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Appendix A: Evaluation of the Predictive Ecological Model for the Edwards Aquifer Habitat Conservation Plan: An Interim Report as Part of Phase 2
Pages 125-158

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From page 125...
... Appendix A Evaluation of the Predictive Ecological Model for the Edwards Aquifer Habitat Conservation Plan: An Interim Report as Part of Phase 2 Committee to Review the Edwards Aquifer Habitat Conservation Plan Water Science and Technology Board Division on Earth and Life Studies 125
From page 126...
... 2016. Evaluation of the Predictive Ecological Model for the Edwards Aquifer Habitat Conservation Plan: An Interim Report as Part of Phase 2.
From page 127...
... APPENDIX A 127 The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research.
From page 128...
... The statements and opinions contained in proceedings are those of the participants and have not been endorsed by other participants, the planning committee, or the National Academies of Sciences, Engineering, and Medicine. For information about other products and activities of the National Academies, please visit nationalacademies.org/whatwedo.
From page 129...
... LONG, U.S. Geological Survey, Tacoma, Washington JAYANTHA OBEYSEKERA, South Florida Water Management District, West Palm Beach KENNETH A
From page 130...
... ACKNOWLEDGMENTS This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge.
From page 132...
... . The Committee to Review the Edwards Aquifer Habitat Conservation Plan is focusing on the adequacy of information to reliably inform assessments of the HCP's scientific initiatives, ensuring that these initiatives are based on the best-available science.
From page 133...
... the Edwards Aquifer Authority (EAA) to the Committee's questions and ­ inquiries, as this greatly helped the review process.
From page 134...
... Part of the objectives is to use these models in exploratory and scenario analyses designed to assess HCP actions. This would include model simulations designed to quantify how different scenarios of spring flows and conservation measures under the HCP would affect SAV biomass and distribution and consequently FD population dynamics.
From page 135...
... The knowledge, assumptions, and decisions made by the modeling team during model development are important for subsequently using the models in an effective manner. Also, key questions can be more fully addressed, and additional questions can be addressed, by having the ability to make structural changes in the models, rather than being limited to parameter changes or to a small subset of possible changes determined by the development team before a model hand-off.
From page 136...
... provide a systematic analysis of what life stages, processes, timing, and spatial areas are important to FD population dynamics; ­ and (2) include explanations of why model responses are predicted (not just the final predictions of abundance)
From page 137...
... The goal of creating an SAV model that simulates dispersal and predicts how flow affects SAV has not yet been met. The objectives of the SAV modeling are to predict the percent SAV coverage under different flow regimes, and to then use these predictions as input (habitat)
From page 138...
... . Every decision in these models should be carefully examined against the overarching question regarding how flow affects SAV, and in this way additional processes will be identified that connect flow to SAV dynamics.
From page 139...
... The use of an individual-based approach imbedded within a 2-D spatial grid for full life-cycle simulations of FD population dynamics is a scientifically sound framework for the questions being asked, but there remain some important steps to link the FD dynamics to their habitat. The parallel development of the FD and SAV modeling has advantages in that adjustments can be made in each to ensure both models are configured to allow accurate transfer of habitat information from the SAV to the FD models.
From page 140...
... The movement-related mortality rate is triggered when the number of movement time steps (24 per day) that an individual spends in open water or without options to move to other less crowded vegetated cells is exceeded (see Movement paragraph below)
From page 141...
... The number of times the individual is in water cells is accumulated and used to determine death (too many time steps in water cells leads to death)
From page 142...
... Information on the typical distances moved by individuals and plotting of the Lagrangian trajectories of individuals under different vegetation and flow conditions should be presented to confirm the realism of the simulated movement behavior. Another potential difficulty with a cellular approach to movement is if the spatial resolution of the FD grid is changed -- movement to a cell now involves traveling a different distance in the same time step.
From page 143...
... Thus, interpreting how alternative flows affect FD using the FD model requires understanding how changes in flow affect velocities and depth that are then used as input to the QUAL2E model, and then how these changes in hydraulic outputs affect QUAL2E's predictions of maximum daily temperature and minimum daily DO. The use of observed densities for maximum FD densities by vegetation type acts to smooth over the threshold effect of capping FD densities by vegetation type.
From page 144...
... They will offset some of the response of the population to changes in habitat and other factors. For example, a decrease in spring flow can cause reduced SAV habitat for FD and increases their mortality rate because of less cover resulting in increased predation.
From page 145...
... A common measure of spawners is total eggs produced in a year, and a common measure of recruitment would be the number of individuals that survived from those eggs to become juveniles and then to become adults. This can be difficult with a species like FD that spawns all year long and for which the present formulation includes d ­ ensity-dependence in the adult stage; defining over what months to sum egg production and how to accumulate recruits to obtain annual values needs to be considered.
From page 146...
... The direct effects are limited to how flow affects daily maximum temperature and minimum daily DO (from QUAL2E) , both of which affect mortality rates.
From page 147...
... , many would consider it under-studied in terms of process studies, especially those that relate flow to growth, mortality, reproduction, and movement of FD by life stage. Thus, the FD model reflects what is clearly known about flow effects but likely is missing other effects because of lack of site-specific measurements to justify their inclusion in the model.
From page 148...
... The SAV modeling group has been very helpful in answering questions related to the BIO-WEST (2015) report.
From page 149...
... 13. The SAV model grapples with the difficult challenge of handling maximum biomass per cell, as well as conversion of cells from one SAV species to another.
From page 150...
... If the development team instead considers this limit to be related to colonization of adjacent cells, then this could be explicitly linked to the transition probabilities. Another option would be to have a variable translocation term, where more growth is allo­ cated below ground as the above ground biomass in a cell becomes larger.
From page 151...
... The maximum densities were set to observed densities by vegetation type. So the fact that the sum of FD densities (abundance)
From page 152...
... The calibration and validation can be strengthened by examining additional model outputs and years, and by quantifying the uncertainty associated with predictions. Some of this has been done by the model development team but could be better documented, more rigorously compared to the field and lab data, and additional outputs considered.
From page 153...
... Rather, validation exercises should be considered that take SAV coverage into account at larger spatial scales and compare patterns of SAV coverage between predicted and observed maps. A "pattern-oriented approach" similar to that described by Grimm et al.
From page 154...
... Validation should also consider the use of the SAV model as both a standalone model and in its role as generating habitat input for the FD model, to ensure that the appropriate aggregate measures are evaluated. MODEL COUPLING Model coupling is a special topic because of the plans by the model development team to use the results of the SAV modeling to provide habitat inputs to the FD model.
From page 155...
... Careful consideration of whether this, as well as how other variables are transferred, is sufficiently accurate for use in the FD model is warranted. The SAV modeling is still unsettled, but it seems that a reasonable compromise can be found such that the SAV modeling can be used both for simulating SAV responses to flow and for providing habitat inputs to the FD modeling.
From page 156...
... more linked to environmental variables such as flow. Logic charts showing how HCP actions can cause responses in the information passed from the hydraulics and water quality models to the SAV model; from the hydraulics, water quality, and SAV models to the FD model; and within the FD model itself, would benefit model communication and interpretation of the FD modeling results.
From page 157...
... Edwards Aquifer Habitat Conservation Plan. Interim Report.
From page 158...
... 158 REVIEW OF THE EDWARDS AQUIFER HABITAT CONSERVATION PLAN Parrish, R


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