Bandelier National Monument experienced another significant flash flood in Frijoles Canyon on September 5th. An intense rainstorm dumped substantial rain on the park and the Los Alamos area that afternoon and evening. The water in Frijoles Creek rose to more than five feet deep, carrying logs and other debris with it as it scoured the streambed.
Rangers report that the trail washed away from the base of the last new bridge up canyon toward Alcove House while a big field of large logs were scattered over that area. The bridge at the lower end of the Headquarters parking lot may have sustained damage from logs accumulating against it in the flood waters.
The trail to Alcove House is closed until staff can deal with these issues. Staff don’t know yet if the other canyons in Bandelier also suffered flooding. The trail from Upper Crossing down canyon is also closed.
In 2013, a much larger flood ravaged Frijoles Canyon, sending water into the parking area and flushing miles of vegetation and soils from the canyon. That flood happened after the Las Conchas Fire severely burned upper Frijoles Canyon in 2011, leaving slopes denuded and the land vulnerable to flash flooding and landslides. The recent flood was less intense than the 2013 flood, but it fits with a disturbing pattern for areas affected by past high severity wildfire throughout the West.
Unfortunately, flash flooding in fire affected canyons in the Southwest is likely the new norm. At Bandelier, land managers and others expected that new vegetation cover in the fire scar would absorb and slow rain runoff and prevent floods. This is apparently only partially true though NPS scientists have a more complete understanding.
The Valles Caldera suffered flash flooding after the Las Conchas Fire as well. Water rushing off hills into the Valle Grande caused a major flood in the Jemez River that killed or washed away game fish. The gullies from these floods are a permanent part of the landscape.
Climate change is causing increasingly intense rainfall as the atmosphere warms and absorbs and holds more moisture than before recent temperature increases. Not only will more rain fall, even in desert areas like New Mexico, the rainfall will be more intense in many storms. Researchers know that with every 1 degree of global temperature increase, the atmosphere holds 4% more water. Temperatures have increased almost two degrees (F) since the industrial revolution.
An organization called Climate Central analyzed rainfall changes at 150 weather stations around the US. They found that more than 90% experienced more intense rainfall since 1970 and the Southwest experienced a 14% increase in rainfall intensity. Anyone following the news sees more flooding worldwide recently.
For an organization like the National Park Service at Bandelier, with limited staffing and budgets, ongoing flash flooding creates a big problem. Not only must the Park Service protect public safety, but they also need to maintain basic infrastructure like trails, roads and bridges.
At Bandelier, beaver have been reintroduced into Frijoles Canyon over the last 5 years and the beaver established multiple dams in the canyon. Beaver dams slow floods and help recharge aquifers. But intense floods can wash out beaver dams. NPS staff will visit the dams soon to see how the beaver fared.
