GeoTools for Rapid Dynamic Channel Analysis and Biological Assessment
* Can Reclamation managers and decisionmakers make quick, accurate assessments of how changes in water operations will affect geomorphic stability of channels, sediment transport, and biologically significant flow variables?
GeoTools is a comprehensive package of tools designed to rapidly and easily analyze changes in the instream flow environment through the assessment of sediment transport, bed shear, stream power, and the overall effective discharge. Preventing potential geomorphic and biological problems before they arise or selecting the proper course of action once problems are identified is often a question of analyzing many possible scenarios in an efficient manner. The current form of GeoTools and its users manual can be downloaded from .
Need and Benefit
There are currently a number of sediment transport and geomorphic analysis models available to Reclamation (e.g., GSTARS 1D, GSTARS 2D). These models are capable of predicting the sediment transport for specific systems; however, they are data-intensive, require extensive calibration, and are costly to implement. Many questions about the geomorphic stability or changing instream flow environment as a function of flow regime alteration can be answered in a much more timely manner; or, larger projects can be prioritized based on significance using tools which characterize the general sediment transport characteristics of the system. Costs to Reclamation managers are high when an in-depth sediment transport study becomes necessary; however, there is no general tool available to managers to determine when and where these expensive studies are necessary.
The proposed application of GeoTools to Reclamation projects is not meant to replace these tools, which are adequate to solve problems, but rather to provide a window to the problem in a timely manner and identify whether more expensive projects are warranted. GeoTools also represents a capability of rapidly investigating the biological significance of changing instream habitat that clearly differentiates it from the physically based sediment transport models described above. The models currently available to Reclamation, such as the GSTARS suite, rely on solving forms of the hydrodynamic equations that, in turn, require distributed channel geometry information. The hydrodynamic equations are inherently difficult to solve and combined with sediment transport equations are prone to instabilities. Proper application, therefore, requires a level of expertise on the users part that is often only available through the Technical Services Center.
GeoTools is an Excel based, easy-to-use package of sediment transport and effective discharge modules that can be readily used by Reclamation staff with experience in basic hydraulics to characterize the sediment transport characteristics of a system. GeoTools relies on time series flow data that can come from either historical records or simulated data. In terms of channel geometry, all that is needed is general hydraulic geometry. GeoTools already includes many theoretical sediment transport equations for gravel bed, sand bed, and mixed bed waterways as well as the opportunity to use user-specified sediment transport rating relationships. The outputs produced from GeoTools are characterizations of the effective discharge, total sediment transported, percent of time that varying amounts of sediment and water are in the waterway as well as the density functions of shear stress and stream power. Comparisons can be made between multiple sets of time series for a quick analysis of how the characteristics of the system will change. GeoTools can be downloaded from .
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