Figure 1. A view of the world-famous Number 6 Hole of the Mauna Lani Golf Course, island of . Water ... The Limiting Factor for Golf Course Development in Hawaii by DR. CHARLES L. MURDOCH Department of Horticulture, University of Hawaii

OMMON MENTAL images of ing occurs and moisture is released. Ex- lates through the porous lava, and Hawaii include lush tropical tremely heavy amounts of rainfall may perches as a lens of fresh water of vary- Cforests, rainbows, waterfalls, and occur in some areas. Mount Waialeale, ing thickness on top of the heavier exotic tropical flowering plants. While on the Island of , for example, is salt water in the porous rock formation these are all certainly part of Hawaii, the said to be the wettest spot on earth, of the island. The older islands, Kauai, availability of adeq uate high-quality with an annual rainfall of 460 inches. Oahu, and , have caprock for- irrigation water is the limiting factor The leeward side of all islands, however, mations at their coasts. These are for development of golf courses in many is very dry because most of the moisture denser lava formations that occurred parts of the state. is released by the clouds as they sweep after the islands were almost completely How could this be? Why is water a up the windward slopes. Great variation formed. Cap rock formations, being limiting factor in golf course develop- in rainfall can occur in very short dense and practically impervious to ment in a state that includes the wettest distances. For example, famous Waikiki water, help to hold the fresh water in spot on earth? The problem is not in beach, on the Island of Oahu, is located and greatly increase the thickness of the the amount of water that falls, but in the at the foot of Manoa Valley. Annual freshwater lens. groundwater system of the islands, and rainfall at the beach is approximately The island of Hawaii, which is still in where good water is found in relation to 20 inches. At the back of Manoa Valley, the formation process, does not have a where golf courses are developed. perhaps less than five miles as the crow cap rock formation, and thus the lens of The Hawaiian Islands are relatively flies, annual rainfall is about 250 inches. fresh water is not nearly as thick. In high islands. Northeasterly trade winds The freshwater system typical of those addition to the basal lens of fresh water, carry moisture-laden clouds over these of all islands is shown in Figure 2. Rain- significant amounts of water may be volcanic peaks. As the clouds rise, cool- fall occurs at higher elevations, perco- held in porous materials between denser

JANUARY/FEBRUARY 1987 11 (Below) Figure 2. Typical groundwater system of the Hawaiian islands. (Right) Figure 3. Resort golf courses in Hawaii are typically near the beach on the drier side of the islands. (Opposite page, top) Figure 4. Diagramatic illustration of the method of obtaining soil solution samples by means of suction lysimeters. (Bottom) Figure 5. Golf courses on the leeward coast of the island of Hawaii are often constructed in raw lava flows.

A Saltwater Artesian Well B Brackish Water Artesian Well C Freshwater Artesian Well fresh water perched D Skimming Tunnel on ash bed E Dike Spring F Dike Tunnel G Perched Water Tunnel

uneroded state----a.I6-,------eroded state

lava in vertical formations. This type the water supply on Oahu is particularly salinity. Because of low rainfall, high of formation is termed a dike. There is critical. temperatures, and constant winds, water also some water perched in porous With the exception of Oahu, there is use requirements of turfgrasses is high material on impervious volcanic ash little concern for potable water supplies. on the leeward coasts, further increasing formations. The latter two types of There are severe problems, however, in the demands on available water. water systems are being developed for regard to water for irrigation of golf Golf courses being constructed on potable water on Oahu. courses, especially on Oahu and Hawaii. the leeward coast of the island of Most golf courses in Hawaii are con- Hawaii present special problems in ORTUNATELY, because of high structed as part of resort developments obtaining suitable materials for growth Frainfall on the windward elevations or real estate projects. Because of the of turfgrasses. This coast of Hawaii is of all the major islands, there has been attraction of the ocean with the beautiful composed of raw lava flows that have ample water of very high quality for sand beaches and palm trees, resort undergone little weathering. Golf courses potable water supplies. Recently, how- developments and real estate projects are constructed by first crushing the ever, because of tremendous population are usually located near the ocean, lava to a workable size by heavy equip- increases on the island of Oahu, the usually on the drier, leeward side of the ment, grading to the golf course archi- thickness of the basal lens has been islands. tect's specifications, adding a filter layer decreasing at an alarming rate. The Figure 3 shows a typical resort golf of cinder or other available material, period from 1978 through 1980 saw course on the leeward coast of Oahu. and finally adding a rootzone layer of three consecutive years of extremely This presents a critical problem of volcanic ash soil, fine cinders, or what- low rainfall. At this time, the Oahu obtaining water of suitable quality to ever material is available. The contrast Board of Water Supply instituted severe irrigate the golf course. On the leeward between raw lava flows and green grass water restrictions, with limits on the coast of Oahu, wells near the coast have results in some of the most beautiful amount of water per household, as well become increasingly salty as the thick- golf courses in the world. as restrictions on commercial users of ness ofthe freshwater lens has decreased. Figure 1 shows a view of the sixth water, such as golf courses. Golf course On the leeward coast of Hawaii, the hole of the Mauna Lani golf course. water allotments were set at 50 percent freshwater lens is very thin because of Figure 5 shows a closer view of a fairway of the average use of preceding years. the lack of a caprock formation. Large bordered by raw lava. This type of con- Since that time there have been periodic demands placed on the lens, as in the struction, with a fine rootzone material appeals to homeowners and others to case of several golf courses located in overlying a coarser lava su bsurface conserve water. Because of the large close proximity, results in mixing of layer, results in a perfect example of a amount of development in recent years, underlying salt water and increasing perched water table, which is the under-

12 USGA GREEN SECTION RECORD The Turf

Because oflow rainfall at this location, Advisory Service: there is little chance of extended periods of rainfall to saturate the soil and leach accumulated salts. Since the available Won't You Join water in this area of Hawaii is brackish (average salinity readings of 3.0 to 3.5 mmhosj cm) and the water infiltration Usin 1987? rate of the rootzone material is slow, T'S THE START of another and extremely high salt buildup is occurring new high-tech year in turfgrass In some cases. Imanagement. In many cases, one small bit of new information given by ECAUSE OF the problems with the visiting Green Section agronomist B obtaining adeq uate high-q uality has saved many clubs the actual cost of irrigation water, research is being con- the Green Section Turf Advisory Visit, ducted at the University of Hawaii on if not more. Of greater importance, effects of sewage effluent and brackish however, is the significant improvement irrigation water on soil chemical proper- in turf and playing conditions one might ties and growth of turfgrasses. As part of expect from such a consultation. No this research, soil solution sampling small part of this is the authoritative stations have been established at four backing and second opinion the agrono- golf courses, two each on Oahu and mist provides the golf course super- Hawaii. intendent. The soil solution is sampled monthly The fee schedule for TAS visits in 1987 by means of suction lysimeters installed is: at different depths (Figure 4). Table 1 shows selected soil chemical properties Half-day visit: from these four locations. It is clearly $550 if paid by April 15 apparent that soil salinity levels have $600 if paid after April 15 reached excessive levels in certain cases. Full-day visit: Fortunately, bermudagrasses are used $850 if paid by April 15 lying principle for the USGA Green on golf courses in Hawaii and are very $900 if paid after April 15 Section specifications for construction salt tolerant. Experiments are presently For less than one-quarter of one of golf putting greens. Water will not being conducted to determine if salinity percent of most golf course maintenance move out of the finer layer until it is levels can be red uced by increasing budgets today, your club will receive a completely saturated. Then water only leaching, gypsum applications, and half-day or full-day visit and tour of moves by gravity. aerification treatments. the course, followed by a written report of all recommendations by an experi- enced, highly trained and qualified Green Section scientist. The fee also covers travel expenses, emergency con- sultations and other requests via tele- phone, a one-year subscription to the GREEN SECTION RECORD, news of the USGA Regional Meetings and the annual Green Section Educational Program, as well as the informative annual Turfgrass Research Report from the USGA. Green Section services are offered for the benefit of golf by the USGA, a non- profit organization. The Green Section agronomists have no axes to grind - no strings attached - no peers in the field of turfgrass consultation for golf. lfyour club was not a TAS subscriber in 1986, won't you join us in 1987? Take advantage of this professional, experi- enced, nationwide staff now visiting courses in many golfing nations of the world. Help yourself to the finest golfing turf your club has ever known.

JANUARY/FEBRUARY 1987 I3