Monday, August 12, 2013

Another view of Elephant Butte Reservoir

If you live in New Mexico, follow the news about the drought, and concerned about water supplies you probably have seen a graphic comparing Elephant Butte Reservoir this year with 1994. If you have not viewed this, I urge you to see it on the NASA Earth Observatory webpage. I can't count the number of times someone has emailed this to my inbox.  The number of times it has been emailed brings to attention the importance of this body of water to the region and how it responds to upstream water supply and downstream demand.  Max Bleiweiss, Director of CARSAME, printed a couple of Landsat 8 images of the reservoir about a month apart that I found striking. He compared June 6 and July 8, 2013 on a poster side by side similar to the images below.
Elephant Butte storage on June 6 was 172,470 acre-ft and 60,327 on July 8.  The July date was about the minimum storage for the year after the irrigation. I find it amazing what one month of  about 2000 cubic feet per second flow out of the reservoir can do to the appearance of the lake. Even with a record low irrigation season, you can still a lot of changes.  Since the north end (greenish color) of the reservoir is shallow, most of the changes are seen there. Based on the US Bureau of Reclamation data the difference in surface area between the two dates was 3,190 acres.