GCDAMP- Questions and Answers Page

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Library Book- Pic.jpg Research Questions and Information Needs Identified in the 2013-14 Glen Canyon Dam Adaptive Management Program Biennial Budget and Work Plan

  • Revision Date_140212


Num Project, Elements, and Sub-elements Project/Element summary (2012-13 BWP) Research Questions, Uncertainties, & Information Needs identified in the 2012-13 BWP Relevant Research Questions & Information Needs identified from: Project timeline: When will data obtained through this project be able to answer the relevent science questions? Project funding (FY) Reporting links NOTES
000 Project A. Sandbars and Sediment Storage Dynamics: Long-term Monitoring and Research at the Site, Reach, and Ecosystem Scales Project will evaluate the geomorphology of fine sediment deposits in and near the Colorado River. Supports the direct measurements of the volume of fine sediment, especially sand, that is stored on the bed of the Colorado River, in its eddies, or at higher elevation along the river's banks. Supports the direct measurement of the volume of fine sediment, especially sand, that is stored on the bed of the Colorado River, in its eddies, or at higher elevation along the river’s banks for the HFE protocol. Monitoring will include daily and annual observations of long-term sandbar monitoring sites by remote camera and conventional topographic survey, respectively. Also includes the analysis of system-wide airborne remote-sensing data to monitor a much larger set of sandbars every four years to assess sandbar size and abundance "Project will address the broad questions of:

(1) Will multiple high flows conducted over a period of years result in net increases in sandbar area and volume?; (2) With the available sand supply (i.e. tributary inputs), is the approach of using repeated floods to build sandbars sustainable?;and, (3) Will multiple high flows conducted over a period of 10 years result in net increases in campable area along the Colorado River?"

"How can erosion of sandbars after an HFE be minimized or offset? (IV: Dept. of Interior 2011a)

Do sandbars deposited by HFEs contribute to preservation of archaeological sites in the river corridor? (II: Mellis et al. 2007) Is sediment conservation more effective when an HFE is held in rapid response to sediment input from the Paria River? (IV: Dept. of Interior 2011a) What are the effects of ramping rates on sediment transport and sandbar stability? (USGS 2007b; SSQ RIN 4) What is the desired range of seasonal and annual flow dynamics associated with powerplant operations, BHBFs, and habitat maintenance flows, or other flows that meet GCDAMP goals and objectives? (USGS 2007b; RIN 7.4.1) What is the desired pattern of seasonal and annual flow dynamics associated with powerplant operations, BHBFs, HMFs, or other flows to meet GCDAMP Goals and Objectives? (USGS 2007b; RIN 7.4.2) What elements of ROD operations (upramp, downramp, maximum and minimum flow, modified low fluctuating flow (MLFF), habitat maintenance flow (HMF), and BHBF) are most/least critical to conserving new fine-sediment inputs, and stabilizing sediment deposits above the 25,000 cfs stage? (USGS 2007b; RIN 8.5.1) How do sandbar textures influence biological processes? (USGS 2007b; SIN 8.5.) What is the relationship between the fine-sediment budget and turbidity? (USGS 2007b; SIN 8.5.2) How can the ongoing fine sediment supply be managed to achieve sustainable habitats? (USGS 2007b; SIN 8.5.5)"

AMWG
000 Project Element A.1. Sandbar and Camping Beach Monitoring ($269,000) Track trends in the status of sandbars throughout Marble and Grand Canyons that are emergent above the water surface at 8,000 ft3/s.
000 Project Element A.1.1. Monitoring sandbars using topographic surveys and remote cameras Sandbar monitoring is conducted at a daily (using remote cameras) and annual (by conventional survey) interval in order to track local response to individual events in the context of a long-term record. Monitor selected high-elevation sandbars (~50) with conventional topographic surveys (volume and area; “long term sandbar time series”) yearly for annual status check on sandbar and camping beach condition. In addition, campable area is measured at a subset of 37 of these sites. Monitor selected high-elevation sandbars (~30) with remotely deployed digital camera (approximate size) for daily status check on sandbar condition at ~6-month intervals. "(1) What is the long-term net effect of dam operations, including high flows, on changes in high-elevation sandbar area and sand storage (i.e. the sand above the 8,000 ft3/s stage)? These changes are relevant to camping beaches, riparian vegetation, backwater habitat, and control the supply of bare sand that is redistributed by wind." "Given that sandbars are naturally dynamic and go through cycles of building and eroding, can a protocol of frequent high flows under sediment-enriched conditions be effective in sustaining these dynamic habitat features? (IV: Dept. of Interior 2011a)

Will multiple high flows conducted over a period of 10 years result in net increases in sandbar area and volume? (V: Dept. of Interior 2011b) What is the minimum duration for HFEs needed to build and maintain sandbars under sand enrichment? (II: Mellis et al. 2007) How do post HFE flows affect the persistence of sandbars and related backwater habitats? (II: Mellis et al. 2007) Is there a “flow-only” operation (i.e., a strategy for dam releases, including managing tributary inputs with BHBFs, without sediment augmentation) that will restore and maintain sandbar habitats over decadal time scales? (USGS 2007b; SSQ 3.1 / 4.1)"

000 Project Element A.1.2. Monitoring sandbars by remote sensing A larger collection of high-elevation sandbars (>1000 sites) are also monitored every four years using remote sensing (2002, 2005, 2009, and 2012 over-flights), in order to provide a synoptic view of the entire Colorado River for long-term trend of sandbar condition. Since 2002, how has the area of vegetation and sand coverage changed at the 1000+ eddy sandbars larger than about 250 m2 (inclusive of nearly every location that has had a camping beach in any campsite inventory since 1975).
000 Project Element A.1.3. Geomorphic attributes of camping beaches Track trends in specific camping beach attributes (i.e. spatial distribution of sand and other geomorphic units, the slope of the sandbar, and the distribution and density of vegetation) over time and in response to changes in flow regime. (7) How have changes in sandbar size, sandbar characteristics (e.g., slope, roughness), and vegetation cover affected the Marble and Grand Canyon camping beach resource? This builds on sandbar monitoring (Question 1) to address the recreation resource. "Will multiple high flows conducted over a period of 10 years result in net increases in campable area along the Colorado River? (V: Dept. of Interior 2011b)

How do varying flows positively or negatively affect campsite attributes that are important to visitor experience? (USGS 2007b; SSQ 3.9) How are sandbar textures related to recreational site stability? (USGS 2007b; SIN 8.5.10)"

000 Project Element A.1.4. Analysis of historical images at selected monitoring sites Extend the length of the monitoring record back in time for the long-term sandbar monitoring sites (Project A.1.1.) by incorporating data from air photos taken before 1990. Produce digital elevation models using digitally scanned 1984 stereo photographs. Many perceptions regarding the current condition of sandbars is based on limited observations of sandbars following the floods of 1983-86 (Schmidt and Grams, 2011). However, those observations are based largely on imprecise photo comparisons and are not quantitatively tied to the current sandbar monitoring program.
000 Project Element A.2. Sediment Storage Monitoring ($609,000)
000 Project Element A.2.1. Bathymetric and topographic mapping Track longterm trends in sand storage to provide a robust measure of whether or not management objectives for fine sediment conservation (HFEs) are being met. Track the location of changes in sand storage between the channel and eddies and between high- and low-elevation deposits. Monitor low-elevation fine sediment storage in 30 to 80-mile segments with combined bathymetric and topographic surveys (area and volume) every 3 to 10 years, depending on reach for long-term trend in fine sediment storage. "(2) What is the long-term net effect of dam operations, including high flows, on changes in low-elevation sand storage and bed sediment texture (the sand below the 8,000 ft3/s stage)? These changes are relevant to backwaters and other aquatic habitat, the foundation of eddy sandbars, and as the source of sediment that fuels transport and determines whether the use of high flows is sustainable." "When are there optimal times to conduct high flows in regard to sediment building, humpback chub survivability, and ecosystem response? (IV: Dept. of Interior 2011a)

Is sediment conservation more effective following a sediment enrichment period in the context of multi-year, multi-event experiments? (IV: Dept. of Interior 2011a) With the available sand supply that comes from tributary inputs, is the approach of using repeated floods to build sandbars sustainable? (V: Dept. of Interior 2011b) Can the decline in sediment resources since 1990 be reversed using “flow” options with remaining downstream sand supplies from tributaries (Paria and Little Colorado Rivers and lesser tributaries)? (III: USGS 2007a) What is the rate of change in eddy storage (erosion) during time intervals between BHBFs? (USGS 2007b; SSQ RIN 5) What is the longitudinal variability of fine-sediment inputs, by reach? (USGS 2007b; RIN 8.1.1) What is the temporal variability of fine-sediment inputs, by reach? (USGS 2007b; RIN 8.1.2) What fine sediment abundance and distribution, by reach, is desirable to support GCDAMP ecosystem goals? (Note: Definition of “desirable” will be derived from targets for other resources and managers goals. (USGS 2007b; RIN 8.1.3, 8.2.1, 8.3.1, 8.4.1, 8.5.6) What is the reach-scale variability of fine-sediment storage throughout the main channel? (USGS 2007b; RIN 8.5.2) What are the historic and ongoing longitudinal trends of fine-sediment storage, above 25,000 cfs? (USGS 2007b; RIN 8.5.5)"

000 Project Element A.2.2. Bed-material characterization Improve the method used to characterize bed texture using the backscattering data from the multibeam sonar surveys used to identify and map bed material by calibrating and validating with observations of bed material characteristics made by underwater video camera. "(5) What is the spatial distribution of bed sediment texture, and how does it affect primary production, fish habitat, and sediment transport modeling? This builds on low elevation sand monitoring (Question 2) to support sediment transport and biological prediction." "What are the limiting factors that regulate substrate availability and its distribution? (USGS 2007b; SIN 8.5.7)

What is the total area of different aquatic habitat types (cobble, gravel, sand, talus, etc,) in the CRE? (USGS 2007b; SIN 8.5.8)"

000 Project Element A.3. Investigating Eddy Sandbar Variability and the Interactions among Flow, Vegetation, and Geomorphology ($104,000) Even when there is a large supply of sand on the river bed, as was the case in 2008, sandbar response is highly variable. Investigate the dynamics of eddy sandbar deposition by coupling a large existing dataset of eddy sandbar behavior with metrics that describe site geometric and hydrodynamic characteristics. Look for statistical relations between observed eddy behavior and site characteristics. Develop a tool for predicting sandbar response to given flow events. "4) What are the causes of variability in sandbar response to controlled floods and other dam operations (i.e. why do sandbars respond differently from place to place to the same flow and sediment supply conditions?), and how does vegetation affect sandbar response? This builds on sandbar monitoring (Question 1) to support prediction of sandbar response."
000 Project Element A.4. Quantifying the correlation between bed and transport grain size ($244,000) Use both field measurements and modeling to partition the effects of bed grain size, areal sand coverage, and the spatial distribution of bed shear stress in order to provide a more reliable link between bed and transport grain size. This work will improve our understanding of the linkages between suspended-sediment observations and bed-sediment texture, which will provide greater understanding of the upstream extent of river that determines concentration and grain size at sediment gaging stations. Findings from this work will be used to improve models for suspended sediment transport and may provide improved methods for tracking the abundance of sand on the river bed using the suspended sediment monitoring network. Better understanding of temporal changes in bed texture will also be used to improve our ability to model and predict aquatic primary productivity. "(6) Can we relate changes in the spatial distribution of bed sediment texture to observed changes in suspended sand concentrations and grain size? This would enable use of the continuous record of suspended sediment to infer changes in bed sediment composition for use in modeling of sediment transport and primary production." "How do ongoing inputs of coarse-sediment from tributaries influence storage of fine sediment within pools, runs, and eddies throughout the CRE? (USGS 2007b; RIN 8.6.1)"
000 Project Element A.5. Geochemical Signatures of Pre-Dam Sediment ($56,000) Provide an additional measure to evaluate long-term trends of sediment abundance in Marble Canyon and the ability to detect mined pre-dam sediment in future high flows. "(3) What are the relative proportions of pre-dam sediment (sediment that entered the Colorado River before dam completion) and post-dam sediment (sediment from tributaries that has entered the Colorado River following dam completion) present in deposits formed by dam operations, including HFEs? Do the proportions of pre- and post dam fine sediment indicate depletion of non-renewable pre-dam fine sediment from storage or accumulation of tributary-derived post-dam fine sediment? This question is relevant to determining whether the use of HFEs is sustainable." "How do flows impact old high water zone terraces in the CRE (where the majority of archaeological sites occur), and what kinds of important information about the historical ecology and human history of the CRE are being lost due to ongoing erosion of the Holocene sedimentary deposits? (USGS 2007b; SSQ 2.2)

What is the pre- and post-dam range of grain-size in fine-sediment deposits, by reach? (USGS 2007b; RIN 8.5.3)"

Project Element A.6. Control Network and Survey Support ($37,000) An accurate geodetic control network is required to support nearly every aspect of this project as well as other GCMRC monitoring projects. The control network is the set of monumented and documented reference points (benchmarks) that exist along the river corridor and on the rim together with the collection of observations that determine the relative and absolute positions of those points. Those points serve as the basis for referencing all ground- and air-based monitoring observations. The purpose of the control network is to ensure that spatial data acquired on all projects are collected with accurate and repeatable spatial reference. This effort is nearing completion, and most segments of the river corridor now have a sufficient number of control points to support monitoring activities. In 2013 and 2014, field work will be required to complete this task in Glen Canyon (between the dam and Lees Ferry), RM 81 to RM 91, RM 98 to RM 119, RM 144 to RM 166, and RM 225 to 277.
000 Project B. Streamflow, Water Quality, and Sediment Transport in the Colorado River Ecosystem ($1,287,000) Ongoing measurement and interpretation of stage, discharge, water quality (water temperature, specific conductance, turbidity, and dissolved oxygen), suspended sediment, and bed sediment data at gaging stations in the Colorado River ecosystem (CRe) downstream from Glen Canyon Dam in Glen Canyon National Recreation Area and Grand Canyon National Park. These parameters are measured at USGS stream-flow gaging stations located on the Colorado River in Marble and Grand Canyons at river miles 0, 30, 61, 87, 166, and 225. The data collected by this project provide the fundamental stream flow, sediment transport, temperature, and water quality data that are used by other physical, ecological, and socio-cultural resource studies. One of the major products of this project has been the mass-balance sand budgets (e.g., Topping and others, 2010) used to trigger controlled floods and to evaluate the effects of all dam operations on the CRe. It is also proposed to continue the development and application of a one-dimensional sand routing model (Wright and others, 2010a). One task for this modeling component will be to extend the existing model, whose downstream boundary is river mile 87, through the central and western part of Grand Canyon to river mile 225. This is the measurement program for the HFE Protocol that describes the fate of new fine sediment once it enters the Colorado River. How do dam release temperatures, flows (average and fluctuating component), meteorology, canyon orientation and geometry, and reach morphology interact to determine mainstem and nearshore water temperatures throughout the CRe? (USGS 2007b; SSQ 5-1)
000 Project C. Water-Quality Monitoring of Lake Powell and Glen Canyon Dam Releases ($236,000) Describe the current quality of Glen Canyon Dam releases to the downstream ecosystem, as well as describe the current water-quality conditions and hydrologic processes in Lake Powell, which can be used to predict the quality of future releases from the dam. The water-quality monitoring program consists of monthly surveys of the reservoir forebay and tailwater, as well as quarterly surveys of the entire reservoir, including the Colorado, San Juan, and Escalante arms. The entire funding for this project is provided directly by the Bureau of Reclamation (no AMP funds).
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UNDER CONSTRUCTION:

  • To be added: From Knowledge Assessment_"Assessing what we know and don't know_8-22-2011"- USGS
  1. The food web on which fish depend is very simple
  2. Availablitity of high-quality food resources limits fish populations- Black Flies and midges are the most important parts of the present food web.
  3. The mainstem Colorado River water temperature is typically well velow the termal optimum for native fishes, but recently has been warmer.
  4. Warming increases growth/ production of algae and invertebrates.
  5. Warming increases the growth rate of humpback chub.
  6. We don't understand the decline in RBT between 2001 and 2007.
  7. Rainbow and brown trout disproportionately prey on native fish.

WHAT WE DON'T KNOW--

  1. Will warmer mainstem temperatures alone allow for increased survival of humpback chub?
  2. Do trout have substantial population-level effects on humpback chub?
  3. What ages of HBC are most impacted, and by what mechanisms? Competition, predation...


RAFTING RELATED

  • Do rafting groups get told not to cave-in sandbars?

SEDIMENT RELATED

  • Sediment Retention:
  1. Q: How do intervening flows effect retention of sand bars? A
  2. Q: In order to retain sandbar life following an HFE, has riprap been considered as a possible action against erosion in the Grand Canyon?

A: The park system was created to conserve unimpaired the resources and values that the park was set aside to protect. Natural landscapes disturbed by natural phenomena will be allowed to recover naturally (where possible). Landscape and vegetation conditions altered by human activity may be manipulated where the park management plan provides for restoring the lands to a natural condition. This usually entails removing the man-made objects (like a fence, structure, or even a dam) to bring the area back to a natural state. If the use of man-made objects or non-native species proves worthy in restoring a landscape, it can be used to a limited degree, and as long as it is done on a temporary basis and does not impair the resources.

In addition, one needs to factor in wilderness management (which applies to the lands along the river). Because the beaches are within NPS proposed wilderness recommendation, They are required to manage the area as Wilderness; including the values of naturalness, primitive and unconfined recreation, solitude, and special values. No action can be taken that would diminish the area's wilderness eligibility until after Congress and the President have taken action. This aspect takes us back to the "as natural as possible" discussion and would be a prohibitive factor for such actions as rip-wrapping and other such man-made structures.

>>Also consider-- the cost of doing such work in the Grand Canyon may even exceed that of sediment augmentation. ---Riprap, HFE, Sandbars erosion

FISH RELATED

  • How often do native fish get handled?


DAM- General Overview

  • What resources have been improved because of the dam?
  • Was there more or less vegetation along the river after GC Dam was built?

Monitoring

  • How far back does the readings of the gauges go? Pre-dam?


Flow Regimes

  • Do steady flows produce more trout?
  • Do steady flows lead to increases in vegetation encroachment?
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