The app allows users to explore the potential magnitude of coastal flooding for different flood frequencies under a range of flood scenarios. Under the “Chose Type of Flooding” slider, select from a choice of flood frequencies – “Frequent”, “Semi-Frequent”, “Infrequent”, and “Rarely”. Respectively, these correspond to the associated flood elevation/area on the map occurring roughly once every day or two, once or twice every month, once or twice year, and once every 100 plus years.

Under the “Chose Scenario Year” slider, select from a choice of flood scenarios for different time periods – “Recent”, 2025, 2035, 2050, and 2080. Excluding the Recent scenario, each of the scenarios reflect an increase in regional sea level rise linked to projected global increases in mean sea level around the respective time period. They may also include a small contribution attributable to climate variability, changes in sea level associated with changing patterns in atmospheric and oceanic circulation occurring on time scales of years to decades.

It is important to note that the flood magnitudes are associated with what is known as the “Still Water Level” (SWL). The SWL includes various contributions to high water levels (e.g. tides and storm surge, patterns of atmospheric and oceanic circulation, regional and global changes in absolute sea level and vertical land motion). However, it does not include wave runup, and is therefore an underestimate of the Total Water Level (TWL) observed at the shoreline. Further, these flood magnitudes and their associated frequencies and time periods, are derived from a more extensive analysis of the potential for coastal flooding along the Kona coast. This included an analysis of flood frequencies derived from the normal distribution as well as a flood extremes derived from the Generalized Extreme Value (GEV)
distribution of observed water levels in tide gauges. The information shown here is the result of a blending and simplification of these analyses. It is intended to illustrate how information of this nature can be used to support resource management, community planning, and other purposes. Prior to attempting to use this information for these purposes in any formal way, examination of the full results of the analysis along with a review of the methods should be conducted.

Data Sources:

• Land Use Pattern Allocation Guide
• 2014 On-site Sewage Disposal Systems (OSDS) risk severity score distribution of Hawaii Island. Whittier et al.
• Hawaii State GIS