New Geography in Action Junior Cycle Geography CASE STUDY
Irrigation scheme: Central Valley Project, California Sacramento River
Why does the valley need irrigation?
The area has a very warm climate with mild winters. There are very hot summers from June to August each year. The region often suffers from drought (a lack of rainfall). This used to mean that it was difficult to grow crops on the farmlands of the San Joaquin Valley in the south. However, the Sacramento River in the northern region of California has been used to irrigate the valley and provide water for drinking.
About the Central Valley Project
• Dams were built on the river to create large reservoirs where water can build up.
• Canals and aqueducts (human-made channels) were then used to pipe the water from the north of the valley to the south.
• The valley is now a region that produces a variety of crops such as vegetables and fruit. Advantages of the scheme
• The valley is irrigated in times of drought. • The towns and cities in the area have a water supply.
Disadvantages of the scheme
• It was very expensive to build the dams, and the cost of pumping the water is high, so it increases the cost of the produce.
• A lot of water evaporates from the reservoirs. This leaves a high salt content and can lead to poisoning of the land.
: Figure 4.8 An aqueduct running through farmland in Central Valley
: Figure 4.7 Map of San Joaquin Valley and Sacramento River
USA San Joaquin Valley
California
(i) What are the four main stages of the water cycle? (ii) Name a chemical that is added to water. What does it do? (iii) Why are there no irrigation schemes in Ireland?
/ I can explain the water cycle. / I can explain how a local water supply works. / I can explain the sustainable exploitation of water. / I can explain what an irrigation scheme is.
