1. Access Geography Unit 3 Lesson 2 Hydrology

2. Todays objectives

Significance of water

Water availability

Hydrological system

Stores and transfers

3. Why study physical systems?

Human activities are frequently effected by physical systems on the planet. In groups,write at least 3 ways that each system (water, earth, air) can have an effect

Examples

Direct and indirect

Water:river floods, rain on crops, rising sea levels, water supply, transport, power

Earth:soil type for agriculture, natural hazards (earthquakes, volcanoes, mudslides), landforms for settlement (favourable or hindering) or tourism

Air:tourism and leisure, agriculture (economic impact), travel, money spent on predicting the weather, power

Life:food, resource for settlement and housing, transport, aesthetics, economic

4. Energy from the Sun

The energy received from the sun radiated into space is known as insolation.

This energy is sufficient to provide light and warmth for life on this planet plus the heat to drive atmospheric and oceanic movements

There are thus two major systems powered by solar energy: the living system and the ocean-atmosphere system

Both are closed systems in that there is no exchange of mass with the surrounding space system

However, both systems are dependent on materials supplied by the solid Earth

5. The energy balance 6. The Hydrological System: Water on Earth

The Earth is located in the habitable zone of the solar system

5% (8 Million km) either way and water would not be able to exist in its 3 states simultaneously

Earths mass allows gravity to hold an atmosphere

Water vapour and C02 in the atmosphere produce a greenhouse effect which has helped maintain a steady state over geologic time

7. 2. The Miracle of Water

All forms of life depend on water. It is central to:

• • Photosynthesis

• • Respiration

• • Enzyme function

Within conditions on the Earth, it has unique properties:

• • It is naturally occurring in all 3 states

• • It is a very strong solvent (the universal solvent)

• • It has a very high specific heat capacity (can buffer changes in temperature)

• • Its solid form floats on its liquid form

8. 3. Water Availability & Use

70% of the Earths surface is water

Of this, 97% is in the oceans

Of the available 3% freshwater, over 75% is locked in polar ice and glaciers

Only 1% of freshwater is easily accessible in lakes, rivers and shallow soil moisture

Globally the average amount of water available per person per year is 9000m3

By 2025 with the increase in population, this will drop to 5100m3 per person per year.

This would be enough if it was distributed evenly

9. 4. Distribution: Water Stores 10. Hydrology

The study of water and its properties including its distribution and movement through the land areas of the earth

Principally concerned with the part of the cycle after the precipitation of water onto the land and before its return to the oceans

Hydrologists study the cycle by measuring such variables as:

• Precipitation

• Ice and glacier stores

• Water flow in rivers

• Soil-water balance

• Amount and flow of groundwater

11. Before we can understand the Hydrological cycle we need to understand a little about weather 12. So it is hotter at the equator but why??? 13. Where on earth receives the most year round sunshine to provide good growing conditions? 1) Distance the suns rays have to travel through the atmosphere Equator SunRays Longer Distance Shorter Distance 14. 2) The curvature of the earth 15. 3) The suns rays have to travel through thicker atmosphere at the poles Thinner atmosphereThicker atmosphere 16. What causes it to rain? 1) The sun heats up the sea.This causes water to be evaporated (made into a gas called water vapour). 2) The warm air full of water vapour rises high into the sky.Because it is so warm it is very light, thats why it rises. 3) The higher up the air gets, the colder it gets as well.This makes the water vapour condense (turn back to liquid) and form clouds. 4) These clouds eventually drop all of the water in them as rain. This type of rain is called CONVECTIONAL rain 17. The UK is affected by a number of different air masses.Air masses are huge blocks of air at different temperatures.Some of the air masses arewarmand some of the air masses arecold . 18. But air masses at different temperatures DO NOT like one another so they wont mix together.Birmingham is affected by cold air coming down from the north and warm air coming up from the south. The junction between these two different air masses is called afrontso when they cause it to rain it is calledFRONTAL RAIN . 19. But if they wont mix, what happens when they meet? 20. Its fair to assume then, that the final type of rainfall will also follow the same process.But what is it that iscausingthe air to rise? A FEW CLUES Name:RELIEF rainfall 21. Meet Reggie, the RELIEF RAIN raindrop Reggieis a gas flying in the air(water vapour)but when he meets a hill he has to climb over it.It gets very cold near the top of the hill as he is so high and Reggie changes from a gas to a liquid and settles into some clouds(condensation). When lots of Reggies friends arrive in the cloud it is too cramped to stay so some of them fall back to earth as relief rainfall(precipitation). 22. The Hydrological Cycle 23. Hydrological Cycle Matching Resurgence Overland Flow (surface runoff Ground water flow Infiltration Surface water storage Percolation Transpiration Isolation Precipitation Atmospheric Store Snowmelt Saturated zone (aquifer) evaporation Soil moisture Ocean store Base flow Atmospheric condensation Water table Volcanic water Ice cap storage Human activities Interception Stream runoff Impervious bedrock Reabsorbed by plants 24. The Drainage Basin

This is the area of land drained bya single riverand its tributaries

Water drains downhill into a lake, river, dam, wetland, sea or estuary

Theboundary (or watershed)is the ridge of high land, hill or mountain beyond which any precipitation will drain into adjacent basins

The drainage basin includes both the streams and rivers that convey the water as well as theland surfacesfrom which water drains into those channels

25. Drainage Patterns

Dendritic completely random like blood vessels

Trellis strong geology structure produces parallel forms with right-angled tributaries

Deranged highly irregular often as a result of repeated glaciations

Rectangular grid like pattern reflects tectonics faults or bedrock joints

Parallel - often found in areas with steep relief or where flow is over non-cohesive materials.

26. Nested Basins

This image shows the nested order of drainage basins.Rivers are in blue

The red lines describe the watersheds for the drainage basins of first order streams

The yellow lines define the watersheds for two drainage basins from locations further upstream

Notethat the first order basins are components of these much large drainage basins.