Our Changing Landscape – 2023 Sierra Nevada Snowmelt - Apollo Mapping
Posted on August 1st, 2023

Our Changing Landscape – 2023 Sierra Nevada Snowmelt

In this monthly feature, we span the globe to examine Our Changing Landscape with a time series of medium-resolution PlanetScope satellite imagery. The PlanetScope constellation dates back to 2016 and collects hundreds of millions of square kilometers of four and eight-band 3-meter imagery daily! In July, we looked at the colorful superbloom happening in California. This month, we’re actually staying in California to check out the incredible snowmelt happening in the Sierra Nevada mountain range!

Click on the image above to see an animation of 3-meter natural color PlanetScope imagery collected over the Sierra Nevada mountain range close to Lake Tahoe, California on May 22 and June 4, 2023. Originally we planned on showing a layer stack that went back to March but unfortunately the earlier images were covered with flares which can appear purple-blue (as you see in the June 4th image) and thus were unusable. However, even in these images collected about two weeks apart, the rapidity of the snowmelt is obvious as in the June image there is little snow left in the valley by the road and the snow in the mountains has thinned significantly. (Images Courtesy: © Planet 2023)

The PlanetScope Microsat Constellation

PlanetScope is a constellation of more than 240 microsats (as of January 2022) referred to individually as Doves. Each Dove is able to collect up to 20,000 square kilometers (sq km) per day of 3-meter (m) 4-band multispectral (i.e. blue, green, red and near-infrared [NIR]) imagery; and newly launched SuperDoves collect 8-band multispectral adding in valuable red-edge spectral data. Across the constellation, PlanetScope is archiving more than 200 million sq km of medium-resolution imagery a day, making it the go to source for daily imagery over most locations. This massive archive dates back to 2016, offering the most complete and continuous record of spatial data on the planet since the start of the constellation’s ongoing launch schedule. Collecting 3-meter multispectral imagery is the equivalent of ‘high-resolution’ multispectral data imaged by a 75-centimer (cm) satellite (as this satellite would feature 75-cm panchromatic and 3-m multispectral), making PlanetScope an extremely competitively priced option at just $2.25 per sq km. With well registered images and nearly daily collections of most locations, PlanetScope is the ideal imagery source for this current-events focused series, Our Changing Landscape.

2023 Sierra Nevada Snowmelt

What a wild year of climate events California has had with atmospheric rivers, superblooms, and a record snowpack/snowmelt!

According to the UC Berkley Central Sierra Snow Lab, the total snowfall in the Sierra Nevada Mountains was 677 inches as of March 2023. By April 1, 2023, the average snowpack in the mountains was more than four times its usual. The California Department of Water Resources (DWR) says that across the entire state, the snowpack’s snow water equivalent is 237% higher than average.

In the DWR’s April news release, Director Karla Nemeth asserts that “California’s climate is becoming more and more extreme”. This is exemplified by the years 2020-2022 being recorded as the state’s driest three-year period ever, now followed by this year’s monumental amounts of water. It seems the state is facing a disproportionately high number of climate-drive challenges.

Indeed, the state of California has been deluged with so much water that it has seen previously dry lake beds resurrected. Lake Tulare is one such phantom water source. Located in the San Joaquin Valley, the historic lakebed has been dry since the 1920’s, when the lake’s sources were rerouted. The land has since been used for farming. With the atmospheric river storms early this year, however, Lake Tulare has reemerged. The lake’s apparition has flooded farms that produced cotton, tomatoes, dairy, pistachios, and wheat. According to CBNC, the flooding of the area could remain for up to two years, cost billions of dollars in economic losses and displace thousands of farmers.

Lake Tulare isn’t the only area with a surplus of water. Due to the record amounts of snow and water, the state’s reservoirs and damns are full to bursting. So full, in fact, that state officials have been forced to release water from dams and reservoirs in order to make way for the oncoming snowmelt water. Hopefully lowering the reservoir levels now will help prevent flooding later in the season. The snow that falls in the Sierra Nevada acts as a store of water for the surrounding rivers and valleys each year, melting slowly throughout the summer. In a typical year, this snowmelt can account for up to 30% of California’s water supply.

The astonishing snowpack – and thus anticipated snow melt – has officials worried about flooding as the year wears on. The DWR is working with communities to help prevent damage from potential floods by releasing water from the reservoirs, diverting water into groundwater basins, and building levees in at-risk locations. Officials hope the weather will stay cool, slowing the snowmelt and thus giving communities time to prepare for the eminent flood danger.

The state has also seen an increase in drowning deaths this year. As rivers swell with melt water, they become more dangerous due to the colder temperatures and faster currents. The California Department of Parks and Recreation has issued public safety warnings, advising people to stay out of the treacherous waters.

It will be interesting to see what the next few weeks bring to the state of California. Hopefully the temperatures will stay cool so the state has time to mitigate the astronomical amounts of water they will receive from the snow melt. Between the crazy climate events of the atmospheric rivers and flooding so far this year, we feel like they’re about due a break! Now it is time to turn our attention to the 3-meter PlanetScope archive over the Sierra Nevada mountain range to track the spring snow melt.

If you would like to find out more about using 3-meter PlanetScope imagery for your academic studies, engineering projects or any landscape analysis, let us know at sales@apollomapping.com or (303) 993-3863.

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