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Pelagic Organism Decline Program: Three Dimensional Particle Tracking
The motivation for this study is the observed decline of delta smelt and other pelagic organisms of the upper San Francisco Estuary. Three general factors identified to explain lower pelagic productivity are 1) toxic effects; 2) exotic species effects; and 3) water project effects (Resources Agency, 2007). For each of these factors the location and movement of delta smelt are likely to be critical for understanding the reasons for the pelagic organism decline (POD) and the efficacy of any actions taken to sustain pelagic fish populations. In order to investigate the location movement of delta smelt within the Delta, a three-dimensional hydrodynamic model was applied to simulate hydrodynamics in the Sacramento-San Joaquin Delta, and the hydrodynamic results were used with a particle tracking model to investigate delta smelt distribution and behavior. The model was used to predict the distribution of delta smelt hatching and the portion of the delta smelt population lost to entrainment at water exports under a range of operating conditions. Results/Successes · Developed hydrodynamic model results for three Delta smelt study periods. · Successfully developed particle tracking model that accurately represents transport processes. · Predicted the delta smelt hatching distribution which results in predicted delta smelt distribution and salvage similar to observed distribution and salvage. · Illustrated the critical importance of hydrology to entrainment calculations. The particle tracking model results suggest the potential for substantial error in previous estimates of entrainment that did not explicitly account for flow paths through the Delta. · Demonstrated that hypothesized vertical behaviors of delta smelt have minimal influence on estimated distribution and entrainment. · Collaborated with DWR and RMA to perform particle tracking inter-model comparisons between the FISH-PTM, RMA2, and the DSM2 PTM. · Showed substantial differences among 1-D, 2-D and 3-D particle tracking models and illustrated the effects of shortcomings of the DSM2 PTM. Client Testimonial “Uncertainties about the responses of the San Francisco Estuary to hydrodynamic changes remains one of the greatest issues facing regional efforts to restore and manage aquatic resources. The model results that you produced were informative, detailed and excellent, producing many favourable comments from colleagues from multiple agencies. The many presentations about your Delta model and simulation results have been very helpful for information transfer to scientists, engineers, and managers.” Ted Sommer, Program Manager II California Department of Water Resources |
