Droughts


Open main menu Wikipedia Search EditWatch this page Droughts in California Percent Area in U.S. Drought Monitor Categories Throughout history, California has experienced many droughts, such as 1841, 1864, 1924, 1928-1935, 1947-1950, 1959-1960, 1976-1977, 2006-2010, and 2012-2017.[1] As the most populous state in the United States and a major agricultural producer, drought in California can have a severe economic as well as environmental impact. Drought may be due solely or in combination to weather conditions; economic or political actions; or population and farming. The article will touch on the causes of drought, such as lack of new infrastructure, limited reservoir capacity, leaky distribution systems, etc... Also following up with the effects of these droughts and their impacts on the state of California, short term and long term. Then discussing the top historically droughts throughout history and finishing with possible responses, which will discuss mitigation and adaptation to the droughts that can possibly be implemented. A dry riverbed in California, 2009 Causes Edit Water in California is very closely managed, with an extensive pipeline network to serve the most populated and dry areas of the state. Precipitation is limited, with the vast majority of rain and snowfall occurring in the winter months, in the northern part of the state. This delicate balance means that a dry rainy season can have lasting consequences. Lack of new infrastructure Edit Very few large-scale water projects have been built since 1979, despite a doubling of the population since that year. [2] [3] Inefficient distribution systems Edit Because much of California's water network relies on a system of pumps to move water from north to south, large volumes of water are often lost to the Pacific Ocean during winter storms when river flow exceeds the capacity of the pumps. This is further complicated by environmental rules which restrict pumping during certain months of the year, to protect migrating fish. In water year 2015, 9,400,000 acre feet (11.6 km3) of water flowed through the Sacramento–San Joaquin River Delta, but only 1,900,000 acre feet (2.3 km3) were recovered into water distribution systems.[4] Reservoir capacity reserved for flood control Edit Dry boat ramp at Folsom Lake, January 2014 Most of California's major reservoirs serve important flood control functions. Due to the limited capacity of river channels and dam spillways, reservoirs cannot be quickly drained before major storms. This limits how much of a reservoir's capacity can be used for long-term storage. Reservoirs in California are designed to control either rain floods, snowmelt floods or both. In the coastal and southern parts of the state, and much of the Sacramento River system, the primary threat is rain floods in the November–April wet season. Oceanic "atmospheric river" or Pineapple Express storms can generate massive precipitation in a short period (often up to 50 percent of the total annual rainfall in just a few storms).[5] This requires a certain safety margin to be maintained in reservoirs, which are often not allowed to capacity until late April or May. Shasta Lake, California's largest reservoir, is limited to approximately 71 percent of capacity in the winter in order to control rain flooding. Levees along Northern California rivers, such as the Sacramento and American rivers, are quite generously sized in order to pass large volumes of floodwater.[6] In the San Joaquin River basin (San Joaquin Valley) and other areas of the state where snowpack is the primary source of river flow, river channels are sized mainly to control snowmelt floods, which do not produce the huge peaks typical of rain floods, but are longer in duration and have a much higher total volume. As a result, reservoirs in this region have very strict restrictions on the amount of water that can be released. An example of a reservoir operated for snow floods is Pine Flat Lake near Fresno, which is restricted to about 53 percent capacity well into spring in order to capture summer snowmelt.[7] However, Pine Flat and other San Joaquin reservoirs are frequently ineffectual in controlling rain floods, because they cannot release water fast enough between winter storms.[7][8] Certain parts of the state, especially in the central Sierra Nevada, are prone to both rain and snow floods. Reservoirs such as Lake Oroville and Folsom Lake must respond to a wider range of runoff conditions. Lake Oroville is typically limited to 79–89 percent of capacity during the winter and Folsom Lake to 33–60 percent. These values are often adjusted up and down based on the amount of rain and snow forecast.[6] At Folsom Lake, due to the small size of the reservoir, it is difficult to balance the need for winter flood-control space with the need to store water for the summer. This often results in a failure to fill the lake due to a lower than expected spring snowmelt. Water managers and hydrology experts have criticized the outdated, overly conservative operation criteria at Folsom Dam, citing improved weather forecasting and snowpack measurement technology.[9] Progress in forecasting methods has allowed more efficient or "smart" operation at certain California reservoirs, such as Lake Mendocino. If dry weather is forecast, water is allowed to be stored above the legal flood control limit, rather than being wasted downstream. This program is known as "Forecast Informed Reservoir Operations".[10] In addition, capital improvements such as the $900 million spillway project at Folsom Dam[11] will allow greater flexibility in water releases, making it safer to maintain a high reservoir level during the wet season. Flood control limitations at selected California reservoirs[7] Reservoir River Capacity Max. flood control reservation Percent of total capacity Target flood water release Acre feet km3 Acre feet km3 ft3/s m3/s Shasta Lake Sacramento River 4,552,000 5.615 1,300,000 1.6 28.5% 79,000 2,200 Lake Oroville Feather River 3,540,000 4.37 750,000 0.93 21.1% 150,000 4,200 New Bullards Bar Reservoir Yuba River 966,000 1.192 170,000 0.21 17.6% 50,000 1,400 Folsom Lake American River 977,000 1.205 670,000 0.83 68.5% 115,000 3,300 Camanche Lake Mokelumne River 417,000 0.514 200,000 0.25 48.0% 5,000 140 New Hogan Lake Calaveras River 317,000 0.391 165,000 0.204 52.1% 12,500 350 New Melones Lake Stanislaus River 2,420,000 2.99 450,000 0.56 18.6% 8,000 230 Lake Don Pedro Tuolumne River 2,030,000 2.50 340,000 0.42 16.7% 9,000 250 Lake McClure Merced River 1,024,600 1.2638 350,000 0.43 34.2% 6,000 170 Millerton Lake San Joaquin River 520,500 0.6420 390,500 0.4817 75.0% 8,000 230 Pine Flat Lake Kings River 1,000,000 1.2 475,000 0.586 47.5% 7,950 225 Lake Isabella[12] Kern River 568,000 0.701 398,000 0.491 70.1% 4,600 130 Weather cycles Edit California has one of the most variable climates of any U.S. state, and often experiences very wet years followed by extremely dry ones.[13] The state's reservoirs have insufficient capacity to balance the water supply between wet and dry years. El Niño and La Niña have often been associated with wet and dry cycles in California, respectively (the 1982–83 El Niño event, one of the strongest in history, brought record precipitation to the state), but climate data show scant evidence for such a relationship. The very wet 2010–2011 season occurred during a strong La Niña phase, while the 2014–16 El Niño event, which surpassed 1982–83 in intensity, did not bring an appreciable increase of precipitation to the state. The 2012–15 North American Drought was caused by conditions of the Arctic oscillation and North Atlantic oscillation which removed winter storms from the U.S. the winter of 2011–2012. Climate change Edit Main article: Climate change in California § Drought According to the NOAA Drought Task Force report of 2014, the drought is not part of a long-term change in precipitation and was a symptom of the natural variability, although the record-high temperature that accompanied the recent drought may have been amplified due to human-induced global warming.[14] This was confirmed by a 2015 scientific study which estimated that global warming "accounted for 8–27% of the observed drought anomaly in 2012–2014... Although natural variability dominates, anthropogenic warming has substantially increased the overall likelihood of extreme California droughts."[15] Increasingly dramatic fluctuations in California weather have been observed in the 21st century. In 2015, California experienced its lowest snowpack in at least 500 years; the 2012–15 period was the driest in at least 1200 years.[16][17][18][19][20][21] However, the winter of 2016–17 was the wettest ever recorded in Northern California, surpassing the previous record set in 1982–83. In February, Shasta, Oroville and Folsom Lakes were simultaneously dumping water into the ocean for flood control. Lake Oroville flowed over the emergency spillway for the first time in 48 years, after the main spillway was damaged resulting in the temporary evacuation of 200,000 people.[22] The combined inflow to Shasta, Oroville and Folsom Lakes on February 9 was 764,445 acre feet (0.942929 km3). Two days later, the combined flood control release was 370,260 acre feet (0.45671 km3).[23] This water would have been worth $370M at Los Angeles County municipal rates.[24] Water rights complexity Edit Main article: Water in California § Water rights Without changes in water use, it would take about 6 dry years to deplete the state's reservoirs. [25] Large water consumers Edit Approximately 2.7 trillion gallons are effectively exported from California every year in cattle feed. [26] This is more than California's annual urban water consumption, which is only 2.3 trillion gallons. [27] California's annual cattle feed production is worth only $1.3 billion. [28] Also, from 2008–2015, 1.4 trillion gallons were dumped into the ocean to save 36 Delta smelt. [29] An alternative, salinity barriers, is being installed.[30] Supply and Demand Edit Water in California can be rather expensive. [24] These conditions lead to awareness of water management challenges. [31] In rain rich states and countries, which are not drought prone, the water, as elsewhere, is managed by government consent, which assumes ownership and management of all free flowing rivers, lakes, and bodies of water in its parameters. The water being used for commercial purposes, such as NESTLE'S 72 brands of bottled water, is done so only as permitted and granted by governmental authorities. Lately, locales have been fighting back against the "stealing" of precious resources by opposing and not allowing huge water draw down facilities to be set up. [32] In some instances, water tables underground have dropped from 100 to 400–600 feet deep, basically shutting down most private well owners from their own water sources. [33] [34] Orange County is working toward water independence by building the world's largest indirect potable water recycling project - the Groundwater Replenishment System. Poseidon Water is also developing a seawater desalination plant in Huntington Beach for Orange County and has already built and is operating a seawater desalination plant in Carlsbad for San Diego County. Combined the two plants will provide 100 million gallons of drinking water per day, or enough water for about 800,000 people.

Comments

Popular Posts