Broward County 100-Year Flood Elevation Mapping Incorporating Future Conditions

Transcription

1

2 Introduction What is this project really about? How will this project be used? How will Broward County be better for doing this project? Flood Control Finished Floor Level of Service Infrastructure Design Criteria Capital Improvements Emergency Management Coastal Resiliency Water Resource Management Smart Development Planning Sustainability Future Adaptability

3 Presentation Outline The Evaluation Committee requested that the firms address the following in their presentation: Identification of the key members, their role in the project and their capabilities Brief review of the project approach How your firm intends to identify and address model improvements that might be required How your firm will validate those improvements How your firm intends to address non-stationarity as it relates to development of IDF curves for future conditions Unique tools and utilities that your firm intends to apply in this project How your firm intend to use the community outreach process to actually inform the project

4 Identification of Key Members Flood Mapping Coastal Resiliency Public Outreach

5 Project Approach Review Update the existing Broward County-Wide Integrated MIKE SHE/MIKE 11 Hydrologic-Hydraulic model. This task includes development of a utility to reprocess the results of FEMA Coastal A Zone modeling. Develop future conditions model scenarios based on sea level rise and climate projections for year and This task includes development of a utility to convert updated MODFLOW output files to MIKE SHE / MIKE 11 input files to allow for future updates to the groundwater model. Develop updated 100-year Flood Elevation Map of future conditions ( ) in similar format to the 1977 map and a format similar to the 2014 FEMA DFIRMs. This task includes development of a utility to easily update the flood elevation digital map, as new results become available. Develop a plan to maximize National Flood Insurance Program (NFIP) Community Rating System (CRS) credit points from this project for Broward County. Also, provide CRS credit recommendations to the involved communities. Develop a summary report detailing the project methodology, stakeholder process, model improvements, calibration parameters, and results, production runs results, map development process, and the evaluation of potential CRS creditable criteria resulting from the project. Experts Familiar with Technical Tools & Methods to Support Regulatory Decisions Technically Defensible Product Sensitive to Schedule and Budget to Efficiently Meet Project Goals Understand Stakeholder Interests

6 Identifying Model Improvements Potential Improvements to 2-D Overland Flow Routine: Vary Roughness Coefficient by Land Use Vary detention storage by land use, or implement new (v2017) ponded drainage routine May consider reducing grid size

7 Identifying Model Improvements (continued) Potential Improvements to MIKE-11 1-D Network: Add detail where warranted City of Ft. Lauderdale SMP Hollywood Pompano / Other Public Comment Update cross sections (e.g., for sedimentation) Update control structure input with latest information Proposed water management system upgrades (e.g., C-9 and C-11 Impoundments)

8

9 Validation of Improvements Previous calibration Irene 1999 Select one or more storm events for model calibration/ validation Hurricane Irma may be a good test of the model response Very recent event 5 to 11 inches of rainfall Storm surge of approx. 2-3 feet NNR Canal - Hurricane Irma Response

10 Coastal Mapping Current conditions Validated SWAN+ADCIRC model Incorporate FEMA s 2017 revision Combine with upland flood levels statistically Future conditions Sea level rise Change in climatology Landform changes Simulation of individual storms to estimate future surge levels Combined riverine and coastal levels Added statistically

11 IDF Curves for Non-Stationary Future Conditions Non-stationarity and uncertainty of South Florida rainfall projections Annual rainfall increase or decrease in South Florida as much as 20% 1 Largest decreases predicted for wet season 1 Fewer tropical cyclones 2 Up to 20% rainfall increase within 60 miles of tropical cyclones 2 Significant uncertainty regarding timing, amounts, and distribution 1 Source: IPCC Climate Change & Water Management in South Florida 2 - Hydrologic and Environmental Systems Model Technical Report, SFWMD, July 2011

12 IDF Curves for Non-Stationary Future Conditions Current IDF Curves (Assume Stationarity) SFWMD, Trimble (1990) Currently used for surface water management permit NOAA Atlas 14 (2013) IDF Curves based on downscaled global climate models (Non- Stationarity) SFWMD study DRAFT - Determination of Future Intensity- Duration-Frequency Curves for Level of Service Planning Projects Active research area, no standard practice

13 IDF Curves for Non-Stationary Future Conditions Simple probabilistic modeling approach Gain consensus on baseline IDF curves for future (2060 and 2100) conditions Scale up or down rainfall intensity to establish upper / lower limits for extreme events Bracket the range of probable impacts to Broward County Adaptability built into mapping to develop flood maps from probabilistic model results Rainfall Intensity (in/hr) NOAA Atlas 14 IDF Curves (100-YR) for Ft. Lauderdale Intl. Airport Duration (hr) NOAA Atlas 14 5% Increase 10% Increase 15% Increase 20% Increase

14 Unique Tools and Utilities MODFLOW conversion utility convert new groundwater to MIKE SHE initial conditions Coastal model interfacing update and run model based on new coastal results Future model updates run and produce updated results from new simulations

15 Unique Tools and Utilities Custom ArcGIS Tools, ArcServer Deployment VB / Python / R Scripting Model Interfacing Taylor TackleBox Coastal Analyst Channel builder Diagnostic Modeling System (DMS ) Data Manager Miscellaneous customized tools 256 core High-Performance Cluster Computing system

16 Unique Tools and Utilities Web-based data solutions Map production Model Data Management Data Visualization Non-proprietary, web-browser based

17 Unique Tools and Utilities Decision support interfaces Risk Management

18 Community Outreach Approach Planning with County to identify stakeholders and communication methods Initial 3 stakeholder / public meetings Assimilate input and close loop Follow up meeting to present results Geosyntec Team Assist with getting the word out Prepare presentations Prepare administrative materials Direct Q&A Identification and partnering with key stakeholders, decision makers, and knowledge experts is key to success Geosyntec led a public forum for a stormwater project that will positively impact several communities.

19 Community Outreach Web Pages Comment capture Progress updates Disseminate results Social Media PSAs Newsletters Large Scale Exhibits Visualizations Outreach process can be leveraged to facilitate CRS improvements for Broward County and communities

20 Community Outreach Translate complex results to public such as incremental impact of climate change on flood levels based on model results Animations to demonstrate graphics for public consumption

21 Presentation Outline The Evaluation Committee requested that the firms address the following in their presentation: Identification of the key members, their role in the project and their capabilities Experts Familiar with Technical Tools & Methods to Support Regulatory Decisions Brief review of the project approach How your firm intends to identify and address model improvements that might be required How your firm will validate those improvements How your firm intends to address non-stationarity as it relates to development of IDF curves for future conditions Unique tools and utilities that your firm intends to apply in this project How your firm intend to use the community outreach process to actually inform the project Technically Defensible Product Sensitive to Schedule and Budget to Efficiently Meet Project Goals Understand Stakeholder Interests

22 Q&A