Practices for Integrated Flood Prediction and Response Systems (2021)

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4 This chapter introduces background information and highlights the importance of integrated flood prediction and response systems. The survey and interview processes and organization of the report are also described. Background A critical issue facing departments of transportation (DOTs) across the United States is determining the extent and the severity of flooding events. Roadways and bridge flooding have significant economic impacts. State DOTs and other state and local agencies have implemented integrated flood warning and response systems to mitigate the effects of floods. These systems are critical for staging personnel, deciding when to close roads, inspecting bridges, tracking floods throughout the state, and planning recovery. Support for these efforts often integrates items such as internal products, flood inundation mapping using current and projected condi- tions, turnkey products on the market, the United States Geological Survey (USGS) gaging network, and the National Weather Service (NWS) flood forecast. In addition to predicting flood inundation, states are tasked with alerting the public about affected areas and protecting them from these hazards. DOTs and other agencies must determine the flood’s extent and severity to effectively work with emergency management and to inform the public about road closures and detour routes. The multiple methods of warning the public about floods vary by scale, including (a) warnings on official websites, (b) warning lights tied to stream gages, (c) sensors, (d) personnel blocking off areas, and (e) leveraging of federal resources, such as USGS and NWS products. Communication is key for the effective response before, during, and after flood events. Commu- nication gaps within and between agencies have been identified following recent flood events as opportunities for growth. Synthesis Objective The objective of this synthesis is to document the integrated flood prediction and response systems being used by state DOTs. The project gathered information on the state of the practice from agencies involved in finding new or innovative ways to improve flood management and response systems. State DOTs with a track record of successfully implementing strategies and practices in managing critical flooding cases are identified. Information gathered includes, but is not limited to, the following: • Flood prediction methods • Risk thresholds that trigger action • Methods and instruments used by DOTs to monitor flooding C H A P T E R 1 Introduction

Introduction 5   • DOTs’ approach to determine the extent and severity of floods • Available warning systems and methods • DOTs’ practices for alerting the public, working with other agencies, and internal communication • Successful systems as reported by DOTs • Weaknesses in existing methods and problems that remain unsolved Several reports and studies have been completed on the importance of integrated, accurate, and timely flooding prediction, monitoring, warning, response, and impact assessment methods. There is a need to synthesize these efforts and garnish examples of successful state DOTs that are reported to be effective, in order to assist other states in managing critical flood events. This study provides state DOTs and other transportation agencies with useful information on successful practices that address the critical flooding events. Study Approach A multifaceted approach was taken to document the various efforts that have been made recently by some states in working with local public agencies to integrate roadway safety data from local and state sources. The approach to this study included (a) a literature review (Chapter 2); (b) a survey of all state DOT personnel responsible for the integrated flood prediction, monitoring, warning, and response systems that will be distributed to state DOTs’ Hydraulics Office (Chap- ter 3); and (c) selected interviews with state DOT personnel for case examples (Chapter 4). The findings of this investigation are provided in Chapter 5. On the basis of the state DOT survey responses and in-depth interviews with state DOT personnel, state DOT methods and tools that result in noteworthy practices will be summarized. Literature Review A comprehensive literature review of U.S. sources establishes background information on the scope and impact of practices that have been applied with respect to integrated flood predic- tion and response systems. A number of resources were available to the consultants and were used, including (a) Transport Research International Documentation (TRID); (b) internet and web searches; (c) FHWA, Federal Emergency Management Agency (FEMA), and DOT internal reports; (d) journal publications; (e) conference proceedings; (f) other published media, including newspaper and magazine articles; and (g) resources of professional associations to which the inves- tigators belong. Results of the literature review are reflected throughout the synthesis report, concentrated mostly in Chapter 2. Particular attention was paid to references suggested in the project scope and other related resources. Survey of State Departments of Transportation The survey consisted of 78 questions that included nested questions (programmed with the logic functions available in SurveyGizmo software) in order to obtain further details from those states that identify successful and noteworthy practices for integrated flood prediction and response systems. The survey was sent to all DOT contacts through the state Hydraulics Office list provided to the research team by the panel members to ensure that each state was invited to contribute. Verbiage in the invitation encourages the main survey contact persons to distribute portions of the survey (if needed) to other members of their organizations in the State Emer- gency Management Office, Asset Management Office, and Risk Management Office, as well as to the chief engineer, for completion. Forty-seven state DOTs and the District of Columbia’s DOT responded to the survey; the survey questions and results are included in Appendices A and B of this report.

6 Practices for Integrated Flood Prediction and Response Systems In-Depth Interviews As part of the interview process, key members from various FHWA offices (e.g., Office of Bridges and Structures, FHWA Resource Center, and Office of Operations) were interviewed to determine their perspective on the extent of the integrated flood prediction and response systems currently being used. Furthermore, to gather more details on the examples of effective state practices regarding the integrated flood prediction and response systems, the research team conducted interviews with representatives from case example states. These state DOTs were selected on the basis of the results of the survey and literature review. A number of criteria were used to select the states to serve as case examples. As part of the survey, each state DOT was asked to provide the current status of its integrated flood prediction and response systems. That information includes whether the state DOT has successful practices in place regarding each topical area (i.e., flood monitoring, flood prediction, flood warning, and response systems) and whether it ranks the effectiveness of such practices. In addition, geographic and physiographic distribution, differing flood causes and types, different types of land cover and development, and population densities were also considerations. States that highlighted particular strengths in their approach to flood management were also considered. Ultimately, their responses resulted in a diverse group of states facing a range of challenges and practicing innovative solu- tions. Multiple representatives from the organizations listed in Appendix D were interviewed by phone, videoconferencing, and email to gather their input on issues and practices in their state related to flood management. Appendix E includes links to resources identified through the litera- ture review or shared by the agencies interviewed, while a listing and sampling of documents obtained as examples of current practice are included in Appendix F. Figure 1 shows a map of the specific states whose practices were reviewed and the states that responded to the survey. Figure 1. Location of agencies that responded to the survey, were interviewed, and were selected as case example agencies.

Introduction 7   Organization of Report This synthesis report is organized into five chapters. The balance of this chapter presents the report’s background, objectives, and organization and defines key terms. The report’s structure is summarized with brief explanations of the content of each chapter. Chapter 2 describes and highlights the literature review on state practices addressing flood management, especially focusing on integration of flood prediction and response systems and each of the topical areas: flood monitoring, flood prediction, flood warning, and response systems in the United States, as documented in published literature and in online state and local resources. Climate change and resilience were also reviewed because of their relevance to the synthesis topic. Chapter 3 presents the results of the detailed survey questions as reported by the DOTs in their survey responses. The survey results shed light on the state of the practice in many states on the integrated flood prediction and response systems. An overview presents the various note- worthy practices and partnerships that demonstrate effective and successful flood prediction and response systems. Chapter 4 examines and reports the findings of the specific noteworthy practices on the synthesis topic that were collected through published literature, survey responses, and a series of detailed interviews with the individuals listed in Appendix D in each of the case example agencies selected for further review. The chapter is organized to provide more details on the identified noteworthy and innovative examples of state practices pertaining to (a) flood monitoring, (b) flood prediction, (c) flood warning and response systems, (d) the implementation and oversight of innovative and successful practices, (e) challenges faced at the state and local levels, and (f) the lessons learned on establishing successful models and programs. Chapter 5 presents a summary of findings, conclusions, knowledge gaps, and suggestions for further study and research. This information was obtained from the literature review, the state DOT survey, and the in-depth interviews conducted with state DOTs. These chapters are followed by the references, bibliography, a list of abbreviations and acro- nyms, and six appendices. Appendices A and B present a blank survey questionnaire and a copy of survey responses, respectively. Appendix C presents a comprehensive table of state DOT practices and approaches relevant to the synthesis topic. The list of agencies that contrib- uted to this synthesis development is presented in Appendix D. Appendix E includes links to resources identified through the literature review or shared by the agencies interviewed, while a listing and sampling of documents obtained as examples of current practice are included in Appendix F. Definitions Some key terms are defined that pertain to the scope of the synthesis. Additional terms are defined within the context of their relevant sections. BridgeWatch: BridgeWatch is a proprietary software that provides real-time monitoring tech- nologies for public officials and field personnel to use to focus their efforts on specific at-risk sites, rather than entire counties or large watersheds. The software compiles, monitors, and overlays multiple streams of official real-time information from the National Weather Service, U.S. Geological Survey, the National Oceanic and Atmospheric Administration (NOAA), and client metered devices into a web application platform. Users can use BridgeWatch on mobile devices to document and report field observations via system tickets and customizable client- specific digital forms.

8 Practices for Integrated Flood Prediction and Response Systems Esri (Environmental Systems Research Institute): Esri is an international supplier of geographic information system (GIS) software, web GIS, and geodatabase management applications focused on information collection, storage, and analysis. Flood forecasting: Flood forecasting is a set of forecast temporal channel flows or river stages at various locations. Forecasting is typically based on projected precipitation and streamflow but may also include snowmelt and tides. Forecasts can range from a few hours to a few weeks or use records from similar events. Flood monitoring: Flood monitoring is the observational data associated with flooding. This type of information can be collected as gage data, imagery, or human observations. It may be linked to water surface elevation, water flow, or water flow related to a specific infrastructure (e.g., a bridge deck). Typically, these systems function in real time, reporting on the status of the flood to decision makers. Flood prediction: Flood prediction seeks to determine the frequency and magnitude of floods. Predictions are made on the basis of rainfall patterns, catchment characteristics, and river hydrographs. Flood response: Flood response occurs during or after a flood. It describes the actions taken in reacting to a flooding event, typically associated with recovery. Flood warning: Flood warning is the task of leveraging flood forecasts to make decisions about alerting the general public to potential flooding, escalated flooding, or change of flooding status. Warning systems are typically based on flood forecast or threshold information and the time needed to alert the public. In the United States, the National Weather Service issues flood warnings to alert the public to flooding along larger streams that is a serious threat to life or property. Geographic information system (GIS): GIS is a computational data management system designed to capture, store, retrieve, analyze, and communicate geographically referenced information. For purposes of the Highway Performance Monitoring System (HPMS), GIS is leveraged to produce a highway network (spatial data that graphically represent the geometry of the highways, an elec- tronic map) and its geographically referenced component attributes (HPMS section data, bridge data, and other data, including socioeconomic data). GIS allows for the integration and analysis of this information on a single platform. From this information, GIS can display attributes and analyze results electronically in map form. An example related to flood management includes the geographic representation of flood inundation predictions, identification of at-risk bridges, or the storage of historical flood information. Global Positioning System (GPS): GPS is a global navigation satellite system that provides location and time information in all weather conditions, anywhere on or near Earth where there is an unobstructed line of sight to four or more GPS satellites. Hydrologic Engineering Center’s River Analysis System (HEC-RAS): HEC-RAS is an integrated system of software produced by the U.S. Army Corps of Engineers (USACE) for modeling river dynamics. The software allows users to model one-dimensional and two-dimensional flow, water quality, and sediment transport. LiDAR (light detection and ranging): LiDAR is a surveying method that measures distance to a target by illuminating the target with a laser light. LiDAR is popularly used to make high- resolution maps and is being used increasingly for infrastructure inspection. Local public agency (LPA): An LPA is any agency that receives federal transportation funds. These funds are administered by FHWA and passed through the state DOT to the local agency applicants for improving their infrastructure or other transportation services. Each agency that receives these

Introduction 9   funds has a designated LPA coordinator with the responsibility to ensure compliance of all state and federal aid regulations related to the delivery process of locally administered projects. Metropolitan planning organization (MPO): Per federal transportation legislation [23 USC 134(b) and 49 USC 5303(c)], an MPO is defined as the designated local decision-making body that is responsible for carrying out the metropolitan transportation planning process. An MPO must be designated for each urban area with a population of more than 50,000 people. National Water Center (NWC): The NWC is a facility under the National Oceanic and Atmospheric Administration that facilitates collaboration between federal agencies to provide state-of-the-art water information and services to the nation. The products of the NWC aim to strengthen the nation’s water forecast capabilities for floods and droughts, improve preparedness for water-related disasters, and inform water decisions for a range of stakeholders. National Water Information System (NWIS): NWIS is a relational database of quantity and quality stream observations for the entire United States, including U.S. protectorates. This data- base includes all historical gage records in the United States. National Water Model (NWM): The National Water Model is a spatial streamflow model that covers the entire contiguous United States. The inter-agency project, led by NOAA, forecasts streamflow. National Weather Service: NWS is an agency under NOAA with the mission of providing data, forecasts, and warnings regarding weather, water, and climate for the protection of life and property and enhancement of the national economy. Sedimentation and River Hydraulics—Two-Dimension (SRH-2D): SRH-2D is a two-dimensional hydraulic and sediment transport model designed for river systems. This model was developed by the U.S. Bureau of Reclamation. Continued model extension and updates have also been supported by FHWA and the Taiwan Water Resource Agency. United States Geological Survey (USGS): USGS is a scientific agency under the Department of the Interior within the U.S. government. USGS scientists study the landscape, natural resources, and natural hazards of the United States.