A project to measure sediment runoff on Lāna‘i is connecting the effectiveness of watershed restoration techniques used on land. Runoff is caused by soil erosion, allowing dirt to flow downstream where it empties onto coral reefs.
A project between Conservation International, the University of Hawai'i Mānoa, the Maunalei Community Managed Makai Area and the Pacific Islands Ocean Observing System Hawai‘i (PacIOOS) monitored sediment entering the ocean from two streambeds and their corresponding adjacent coral reefs. It’s the first study to examine the sediment dynamics of Lana‘i Island. They devised a series of kiawe wood dams to trap sediment, eventually collected 77-tons of debris, the equivalent of nearly 10 dump trucks of sediment, which would have washed into the sea.
The research showed that without the dams, the adjacent reef area would have needed about 5 weeks of natural water flow around the reefs to flush that amount of sediment. Lida Teneva is the Science Adviser for Conservation International Hawai‘i. She says the experiment demonstrates the importance of proper land management, and its effect on coral reefs.
The study was recently published in the journal “Collabra”.