FORT scientists study interactions among river flow, riparian vegetation and channel change at low elevations across the western United States. Cooperators include the National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service and Bureau of Reclamation. Research areas include reservoir management, control of invasive species, drought response and flood erosion after fires. Much of our recent work has been in the Colorado River Watershed, where ongoing drought is threatening agriculture as well as riverine and riparian ecosystems.
Ecological and Hydrological Assessment of Riparian Ecosystems Along the Yampa and Green Rivers
Working with the National Park Service Northern Colorado Plateau Network we are analyzing data from over 20 sites along the Green and Yampa rivers in Utah and Colorado, integrating annual data from thousands of one-meter squared plots, including plant species occurrence, surface elevation and percentage of time under water.
This data is being used to inform guidelines for post-2026 management of Colorado River Reservoirs by the Bureau of Reclamation. Photos from National Park Service Northern Colorado Plateau Network.
Published Studies
The effects of streamflow withdrawals on the Yampa River and its surrounding habitat
A 2024 report provides information on the potential impact of flow extractions — water withdrawn from rivers for human consumption or use — on the Yampa River in Dinosaur National Monument, and lays out a flow prescription framework that can be used to minimize negative effects.
Although all water withdrawals would have negative effects on the river, withdrawals during the spring before the peak are less damaging than those at other times of the year.
Downstream decreases in water availability, tree height, canopy volume and growth rate in cottonwood forests
In this study, researchers investigated the effects of streamflow, water availability and temperature on cottonwoods along the Yampa and Green Rivers. To do this, they measured cottonwood growth along a streamflow and temperature gradient.
In sites with highest hydrologic stress — less stream flow, lower water availability, and higher temperatures — trees were shorter and in poorer condition. These results help to quantify the flow necessary to support trees. As drought continues to threaten the southwest, resource managers can use these results to identify which sites are most vulnerable to forest loss, and determine locations where potential loss may be mitigated through streamflow management.
Fire Leads to Floods and Debris Flows
Intense fires reduce vegetation and other organic matter, resulting in higher levels of stormwater runoff and erosion, and an increased potential for runoff-initiated landslides known as debris flows. Predicting when a debris flow will occur and how it will impact rivers, however, is difficult, as numerous factors contribute to their initiation and size. In this study, researchers used topographic data from the Rito de los Frijoles Basin to test predictions of debris flow occurrence and calculate the downstream response.
The Digital Elevation Model of Difference, created by subtracting lidar elevation in 2010 from that in 2016, shows patterns of erosion and deposition in extreme floods following fire. This differencing shows debris-flow erosion in the tributary, deposition of a debris fan at the tributary mouth, and longitudinal variation in deposition along the Rito de los Frijoles, Bandelier National Park, New Mexico.
This study also found that fire promoted debris flows and increased flood discharge by two orders of magnitude. Occurrence of debris flows was well predicted by debris-flow hazard models based on the topographic data. The riverbed rose in elevation as much as two meters at mouths of tributaries that experienced debris flows and dropped in elevation as much as two meters at mouths of tributaries that did not experience debris flows.
River channel response to invasive plant treatment across the American Southwest
Invasive riparian vegetation is often removed to promote native species and increase river flow, but this generally increases erosion. At 15 different rivers, researchers calculated erosion rate using aerial photos in reaches with and without invasive vegetation removal.
They found that treated reaches had higher floodplain destruction at 14 of 15 sites and treatment increased floodplain destruction by 1.9 times.
FORT scientists study interactions among river flow, riparian vegetation and channel change at low elevations across the western United States. Cooperators include the National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service and Bureau of Reclamation. Research areas include reservoir management, control of invasive species, drought response and flood erosion after fires. Much of our recent work has been in the Colorado River Watershed, where ongoing drought is threatening agriculture as well as riverine and riparian ecosystems.
Ecological and Hydrological Assessment of Riparian Ecosystems Along the Yampa and Green Rivers
Working with the National Park Service Northern Colorado Plateau Network we are analyzing data from over 20 sites along the Green and Yampa rivers in Utah and Colorado, integrating annual data from thousands of one-meter squared plots, including plant species occurrence, surface elevation and percentage of time under water.
This data is being used to inform guidelines for post-2026 management of Colorado River Reservoirs by the Bureau of Reclamation. Photos from National Park Service Northern Colorado Plateau Network.
Published Studies
The effects of streamflow withdrawals on the Yampa River and its surrounding habitat
A 2024 report provides information on the potential impact of flow extractions — water withdrawn from rivers for human consumption or use — on the Yampa River in Dinosaur National Monument, and lays out a flow prescription framework that can be used to minimize negative effects.
Although all water withdrawals would have negative effects on the river, withdrawals during the spring before the peak are less damaging than those at other times of the year.
Downstream decreases in water availability, tree height, canopy volume and growth rate in cottonwood forests
In this study, researchers investigated the effects of streamflow, water availability and temperature on cottonwoods along the Yampa and Green Rivers. To do this, they measured cottonwood growth along a streamflow and temperature gradient.
In sites with highest hydrologic stress — less stream flow, lower water availability, and higher temperatures — trees were shorter and in poorer condition. These results help to quantify the flow necessary to support trees. As drought continues to threaten the southwest, resource managers can use these results to identify which sites are most vulnerable to forest loss, and determine locations where potential loss may be mitigated through streamflow management.
Fire Leads to Floods and Debris Flows
Intense fires reduce vegetation and other organic matter, resulting in higher levels of stormwater runoff and erosion, and an increased potential for runoff-initiated landslides known as debris flows. Predicting when a debris flow will occur and how it will impact rivers, however, is difficult, as numerous factors contribute to their initiation and size. In this study, researchers used topographic data from the Rito de los Frijoles Basin to test predictions of debris flow occurrence and calculate the downstream response.
The Digital Elevation Model of Difference, created by subtracting lidar elevation in 2010 from that in 2016, shows patterns of erosion and deposition in extreme floods following fire. This differencing shows debris-flow erosion in the tributary, deposition of a debris fan at the tributary mouth, and longitudinal variation in deposition along the Rito de los Frijoles, Bandelier National Park, New Mexico.
This study also found that fire promoted debris flows and increased flood discharge by two orders of magnitude. Occurrence of debris flows was well predicted by debris-flow hazard models based on the topographic data. The riverbed rose in elevation as much as two meters at mouths of tributaries that experienced debris flows and dropped in elevation as much as two meters at mouths of tributaries that did not experience debris flows.
River channel response to invasive plant treatment across the American Southwest
Invasive riparian vegetation is often removed to promote native species and increase river flow, but this generally increases erosion. At 15 different rivers, researchers calculated erosion rate using aerial photos in reaches with and without invasive vegetation removal.
They found that treated reaches had higher floodplain destruction at 14 of 15 sites and treatment increased floodplain destruction by 1.9 times.