In 119 years of recorded history, 2013 was the driest calendar year for the state of California. On January 17, 2014 California State Governor, Jerry Brown, declared a drought state of emergency.
Snowpack, through runoff, provides about one-third of the water used by California's cities and farms. On May 1, 2014, the Department of Water Resources released their final Snow Survey of the year results stating that the statewide snowpack's water content is at 18% of normal. As of April 1, 2014, the California Department of Water Resources measured the statewide water content of snowpack at only 32% of the average historical April 1 snowpack measurement - crucial because this is when the snowpack is normally at its peak and begins to melt into streams and reservoirs.
Closely monitoring the effects of, and studying the current drought in the context of long-term hydrologic, climatic, and environmental changes, is essential for successful science-based planning and preparedness for future droughts.
A drought is a period of drier-than-normal conditions that results in water-related problems. When rainfall is less than normal for several weeks, months, or years, the flow of streams and rivers declines, water levels in lakes and reservoirs fall, and the depth to water in wells increases. If dry weather persists and water-supply problems develop, the dry period can become a drought.
The term "drought" can have different meanings to different people, depending on how a water deficiency affects them. Droughts have been classified into different types such as:
After several consecutive years of below-normal precipitation, the U.S. state of California is preparing for its most severe drought emergency in decades. The current drought is due in part to decreased rainfall along with reduced winter snowpack in the Sierra Nevada mountain range. In 2013, California received less precipitation than any other year since it became a state in 1850. Water conservation efforts are already in place for many locations. For 2014, there is potential for major agricultural impacts, and the wildfire danger is expected to be unusually high.
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 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 in the images.
The 40-year archive of Landsat imagery is useful for monitoring the changing conditions of Earth's surface areas through time. View the full sized image.
Trinity Lake is a major California reservoir with water storage capacity of 2,448,000 acre-feet. It is located about 60 miles northwest of Redding. The USGS California Water Science Center operates two streamgages near the reservoir to continuously monitor flows into and out of Trinity Lake. The Bureau of Reclamation uses the data from these gages to monitor and regulate Trinity Lake and Trinity River Dam operations. These operations include oversight of downstream flows and surplus water stores that are directed to California's Central Valley for irrigation, provides water for the Trinity River Restoration Project, and provides hydroelectric power.
Data from the streamgage located above Trinity Lake, the Trinity River Above Coffee Creek gage, coupled with snowpack measurement data, allows Reclamation to forecast water availability and manage dam operations. Reclamation also uses the data from the Trinity River Above Lewiston streamgage, below the Dam, to confirm and report the amount of water released. Photo by: Tim Reed, USGS California Water Science Center Supervisory Hydrologist; taken February 4, 2014.
Water quality degradation, surface and groundwater level declines, land subsidence - all are impacts of drought. Understanding the impacts of drought can help mitigate drought-related issues and prepare for future dry periods.
Groundwater provides drinking water for a large portion of the nation's population, supplies business and industries, and is used extensively for irrigation. But what happens to this resource during drought?
Careful observation and analysis of the movement and condition of surface water is essential for understanding this resource, especially during times of drought. The California Water Science Center uses a network of over 400 streamgages to collect real-time data on surface water at locations across the state.
Water shortages during drought are not only a concern for humans, but for ecosystems in the Bay Delta and Central Valley as well.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://ca.water.usgs.gov/data/drought/index.html
Page Contact Information: gs-w-cadist_www@usgs.gov
Page Last Modified: Monday, 23-Jun-2014 12:45:10 EDT
