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| Heavy rainfall events are occurring more frequently on Hawai`i Island, according to University of Hawai`i researchers. Photo by Julia Neal |
HAWAI`I FARMERS UNION UNITED has issued a list of bills being considered by state Senate committees this week that it supports. The bills, related to agriculture, could be of interest to Ka`u residents who may want to testify. Testimony is due 24 hours before scheduled hearings.
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| Ka`u residents can testify on ag bills being considered by Hawai`i state Senate committees this week. |
SB 375 authorizes growing of industrial hemp for certain purposes under specified conditions. Appropriates funds for department of agriculture staff to assist in registration of industrial hemp growers and seed testing. Testimony is due tomorrow by 2:45.
SB 969 allows one or more employee dwellings to be built on agricultural lots of at least five acres, with restrictions. Testimony is due tomorrow by 3 p.m.
SB 797 establishes notice, reporting and use requirements for any entity or person that uses pesticides under certain circumstances. Testimony due Wednesday by 3 p.m.
SB 379 expands and creates new categories for homemade food processing for sale to the public. Testimony is due Wednesday by 3:40 p.m.
SB 588 permits the acquisition of raw milk and raw milk products by consumers if certain conditions are met. Testimony is due Wednesday 3:40 by 3:40 p.m.
Testimony on these and other bills can be submitted at capitol.hawaii.gov.
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HEAVY RAINFALL EVENTS HAVE BECOME more frequent over the last 50 years on Hawai`i Island, according to a recent study by University of Hawai`i at Manoa researchers. A rare storm with daily precipitation of nearly 12 inches, occurring once every 20 years by 1960, has become a rather common event – occurring every three to five years by 2009.
To comment on or like this story, go to facebook.com/kaucalendar.
HEAVY RAINFALL EVENTS HAVE BECOME more frequent over the last 50 years on Hawai`i Island, according to a recent study by University of Hawai`i at Manoa researchers. A rare storm with daily precipitation of nearly 12 inches, occurring once every 20 years by 1960, has become a rather common event – occurring every three to five years by 2009.
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| Dr. Pao-Shin Chu |
In a paper published in the International Journal of Climatology, Ying Chen, a UH-Manoa graduate student at the time of the study, and Dr. Pao-Shin Chu, professor of atmospheric sciences at UH-Manoa and head of the Hawai`i State Climate Office, analyzed extreme precipitation events and the frequency with which they occur on Hawai`i Island, Oʻahu and Maui.
While they found that heavy rainfall events have become more frequent over the last 50 years on easternmost Hawai`i Island, the opposite behavior was observed for O`ahu and Maui, to the west. There, rainfall extremes have become less frequent in the last five decades. This study reveals a regional, east to west, difference in how precipitation patterns are responding to a changing climate.
“In the past, the frequency of heavy rainfall events was assumed to be fairly constant,” Chu said. “However, because climate is changing, the assumption of stable precipitation climatology is questionable and needs to be reconsidered.
“Changes in the frequency of heavy rain events have repercussions on ecological systems, property, transportation, flood hazards and engineering design, including sewage systems, reservoirs and buildings.”
This study also provided clues about why and how the frequency of precipitation extremes has changed. Chu and Chen found a greater number of extreme rain events during La Nina years and the opposite during El Nino years.
In this study, the number of rain gauges used was limited. The researchers used information from 24 weather stations on the three islands. For future work, Chu hopes analyzing data from additional stations will provide a more detailed assessment of changing rain patterns across the Hawaiian Islands.
To comment on or like this story, go to facebook.com/kaucalendar.
While they found that heavy rainfall events have become more frequent over the last 50 years on easternmost Hawai`i Island, the opposite behavior was observed for O`ahu and Maui, to the west. There, rainfall extremes have become less frequent in the last five decades. This study reveals a regional, east to west, difference in how precipitation patterns are responding to a changing climate.
“In the past, the frequency of heavy rainfall events was assumed to be fairly constant,” Chu said. “However, because climate is changing, the assumption of stable precipitation climatology is questionable and needs to be reconsidered.
“Changes in the frequency of heavy rain events have repercussions on ecological systems, property, transportation, flood hazards and engineering design, including sewage systems, reservoirs and buildings.”
This study also provided clues about why and how the frequency of precipitation extremes has changed. Chu and Chen found a greater number of extreme rain events during La Nina years and the opposite during El Nino years.
In this study, the number of rain gauges used was limited. The researchers used information from 24 weather stations on the three islands. For future work, Chu hopes analyzing data from additional stations will provide a more detailed assessment of changing rain patterns across the Hawaiian Islands.
To comment on or like this story, go to facebook.com/kaucalendar.
HAWAIIAN VOLCANO OBSERVATORY scientists discuss upslope portions of the June 27th lava flow that continues to be active in Puna in the current issue of Volcano Watch.
Daily reports on the June 27th lava flow posted by Hawai`i County Civil Defense and USGS Hawaiian Volcano Observatory always include an update on the position of the leading tip of the flow. The flow front position is the simplest indicator of the activity and its potential threat. But the June 27th flow, like other pahoehoe lava flow fields, is expansive and dynamic, and the flow front location is only part of the story.
For the broader picture, let’s look at the June 27th lava flow as a whole. The flow covers an area of about 3,100 acres, but only a tiny fraction of this area consists of active, flowing lava on the surface. Based on measurements taken on Jan. 29, for example, the area of active lava was about 10 acres. In other words, only about 0.3 percent of the June 27th flow field surface consists of active, flowing lava. The rest of the surface is warm, but solidified.
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| In this thermal map from HVO, temperature is displayed as gray-scale values, with brightest pixels indicating hottest areas and white showing active breakouts. |
Much of the active lava on the surface, what we call breakouts, is focused around the farthest portion of the flow – near, but not always at, the flow front. The lava gets from the vent to this distal part of the flow via a subsurface lava tube. For much of the length of the flow field, this lava tube is a single ‘master’ tube, perhaps a few yards wide. The June 27th lava flow is about 14 miles long, but this master tube appears to reach no farther than about 12 miles. Over the final two miles of the flow length, the lava moves beneath the surface via a complicated network of minor lava tubes. The master tube can be thought of as an artery that branches out into small capillaries. This network of minor tubes is what supplies lava to the surface breakouts near the flow front.
When the rate of lava supply from the vent is high, lava moves efficiently through the network of minor tubes, feeding vigorous surface breakouts that reach the flow front. In this case, the flow front advances downslope. But when the lava supply rate is low, the lava on the surface and within the system of minor tubes may cool to the point of solidifying and stalling, and active lava may not be able to reach the flow front. In this scenario, the flow front stalls, but weak breakouts can nevertheless persist a short distance upslope, closer to the end of the master tube.
It is this second scenario – a lower lava supply and stalling flow front – that appears to have been in play over much of January. If people only hear that the flow front has stalled, they might get the false impression that the flow as a whole is inactive. But scattered breakouts have persisted upslope of the stalled flow front for weeks now.
HVO and Hawai`i County Civil Defense keep a close watch on these upslope breakouts because they can help determine the future path of activity. The network of minor lava tubes supplying the breakouts is unstable and can change through time, shifting the location of breakouts on the flow field. Once the breakouts have shifted, an increase in the lava supply rate can re-energize the breakouts and feed a new lobe of lava traveling in a new direction.
HVO's daily eruption updates at http://hvo.wr.usgs.gov/activity/kilaueastatus.php describe these upslope breakouts, but to better show their locations and extent, we have also recently begun posting thermal maps of the flow field at http://hvo.wr.usgs.gov/maps/. These thermal maps are made with images collected by a handheld thermal camera during our helicopter overflights. HVO also posts satellite images, when available, that show hotspots (red pixels) indicating the areas of active breakouts.
Keeping an eye on the flow front position is an important part of staying abreast of current activity and the ongoing lava flow hazard. But for sure, it is important to be mindful of what’s going on upslope as well.
When the rate of lava supply from the vent is high, lava moves efficiently through the network of minor tubes, feeding vigorous surface breakouts that reach the flow front. In this case, the flow front advances downslope. But when the lava supply rate is low, the lava on the surface and within the system of minor tubes may cool to the point of solidifying and stalling, and active lava may not be able to reach the flow front. In this scenario, the flow front stalls, but weak breakouts can nevertheless persist a short distance upslope, closer to the end of the master tube.
It is this second scenario – a lower lava supply and stalling flow front – that appears to have been in play over much of January. If people only hear that the flow front has stalled, they might get the false impression that the flow as a whole is inactive. But scattered breakouts have persisted upslope of the stalled flow front for weeks now.
HVO and Hawai`i County Civil Defense keep a close watch on these upslope breakouts because they can help determine the future path of activity. The network of minor lava tubes supplying the breakouts is unstable and can change through time, shifting the location of breakouts on the flow field. Once the breakouts have shifted, an increase in the lava supply rate can re-energize the breakouts and feed a new lobe of lava traveling in a new direction.
HVO's daily eruption updates at http://hvo.wr.usgs.gov/activity/kilaueastatus.php describe these upslope breakouts, but to better show their locations and extent, we have also recently begun posting thermal maps of the flow field at http://hvo.wr.usgs.gov/maps/. These thermal maps are made with images collected by a handheld thermal camera during our helicopter overflights. HVO also posts satellite images, when available, that show hotspots (red pixels) indicating the areas of active breakouts.
Keeping an eye on the flow front position is an important part of staying abreast of current activity and the ongoing lava flow hazard. But for sure, it is important to be mindful of what’s going on upslope as well.
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| The public is invited to Ka`u CDP Steering Committee's meeting Tuesday. |
SENIOR ID CARDS, for residents ages 60 and over, are available tomorrow from 9 a.m. to 11 a.m. at St. Jude’s Episcopal Church in Ocean View. Call 928-3100 for more information.
KA`U COMMUNITY DEVELOPMENT PLAN Steering Committee meets Tuesday at 5:30 p.m. at Na`alehu Community Center. The committee will discuss plans for community review of the draft CDP and ways to help members prepare for it and decision-making that will follow. Public feedback is welcome on these agenda items.
The agenda, draft CDP and other information is available at kaucdp.info.
SUPPORT OUR SPONSORS AT PAHALAPLANTATIONCOTTAGES.COM AND KAUCOFFEEMILL.COM. KA`U COFFEE MILL IS OPEN SEVEN DAYS A WEEK.
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| See kaucalendar.com/KauCalendar_February2015.pdf. |
