.

CloudsA mass of liquid droplets or

frozen crystals.

1. Earth’s water transportation system.

in conjunction with wind

2. Determine how much of earth energy is absorbed.

block solar rays

3. Alters temperature of air on earth’s surface

traps heat on the surface

The process of evaporation and condensation purifies water

naturally.

Evaporation: only the water molecules leave the surface; the dissolved salts and other solids remain behind in solution.

Condensation: when the water vapor condenses again it is pure. It may become contaminated as it falls through the atmosphere: sulfates and nitric oxides ( NOx)

cause acid precipitation.

Precipitation

Water droplets coalesce to form precipitation.

Gravity pulls it to the earths surface.• Hail• Rain• Sleet• Snow

Precipitation

Interception: falls on leaves or stems of plants.

Percolation: moves downinto the soil and ground water.Runoff: does not infiltrate soil but

travels across the surface of land.

• Subsurface Flow

– movement of water within the earth, or within aquifers.

ECOWLECJuvena May Alegre

Ground Water

Together ground water and soil water make up .5% of freshwater.

Ground Water Zones

1. Unsaturated- soil and water 2. Saturated- ground water

Vadose: soil moisture

Water table: divides the 2 zones.

Zone of Saturation

Aquifer- body of earth material that has the ability to hold and transport water.

• Unconfined- “open” connected to the surface above.

• Confined- “closed” sandwiched between dense impermeable layer of earth.

Groundwater Movement

• Replenished by percolation from zone of aeration downward to zone of saturation.

Recharge zone- where confined aquifer is exposed at the surface.

Groundwater flow

Seepage: ground water flows to a stream channel, lakes, and wetlands

Hydraulic conductivity- the measure of the ability of a material to transport water.

Lets talk TIME for a secondHow long does it STAY in each place.This is called “residence time” • Some places you can guess have

LONG residence times– Oceans, lakes, glaciers, groundwater

• Some places you can then guess have SHORT residence times– Clouds, rivers, soils, animals and plants.

Lets talk SPECIFIC timesReservoir

Average residence time of a water molecule

Antarctica 20,000 years

Oceans 3,200 years

Glaciers 20 to 100 years

Snow 2 to 6 months

Soil moisture 1 months

Groundwater 100 – 10,000 years

Lakes 10 to 100 years

Rivers 1 to 6 months

Atmosphere 9 days

A single cloud 40 minutes

Lets talk Water USES

City use• Drinking

water• Sanitation• Lawn• Car

washing

Farm use• Um.. duh

Industry use• making

energy.• Cooling

plants• Used in the

manufacturing process

Human Connection

United States Family

Effects of Human Activities on Water Cycle

• We alter the water cycle by:–Withdrawing large amounts of freshwater.– Clearing vegetation and eroding soils.– Polluting surface and underground water.– Contributing to climate change.

Water Issues

The amount of water on earth remains constant.

World population- 7.111 billion & growing

• 783 million people do not have access to clean water.

• 2.5 billion do not have access to adequate sanitation.

• Demand for food, space, energy and clean water continues to rise.

What can you do?