Case studies for rivers - created from Mind Map

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Mozambique

Causes

Effects

Flood defences

3 days of heavy rain in January

5 weeks of continuous rain

Cyclone Eline 22nd Feb

Less grassland so less infiltration

No flood area - being used for farming

Urabanisation

Causes water to flood in upper courses of river

More than 1 mill homeless

Thousands drowned

Quick spread diseases in refugee camps

Destroyed farmlands

Repair costs

83% pop work in agriculture

$30mill roads

$6mill railways

$4mill electric supplies

Can't afford

Able to start flood warnings due to funding from EU

Can't control river as upper courses in other countries

Sheffield

Causes

Effects

1 months rain fell in one day on June 15th 2007

10cm fell on 25th June

The confluence of several rivers

Sheffield in a valley = surface run off

Soil saturation

The 10cm ran into lakes and rivers and surface runoff

2 rivers joined and one was already full - water backed up

Banks overflow causing flooding

Reservoirs filled up and flooded

Flooded football stadium - 8 metres deep

43% houses flooded - 9 months to sort out

People had temporary housing in caravans

Sewage escaped into drinking water

Dangerous situations - evacuated

400 people slept overnight in offices

23 airlifted to safety

Tool making company had repair costs of £15mill

Shopping centre badly flooded and stock lost

Cost several mill to remove water

Health risks

Preventing flooding in River Derwent - North Yorkshire

Soft engineering

Hard engineering

Washlands between embankments and river

Building restricted on floodplain

Planting in catchment

Reinforcing banks with woven willow to stop bank erosion and so the river doesn't get silted up

Warning systems

Data on rainfall

Embankments

Sluice gates upstream hold back water and let it out steadily

Rural area and high value land - hard engineering isn't appropriate for the whole area

Didn't prevent flood damage in 1999

The Sahel - desertification

Causes

Effects

Overgrazing

Farming of average land

Destruction of plants in dry regions

Normally rains 1-2 months a year

Rainfall been below average since 1970 - some years 25% less

When it does rain - surface runoff

 Other years there is no rain at all  rivers dry up  water table falls  farmers crops fail  animals die  desertification  decreased food supplies  famine

Soil becomes less usable

Lack/damage of vegetation

Famine

Food loss

People near affected area

Colorado dam

Regulates river flow

Creating resevoirs

Trap sediment behind dam

Costs

Benefits

Less energy left to move sediments

Which keeps water warm for fish

Less flood risks - flood peaks smoothed out

Costs

Benefits

Loss of land flooded by reservoir

Regular all-year water supplied for cities like Las Vegas

Costs

Benefits

Shrinking sandbanks means some animals lose habitat and tourists lose rafting

/

Water stress

Lake Chad

South East England

Sonoran desert

Australia

One of largest lakes in world

Supports over 20mill people

Global warming is evaporating lake

Lack of rain

People need lake for fishing, drinking and farming

Dry winters so reservoirs didn't fill up

Last Jan only 2/3 of annual monthly rainfall

Hose pipe bans

High pop and low precipitation

2011 farmers lost out on crops

In 30 years there will be bad drought if nothing is done

One farmer lost £20,000 due to spring drought

Uses of water

Why rate is increasing

Impact

Supply pop demand

Water features

Farms

Pop increasing 1.8 - 3.6 mill

Urbanisation

Water supply not sustainable

Water quality deteriorating

Expensive

Water table falling 3m in ayear

Building canals-destroying habitat

Ground giving way

Dhaka, Bangladesh

slum on disused railway station. No safe water or toilets

 WaterAid constructed 6 tube wells and 2 new sanitation blocks

people are no longer continually ill

they can run facilities themselves

moving out of poverty

Case studies for rivers