Iowa Flood Frequency and Projections: Analysis and Web-Tool

Iowa is a state which has been devasted by flooding especially in recent years, highlighting a need to understand future changes in flood frequency at the community level. To explore these changes, we examine flood frequency projections and present a web-tool that provides information for Iowa communities. We use the Iowa Flood Center’s Hillslope-Link Model (HLM) to estimate discharge projections utilizing forcings derived from global climate models (GCMs) part of the Coupled Model Intercomparison Projected Phase 5 (CMIP5) and Phase 6 (CMIP6). We summarize the main findings of this hydrologic assessment through a web-tool. For the main service, we provide flood frequency estimates based on default settings. Specifically, the approach provides estimates by fitting a subset of discharge projections to a nonstationary generalized extreme value distribution. These settings cannot be edited and would reflect our best assessment of the projected changes in flood frequency. Additionally, we provide another service which allows users to explore how the selection of the CMIP suite, emission scenario, climate models, and distribution type impact flood frequency projections and uncertainty. We examine case studies with our web-tool to highlight important characteristics in flood frequency projections.