Google Earth Engine Implementation of the Floodwater Depth Estimation Tool (FwDET-GEE) for Rapid and Large Scale Flood Analysis

Abstract:

Floods are Earth’s most prevalent natural disaster, negatively impacting the socioeconomic well-being of humans globally. During a flood event, responding agencies and decision makers require information on floodwater extent and depth in a timely manner in order to effectively assess damages to infrastructure and livelihoods and to plan rescue operations. Rapid floodwater extent mapping has been extensively studied and put into practice, but modeling floodwater depth accurately and at the required speed of dissemination has not been fully developed. The Floodwater Depth Estimation Tool (FwDET) was developed to provide rapid-response floodwater depth estimations during time-sensitive flood events. Modern cloud-computing advancements and platforms, such as Google Earth Engine (GEE), enable streamlining and scalability of large-scale geoprocessing. In this study, we present a FwDET implementation in GEE (FwDET-GEE) that is open access, utilizes cloud-stored elevation data, and performs geospatial analytics on the fly. FwDET-GEE features a new outlier removal procedure and buildings impact analysis using the Microsoft Building Footprint dataset in GEE. Recent case studies will be presented showing use cases of FwDET-GEE during flood events from local to regional scales to demonstrate the geographic scalability of the model. These case studies include the Midland, Michigan dam failure of May 2020, spring flooding along the Missouri River in 2019, and flooding along the Brazos River during Hurricane Harvey in 2017. Additionally, an analysis overlaying an Alabama 100 year flood extent over the Microsoft Building Footprint dataset to assess buildings most at risk will be presented. GEE applications have been created using outputs from the FwDET-GEE implementation to enhance visualization and output interpretation for decision makers. Ongoing work continues to create a web portal that will allow users to produce and visualize flood depth estimations through a simple web-interface. This tool offers an innovative solution for producing timely floodwater depth information during flood events that require emergency response and post-flood assessment.