Sacramento-San Joaquin River Delta
The Sacramento-San Joaquin River Delta is a large inland delta and estuary in Northern California on the Pacific coast of the United States of America .
geography
The delta is formed by the mouths of the Mokelumne River and the Calaveras River in the San Joaquin River , and the same in the Sacramento River at the west end of the Central Valley . The only outflow is Carquinez Street , which leads into the Pacific via the San Pablo and San Francisco Bays and the Golden Gate .
The delta consists of countless canals and natural waterways ( Slough ) which (sometimes a number of islands Tract called) and wetlands form. Due to soil erosion , most of these islands are below the water level of the surrounding canals or rivers; a system of dikes protects against flooding.
development
The delta is an estuary with a catchment area of more than 150,000 km². The catchment area extends from the southern end of the Cascade Range in northern California along almost the entire western flank of the Sierra Nevada . For thousands of years, floods and snowmelt regularly inundated large parts of the delta.
Towards the end of the California gold rush , Chinese workers began to draw canals and build dikes to gain land for agriculture . These canals were first dug by hand , and steam-powered dredgers ( clamshell dredgers ) were not used until around 1870 , until the current shape of the delta was achieved by the end of 1920.
It was around this time that steam navigation reached its peak in the Delta and its tributaries, and it was easy to travel from San Francisco to Sacramento , Stockton, and even Fresno or Red Bluff . Around this time up to 300 paddle steamers were in use, of which the legendary sister ships Delta King and Delta Queen were the largest. However, when bridges such as the Golden Gate Bridge , the Bay Bridge and the Carquinez Bridge were opened in the 1930s, thereby significantly easing car traffic to the north and west, steam navigation in the delta declined rapidly until after the outbreak of the Second World War was practically completely discontinued.
The soil erosion that started due to the nature of the soil and intensive agricultural use has significantly lowered the islands created - sometimes more than 6 meters - so that entire stretches of dyke are threatened with collapse. Several levee breaches were the result (e.g. Frank's Tract and Mildred Island ), the last one occurred on June 3, 2004 16 km west of Stockton , where a 110 m long section of the levee collapsed and the Upper Jones Tract - a 49 km² large Island - flooded. After similar dike breaches became more and more likely, the California Governor Arnold Schwarzenegger signed a billion dollar program on May 19, 2006 to repair and modernize the dikes in the delta.
use
Due to the mild climate , the fertile peat soils and the rich water resources , intensive agriculture is practiced in the delta , which contributes billions of dollars to the gross domestic product of the California economy . Numerous special crops such as tropical fruits , fruit , asparagus and, more recently, viticulture are also grown . Several harvests a year are sometimes possible.
In addition, the delta provides around 25 million people - about two-thirds of the population of California - with drinking water and a large part of the agriculture in southern California with irrigation . The water is drawn off in the south of the delta, at the Clifton Court Forebay . Both the California Aqueduct - which supplies large parts of Central Valley and Los Angeles - and the South Bay Aqueduct - which leads to Silicon Valley and the San Francisco Bay Area - are fed from here.
The delta with its "Thousand Miles of Waterways" is also a great recreational area . Warm summer days, moderated by the so-called Delta Breeze , attract numerous water skis , wakeboarders and sports boats . In the cooler winter months, which are characterized by fog ("Tule Fog"), anglers and hunters can be found mainly .
Individual evidence
- ↑ Archived copy ( memento of the original from October 3, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Support Habitat Restoration in the California Delta ( Memento of the original from June 23, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ http://modeling.water.ca.gov/delta/reports/annrpt/2005/2005Ch3.pdf Annual report 2005
- ↑ http://gov.ca.gov/press-release/809/ Gov. Schwarzenegger Signs $ 4.5 Billion Levee Repair and Flood Control Component of Strategic Growth Plan
- ↑ Archived copy ( memento of the original of July 7, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. State Water Project - Delta
