About two months ago I had the post How low is Lake Mead? The graph in the post was the yearly minimum end of month elevation. In this post we have a closer look at the end of month elevation since 2011. The last month in the data is July 2021, which is a record low following the previous record low in June 2021. In the previous post I mentioned that this really should be given in some per capita format. I’ll add that presumably the decrease in the volume of water is not linear with the lake elevation. Data here.
The USGS post High Plains Aquifer Groundwater Levels Continue to Decline (6/16/17) summarizes the results from the USGS report Water-Level and Recoverable Water in Storage Changes, High Plains Aquifer, Predevelopment to 2015 and 2013–15.
In 2015, total recoverable water in storage in the aquifer was about 2.91 billion acre-feet, which is an overall decline of about 273.2 million acre-feet, or 9 percent, since predevelopment. Average area-weighted water-level change in the aquifer was a decline of 15.8 feet from predevelopment to 2015 and a decline of 0.6 feet from 2013 to 2015.
A little geography:
The High Plains aquifer, also known as the Ogallala aquifer, underlies about 112 million acres, or 175,000 square miles, in parts of eight states, including: Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming. The USGS, at the request of the U.S. Congress and in cooperation with numerous state, local, and federal entities, has published reports on water-level changes in the High Plains aquifer since 1988 in response to substantial water-level declines in large areas of the aquifer.
A more recent article in the Conversation, Farmers are drawing groundwater from the giant Ogallala Aquifer faster than nature replaces it by
In my view, Plains farmers cannot afford to continue pushing land and water resources beyond their limits – especially in light of climate change’s cumulative impact on the Central Plains. For example, a recent study posits that as droughts bake the land, lack of moisture in the soil actually spikes temperatures. And as the air heats up, it further desiccates the soil.
This vicious cycle will accelerate the rate of depletion. And once the Ogallala is emptied, it could take 6,000 years to recharge naturally. In the words of Brent Rogers, a director of Kansas Groundwater Management District 4, there are “too many straws in too small of a cup.”
The USGS post and the Conversation article are useful for a QL based course. The full USGS report has links to water-level data sources starting on page 7.
The NYT article, In a Warming West – the Rio Grande Is Drying Up by Henry Fountain (5/24/2018) answers the question.
Even in a good year, much of the Rio Grande is diverted for irrigation. But it’s only May, and the river is already turning to sand.
“The effect of long-term warming is to make it harder to count on snowmelt runoff in wet times,” said David S. Gutzler, a climate scientist at the University of New Mexico. “And it makes the dry times much harder than they used to be.”
With spring runoff about one-sixth of average and more than 90 percent of New Mexico in severe to exceptional drought, conditions here are extreme. Even in wetter years long stretches of the riverbed eventually dry as water is diverted to farmers, but this year the drying began a couple of months earlier than usual. Some people are concerned that it may dry as far as Albuquerque, 75 miles north.
What the article is missing is data. For example, we have here a graph of daily discharge in cubic feet per second at the Albuquerque station (directions below on how to obtain this graph and associated data.). Note, that the graph is on a log scale and so is there is downward trend in this data? Since 1991, the Rio Grande hasn’t stopped flowing in Albuquerque, although is came close around 2014. Other stations farther south have periods of zero discharge. Use the directions below to explore water flow of the Rio Grande at several locations. The data is naturally collected as a rate and so it is interesting for calculus classes as well as statistics classes.
To obtain water flow data at any USGS station around the country start at the National Water Information System: Mapper (Note: Different sites around the country will have different dates and type of data available.) Click on any of the sites to get a window with a link to access the data. The graph here comes from selecting the USGS 08330000 RIO GRANDE AT ALBUQUERQUE, NM station. On that page under Available data for this site select Time series: Current/Historical observations. For this specific graph we selected a time frame for the whole data set and selected Graph. You can also select tab-separated file, as well as a few other options. Further historical data for the Rio Grande can be found at the Rio Grande Historical Mean Daily Discharge Data page.