Calculation of the changes in the reservoir surface in the Colorado River Basin

On August 16, 2021, the US Bureau of Reclamation declared to be an unprecedented one Lack of water for the Colorado River, a vital artery that meanders 1,450 miles through seven states in the western United States. From its beginnings in the Rocky MountaIn its drainage in the Gulf of California, the river generates electricity at several dams, supports the extensive agricultural industry in the region and provides a vital water supply for around 40 million people. The current mega-drought – a decades of time extreme drought – the system has storage of the river on 40% capacity and lowered its reservoirs to historic levels, resulting in drastic government interventionn.

Quantifying the effects of drought is a critical stepp in monitoring its severity and providing tThe data regional authorities need to act. There are several indices used to measure hydrological drought, however a shortage of earth observation data has limited their effectiveness. Planet’s remote sensing satellites can help calculate the surface area of ​​inland waterways, including reservoirs, on an unprecedented spatial and temporal scale, and contribute to globally repeatable drought quantification.

Planet has discovered the surface of four reservoirs in the Upper Colorado River Basin. Above are the two-week median extensions in Lake Powell in Warm Creek Bay from May 2021 to August 2021 and the maximum two-week extension for 2019. Our data show a significant year-on-year decrease in reservoir surface area and at two-week intervals in summer 2021. © 2021, Planet Labs Inc. All rights reserved.

Historical context

Lake Powell, the second largest man-made reservoir in the United States, serves as the hub for the distribution of water between the rivers of the Colorado River upper (Colorado, New Mexico, Utah, and Wyoming) and lower (Arizona, California, and Nevada) basins. It is that ‘Bank account‘the top four states to make sure they are theirs necessary supplies on the bottom three, during times of drought-related stress. When its water reserves are threatened, the reservoir network and the people and industries that depend on it are also threatened.

Decades of aggravating consequences from KliChanges of partner have matured the conditions for severe drought. Stored water resources are exhaustedng fast like drier soils Swallow water drain before they invade stream beds and warmer temperatures The snow cover evaporates Storage. As a result, reservoirs are drying up throughout the western United States and their water levels reach historic lows, visually indicated by “bathtub rings” from recently revealed rock bands at its edges. Lake Powell is only expected to receive 30% or 3.2 million acre-feet, its natural influx in 2021. July 24th Lake Powell has fallen to a record low Pool height of 3,554.9 feet, and the Bureau of Reclamation Projects continue to decline.

In response, the office announced that they would begin diverting water from three reservoirs – Blue Mesa, Navajo Lake, and Flaming Gorge – into Lake Powell in August to ensure adequate supplies are in place. Blue Mesa is through December is expected to be lowered 8 feet, Navajo Lake by 2 feet, and Flaming Gorge by 4 feet. Together the Releases will add a total of 181,000 acre-feet of water to Lake Powell, adding 3 feet to its surface area. The main incentive for the diversion is to keep the level safely above its. to keep critical threshold of 3,525 feet. Below this point is water can not happen through the pressure pipes of the Glen Canyon Dam, the Billion kilowatt hours of hydropower.

How can Planet help?

The creation of a way of measuring changes in the surface of reservoirs at submonth intervals could be help local authorities manage water resources and improve our understanding of hydrological systems. However, current measurements are hindered by limited observational data and model uncertainties. High-resolution, high-rate satellite imagery is in a unique position to meet this need and to complement existing indices based on drought-affected reservoirs.

To keep track of how the office’s diversions affect the water supply in the four reservoirs, we have public data sources like that Global reservoir and dam database (GRanD), in addition to our own daily PlanetScope 3m images. We then have a semi-supervised approach to learning for that Google cloud platform to identify water and calculate the two-week mean surface area of ​​the four reservoirs. This classification was carried out on each water body from March to August using Data from 2019, 2020 and 2021.

Flaming Gorge Reservoir, Wyoming and Utah

The first planned release from the Flaming Gorge Reservoir started on July 15, 2021 and is set to continue through October with a planned release of 125 thousand acres-feet (kaf) of water. Despite a relatively constant altitude difference up to then Period, our surface measurements for Flaming Gorge reflect a significant decline in land exposing land in the upper part of the reservoir as the drought persists.

Graphics are not scaled to zero.

Blue Mesa Reservoir, Colorado

Blue Mesa releases are slated to begin in August 2021 and continue through October, with a planned release of 36 kaf.

Graphics are not scaled to zero.

Navajo Lake, New Mexico

A planned release of 20 kaf from Navajo Lake is planned for November and December 2021.

Graphics are not scaled to zero.

Lake Powell, Utah and arizona

Lake Powell has had two significant periods since MarchAnt loss. The reservoir lost water more quicklyly in the second decline during the warm summer months, recognizable by a steeper rise in altitude. As water is diverted into Lake Powell in the following months, we expect a relative increase in both elevation and surface area.

Graphics are not scaled to zero.

Our surface area calculations correlate strongly with the changing height of the reservoirs and are consistent with the reported decrease in volume over all four water bodies during the late spring and summer months. By quantifying the surface area, we are able to provide a much-needed data point to measure the effects of drought and evaporation on inland waters.

Planet’s almost daily and high-resolution satellite imaging enables us to measure, analyze and visualize changing deposit levels all over the world. This database provides another critical measurement tool for researchers, water managers, and local communities to monitor vital water resources and the environmental variables that threaten their supplies.

Additional data sources

Reservoir height data source: Complaint Office

Maximum reservoir dimensions of the planet with the pruned National Hydrology Dataset

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