In this monthly feature, we span the globe to examine Our Changing Landscape with time series of medium resolution RapidEye satellite imagery. The RapidEye archive dates back to late 2008 and already contains more than 5 billion square kilometers of data. This month, we look at recent changes in the water level of Folsom Lake which is one of California’s many reservoirs.
The RapidEye Constellation
RapidEye is a constellation of five 5-meter medium resolution satellites each offering five spectral bands of information. The RapidEye constellation offers daily revisits to every location on the planet with a huge footprint that is 77-km wide. The data is priced competitively with a starting cost of $1.28 per square kilometer for all five spectral bands – academics do receive discounts. RapidEye adds a fifth band, the red edge, to the ‘traditional’ multispectral set of blue, green, red and near-infrared (NIR). The additional spectral data in the red edge band allows users to extract more useful land ‘information’ than can be from traditional 4-band imagery sources. When RapidEye imagery is ordered as a Level 3A Orthorectified product, images from multiple dates are extremely well registered, making it the ideal data source for Our Changing Landscape.
California Droughts – An Update on Folsom Lake
In the July 2014 edition of Our Changing Landscape, we set the stage for a discussion of the historic California droughts as well as of the reservoir in the northern part of the state, Folsom Lake. It is the goal of this edition of Our Changing Landscape to see how the recent rainstorms that hit both northern and southern California impacted the water level of the state’s reservoirs.
The month of December brought torrential downpours across much of the state of California as it was one of the wettest on record for the city of San Francisco. In one weather event on December 11th and 12th, 3 to 6” of rain fell on northern California and then 1 to 3” fell on coastal Southern California, with pockets of higher amounts in the north and lower amounts over inland SoCal. And while this major rainstorm certainly impacted the drought in California, 98% of the state remained in severe drought conditions the week following the storm, with 32% of the state still in exceptional drought (down 55% from the week before). In the storm, the Los Angeles County Department of Public Works reportedly captured 1.8 billion gallons of water, which is enough for just 44,000 of LA’s 10 million plus residents.
In the most recent climate report put out every two weeks by the State of California, it is clear that while the December rainstorms made a dent in the historic drought, there is still a long way to go to return to “normal.” Here are some statistics that highlight just how drastic the situation in California has become:
- The snowpack is between 31 and 33% of the normal January average, depending on which report you might look at.
- The December rains increased average reservoir levels by about 10% across the state but they still remain dangerously low, for example Lake Shasta, CA’s largest, is at 43% of capacity while Folsom Lake is at 46% and Pine Flat is at 13%.
- Through December 12th, Los Angeles was 23” off its average rainfall since July 2011 and San Francisco was nearly 19” off.
As a sign of possible good things to come for California, NOAA established a 75% probability for average to above-average rainfall from January to March – let’s keep our fingers crossed this prediction comes true!
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