GCD AMP SCIENCE ADVISORS 

RAPID RESPONSE REVIEW: A DRAFT REPORT TO THE 

TECHNICAL WORK GROUP OF THE GLEN CANYON DAM 

ADAPTIVE MANAGEMENT PROGRAM: RECOMMENDED 

PROTOCOLS FOR CORE MONITORING OF SEDIMENT 

BY 

GCD AMP SCIENCE ADVISORS 

JUNE 2007 
GCD AMP SCIENCE ADVISORS 

RAPID RESPONSE REVIEW: A DRAFT REPORT TO THE 

TECHNICAL WORK GROUP OF THE GLEN CANYON DAM 

ADAPTIVE MANAGEMENT PROGRAM: RECOMMENDED 

PROTOCOLS FOR CORE MONITORING OF SEDIMENT 

BY GCD AMP SCIENCE ADVISORS 

INTRODUCTION 

 The GCD AMP Science Advisors are often asked to provide immediate input to a draft 

AMP science or management document. These comments are provided quickly, normally 

within a week of the request. Rapid Response Reviews are provided with the assumption that 

the SAs will be asked to review a final document at a later date. The inputs provided are 

therefore focused on making sure the document contains all necessary sections, that no 

significant elements to support the proposal are omitted, and that the presented argument, 

proposal, plan etc. are well developed, logical, and complete. 

 

 This review is of a draft document titled, "A Draft Report to the Technical Work Group 

of the Glen Canyon Dam Adaptive Management Program: Recommended Protocols for Core 

Monitoring of Sediment." It was drafted by the Physical Science Group Program Manager of 

GCMRC: The review was requested on a SA/GCMRC river trip June 1-8, 2007, and was 

completed the following week June 10-17, 2007 

SCIENCE ADVISORS COMMENTS 
The presented protocols for core monitoring of sediment within the Colorado River Ecosystem 

(CRE) were prepared by the GCMRC Physical Science Group in June 2007. They represent the 

first proposal for core monitoring to be presented by one of the three primary GCMRC 

programs (i.e., physical, biological and cultural). The following comments by the Science 

Advisors are presented with this being the first set of monitoring protocols in mind and address 

both this specific proposal and potentially the core monitoring proposals that will be developed 

by the other two primary programs. 

The proposed sediment monitoring program is designed around four major tasks: (i) continuous 

monitoring of flow and suspended-sediment flux; (ii) annual ground-based measurements of 

selected higher elevation sand deposits; (iii) repeat inventories conducted approximately every 4 

years of all exposed mid- to higher-level sand deposits within the CRE using remote sensing 

imagery; and (iv) annual to biennial repeat topographic channel mapping of sediment below the 

river surface using bathymetric surveys along selected stream reaches (different reaches 

selected each year on a rotating basis). 

The first task involves developing a sediment mass balance for the CRE, as recommended by 

the 2006 SEDS-PEP III external review panel, using field measurements to develop and test 

physically-based models. The mass balance will be individually calculated for five stream 

segments that together completely cover the CRE between river-miles 0 and 226. The second, 

third, and fourth tasks (collectively known as SED TREND) focus on long-term monitoring of 

the physical characteristics of sediment deposits throughout the canyon. These tasks utilize data 

collected from ground surveys of sediment above the river surface, from bathymetric surveys of 

sediment below the river surface, and from remote sensing. 

We start from the premise that many vitally important aspects of the CRE, including aquatic and 

riparian habitat and geomorphic processes influencing archeological sites and recreational sites, 

depend on water and sediment dynamics. Adaptive management of the CRE, therefore, requires 

knowledge of water and sediment dynamics sufficient to support the use of models that predict 

the response of sediment transport and storage to changes in flow regime and sediment supply. 

The proposed protocols for core monitoring of sediment represent an acceptable program for 

continuing to develop this knowledge. 

It is our opinion that all four of the major monitoring components are needed to document and 

understand trends in sediment transport and storage within the CRE and their relationships to 

other resources. Tasks ii and iii address the most immediate concerns regarding recreational 

areas, archeological sites, and aquatic and riparian habitat within the CRE. Implementing only 

these tasks, however, would result in a "black box" approach to sediment dynamics in which 

changes in sediment storage could be observed but not understood. Lack of understanding of the 

underlying processes driving observed changes in sediment storage would preclude designing a 

flow regime or other management strategies to conserve and restore desired characteristics of 

the CRE. 

 

Adjustments in the implementation of the four major monitoring components in response to the 

occurrence of BHBFs form an important component of the proposed protocols for core 

monitoring. BHBFs represent disturbances that allow GCMRC scientists to test their ability to 

understand and predict the response of the CRE to perturbations. The CRE is a dynamic and 
complex system in which continual changes in sediment and water supply create both systemwide and local changes in sediment storage. Multiple BHBFs allow scientists to refine the 

sediment mass balance and modeling described in the proposed protocols to the level where 

thresholds and longer-term trends can be predicted in relation to both controlled (e.g., flow 

regime) and uncontrolled (e.g., climate change, tributary sediment inputs) sources of variability 

in water and sediment supply. The ability to implement BHBFs depends primarily on sediment 

inputs from the Paria and Little Colorado River, and the proposed monitoring protocols 

effectively explain how the four major monitoring components will be implemented under 

differing time intervals between successive BHBFs. 

Information gathered from the proposed sediment monitoring plan will also be a necessary 

component of the overall adaptive management program. Active adaptive management 

involves direct manipulation, such as the BHBF experiments. Passive adaptive management 

utilizes natural variation in ecological processes to help develop understanding of system 

dynamics. As the Glen Canyon adaptive management program is becoming a combination of 

both active and passive approaches, it must have a rigorous and continuous monitoring plan in 

order to capture information for learning, and optimize opportunities for increasing 

understanding. 

The draft report is particularly effective at explicitly stating how each monitoring task links to 

other resource programs and issues, which is critical given that the data collected on sediment 

storage and flux will be integral to research and monitoring efforts in the other GCMRC 

programs. We expect that subsequent monitoring proposals from these programs will include 

the same level of integration with this sediment monitoring, with other GCMRC programs, and 

with the conceptual model of the CRE 

 

It is important that the techniques initially established for each of the four major monitoring 

components be maintained if investigators other than the original GCMRC scientists continue 

the monitoring work. This need for stability of monitoring techniques appears to be addressed in 

the proposed protocols. It is also important that the monitoring be long term (i.e., maintained at 

least beyond 5 years), and this is also addressed in the proposed protocols. We feel that the 

reporting format described in the proposed protocols, which includes peer-reviewed journal 

articles and regular reports to TWG and AMWG, is well-designed and should be effective in 

communicating ongoing results to the greater community 

The Science Advisors may not necessarily have to review each additional monitoring proposal, 

for we are confident of the ability to GCMRC directors to design these monitoring protocols so 

that they are both stable and intregative. However, it is unclear if the format and approaches 

presented for sediment monitoring protocols and developed linkages to other resource 

monitoring will be repeated in core monitoring plans for cultural and biotic resources. If they 

are, the need for review of these protocols may be minimized. 

Some of the above evaluations by the Science Advisors (SAs) can be better determined when 

the final sediment core monitoring document is submitted for review. The SAs look forward to 

conducting that in depth review in the near future.