Research & News
Center for Colorado River Studies
In the News
27 October 2017
Should Iconic Lake Powell Be Drained?
"Jack Schmidt, a former chief of the U.S. Geological Survey's Grand Canyon Monitoring and Research Center, says the science doesn't back it up. Instead, it could cause "one hell of a problem," said Schmidt, a professor of watershed sciences at Utah State University."
16 May 2017
Calls to Rethink the Colorado River’s Iconic Dams Grow Louder
With two major reservoirs on the Colorado River, Lake Powell and Lake Mead, sitting half empty, will a new hydrologic reality be enough to push for big management changes? One conservation group hopes so.
27 April 2017
Upper Colorado River Basin Water Forum 2017
18 April 2017
John Fleck from JFleck@Inkstain
"There are 5 key reasons why the Fill Mead First argument doesn’t hold water, and while each of them on their own could be a good enough reason to look past the reality of the situation, together they make a compelling case for keeping Glen Canyon Dam in place, at least for now."
10 March 2017
Fill Mead First" plan to drain Lake Powell has sprung some big leaks, a new assessment finds
Whether we are talking about draining all of its water or just most of it, reducing Lake Powell to a secondary status behind Lake Mead would fail in two of the plan’s most important goals, according to a technical assessment released last fall by Utah State University researchers. One of the primary conclusions of the so-called “Fill Mead First” proposal was that water loss, through evaporation and through reservoir bank storage and seepage into the bedrock below Lake Powell, would be greatly diminished by storing water primarily in Lake Mead.
13 August 2016
High Country News: Dammed if you do...
Recently Published Research
In AGU Publications
Estimating the Natural Flow Regime of Rivers with Long-Standing Development: The Northern Branch of the Rio Grande
by Todd L. Blythe and John C. Schmidt
Abstract: An estimate of a river’s natural flow regime is useful for water resource planning and ecosystem rehabilitation by providing insight into the predisturbance form and function of a river. The natural flow regime of most rivers has been perturbed by development during the 20th century and in some cases, before stream gaging began. The temporal resolution of natural flows estimated using traditional methods is typically not sufficient to evaluate cues that drive native ecosystem function. Additionally, these traditional methods are watershed specific and require large amounts of data to produce accurate results. We present a mass balance method that estimates natural flows at daily time step resolution for the northern branch of the Rio Grande, upstream from the Rio Conchos, that relies only on easily obtained streamflow data. Using an analytical change point method, we identified periods of the measured flow regime during the 20th century for comparison with the estimated natural flows. Our results highlight the significant deviation from natural conditions that occurred during the 20th century. The total annual flow of the northern branch is 95% lower than it would be in the absence of human use. The current 2 year flood has decreased by more than 60%, is shorter in duration, and peaks later in the year. When compared to unregulated flows estimated using traditional mass balance accounting methods, our approach provides similar results.
The role of feedback mechanisms in historic channel changes of the lower Rio Grande in the Big Bend region
by David J. Dean and John C. Schmidt
Abstract: Over the last century, large-scale water development of the upper Rio Grande in the US and Mexico, and of the Rio Conchos in Mexico, has resulted in progressive channel narrowing of the lower Rio Grande in the Big Bend region. We used methods operating at multiple spatial and temporal scales to analyze the rate, magnitude, and processes responsible for channel narrowing. These methods included: hydrologic analysis of historic stream gage data, analysis of notes of measured discharges, historic oblique and aerial photograph analysis, and stratigraphic and dendrogeomorphic analysis of inset floodplain deposits. Our analyses indicate that frequent large floods between 1900 and the mid-1940s acted as a negative feedback mechanism and maintained a wide, sandy, multi-threaded river. Declines in mean and peak flow in the mid-1940s resulted in progressive channel …
The geomorphic effectiveness of a large flood on the Rio Grande in the Big Bend region: Insights on geomorphic controls and post-flood geomorphic response
by David J. Dean and John C. Schmidt
Abstract: Abstract Since the 1940s, the Rio Grande in the Big Bend region has undergone long periods of channel narrowing, which have been occasionally interrupted by rare, large floods that widen the channel (termed a channel reset). The most recent channel reset occurred in 2008 following a 17-year period of extremely low stream flow and rapid channel narrowing. Flooding was caused by precipitation associated with the remnants of tropical depression Lowell in the Rio Conchos watershed, the largest tributary to the Rio Grande. Floodwaters approached 1500 m 3/s (between a 13 and 15 year recurrence interval) and breached levees, inundated communities, and flooded the alluvial valley of the Rio Grande; the wetted width exceeding 2.5 km in some locations. The 2008 flood had the 7th largest magnitude of record, however, conveyed the largest volume of water than any other flood …
In GSA Bulletin
Stratigraphic, sedimentologic, and dendrogeomorphic analyses of rapid floodplain formation along the Rio Grande in Big Bend National Park, Texas
by David J. Dean, M. Scott, Patrick Shaffroth and John C. Schmidt
Abstract: The channel of the lower Rio Grande in the Big Bend region rapidly narrows during years of low mean and peak flow. We conducted stratigraphic, sedimentologic, and dendrogeomorphic analyses within two long floodplain trenches to precisely reconstruct the timing and processes of recent floodplain formation. We show that the channel of the Rio Grande narrowed through the oblique and vertical accretion of inset floodplains following channel-widening floods in 1978 and 1990–1991. Vertical accretion occurred at high rates, ranging from 16 to 35 cm/yr.
In Journal of Geophysical Research
Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads
by David J. Dean, John J. Topping, John C. Schmidt, Ronald E. Griffiths and Thomas A. Sabol
Abstract: The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form. In this study, physically based analyses suggest that channel change in the Rio Grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales. Channel narrowing is primarily caused by substantial deposition of sediment supplied to the Rio Grande during tributary-sourced flash floods. Tributary floods have large suspended …