Watershed Restoration
Tipu Tipu Restoration and Sustainability works with nature based solutions to remediate human impacts from farming and living in the watershed.
We have designed and implemented BMPs (Best Management Practices) to collect sediment and reduce erosion to stabilize and reforest threatened areas in the watershed and contribute to improving water quality along the coast.
Using native plants and grasses, vetiver and all natural materials such as coconut coirs, jute matting and sandbags, Tipu Tipu creates sustainable long-term remediation with the BMP implementation in by capturing legacy sediments and employing stream bank stabilization to protect and improve the health of our coral reefs.
Wahikuli Watershed Restoration Project
As the contractor working with Coral Reef Alliance for the Wahilkuli watershed restoration project in Lahaina, Maui, Tipu Tipu has implemented 4 sections of BMPs comprised of native Hawaiian Pili, Kawelu and Carax grasses, Vetiver, Coconut coirs and Sandbags with plantings of native Hawaiian shrubs and trees such as A’ali’I, Ilima papa, Ma’o, Wili Wili, Koa’ia.
What is a watershed?
Hawaiians have always managed the mountains, stream and nearshore coastline as intrinsically connected ecosystems, realizing when the health of one declines the others suffer. If our islands do not have healthy forests sediment will wash into the ocean and smother coral. If our coral reefs die off waves and storm water will flood low lying areas. And if our streams do not flow both of our forests and near shore reefs suffer.
Managing a watershed as a complete unit was common practice in traditional Hawaiian land management regimes. Watersheds, or ahu`pua`a in Hawaiian, are areas of land that start from the top of the mountain that extended out into the ocean. Konohiki (resource manager) were responsible for managing all of the natural resources in the area from fisheries, to river water and other fresh water resources.
Building on this foundation of knowledge and management Tipu Tipu aims to integrate the technology and methodology of western science with the depths of traditional Hawaiian management. For example, we plant by the Hawaiian moon phases and use statistical analysis to track plant success. Perpetuating the knowledge and culture of Hawaii is an important part of our work and we hope to help restore native forests across Hawaii bring the cultural natural resources back to the islands and Kama `aina.
The Hawaiian islands have been dramatically impacted by industrial agriculture and poor land management practices have led to devastated forests, diverted rivers and streams, and cleaning coral reefs. In turn, this lack of quality habitat has lead to the decline of native flora and fauna. These declines mark the reduction of endemic species, found no where else in the world, which has resulted in many of Hawaii’s species to be on the threatened and endangered species list.
To help mitigate this dire situation, Tipu Tipu works on triaging a large landscape that is bleeding sediment onto the adjacent near-shore coral reefs. What is sediment exactly? Sediment is loose dirt on the land that can be washed downhill by stormwater from rain events. In the latest Department of Health Integrated Report, they found sediment in the water to be the number one threat to the health of our nearshore water quality. This is such an important threat to our ocean and island communities that the Dept of Land and Natural Resources has also identified sedimentation as one the pillars needed to be addressed in the 2030 Hawaii Coral Reef Strategy, calling out West Maui watersheds as particularly important to restore.
With thousands of acres of fallow agricultural land and hundreds of miles of dirt roads contributing sediment to our nearshore environments, Tipu Tipu have focused our efforts on areas near streams. On the top edge of these stream gulches we have been working to restore the riparian buffer zone. Once we have successfully restored these areas the native plants out-planted in these areas will not only help stabilize sediment in place and infiltrate storm water into the ground.
When there are less plants on the land there is more dirt or sediment that is exposed and loose. When storm water from rain events falls in these areas there are no obstacles, such as plants and their roots, to slow down the water and all this storm water starts to run downhill, gaining momentum along the way. The more water there is, and the more velocity it gains the more effective stormwater is at picking up sediment along the way. Meaning more rainwater is moving across a barren landscape leads to higher erosion and dirtier water. To combat this, we focus on finding ways to restore degraded fallow industrial agriculture landscapes to native Hawaiian ecosystems.
Restoring the watershed
How do we do that? Lots of hard work!
We used a phased restoration approach.
The first step and phase is to slow down stormwater and trap sediment on the land. To do that we plant rows of native grasses and vetiver grass perpendicular to the stormwater flow, being sure to follow the contours of the land scape. This helps slow down the storm water and allows the sediment or dirt to fall out of suspension and remain on the land rather than being washed down the mountain.
Once enough sediment has accumulated above the grass row we move on to phase two and plant a series of native plants. Our intention is to revive the native forest in this area so we are sure to out-plant a variety of species and functional groups. To achieve this Tipu Tipu plants native Hawaiian trees, shrubs, grasses and land cover. The roots of these plants help stabilize and trap the sediment on the land as well as bring more rainwater into the land, recharging our valuable aquifers.
The third and final phase is maintenance and monitoring. Tipu Tipu wants to ensure the grass rows and native plants or Best Management Practices (BMPs) we use survive and functioned as designed. To do this we regularly maintain the health of plants by watering and fertilizing plants, replace breaches in grass rows and any other actions needed to ensure the restoration site is successful and thriving. We also monitor BMPs and plants to determine which species are thriving and use adaptive management practices to ensure their success.
