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Environmental Flow Assessments

Environmental Flow Assessments. An Overview. ACFS Governing Board Meeting. December 8, 2011. Some definitions. Getting the words right!. Environmental flow assessments. Determine the amount of water that is available for human use from a particular source Establish

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Environmental Flow Assessments

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  1. Environmental Flow Assessments An Overview ACFS Governing Board Meeting December 8, 2011

  2. Some definitions Getting the words right!

  3. Environmental flow assessments • Determine • the amount of water that is available for human use from a particular source • Establish • the limit at which further water withdrawals will cause significant harm to the water resources of an area and the related natural environment

  4. Environmental flow assessments • Include: • water levels (rivers and lakes) • salinity changes (estuaries) • Protective of • flora and fauna • Natural storage of water • to support human use

  5. Environmental flows • Basic premise • Changes in elevation drive the inundation regimes of flora and fauna communities • Determine the topographic elevation that needs to be flooded and for how long (rivers and lakes) • Changes in location of freshwater-saltwater interface (estuaries) • Salinity, freshwater flows , or other attributes such as temperature or dissolved oxygen • Can be established and used to identify habitat constraints

  6. Steps for developing environmental flows The process

  7. Steps for developing environmental flows • Identify resource management targets • Sturgeon (Apalachicola river) • require 6” of water at riffles for passage • Halloween and blackbanded darters (Chattahoochee and Flint rivers) • Freshwater mussels • richness varies with channel depth, forest cover, and drainage network position • Cypress swamps (rivers and lakes) • Oysters and seagrass (estuaries) • Identify relationships between targets and inundation regime

  8. Steps for developing environmental flows (cont’d) • Identify important periods of inundation • Seasonal blocks of low, medium, and high flows

  9. Steps for developing environmental flows (cont’d) • Use models to translate inundation into flows • HEC-RAS (river analysis system) • Mass balance salinity models, regression analysis, multi-layer hydrodynamic models (estuaries) • Input flows into Black and Veatch model Distribution of salinity

  10. Environmental flows – compliance standards

  11. ACFS contract tasks 3 Tasks

  12. ACFS contract tasks – funded • Task 1 - Evaluate existing Environmental Flow data for the entire ACF Basin • Literature review, including data inventory • To be completed by December 30, 2011

  13. Data inventory – an example

  14. ACFS contract tasks – unfunded • Task 2 - Determine data needs to support different environmental flowapproaches • Task 3 - Identify science needed to develop environmental flows • Evaluate data in context of available approaches • Select appropriate approach • Develop IFA (Apalachicola river) • Identify target resources and relationships • Develop relationships for targets with regard to inundation and elevation • Develop conceptual approach to IFA if data inadequate for development of relationships (Flint and Chattahoochee rivers)

  15. Questions Tom Singleton thomas.singleton@atkinsglobal.com (850) 580-7929

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