通过艾莉森Coughlin，CME集团
AT A GLANCE
- The supply and demand of California water are geographically and seasonally disconnected, a trend that could be exacerbated by climate change
- Agriculture, urban and environmental use compete for limited supply in California’s $1.1 billion water market
California has an intricate and multifaceted system of water management. The state’s $1.1 billion water market allocates a concentrated supply to the areas that need it most. From farming to landscaping and personal consumption, there is a constant tension in the state’s supply and demand of this life-sustaining resource.
Rivers, Lakes and Aquifers
In addition to stored supply, water in California is obtained through several avenues. Precipitation suppliesapproximately 75 million acre feet of usable water每年到加利福尼亚州，主要是从12月到3月。此外，Sierra Nevada Mountains中的积雪可以占加利福尼亚水供应的30％ - 随着春季温暖的温度，从山脉冻结并涓涓细流，在水库和盆地中收集。最后，科罗拉多河是加州水的大型供应源，特别是对于南加州。这些来源中的所有三个都可能受到不变的气候变化的损害。
加州水域中有两种即时水源 - 水面水，在河流，湖泊和水库等东西中发现，地下水在含水层中发现。来自雪熔体和沉淀的水可以成为地表水或地下水，当地下水位高时，地下水可以自然地分布到地表水。地下水盆地的绘图水也改变了地表水和地下水之间的关系，因为地下水的低供应可以改变地表水流动或在状态下“进口”，反之亦然。
来源：西水
Surface water, which accounts for60-70% of the state’s supply，没有地理位置分散 - 它的大多数是在该州的北部发现的，而地下水在加利福尼亚州更均匀地分布。数百英里的水库，渡槽和抽水厂的储水和输送系统几乎将状态的整个长度从其北方的起源输送到南方的需求。
地下水从地下含水层泵出来的利用争议历史，特别是在国家蓬勃发展的农业生产行业。这是加利福尼亚州通过了Sustainable Groundwater Management Act(SMGA) in 2014, a first-of-its-kind law aimed making groundwater resources sustainable by 2040.
使用水的地方
The available water in California is used by three avenues – environmental, agricultural, and urban. Though use by sector can vary dramatically within the state and can change each year, approximately一半的水进入环境用途, 40%的农业部门,10%urban use. There is constant interplay between these three, as they have competing interests over a commodity with limited supply. Let’s look at all three.
Environmental
环境用途包括由联邦和州法律保护的自然水源，如河流保护，水在溪流和小溪中支持现有栖息地以及在湿地和野生动物保存中，以及维护其他用途的水质和水质所需的水人类消费。
Agricultural
农业用途支持现金收据的最大农业生产美国国家。加利福尼亚州约有900万英亩的灌溉农田，需要面积24.5 million acre feet of water in 2018。大多数农业用水从6月到9月发生。虽然农业生产在过去几十年中，在过去几十年中，加利福尼亚州的较小的水投入增加，但是每年需要浇水的树木和藤作物的增长。对这些类型的农产品的依赖使加州农场更容易受到任何水资源短缺的影响。此外，随着种群在本地和全球增加的情况下，加利福尼亚州种植的庄稼需求更多。
Urban
Approximately half of urban water use is dedicated to landscape watering and half is used for human consumption. California’s water resources need to support about 40 million inhabitants – a number expected to grow over the coming years. The strongest urban water demand is seen, like with the agricultural sector, in summer months. A recent focus on water shortages and development of water-saving technologies has resulted in a decline in per capita urban water usage. In 1990, per capita water use was 231 gallons per day, whichdecreased to 146 gallons per day by 2015。然而，人口预期增加明显意味着对水需求更多。
The Climate Change Threat
The supply and demand of California water are geographically and seasonally disconnected. However, climate change threatens to upset supply, change demand, and alter the connection between the two even further.
The precipitation patterns in California have become more variable over time. Scientists with the California Natural Resources Agency have suggested that there will be more dry days in the coming years, with short instances of significant downpours. This will exacerbate the geographic supply disparity within the state, with northern California getting even more water and the more arid southern areas receiving less rain through the year.
春天到达后，升温也意味着较少的积雪将可用。估计表明，塞拉尼达斯斯诺克可以体验低于48-65％的损失over the remainder of this century. The change in temperature also means that the timing of the snowpack melt will be impacted, and more water will run off earlier in the year. This alters the balance of storage and use currently employed in California, and months with the highest water demand could be even drier.
像干旱，大雨和野火一样的恶劣天气事件已经变得更加常见。。从NOAA估计，使用帕尔默干旱严重性指数，建议在未来几年干旱将更加严重，导致供应极为有限的供应和洪水洪水的时期。
These intense storms can add pressure to existing reservoirs and aging infrastructure, leading to potential flooding in certain geographies while making it more difficult to move water to areas of high demand. As sea levels rise, more salt water is introduced into the surface water systems, leading to higher costs for water purification and threatening supply numbers.
除了影响加利福尼亚水供应的气候变化外，更温暖，干燥日将增加需求。作物需要更多的水投入较长的季节，而园景和个人使用的人类消费将会上升。最终，气候变化使得管理加州水系统的优先事项更难以在某些领域进行过度过度过度地储存水流的优先级，而是管理洪水的风险，满足完全需求，保护周围环境。
在这些挑战的核心，为不同的参与者提供了独特的水。管理着定价风险的能力最终最终确定使用该宝贵资源的位置和方式。