TREES TO OFFSET STORMWATER MiamiBeachCase Study 05: City of Miami Beach, Florida September 2018 MiamiBeachCase Study 05: City of Miami Beach, FL Images and illustrations in the report are by the Green Infrastructure Center Inc. (GIC). The work upon which this publication is based was funded, in whole, through a subrecipient grant awarded by the USDA Forest Service through the Florida Department of Agriculture and Consumer Services, Florida Forest Service to Miami Beach. The Green Infrastructure Center is the technical services consultant for the project and the project partner. The contents do not necessarily reflect the views or policies of the USDA Forest Service, nor does mention of trade names, commercial productions, services or organizations imply endorsement by the U.S. Government. Publication Date: September 2018 September 2018 PROJECT OVERVIEW CONTENTS This project Trees to Offset Stormwater, is a study of Miami Beach’s tree canopy its role in taking up, storing and releasing water. This study was undertaken to assist Miami Beach in evaluating how to better integrate trees into their stormwater management programs. More Project Overview ................................................................................... 1 specifically, the study covers the role that trees play in stormwater management and shows how the city can benefit from tree conservation and replanting. It also evaluates ways for the city to Project Funders and Partners ..................................................................................... 1 improve forest management as the city re-develops. Outcomes ......................................................................................................... 1 Community Engagement ......................................................................................... 2 PROJECT FUNDERS AND PARTNERS OUTCOMES Summary of Findings .............................................................................. 3 The project was developed by the nonprofit Green This report includes those findings and recommendations Infrastructure Center Inc. (GIC) in partnership with the states that are based on tree canopy cover mapping and analysis, the of Florida, Georgia, Alabama, South Carolina, North Carolina modeling of stormwater uptake by trees, a review of relevant city Why Protect Our Urban Forests? ................................................................... 6 and Virginia. The GIC created the data and analysis for the codes and ordinances, and citizen input and recommendations Additional Urban Forest Benefits ................................................................................. 9 project and published this report. This study is one of 12 pilot for the future of Miami Beach. More specifically, the following deliverables were included in the pilot study: Quality of Life Benefits ........................................................................................... 9 projects evaluating a new approach to estimate the role of trees in stormwater uptake. Florida received funding from the USDA Economic Benefits ............................................................................................... 10 Forest Service to determine how trees can be utilized to meet • Analysis of the current extent of the urban forest through Meeting Regulatory Requirements ............................................................................... 10 municipal goals for stormwater management. The FL Forest high resolution tree canopy mapping, Service administered the pilot studies in Florida and selected • Possible Planting Area analysis to determine where Miami Beach to be one of the three test cases. The other additional trees could be planted, Natural Ecology in Urban Conditions – Changing Landscapes ................................... 12 Florida municipalities selected were the City of Jacksonville • A method to calculate stormwater uptake by the city’s tree and Orange County. Historic Land Cover ............................................................................................... 12 canopy, Growth and Development Challenges ............................................................................ 12 The project was spurred by the on-going decline in forest cover • A review of existing codes, ordinances, guidance Miami Beach’s Resilient Future .................................................................................. 14 throughout the southern United States. Causes for this decline documents, programs and staff capabilities related to trees arise from multiple sources including land conversion for and stormwater management, and recommendations for development, storm damages and inundation from Sea Level improvement, Analysis Performed ................................................................................ 15 Rise and lack of tree replacement as older trees die. Many • Two community meetings to provide outreach and Method to Determine Water Interception, Uptake and Infiltration .............................................. 15 localities have not evaluated their current tree canopy, which education, makes it difficult to track trends, assess losses or set goals to Land Cover, Possible Planting Area, Possible Canopy Area Analysis ............................................. 18 retain or restore canopy. As a result of this project, Miami • Presentation of the results of the pilot studies as a case study Beach now has baseline data against which to monitor canopy at regional and national conferences, and protection progress, measures of the stormwater and water Codes, Ordinances and Practice Review ........................................................... 22 • A case book and presentation detailing the study methods, quality benefits provided by its urban forest, and locations for lessons learned and best practices. Evaluation and Recommendations ............................................................................... 22 prioritizing canopy replanting. Best Practices for Conserving Trees During Development ...................................................... 26 The project began in September 2017 and Miami Beach Tree Planting ...................................................................................................... 27 staff members have participated in project review, analysis and evaluation. The following city divisions were involved Conclusion ........................................................................................................ 28 in the project planning and review as the Technical Review Committee (TRC): Environment and Sustainability Department; Environmental Resources Division; Urban Forestry Division; Appendixes ......................................................................................... 30 Community Services, Parks and Urban Forestry; Public Services, Appendix A: Technical Documentation ........................................................................... 30 Stormwater Division, and GIS; Planning, Development, and Transportation; and Engineering. Appendix B: Bibliography ......................................................................................... 32 Welcome shade in Miami Beach 1 COMMUNITY ENGAGEMENT SUMMARY OF FINDINGS Satellite imagery was used to classify the types of land cover in of stormwater uptake based on the landscape conditions of the Two community meetings were held. The first meeting held in April Miami Beach (for more on methods see page 15). This shows the city’s forests. It distinguishes whether the trees are growing in 2018 provided an overview of the project. The second meeting held city those areas where vegetative cover helps to uptake water and a more natural setting (e.g. a cluster of trees in an urban forest in September 2018 provided recommendations (listed below) for those areas where impervious land cover is more likely to result or forested wetland), a lawn setting, or over pavement, such as the city and elicited feedback. All individual comments from both in stormwater runoff. High-resolution tree canopy mapping streets or sidewalks. The amount of open space and the condition meetings were provided to the city. provides a baseline that is used to assess current tree cover and of surface soils affect the infiltration of water. to evaluate future progress in tree preservation and planting. An Miami Beach residents emphasized the importance of planting ArcGIS geodatabase with all GIS shape files from the study was native canopy trees because they have far greater stormwater uptake provided to Miami Beach. capacity, than palm trees. They also expressed an interest in knowing the composition of the urban forest with regards to tree species. ISLAND PERCENT The goal of this study was to identify ways in which water Some residents suggested documenting tree species and planting TREE entering the city’s municipal separate storm sewer system (MS4) GROUP dates for newly planted trees on private property. Residents also could be reduced by using trees to intercept and soak up runoff. CANOPY asked for guidance for increasing tree density on their properties Tree canopy serves as ‘green infrastructure’ that can provide and for guidance to select suitable tree species. They also expressed Allison Island 19.21% more capacity for the city’s grey infrastructure (i.e. stormwater interest in applying data from the Trees and Stormwater Project to drainage systems) by absorbing or evaporating excess water Terminal Island 2 0.02% show changes in canopy over time.