Presentation on theme: "Why was it dammed? How has it affected the lives of the local people?"— Presentation transcript:
Why was it dammed? How has it affected the lives of the local people?
Now using the atlas- complete your map following the instructions on the side
Much of the area the river runs through is desert and area twice as big as the UK Early settlers dammed the river to provide water to local cities and towns- much of this comes from the snowmelt in the Rocky Mountains It also regulated the flow of the river to ensure a constant supply of water to cities such as Las Vegas and Phoenix 25 million people in the SW rely on this supply
In Boulder Canyon Lake Mead and Lake Powell are two largest man made lakes in the USA
Using the sheet you have be given colour in the bubbles to show the effects of the dam in the following categories Social Economic Environmental Political
400,000 ha of land is irrigated for farming (most of it in California’s Imperial Valley) Lake Mead and Lake Powell are major tourist centres Lake Powell offers sailing, power boating, water skiing and fishing and attracts over 2 million visitors a year The photo above was taken on July 26 th 2007, 7 th year of drought, lake level dropped more than 100 ft- lowest level since the late 1960’s.
Annual rainfall of 50mm 90% of water from Lake Mead Much of the water is lavish and wasteful- lawns, parks, golf courses and swimming pools are seen as essential and can only be maintained by irrigation Major tourist destination- over 37 million visitors a year Water is becoming increasingly scarce
‘Grass for Cash’- the city pays householders $1 for every square foot of lawn they remove They hope they will replace them with Cacti and other desert plants Pumping water from aquifers (permeable rocks underground) or oases- but what are the issues with this?
This is north of Las Vegas The oases in the desert such as Ash Meadows are rich in wildlife- 239 species of bird, 27 mammals, 20 reptiles, 5 amphibians and 7 fish 25 of which are nowhere else in the world These are protected as national wildlife refuges
The Las Vegas Water Authority wants to pump around 2 million cubic metres of groundwater each year from the aquifer It will lower the water table Springs will dry up The unique environment will be destroyed
How will Las Vegas meet the demands of its growing population and tourism industry? How important is the natural environment compared to urban lifestyles and jobs?