California

• main water sources


  majority of supply comes from surface water (roughly 70%) wiith 30% from groundwater aquifers and a very small proportion from desalinated sea water. However groundwater demands rise up to 60% drought years. This puts huge strain on unstable aquifers where recharge since 1999 has not kept pace with extraction.

  Water is diverted from the North (abundant water) to the South (water scarce and highly populated) - large scale water transport + storage facilities transport surface water via aqueducts (California, LA and Colorado River Aqueducts)
• components of demand


  rainfall is becoming less consistent and predictable - more droughts

  per capita water consumption has dramatically increased - more than 100 times since 1920

  agriculture requires significant irrigation - 27,000km^2 of irrigated land: 80% almonds, 60% walnuts + large amounts of pistachios, citrus fruit + vines also 1/3 of all vegetables consumed in the USA
• Why water stress occurs

  droughts: meterological (less rainfall than usual), agricultural (when demand exceeds natural capacity), hydological (drainage basin conditions insufficient for plants to survive)

  Over-abstraction of the Colorado river. Lake Mead - largest man made resevoir in the USA - falling water levels, Summer '22 levels were at 27% capacity (lowest ever) -> water almost too low for HEP production

  Aug 2022 - 7 states asked to agree to reduce their water use by up to 50%
• How water sources relate to climate, geology and drainage

  snowfall in Sierra Nevada influences water supplies for the rest of the year - below average in 2020-22 due to La Nina

  Agricultural drought: Summer temps often top 40℃ -> surface water lost through evapotranspiration. less water available for plants -> more needed for irrigation. without this landscape would become desert

  droughts -> wetlands becoming rare, vernal pools being draied, salination -> crop yields failing

  more rainfall in the North but most of the population lives in the South so they have to transport it
• how they are increasing water supply

  Over 1300 named resevoirs

  3 vast water transfer schemes: California state water project - largest water transfer system in the world, Central Valley project (LA) & Colorado river water scheme

  seawater desalination - Carlsbad plant converts seawater into drinking water for 400,000 people in San Diego, limitless supply of seawater, more expensive due to energy used, not affected by droughts

  Oroville Dam

  recharging groundwater

  purification of groundwater - filtered captured storm water

  recycled wastewater
• Environmental impacts


  Oroville dam
• Conflicts


  Water rights are disputed. Native American tribes have long standing legal rights and ownership of the Colorado river has long been disrupted by the USA and Mexico

  Nothern Californians fear ownership of their water by the South while Southern Californians worry about the continuity of supply

  Environmentalists are concerned that wetlands have already been drained, natural habitats altered and river fish stocks depleted

  80% of water is used for farming but 1.6 million hectares of land are flood irrigated
• Managing consumption


  rain gardens - swapping grass for drought tolerant plants reduces demand as lawns aren't watered reducing demand for water during the long dry summer months

  rain gardens, hosepipe bans and offering incentives to install water efficient appliances -> 12% reduction in water consumption

  Southern California now uses the same amount of water as twenty to thirty years ago, even though there are one million extra people living there
• How do these factors affect human welfare in California?

  Some farmers have had to change their crops and some land has been left fallow. In Tulare county there were 1500 fewer farmers in 2015 than 2014, a drop of nearly 19%. Also in 2015 1 in 4 Tulare county families lived below the federal poverty line. Families have to relocate, find new jobs and have less money.

  Groundwater wells have become polluted → most communities in southern LA country now rely, at least partially, on contaminated groundwater sources. The contaminated water has to be treated and purified which is expensive. In January 2016 treatment failures led to 20,000 residents in Watts, a poor multicultural community in inner city Los Angeles drinking untreated well water for six hours.

  In 2016 bottled water was donated to Tulare County during a drought. People were so desperate they stole bottled water from their neighbours in one of the richest states of the USA.

  Many residents depends on a private well for water supply but these dry up

  Drought → less water → water prices go up, rich people can afford it (water their lawns) poorer people are using more of their disposable income on water
• Brief evaluation of management of water in Cali

  Water is being provided to the people in the South however there are conflicts over it as there are many different stakeholders who all have different demands. However it is successfully providing some water to the people in the South