Tags

, , , ,

Lake Waiau (means “swirling water” in Hawaiian) is a small lake located at 3970 m above sea level on Mauna Kea. It is among the highest lakes in the world (higher than Lake Titicaca), and one of very few high mountain lakes on Hawaiʻi. It plays an important part in local ecology and in Hawaiian culture.

October 4, 2013

The lake is only about 100 m in diameter. It is very quiet, I have never seen in swirling. The lake varies in size as the water level rises and falls. Or at least it used to. On this trip (September – October 2013) we noticed that the lake has shrunk. And what once was a small, but full and glassy lake, is now more like a drying puddle.

Lake Waiau pictured in September 2007

Lake Waiau pictured in September 2007

Lake Waiau pictured in October 04 2013.

Lake Waiau pictured in October 04 2013. One can see how much smaller it appeared

Lake Waiau is shrinking fast

For some unknown reasons, for the last few years Lake Waiau has shrunk significantly and in September 2013 its diameter was only 15 m.

Lake Waiau  as shown on Google maps in early  2014. Red arrows show the lake size in previous years, before  drought

Lake Waiau as shown on Google maps in early 2014. Red arrows show the lake size in previous years, before drought

Office of Mauna Kea Management Rangers, working cooperatively with the Department of Land and Natural Resources (DLNR), Division of Forestry and Wildlife (DOFAW) have been monitoring the lake closely from 2010 to now and have tracked this remarkable reduction in the lake size. Hawaiian Volcano Observatory (HVO) has also been watching these changes, as part of HVO’s broad mission to monitor Hawaii’s active (and dormant) volcanoes. HVO scientists have compiled numerous high-resolution satellite images to document the surface area of the lake since for the last 15 years. The results are compelling. Prior to 2010, the lake surface area fluctuated between about 5,000 and 7,000 m^2 (1.2-1.7 acres), with the variability accounted to recharge from winter storms and by loss due to evaporation. But in early 2010, the lake surface area began to shrink rapidly and, by late September 2013, had declined to just 115 m^2 (0.03 acres) – that is, about 2% of its normal surface area. Read more on the HVO site.

Scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory run a survey on the available lake photographs and reports over an extended period of time back to the 1950s and even to 1800s. They found  no other water level drops of such scale. According to the survey, 1) neither historical photographs taken through the last hundred years, 2) nor written reports going back to the early 1800s, provide any indication of the lake ever being as small as it is now. This suggests that  the reduction in lake size that we see today is highly unusual. At least for the near 200 years.

Why Lake Waiau is shrinking?

Studies of the chemical signatures of the lake and geomorphology of the surrounding area show that the source of the water is precipitation falling within Puʻu Waiau, mainly from winter storms. The reason for the ponding of the rainwater and snow-melt is less clear, however.

Lake Waiau shrinking

Lake Waiau shrinking

One reason is the ongoing drought that began in 2008 and affected the whole Hawaii. The reports from the Mauna Kea Visitor Center weather station show very little precipitation for several consecutive months in early 2010. That might have been a triggered the dramatic water level drop that somehow has sustained by low precipitation over the subsequent few years. This supports by the data from the National Drought Mitigation Center  that show that the overall drought  across Hawaii was indeed  intensified in early 2010.

[This] may have been a trigger for the level drop that was sustained by low precipitation over the subsequent few years,” says the report from the Hawaiian Volcano Observatory.

Lake Waiau is a “perched” or “floating” water body. The lake is a depression in some impermeable substrate. Hawaiian lavas are typically permeable, preventing the formation of lakes due to infiltration of water. The impermeable substrate that holds the lakes water is an unusual formation. It works as a cup holding water, or rather like a chilli  served in a bread cup.

Topographic map of Mauna Kea

Topographic map of Mauna Kea

Several mechanisms have been proposed to explain what makes this impermeable layer that holds the lake waters. One suggestion is that sulfur-bearing steam emanating from Puʻu Waiau either during or just after eruptions altered the cinder and ash to fine clay minerals with reduced permeability.

Another suggestion is that  the layer is made up of the fine-grained ash beds that are found at Puʻu Waiau. This ash could be a product of Waiau eruptions occurring under glacial ice.

Another scenario suggests that the impervious layer beneath the lake is made from permafrost. It is supported by the existence of permafrost at nearby Puʻu Wekiu. It has been proposed that permafrost also underlies and surrounds the lake and creates a layer that directs water into the lake. But  temperature measurements taken in the bottom sediment of the lake have shown  4 degrees Celsius,  which is a typical temperature for water under the ice, but still above freezing.

For me, the current border of the diminished lake looks indeed as permafrost. We managed to come close the the lake this time (October 2013) and actually walked on the substance that had a look and feel of permafrost.

HVO scientists suggest that changes in the presumed permafrost might have altered the water balance in the lake over the past few years. But, there is no hard evidence to support this possibility. More research needs to be done.

If you have historical photos of the lake that you are willing to share, please contact HVO (askHVO@usgs.gov). DLNR, rangers, and HVO scientists  continue to watch this situation closely.

It would be very sad if the lake disappears. It has  a  big cultural and ecological significance  for the whole Hawaii.

The hike

Topographic map of Mauna Kea. Credit: bigislandhikes.com

The trip to Lake Waiau is part of the trip to the summit of Mauna Kea. Drive from the Mauna Kea Visitor Center up to the summit. Once you approach the 3600 meter mark,  you can  spot the summit cinder cone. This part of the road is very beautiful, with staggering colors and multiple cinder cones. You’ll notice that you are already above the clouds layer.

Cinder cones near lake Waiau

Cinder cones near lake Waiau

Cinder cone near Lake Waiau

Puʻu Wekiu cinder cone as seen from Lake Waiau

Trail to Lake Waiau, we are above the cloud layer now

Trail to Lake Waiau, we are above the cloud layer now

On our way back we spotted the truck that carried the mirror segment to the Keck observatory mirror

On our way back we spotted the truck that carried the mirror segment to the Keck observatory mirror

Soon you will see the parking lot on your right. Park there and cross the road. Be careful, it is already ~ 3700  meters altitude, and you probably  noticed that you are slow. So are the occasional drivers. Persevere through the 13,000 foot mark and spot the trail to Lake Waiau. The National Park sign at the beginning of the trail  tells that “the lake is located at an altitude of 13,022 feet, and it is the highest in the Pacific Basin and the Big Island.” The hike is about 500m round-trip and you gain 30 meter elevation. But it is a nice side trip while driving to the summit. Spend some time marvelling at this lake sitting in such a dry, unforgiving place.

Approaching Lake Waiau

Approaching Lake Waiau

Lake Waiau October 2013

Lake Waiau October 2013

Leave no trace. Read about environmental ethics from bigislandhikes.com

References:

ResearchBlogging.org

  1. Hawaiian Volcano Observatory, Lake Waiau is part of Mauna Kea’s glacial past, September 13, 2012, http://hvo.wr.usgs.gov/volcanowatch/view.php?id=141
  2. Hawaiian Volcano Observatory, Lake Waiau is shrinking fast, November 7, 2013, http://hvo.wr.usgs.gov/volcanowatch/view.php?id=201
  3. Volcano Watch: Lake Waiau is shrinking fast, http://www.hawaii247.com/2013/11/07/volcano-watch-lake-waiau-is-shrinking-fast/
  4. Andre Heath (2013). GEOLOGICAL UPHEAVAL: Hawaii’s Only Alpine Lake Is Now Shrinking At An Alarming And “Unprecedented” Rate – Lake Waiau Is ALMOST GONE! thecelestialconvergence
  5. ALFRED H. WOODCOCK, Hawaiian Alpine Lake Level, Rainfall Trends, and Spring Flow, Pacific Science (1980), vol. 34, no. 2 © 1981 by The University Press of Hawaii.
  6. A collection of rituals and traditions of Mauna Kea – http://hawaii.gov/dlnrlcwi/2013dofaw/nars/reserves/big-island/mauna1.pdf
  7. United States Geological Survey (2009). Complete Report for Mauna Kea Volcano (Class B) No. 2601 United States Geological Survey Other: United States Geological Survey. 26 October 2009.
  8. Wolfe, E.W.; Wise, W.S., and Dalrymple, G.B. (1957). The geology and petrology of Mauna Kea volcano, Hawaii : a study of postshield volcanism. United States Geological Survey
  9. Sherrod, David R.; Sinton, John M.; Watkins, Sarah E.; Brunt, Kelly M. (2007). “Geological Map of the State of Hawaii” Open File report 2007-1089. United States Geological Survey. pp. 44 – 48.