UNIT 3. WATER

1.The water cycle About 71% of the Earth´s surface is covered by water. Blue planet. The amount of water is always the same. Different states (liquid, solid or gas). Water cycle.

Water cycle

Seawater and continetal waters Seawater: 97% of the water on the Earth. Oceans and rivers. High level of salinity.

Continental water Continental water is found in rivers, lakes and ice and snow in glaciers. It is also found as a groundwater. Vocabulary: beneath (below, under).

Activity 2 page 40

Rivers Continuosly moving body of water that flows into an ocean, sea or another river. It is formed by precipitation, or melting ice and snow.

It flows from its source to the river mouth

Some flow into another river (tributary)

Important rivers

Activity 4 and 5 page 41

2.Course and flow of a river

Upper course Near the source (also named headwater(1) of a river, lake or glacier Usually in mountains areas In this course, water flows rapidly down steep slopes Erosion: remove and transport rocks and earth It forms mountain valleys, canyons or gorge (3), rapids, waterfalls (4), lakes, ravines or small rives as creeks, brooks or streams (2) This source is connected with the middle course by the fall line (5)

Headwater or source

Valley

Gorges

Ravine

Waterfall

Rapid

Rapid

Canyon

Middle course It is flatter The water flows more slowly Transport material such earth and stones Creaters landforms such meanders, oxbow lakes or tributary rivers.

Meander and oxbow lake

Meander

Lower course Where abundant water flows. The river flows slowly and deposits mateiral (estuary or delta) and forming a fertile alluvial plain. It reaches the river mouth. Lower course

Alluvial plain/floodplain

Floods on Mississippi river

Estuary

Delta

The flow of a river The amount of water that the river carries. It could be different depend on the part of the year (the river doesn´t have the same amount of water in summer than winter).

Let´s see Rivers fed by melting ice and snow… Have a higher flow inthe spring

Have an abundant flow in the rainy season. Rivers fed by precipitation…

Mediterranean or desert Rivers are dry most of the year. Water only flows when it rains (spring and fall season). When rains a lot in a few houres, it happend disasters (cold front)

A river has a regular water flow when the same amount of water flows thrughout the year. An irregular water flow is when the amount of water varies a lot from one season to another.

A long profile of a river It is a graf thet represent information about the river such its length, places it flows past and its altitude.

Activities 1 and 3 page 43. LOOK, on activity 3 you should answer the questions with the river you described in the activity 5 of page 41.

3. Lakes, groundwater and glaciers

Lakes Lakes are permanent masses of water that have accumulated in inland basins. Most contain fresh water. If they contein salt water we call them inland sea. The water comes from precipitaion, rivers, groundwater or melting ice from glaciers.

The Aral Sea Kazakhstan/Uzbekistan

Activity 1 page 44

Groundwater

It is water stored beneath the Earth´s surface. Almost ¼ of the Earth´s fresh water. Most cames from precipitation filtering through the soil and forming large store of underground water called an aquifer. Vocabulary: store, beneath, rainfall, filter, impermeable, aquifer, well, overexploited, to fill up

Glaciers

Masses of ice created by the accumulation of snow. They are near the poles and on high mountains. Coastal glaciers break up and form icebergs (masses of floating ice).

Iceberg

Activities 2 page 45 Activity 5 page 49

4. Oceans and Seas

Oceans: huge masses of water that sorround the continents. Seas: smaller than oceans and partly enclosed by land

Activity 1 and 2 page 46

Currents, tides and waves

Ocean currents: large masses of water that cross the oceans in similar way to rivers.

Marine currents have influence on the climate of coastal regions. Atacama desert (Chili)

Tides, are the daily rise and fall of the water caused by the gravitational forces of the Moon and the Sun.

Waves, are movements of the surface of the water caused by the wind.

Activity 3 page 47