CALIFORNIA DROUGHT SAI SIMHA AKULA

DROUGHT Drought is an extended time when a region receives a deficiency in its water supply, whether atmospheric, surface or ground water.It is the absence of water for a long period of time, at a place where it is considered ‘not normal’ compared to its usual conditions.Generally, this occurs when a region receives consistently below average precipitation.We often do not see droughts as natural disasters like tornadoes, hurricanes or floods, because they do not have the usual immediate destructive ability, but they can be very catastrophic in the long run. 

CAUSES OF DROUGHT ? It can be caused by not receiving rain or snow over a period of time. Droughts can occur when there is lack of ‘expected’ precipitationDrying of Surface water flow. Surface waters may dry out if the flow from their sources is affected.Human factors-Deforestation will expose surface water to more evaporation and also reduce the ability of the ground to hold water and make it easier for desertification to occurGlobal Warming – Warmer temperatures, often result in more dryness, which also tend to speed up drought conditions.

CALIFORNIACalifornia is the third largest state in the U.S, by area.It is the most populous state in the U.S. If it were a country, California would be the 9th Largest economy in the world and the 34th most populous.At least half of the fruit produced in the United States is grown in California, and the state also leads in the production of vegetables.Agriculture contributes to 80 percent of its water use.California has been the state with the largest water use in the US since the USGS began compiling water-use data in 1950An average Californian uses 196 GWPD compared to 98 GWPD by an average American.

CALIFORNIACalifornia’s proximity to the Pacific Ocean and major mountain ranges define the state’s hydro climate setting.Most of the water vapor that provides the state’s precipitation comes from the Pacific Ocean, as moist air moves over mountains such as the Sierra Nevada or Transverse Ranges the air is lifted and cooled, resulting in condensation and rain or snow.Snowpack in the Cascade Range and Sierra Nevada contributes to the runoff in the state’s largest rivers and to the groundwater basin recharge that support much of California’s urban and agricultural water use.

Much of California experiences a Mediterranean like climate with dry summers that are warm or hot, and wet winters that are cold.Westerly winds transport water vapor that provides winter precipitation; summers are characterized by a blocking high pressure zone that diverts atmospheric moisture away from the state.On average, about 75 percent of the state’s average annual precipitation of 23 inches falls between November and March, with 50 percent occurring between December and February.Ultimately, drought in California stems from an absence of winter precipitation. At the weather timescale this occurs when an atmospheric high pressure ridge blocks winter storms from reaching the state, shunting them to other areas.Records of low rainfall and higher temperatures, vaporized its water supply.

RIDICULOUSLY RESILIENT RIDGERidiculously Resilient Ridge , the nickname given to a persistent region of atmospheric ridge that occurred over the far northeastern Pacific Ocean during 2013-2014.This persistent ridging acts to "block" the prevailing mid-latitude Westerlies, shifting the storm track northward and suppressing extratropical cyclone (winter storm) activity along the West Coast of the United States.The Ridge comprises the western half of atmospheric ridge-trough sequence brought persistent anomalous cold and precipitation to the eastern half of North America during 2014 in addition to record-breaking warmth and drought conditions in California.This anomalous atmospheric feature disrupted the North Pacific storm track during the winters of 2012-2013, 2013-2014 and 2014-2015, resulting in extremely dry and warm conditions in California and along much of the West Coast.

PRECIPITATION

SURFACE WATER SOURCESOverdrawing water from the rivers mainly for agricultural purposes has almost dried them up.

SNOW PACK The state (and much of the West) relies heavily on snowpack each winter to resupply surface water streams and lakes. Because of a lack of winter storms and record high temperatures this past winter, snowpack in California is at an all-time low. This is the fourth consecutive year that the snowpack has been below normal.

These three images show a portion of California's Central Valley (left side of the images) and the neighboring Sierra Nevada mountains as viewed by Landsat in February 2011, 2013, and 2014. The reduced winter snowpack in the Sierra Nevada mountain range is concerning, as snowpack, through runoff, provides about one-third of the water used by California's cities and farms.The decrease of winter snow cover can be seen in this progression of images. The reduction of available water supplies in the Central Valley is also indicated by the changing outlines of Folsom Lake, Camanche Reservoir, and other lakes and reservoirs.

GROUND WATER The Department of Water Resources estimates that groundwater levels across most of the state have dropped 50 feet below historical lows. In many areas in the San Joaquin Valley, groundwater basins are more than 100 feet below previous historic levels. This overdraft partially results from Californians withdrawing groundwater faster than the rate of natural recharge.

During normal years, groundwater supplies between 30 and 40 percent of California’s water. But when surface water availability is reduced during droughts, groundwater can account for closer to 60 percent of water used statewide.

Increasing temperatures will lead to earlier and reduced melting of snowpack, which in turn reduces the quantity of available groundwater.

DROUGHT CONDITION TIMELINE

Around 98% of California now is in a state of drought

EXTENT

Lake Oroville , Before and After

Lake Folsom, Before and After

Snowfall in December 2013 was less than 5 percent; 30 percent is average

Mount ShastaTop left: November 2013Bottom right: January 2014

DROUGHT EMERGENCYGov. Jerry Brown declared a state of emergency over a drought on Jan 1st 2014.He called all Californians to conserve water in every way possible.Brown urged residents to cut their water use by 20 percent, and asked state agencies to conserve water.Describing California's plight, the governor's office cited state officials who say rivers and reservoirs are below record lows – and the state's snowpack is at only 20 percent of its normal average for January.California's state water board in May 2015 approved emergency drought regulations that aim to slash water use in urban areas by 25%.The measures call for cities and water agencies to reduce water usage by amounts ranging from 8% to 36%.

On April 1, 2015, the California Department of Water Resources measured the statewide water content of Sierra snowpack at five percent of average for April 1st. These levels are lower than any year in records going back to 1950. The April 1 snowpack measurement is crucial because this is when the snowpack is normally at its peak and begins to melt into streams and reservoirs. Snowpack, through runoff, provides about one-third of the water used by California's cities and farms.California's 2014 Water Year, which ended September 30, 2014, was the third driest in 119 years of record. It also was the warmest year on record

CHALLENGESLimited water availability Over pumped aquifersReduced water qualityCollapsing Delta ecosystems and fisheries Growing demandsLong-term climate change

DESALINATIONIt is the process of removing dissolved salts from water, producing fresh water from seawater or brackish water.The principle used is Reverse Osmosis.San Diego is currently building the biggest desalination plant in the western hemisphere to the tune of 1 Billion USD. It will make 204 Million liters of portable water daily and sell at a rate of $1 for every 616 lts.The price is 80 % higher than San Diego pays for water from outside the county. It will only cater to 10 % of the county’s needs. It requires a lot of energy.Conservation and recycling may be a better strategy.

SOLUTIONS•Strict enforcement of water shortage contingency plans•Judicious use of groundwater sources to meet requirements•Farmers should trade water hungry crops for drought resistant crops•Use of micro-sprinkling and drip irrigation, and doing laser leveling of fields to reduce runoff•Installation of water meters wherever needed and possible to regulate water use•Investing in public outreach campaigns to educate water users regarding new restrictions and judicious use of water•Incentives for replacing lawns with drought-resistant or native plants.

•Policy to encourage conservation by pricing water in tiers, depending on water usage•Moratorium on issuing new water service permits, a ban on draining and refilling pools, and strict limits on outdoor watering, with penalties imposed for violations•Buying water from farmers north of the Sacramento Delta, who would fallow their fields and profit from the sale of their water rather than their crop•Possibly revisiting California's riparian water right laws (framed in the 19 th century) and make suitable amendments to suit the 21st century needs

REFERENCESwww.water.ca.govwww.californiadrought.orgwww.google.comwww.earthjustice.orgwww.droughtmonitor.unl.eduwww.usgs.govwww.nbcbayarea.com

THANKS FOR WATCHING