South Maui Gulches and Streams

Streams of Kula Kai: The streams of Kula Kai are integral to the hydrology of the watershed and the wetlands. The Kula Kai watershed is the sum total of all of the hydrologic features including the catchment basins, the gulches, and streams. Each wetland has a water source,  and many are closely associated with streams, either by groundwater or in-stream surface-flow. Many of Kula Kai’s Streams are ephemeral (temporary) but must have sustained groundwater and are connected to the aquifer. Every muliwai (coastal wetland) in Kula Kai has its kahawai (stream). Most kahawai in Kula Kai are associated to a coastal estuary or muliwai. It is also interesting to note that every loko kuapā (walled fishpond) has a kahawai as its water source.

There are many streams in Kula Kai. Some are well-known and some have become hidden over time. Each major stream has a mainstream and many tributary streams. They may also diverge and rejoin at various points. Also, many streams may disappear underground and reappear further downslope. Today, many streams have been forced underground into the stormwater system of culverts and pipes, to make way for various developments. The streams in the diagram are a simplified visualization of the area’s main streams. There are many smaller streams that are not pictured. 

The most notable named streams are:  Keahuaiwi, Waiakoa, Ohukai, Kulanihakoi, Ko’ie’ie, Waiohuli, Waipuilani, Kawililipoa, Lā’ie, Kēōkea, Waimahaihai, Kīhei, Kaluaihakoko.

 Stream names:

1. Keahuaiwi,
2. Waiakoa,
3. Ohukai,
4. Kulanihakoi,
5. Ko’ie’ie,
6. Waiohuli,
7. Waipuilani,
8. Kawililipoa (aka Pi’ikea)
9. Lā’ie,
10. Kēōkea,
11. Waimahaihai,
12. Kīhei
13. Kaluaihakoko (aka Nawawaeoalika)

 Streams associated with Fishponds: 

The Fishponds of Kula Kai: We do not know exactly how many fishponds existed in Kula Kai because there were many types of fishponds in use including loko pu’uone (onshore fishponds), but the most visible ones still evident today are the great walled loko kuapā. The loko kuapā are the walled-style fishponds built out onto the nearshore reef. This type of fishpond was reserved for the exclusive benefit of royalty. These massive structures are still visible today. In Kula Kai we have at least 4 loko kuapā that one can still view remnants of, just offshore beneath the waves. 

The four Fishponds are called (north to south): 1) Kalepolepo, 2) Waiohuli Kai, 3) Kēōkea Kai, and 4) Kealamoemalia.

Streams and Wetlands of Kula Kai, courtesy Save the Wetlands

Streams as Wetlands: The streams of Kula Kai are wetlands in their own right, Streams have their own wetland functions and benefits and offer a special habitat defined by their hydrology. 

Watershed catchment basins: Each stream is the result of a watershed catchment basin. Some of the catchment basins in the Kula Area are 5-10 square miles in area and create significant amounts of stormwater runoff.

Wetland characteristics: All sites in the study provide some types of wetland function. Many have either exhibited recent or historical flooding and provide wetland services like floodwater retention, or have exhibited other wetland characteristics which included vegetation types, salt deposits, evidence of flooding, pooling water, and obvious water courses. Some sites are adjacent to streambeds and gulches or are located in known floodways and usually form part of a mauka-to-makai (mountain to ocean) kahawai (stream, gulch, wetland) and/or muliwai (wetland, estuary). Man-made wetlands include the ancient and the modern. We have examples of manmade mitigation wetlands at Pi’ikea, and also historical fishpond wetlands, of both the Loko Kuapā (offshore, walled) variety and the Loko Pu`uone (inland, sandbar estuary) variety.

Kaluaihakoko Stream:
Kaluaihakoko (Kaluaihākōkō.) Stream is located north of Keawakapu. The study area extends upstream from its mouth approximately 3,500 feet. Kaluaihakoko Stream begins upstream of Piilani Highway, flows through a residential and commercial area, and outfalls into the Pacific Ocean at Kihei Road between Kalama Beach Park and Cove Park. (Maui County Flood Insurance Study, Volume 1 of 2, community number 150003, revised  2012).

Kamaole Gulch: Kamaole Gulch has an average slope within the 1,500-foot-long study area of
approximately 2 percent. The gulch runs through pastureland above Kihei Road and between several houses below Kihei Road. (Maui County Flood Insurance Study, Volume 1 of 2, community number 150003, revised  2012). Aerial photographs are those referenced above for the study area (USACE, Topographic Maps, Contour Interval 2 feet, December 1976). Velocities in the channel are as high as 19 feet per second, indicating supercritical flow condition.

Keahaiwai Gulch: The length of Keahaiwai Gulch is approximately 3,000 feet and the average slope of the gulch is 0.6 percent. The gulch runs through sugarcane and corn fields above Mokulele Highway. At the highway, the stream passes through a box culvert and makes its way to Kealia Pond, which has an outlet to the sea near the northern end of the pond. (Maui County Flood Insurance Study, Volume 1 of 2, community number 150003, revised  2012).

Keokea Gulch:
Keokea Gulch is a fairly well-defined watercourse above Kihei Road. However, its course becomes undefined upon entering Kalama Park below Kihei Road. The study area covers 9.15 square miles; its slope varies from approximately 2 percent in the upper reach down to a slope of nearly 0.0 percent at Kalama Park.

Kihei Gulch 1:
The Kihei Gulch 1 watercourse is not well defined. The average slope of this gulch is approximately 0.6 percent over the study length of 1,500 feet, measured from its mouth upstream.

Kihei Gulch 1 and Keokea Gulch
Topographic data were obtained from previously referenced maps (USACE, Topographic Maps, Contour Interval 2 feet, December 1976). Hydraulic computations indicate that stormwater would overtop the banks and result in a shallow flooding for both gulches. The 1-percent annual chance floodplain extends from Auhana Road to Kapu Place and extends approximately 3,400 feet inland along Keokea Gulch and 1,200 feet inland along Kihei Gulch 1.

Kihei Gulch 2:
Kihei Gulch 2 lies to the north of the Wailea Beach Marriott Hotel, and was studied for a distance of 1,500 feet above its mouth. Its slope averages 5 percent.  Aerial photographs of the area were flown at the same time as those for Kihei Gulch 3 (USACE, Topographic Maps, Contour Interval 2 feet, December 1976). Supercritical flow occurs because of a steep channel gradient and high velocities.

Kihei Gulch 3:
Kihei Gulch 3 is located north of and adjacent to the Wailea Beach Marriott Hotel. Its average slope in the study area is approximately 5.5 percent. Kihei Gulch 3 was studied for a distance of 1,500 feet upstream of the mouth. Wailea Alanui Drive separates the hotel grounds from the Wailea Golf Course, and the gulch below Wailea Alanui Drive is approximately 20 feet deep. Its cross sections vary considerably from very steep below Wailea Alanui Drive to this type of moderate slope, which is predominant throughout the golf course areas on Kihei Gulch 3.  High channel velocities indicate that a supercritical flow condition exists.

Kihei Gulch 4:
Kihei Gulch 4 is located to the southeast of Wailea between Wailea and Makena in the vicinity of the Wailea Golf Course. The average slope is approximately 5 percent. The study area on the gulch extends approximately 1,500 feet upstream from the mouth at the shoreline. This stream was recently restudied as part of a LOMR. Because of the steep channel slope, a supercritical flow condition exists for this stream.

Kulanihakoi Gulch
The Kulanihakoi Gulch study area covers 14.97 square miles, and the stream has a 0.4-percent average slope. Kulanihakoi Gulch has characteristics similar to that of the neighboring Waipuilani Stream. The upper one-half of the gulch is mostly covered with Keawe trees and brush. Downstream, there are some scattered trees along the coastline.

Liilioholo Gulch:
Liilioholo Gulch has an average slope of approximately 3 percent within the 2,000 feet of study area extending from its mouth upstream. The present channel is very shallow, ranging from 3 to approximately 6 feet deep. It is also very narrow, from 5 to 10 feet across. In the upper reach of the study area, the alignment of the channel is nearly perpendicular to the shoreline; but, as it nears Kihei Road, the gulch runs northward and intersects Kihei Road. The hydraulic analysis indicates that the existing culvert cannot adequately convey the 1-percent annual chance of flood. Overtopping of the channel banks will result, and stormwater will flow over the roadway and into Kamaole Beach Park No. 2. High channel velocities occur on this stream also, resulting in a supercritical flow condition.

Waipuilani Gulch:
The Waipuilani Gulch Stream’s catchment area (watershed) covers approximately 14.54 square miles. The gulch has a 1-percent slope in the upper course of the study area and a very mild, 0.5-percent slope in the lower portion. Thick Keawe trees and brush cover the upper reach of the stream. The lower stream area varies from moderately thick brush to open beach.

“The total drainage areas of the Kaluaihakoko Stream and Kamaole
Gulch: These are 0.656 sq. miles and 5.209 sq. miles, respectively. For the 1-percent annual chance flood, the Kaluaihakoko Stream and Kamaole Gulch are associated with a peak discharge of 461 cfs and 3,765 cfs, respectively.”

Waipuilani and Kulanihakoi Gulches
Topographic data were obtained from the above-referenced photogrammetric maps (USACE, Topographic Maps, Contour Interval 2 feet, December 1976). The hydraulic analysis for the gulches indicated that they would overflow their banks. Further study showed that overflow from the gulches would merge. This analysis was performed by extending cross-sections across both gulches. The 1-percent annual chance floodplain extends from Hoonani Street to Kenolio Street
and approximately 2,500 feet inland along Kulanihakoi Gulch.

DRAINAGE STANDARDS: The hydraulic analyses for this FIS were based on unobstructed flow. The flood elevations shown on the profiles are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail.