Flood Risk Assessment of the Greater St George, Utah Area Based on Land Cover/Land Use and Watersheds

Abstract

The Greater St George area in Southern Utah is a hot spot for development. The gradual increase in population size has caused a large growth in construction. In 2018, a large storm hit the area and caused massive flooding in Washington, Utah. This was caused by new construction blocking a natural floodplain. This caused a diversion of the waters into the people’s homes below. The point of this project is to identify the changes in the land from the year of 2008 to 2018 along with displaying the natural water passages in the area. The areas that are overlapped with the flood zones that have been developed on, are at a potential risk of dealing with major flood damage. Using the unsupervised and supervised classification systems on ArcMap along with a watershed analysis, the flood hazard zones information will be displayed within the area. The unsupervised and supervised data signifies that the major flood zones are now encountering more developed areas. This indicates that if more work isn’t done to prevent flooding, then more homes are susceptible to damage. Census data also indicates the communities with the most flooding risk are the low income and high minority communities. The impact of developing the area to support the growing population is ultimately having to cost the city and the citizens more money. The developers need to make sure they examine the natural water ways and avoid causing more flood damage to the city.