Flood Forecasting for Transportation Resilience: A Guide (2024)
Chapter: 1 Introduction
CHAPTER 1
Introduction
Transportation systems are exposed to a diverse range of hazards, with flooding being one of the most common and consequential. Roadway flooding can directly affect public safety and disrupt transportation networks and the services they provide. Compounding the challenge for transportation system owners and operators is that, beyond natural variability, flood hazards in different parts of the country are shifting due to global climate change. These changes include altered precipitation patterns, extreme storm events, and sea-level rise. An operational flood forecasting system can provide support to departments of transportation (DOTs) for their immediate flood preparation and response needs as well for longer-term planning efforts. With advanced warning, DOTs can prioritize limited resources to close roads, plan detours, and communicate to the public before motorists are exposed to flood hazards. Travelers can avoid delays and adjust their demands on roadway capacity during the worst events. Further, with the right analytical tools, high-vulnerability locations can be identified, and, where feasible, flooding can be prevented through mitigation investments. This report seeks to empower state DOTs with technical resources and organizational insights to help them better predict the timing and magnitude of flooding and enable advanced early warnings, reducing expensive damage to critical assets and enhancing roadway safety.
1.1 Flood Forecasting Overview and State of Practice
Flood forecasting is a way to proactively monitor, assess, and respond to flood-related hazards and impacts in real time. It involves integrating multiple sources of data and providing notifications to various audiences. Flood forecasting is an area of active exploration and development and has a range of maturing and emerging solutions being evaluated—including sensor technology, connected vehicle data, synthetic aperture radar satellite imagery interpretation—from academic, government, and private-sector contributors. Experimental products and emerging research areas present promising opportunities for developing high-quality hydrometeorological projections and flood forecasts. In addition to tools and resources, a mature flood forecasting capability involves business processes for creating, developing, and maintaining a decision support system appropriate for DOT operations, and, by extension, the traveling public.
Flood forecasting is a way to proactively monitor, assess, and respond to flood-related disasters and hazards in real time. It involves integrating multiple sources of data and providing automated notifications to various audiences.
Although there are data, tools, and models available to forecast weather and climate conditions in many states, these have yet to be truly integrated into most state DOT asset data and communication systems. And for DOTs currently leveraging available data and technology to support flood event decision-making, these systems exhibit varying levels of sophistication.
Even DOTs with the most advanced systems have expressed the need for more effective prediction of expected timing, magnitude, and location of flooding, as well as anticipated impacts on infrastructure, particularly for locations without monitoring gauges.
No tool, no matter how good, is a replacement for doing the hard work to build partnerships and establish business processes fundamental to operationalizing a new capability—especially within complex organizations such as DOTs. The research to date has made clear that while tools and technology such as those featured in this guide will continue to emerge, the business processes needed to integrate data, inform agency decision-making, and communicate such forecasts still need to be matured. DOTs across the nation are at various stages of implementing a flood forecasting capability, and this guide highlights relevant DOT examples across ranges of capability and maturity.
1.2 Who Should Use This Guide?
This guide is designed to support DOTs in advancing their flood forecasting capabilities, regardless of where they are in their journey. Some DOTs are just getting started. There are practical tools, resources, and stories from practice throughout the guide to assist them in taking those first steps. Similarly, the guide shares methods and activities to enhance capabilities for DOTs already progressing down a flood forecasting path.
Flood forecasting is a multidisciplinary activity. In addition to meeting DOTs where they are, the guide breaks down concepts for the various staff involved in building and operationalizing effective capabilities. These staff include individuals with hydrologic and hydraulic modeling responsibilities, operations and maintenance staff, and DOT emergency management professionals. The team needs to understand the whole picture and then identify concrete actions and roles each individual will take.
This guide is designed to:
- Support DOTs in reflecting on current capabilities, identifying goals, and leveraging existing data;
- Identify tools and tactics to support DOTs in getting started with flood forecasting, enhancing capabilities to meet goals, or fitting flood forecasting into their existing operations;
- Help DOTs prioritize where they should invest their time in building capabilities;
- Assist DOTs in building partnerships or getting support from leadership;
- Help DOTs onboard staff to a flood forecasting team; and
- Encourage DOT staff to join a community of practice.
1.3 How to Navigate This Guide
The structure of this guide is oriented around building capabilities and will be useful regardless of where a DOT is in its flood forecasting journey. Five areas emerged from the research as key components of a robust flood forecasting capability. The chapters of the guide follow these key capabilities needed to develop, activate, and use flood forecasting in five areas (see also Figure 1-1):
Research Background and Overview
Since the inception of this work, state DOTs have been essential to providing direction and informing the purpose of the concept and its development. This research effort started in 2015 and has had four phases. In the first phase, the research team identified and curated resources representing effective data, tools, and methods for supporting flood forecasting. The result was a technical memorandum where the research team solicited DOT input and compiled and graded resources, mostly federal, for base data, forecasting, infrastructure, sensors, and inundation. In the second phase, the research team produced a wire-frame proof of concept, depicting both riverine and coastal impacts at a single location. Building on this effort, in the third phase, the team used the prototype as a prompt for gathering requirements from 26 DOTs across the nation. The effort also highlighted key questions a forecasting capability would need to answer and produced a capability maturity model for DOTs to self-evaluate their capabilities in the key flood forecasting areas.
The fourth phase started with a technical evaluation of the (at the time) experimental National Oceanic and Atmospheric Administration (NOAA) National Water Model. The research suggested that it had promise for enabling forecasting of important events with sufficient lead times to aid in response activities. To solicit more useful insights for this guide, the research team created a demonstration dashboard to help DOTs think through how best to set up, operate, and disseminate flood forecast and warning information. The team then worked with 10 DOT partners to set up use of the dashboard, from identifying locations of interest and associated impact thresholds at those locations to designating roles and responsibilities. This yielded insight about the business processes, preparation, and data needs required to instantiate a forecasting capability.
The research team also engaged DOT personnel and captured experiences through a survey that covered questions on data foundations, monitoring, operations, and communications activities. This was supplemented by DOTs self-ranking themselves in the Capability Maturity Model developed in Phase III (Appendix A). Finally, three DOTs were engaged in “flood event debrief” discussions with questions focused on roles, timing, decisions, coordination, and operational systems before and during a theoretical or observed flood event. These insights were then translated into content for this practitioner’s guide.
Each chapter begins with the chapter’s critical focus, key takeaways, and actions to accomplish. Examples of overarching success-enabling factors identified by DOTs through the development of this resource include:
- Identify a Champion and Empower Them. Initiating or developing a flood forecasting capability requires significant time investment and sufficient organizational clout and resources to advance initiatives.
- Develop a Data Validation Process. It is essential to create processes that can evolve and can enhance data accuracy over time. This can include collecting flood event data and refining key forecast inputs such as impact thresholds.
- Be Resourceful. DOTs often possess information (hydraulic models, past event records, bridge inspection reports, culvert location and attribute data, etc.) that is critical for flood forecasting, but such information is not broadly shared or is not stored to support interoperability.
- Share Information Efficiently and Consistently. Spatial databases can help raise awareness about data holdings and data gaps.
- Be Adaptive. There are rapid changes in tools and technologies, and being engaged in a community of practice can help with staying up to date.
Chapters then describe the key attributes of what a mature capability might look like. The rest of the chapter has practical tips, stories, activities, and information to help a DOT choose a path forward and act to move closer to that mature capability ultimately. For example, Chapter 2: Data Foundations has a self-guided activity on assessing and leveraging data, and Chapter 4: Operations has questions to support developing or enhancing hazard response plans. Tables are also used throughout to help a DOT prioritize what is the best fit for its organizational systems and goals. For example, Chapter 3: Prepare and Monitor has a table with real-time data sources to support flood monitoring. Finally, there are snapshots of practice. For instance, Chapter 5: Communications has examples of social media posts and communication resources. The guide marries an overview of the state of practice with more detailed stories and resources DOTs use.
