September Three Steps for Implementing a Complete Flood Management Plan

Transcription

1 September 2016 Three Steps for Implementing a Complete Flood Management Plan

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3 Three Steps for Implementing a Complete Flood Management Plan Executive Summary Flooding is one of the worst natural disasters and the costliest and most difficult for government agencies to manage. Everything from your community s development footprint and growth to changes in the landscape caused by previous natural disasters, such as fire and drought impacts where and how flooding will occur. Knowing ahead of time when a flood is going to happen, what will be flooded, who will be affected, and how to respond is of great importance to reducing loss of life and property. This paper explains three important steps you need to take to prepare and make the most effective decisions for flood management. In the following examples, you will see how Esri Solutions for Flood can help you address many aspects of an event. Solutions for Flood is a configurable suite of Esri technology that gives you fast, understandable, actionable flood information. Step 1: Prepare Any location can experience floods. Unfortunately, most areas lack predictive models showing what the next record flood will look like. So how do you prepare for and respond to flood events? The first step is to build a flood inundation model. To do this, you will need a digital elevation model (DEM). This can be created using the US Geological Survey (USGS) National Elevation Dataset, light detection and ranging (lidar) data, or contours derived from either of these types of data. The DEM would then be used in Arc Hydro to create the flood inundation model, which consists of rasters and polygons. Esri experts can help you create custom flood inundation models with Arc Hydro and a DEM. Arc Hydro allows you to determine the drainage lines, catchments, and flow accumulation for the drainages in your service area. This information can then be fed into the predictive flood modeling tools in Arc Hydro to create flood inundation models for any number of flows or depths. Esri experts can quickly create these models for you as part of a larger engagement around the implementation of Solutions for Flood. You can use your flood inundation model in combination with asset information to determine what infrastructure would be impacted by flooding. Include demographic data to determine how many people would be in danger. Identify critical sites like schools, assisted-living residences, and hospitals.

4 Figure 1: Visualize highly accurate flood depths base DEM, Lidar, and Countours in ArcGIS Pro. Once you have projected where flood will occur and how high waters could rise, you ll need to know when flood events may happen. When extreme rainfall occurs, the National Weather Service (NWS) issues flood watches and warnings based on data from stream gauges. Physically located in rivers and streams, these gauges automatically report near real-time information about water depth and flow. These gauges take predicted information such as, observed rainfall, predicted rainfall, and snowmelt data which the NWS then uses the information to do an analysis of the predicted rainfall, including estimates of the flooding stage (ft) and flow (cfs) for the next five to seven days. Figure 2: Visualize recent flooding to analyze stream guages. ArcGIS software shows predicted rainfall, weather warnings, 15-minute-interval data from stream gauge feeds, and hourly flood prediction model updates from the National Water Center on a map. Using the flood predictions from the National Water Center, you can predict what flooding will look like in the near future. By bringing different types of data together and visualizing it on a map, September

5 you can make fast and effective decisions. Geographic information system (GIS) technology joins the national water model with flood inundation models to help you predict when a flood is coming and visualize its effect. Once you know when a flood will hit and what assets you can expect to be flooded, you will need to determine who will be at risk. Solutions for Flood will help you create mitigation plans that will lower the impacts of the flood on community, property, and organizational assets. Using demographic information from the US Census Bureau and Esri, you can identify populations that would be affected by a flood. For instance, the following map shows 2015 population data, the number of seniors, households with at least one person with a disability, and home value information. This data is then intersected with various flood level measurements. Figure 3: In this image, you can see that a flood at the 30-foot stage would impact a population of 1,914, including 181 seniors and 200 people with disabilities. The analyses that can be performed are limited only by your imagination. These preconfigured maps and reports can help you determine who and what may be at risk for each potential flood stage in your area. For example, a flood analyst can model a 35-foot flood, highlight critical infrastructure, and analyze risk. Step 2: Plan Preparation allows you to plan ahead. Now that you know the areas of flood and what is at risk you can begin planning. Consider where road closures will be needed. What detours can be put in place? Where are the best locations for evacuation areas? How will you communicate this information? Once the impacts of flooding are known, establish a plan of action for when a flood occurs. Be ready to share your data by creating a web map that can be used in an operations dashboard for your response teams, accessed on mobile devices by your field crews, and provided to the media for news reports. Use this same map in an online application that shares information with the public. Having the map online accessible from anywhere and available at any time, on any device will give everyone the information they need when they need it. AN ESRI WHITE PAPER 5

6 Figure 4: A field information dashboard displays work order ticket status in real time. Figure 5: Field data collection with Collector for ArcGIS enables field crew to notify the office of any critical incidents during a flood event. September

7 Figure 6: This flood status map, embedded in a website, displays information about evacuation areas, road closures, detours, and temporary levees. The live map includes contact information for the evacuation areas and indicates whether the evacuation is volutnary or mandatory. Step 3: Recover The data that is collected during and after a flood can be used to plan more accurately and efficiently for future events. Was the flood inundation model accurate? Were there differences? Did the field crews have problems routing around the road closures and storm debris? Using visualization and analysis empowers you to get the most out of the collected data. AN ESRI WHITE PAPER 7

8 Figure 7: This application uses information from your computerized maintenance management system (CMMS) to estimate the repair or replacement costs for flood-impacted infrastructure. Esri is Helping Organizations to Prepare, Plan, and Recover from Flooding. Solutions for Flood empowers decision-makers and executive with the ability to gain the critical insight necessary to manage flood events with confidence and assure the community that the situation is under control. The ArcGIS platform and this suite of configurable applications will help you effectively plan, prepare, and respond immediately to your next flooding emergency. September

9 For more information, visit go.esri.com/solutionsforflood.