Is the long-running NM drought over?
By Mike Cook
Las Cruces Bulletin
In response to the question, “is it safe to say the drought we’ve been suffering from for so long is over?” state Climatologist Dr. Dave DuBois said, “the answer depends on who is impacted and what time scale is important. There are three general drought types to answer your question: meteorological, agricultural and hydrological.
“If we go with meteorological drought, here in Las Cruces we’re in the process of getting out of drought. If you look at the total accumulated precipitation over the last four years, we are about 6.72 inches behind compared to the long-term average. The average is based on the data from the last 120 years collected here in Las Cruces. For reference, our annual rainfall average is 9.74 inches at the campus weather station. In the short term, this water year starting from last October, we are well above average, about 181 percent of average. To make it more interesting, in the really short term, so far in 2016 we are 33 percent of average. That’s why we had so much dust this past Monday when the winds were high. If you only look at the U.S. Drought Monitor, it shows no drought because it puts a lot of weight on meteorological drought and less on the longer-term definitions of drought. I’m carefully optimistic on the seasonal forecasts of a wet spring, but we’ll wait and see.
“Considering agricultural drought, we need to look at how the lack or abundance of precipitation has affected crops and rangelands. Now we consider more than just rainfall, as we have to consider weather patterns (e.g. winds, sunshine, temperatures), timing of precipitation, amount of water for irrigation and soil moisture. Here, I wouldn’t consider us out of drought. Our agriculture has relied on surface- water sources from snowmelt stored in reservoirs with water built up over several years. Roughly around 1999 is when I see this to have started in our area, where the storage of Elephant Butte starts to decline. It hit hard starting in the spring of 2011 and eased up in 2015. I consider an area in drought with heavy reliance on a shortened irrigation season and reliance on ground water. Based on discussions with my various ag contacts, there are still fallow lands due to this.
“Hydrological drought is tied closely with agricultural drought in that we key on the health of our regional hydrologic cycle for answers. Snowpack has been below average for several years and the result has been lack of spring runoff and subsequent water in our primary storage reservoirs, Elephant Butte and Caballo. We’re also seeing the depth of the water fall in many of the wells in southern New Mexico. They are not all falling at the same rate or depth and (that) depends on the sources of water and complex connections within the basins. Hydrological drought changes occur over long times, decades to centuries. Depending on the impacts of climate change over the next several decades, we may not see filling of reservoirs in our lifetime. I hope it doesn’t pan out that way, but we need to prepare for the likelihood that it will happen.”