Adapting structures for Flooding in the Kihei Floodplain

Stormwater flooding is a natural occurrence. What is unnatural is that we are still building in the gulches, wetlands, flood zones, and stormwater drainage ways. And when our streams and gulches get clogged by woody debris, silt, mud, and trash, when stormwater floods, it flows out of the gulches and goes sideways across the “flood plain”. Most all of Kihei Makai is a flood plain, so anyone who has built here (or bought here) should expect occasional flooding, and adapt their homes, condos, and lifestyles to accommodate floodwaters. That means building up on stilts, using concrete floors and tiles for ground floor flooring, and keeping electrical circuits and electrical equipment well above the BFE (base flood elevations). Local residents, home-owners, and business owners on the Kihei flood plain should be aware that our 50-year floods, and 100-year floods are now happening more frequently, and historical flood data does not project the higher flood levels the climate change and SLR are bringing. So let’s all try to Build smarter and adapt our homes and business for flooding, and STOP trying to change the natural watershed features and green infrastructure that we already depend on. We cannot stop flooding, but we can adapt ourselves to minimize its impacts.  For example, we should stop rebuilding and regularly restoring the most frequently-flooded ground floor condos that were built directly in the path of the Waiakoa, Kulanihakoi, and Waipuilani Gulches. 

Flood-proofing Our Infrastructure:

We do, however, need flood-proof bridges, culverts, and flood-resistant roads. This is essential for safety, emergency access, and evacuations. To achieve this South Kihei Road needs to be raised in the sections where they cross the major gulches. The road-crossing stream culverts need to be upsized to accommodate higher flows, and to pass more debris underneath without clogging. Our stormwater system is NOT currently designed to handle any amount of debris. Examples: We need a 600-foot long raised causeway and bridge where South Kihei Road spans the mouth of the Kulanihakoi Gulch, and we need a 70-foot wide culvert with a raised bridge at the South Kihei Road /Waipuilani Gulch crossing. The South Kihei Road/Waiakoa Stream Bridge also needs to be raised and expanded.