KRWG

A Look At Local Watershed Health: Despite Drier Climate Trends Flood Risk Persists

Oct 29, 2021

The state of New Mexico is no stranger to drought. Over the last 20 years, the state has experienced only a few gaps without some form of abnormally dry conditions–with the longest drought in recent history lasting 329 weeks between 2001-2007. 

And the impact of drought remains just as significant today. This year the state recorded its most intensive drought period on record in January. State Climatologist David DuBois says that drought conditions are likely to continue through the end of the year.

“In southern New Mexico, the whole southwest of New Mexico, drought is persisting,” DuBois said. “We've had a good monsoon that brings some of it out of drought. However, the patterns of the La Niña are likely going to bring drought back. Drought is here to stay, at least through the winter.”

DuBois says that even as drier trends continue more extreme precipitation events are likely to occur.

“The climate model ensembles I've been looking at have been showing a modest trend toward stronger monsoons, which is good news for us in summer,” DuBois said. “However, that may be counterproductive in terms of having really dry and higher temperatures for the winter and spring.”

With more intense storm projections comes the need to protect the county from future flooding. Over 100 dams exist within Doña Ana County, many designed independently by farmers to protect agricultural land. Protecting these dams from future flooding will require further promotion of watershed health according to Doña Ana County Flood Commission Director John Gwynne.

“These small structures create a problem now that there's population growth because they are no longer adequate,” Gwynne said. “The one thing that we can really do that helps in terms of flooding, is we can work in the watershed. We basically want to reduce the amount of stormwater runoff and also reduce the sediment reload that goes with that. It'll also help with groundwater recharge.”

Slowing down water through the placement of riparian buffers and manmade structures is one key way the county can control flooding and help to recharge the aquifer. Other infrastructure solutions include the construction of small retention ponds to help channel excess water.

Gwynne estimates these efforts could potentially reduce storm impact by 10% and help to improve drought conditions through increased groundwater recharge.

“We can put in debris dams that will slow the water down just enough to allow some of it to soak in,” Gwynne said. “We can also build berms and swales and terraces on the watershed that are not significant enough to really stop a lot of water, but it slows it down enough to get sediments to drop out and get water to soak into the ground.”

Earlier this year, Governor Michelle Lujan Grisham declared a state of emergency within Doña Ana County due to flooding caused by heavy August rainfall. With that declaration comes access to emergency funding that will be used to construct better infrastructure to protect against flooding.  

Gwynne says that further investment into flood mitigation efforts will take time and that efforts to foster a healthier watershed must be done on a large scale.

“I think it's important for us to note that we've got to do this in all the watersheds,” Gwynne said. “We can't just focus in small areas because with drought going to be persistent this is something that takes years to build up and stay in place and have its effect.”