Show Me The Value! Virginia Beach's Flood Model Visualization Tool

Abstract Background The City of Virginia Beach (City) is faced with the challenge of providing flood control and storm water drainage services while complying with storm water regulations, surface water quality requirements, and climate stressors that are increasing the intensity and frequency of large storms and sea level rise. These conditions have led to increased occurrences of moderate to severe roadway, structural, and residential flooding. Accelerators for City action include Hurricane Matthew, sea level rise, and a voter referendum. In 2016 Hurricane Matthew dropped 12 inches of rain in a 12-hour period. The aftermath of the storm was devastating to many residents and businesses (refer to Figure 1). The storm served as a wake-up call for the City Council and residents. The City embarked upon a long-term Flood Protection Program (FPP) to mitigate flooding by implementing measures to help safeguard Virginia Beach homes, structures, and roadways. In 2020, the City published a climate impact assessment referred to as the Sea Level Wise Report that documented and forecasted the growing impacts of climate challenges including increased frequency and intensity of tropical storms and hurricanes as well as increasing sea levels along coastal stretches. The City's storm water and flood protection infrastructure was not designed for the conditions being experienced today. Some of the City's storm water pump stations are used daily to combat tides and groundwater. In a few cases, these assets are operating more frequently than initially designed. The City experiences flood impacts from intense rainfall as well as Sunny Day flooding. Intense rainfall is defined as pluvial flooding driven by microbursts, thunderstorms, the rainfall component of named storms, etc. Sunny Day flooding is flooding driven by tide and surge conditions occurring without storms. In 2021, the residents of Virginia Beach made it clear during the General Election on November 2, 2021, that flood protection is a top priority. Over 70% of voters agreed to authorize $567.5 million in debt to finance the design and construction of various flood mitigation projects aimed at improving the level of flood protection in the area. As the FPP Program Manager, Jacobs is actively assisting the City with developing critical strategies and procedures necessary to successfully deliver Phase 1 of the FPP and formulate/prioritize future phases. Given the public interest in this project, Jacobs and the city collaborated to create a Flood Model Visualization and Exposure Tool. The tool is a user-friendly geographic information system (GIS) dashboard application developed in ESRI ArcGIS Experience Builder (developer edition). It utilizes the flood model and exposure data hosted by Virginia Beach ArcGIS Enterprise GIS platform. The purpose of the tool is to provide an easy to use interface for the public to select and view the City's flood model results. The public can view model results and other information pertaining to the City's Flood Protection Program (FPP) projects. Residents can see how different weather events could affect their neighbors. They can also view the improved level of flood protection provided from the City's $1 billion FPP. Objectives The objective of the visualization tool is to enhance the City's flood map-based tool by adding an intuitive dashboard that is user-friendly and ready for public use. The tool will achieve this objective by including the following features: 1) buttons to define climate scenarios that are then displayed on the map; 2) summary metrics on exposure, vulnerability, or financial impacts related to the selected scenario; 3) location of projects and their flood mitigation benefits; and 4) access to a photorealistic 3D visuals for select city locations. Methodology The tool uses existing data and platforms currently used by the City to the greatest extent possible as shown in Figure 2. The tool was developed to be easily updated when new information or versions of software and data including: updates for ESRI tools; flood models; vulnerability assessment results; and FPP project information. The framework and structure for the user-friendly dashboard is shown in Figure 3. A guidance document walks the user through how to use the tool. Risk assessment metrics are displayed on the dashboard including total flood area, depth, and duration; commercial districts flooded; socially vulnerable areas flooded; and critical facilities exposed (Figure 4). Users input flood exposure type, type of flooding, rainfall event return period, sea level rise, and FPP project or City location. After selecting scenarios, the tool displays flooding extents on a map. Results and Conclusions The results of the tool include a visual display of flood extents (Figure 4),a side-by-side comparison of before and after flooding (Figure 5), and photorealistic 360-degree street views at select locations (Figures 6 and 7). Jacobs demonstrated the tool to the City Council and they were excited to have such a robust method for showing the true value of the disruption to occur throughout various locations across the City over the next eight years. Without the tool it would be more challenging to message the benefit of the FPP given its success depends upon weather any given day. Jacobs and the City will next solicit feedback from the general public who visit the website and tool.