|California Land use today |
In 2008, California is dominated by two sprawling urban areas: San Francisco and Los Angeles. The originally existing shrublands have been replaced by pastures and the California Sacramento Valley is characterised by intensive agriculture based on irrigation (cultivation of fruits).
The intensive development of California was only possible through extensive technical measures to ensure water supply. This is due to summer droughts or the steppe and desert climate, a problem not only for agriculture, but also for the water supply to the cities. Approximately three quarters of the available surface water in California comes from the region north of Sacramento. There, the rainfall is relatively high (slope rain) and the evaporation has comparatively low levels. However, south of Sacramento, where the rainfall is much lower and evaporation is much higher, four-fifths of the demand is made. As a result, significant water shortages are experienced. In addition, there is the agglomeration of the Los Angeles area. With this spatial imbalance of water, there is the temporal gap between water supply and demand. The water flow of rivers from August to November reaches minimum levels. Therefore, in late summer, only a small supply of water is available while the demand for irrigation water is then particularly high.
To ensure the water supply, large plants have been built for the storage, transport and distribution of water. In the northern part, California's water is collected in the winter months and is generated in large reservoirs and saved especially at the Shasta Dam. Through channels of 560 km of water areas, the demand is supplied for irrigation purposes. The Oroville Dam is at the most important reservoir and the main channel is the 700 km-long California Aqueduct. Twenty dams and reservoirs, five power plants, 17 major pumping stations and 200 km lateral canals are connected to the California Aqueduct and supply the growing areas in Southern California, around San Jose and in parts of the San Joaquin Valley. Supplies to urban areas are part of additional systems. For example, the Los Angeles area also takes water from the Owens Valley (located just east of the southern Sierra Nevada).
These complex systems first made extensive irrigated agriculture possible in California. California is at the forefront of U.S. production with 55 different plant and three animal products. Within the U.S., California is the sole producer of almonds, dates, figs, kiwifruit, nectarines, olives, pistachios, pomegranates, (Clingstone-) peaches, prunes and walnuts. There are also high market shares (75100 percent) for broccoli, melons, strawberries, cauliflower, tomatoes, apricots, avocados, grapes, lemons and plums. In the southern part of the Sacramento Valley (San Joaquin Valley) cultivation of almonds, wine, cotton, tomatoes and citrus fruits are recognisable in the image maps and rice is also grown in the northern part (Sacramento Valley). The Salinas Valley is the "salad bowl" of the U.S. (producing approximately 50 percent of the lettuce crop of the U.S.).
W. Klohn; Ü: C. Fleming
Keywords: California canal crop irrigation irrigation land improvement reservoir United States USA
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