Benefits of Typhoons GQTabios

8/4/2019 Benefits of Typhoons GQTabios

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Benefits of Typhoons: A PhilippinePerspective

Guillermo Q. Tabios IIIInstitute of Civil Engineering and

National Hydraulic Research Center University of the Philippines, Diliman

Workshop on Urban Flood Risk Management in a Changing Climate:Sustainable and Adaptation Challenges@Macao, China on September 6, 2010


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Introduction: Broad Benefit of Typhoons(after Prof. F. Davis, Drexel University)

Back in 1973, meteorologists already startedbelieving that tropical storms may more than offsetthe damage they cause than by the good they do.

In particular, in places such as Southeast Asia(Philippines, Vietnam, Thailand, Indonesia) includingJapan and India, tropical storms provide up to 25% ormore of annual rainfall so that tropical storms is themajor source for agriculture and domestic water

supplies.Meteorologists are now convinced that tropicalstorms play a crucial factor in maintaining theplanet's heat balance, which is essential to the well-

being of all life.


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... introduction

A broad explanation is that as the water vapor risesfrom the sea, it cools, condenses and releasesenormous amounts of heat into the atmosphere. Theheat, in turn, causes more evaporation and

condensation, further fueling the brewing storm likethe updraft in a chimney.

As the winds build and the tropical storm edges awayfrom its birthplace, it releases enormous amounts ofheat and as much energy may be released in a singleday equivalent to detonating 400, 20-megatonhydrogen bombs.


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... introduction

If tropical typhoons were prevented by some meansor some man-made technology from releasing theirheat, the equatorial seas might warm up until theirhuge amounts of stored heat would be released in theform of super typhoons. And in the long term, thetropics can become extremely warm andsimultaneously, the polar regions could becomeextremely colder.


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Disaster or not, storms

benefit us. The tropical regions of the Earth would be too hot to inhabit, and the sub-

polar regions too cold, if we didn't have hurricanes and typhoons to mix the Earths atmosphere and distribute the Earth's heat so efficiently.

On a lighter side, Bill Nye inhis appearance with LarryKing Live at CNN last weekAugust 30, 2010 summarizesthis as follows:


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Some Specific Benefits of Typhoons

1. Domestic & Irrigation Water Supply: Case ofMetro Manilas Angat Reservoir

2. Reduction of Air Pollution: Illustrative Case

for Cagayan de Oro City (major city insouthern Philippines)

3. Carbon Sequestration: Sampling andResearch in Taiwan

4. Sediment Flushing for River Maintenance

5. Support Wetland Flood Dynamics


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Water Supply Derived from Typhoons

Due to the distinct wet and dry seasons in certainparts of the Philippines, surface water reservoirs areneeded if is the only raw water source. However, dueto budget constraints, reservoirs are built with only

within-a-year carry-over storage. More often in thiscase, they can only be filled-up for next years watersupply by tropical typhoons.

Illustrated below is the case of Metro Manilas AngatReservoir for domestic water supply which has oftenreached critical shortage levels of 180 m or below andonly recover due to occurrence of tropical typhoon.


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2000 2001 2002 2003 2004 2005 2006 2007 2008

160

180

200

220

R e s e r v o i r E l e v

a t i o n ( m )

0

1

2

3

4

T

y p h o o n s w

/ i n 2 0 0 k m s

Angat Reservoir Monthly Elevations and Number ofTyphoons within 100 kms Radius(Angat Reservoir is the major and only raw surface water source of Metro Manila)


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5/19 6/21 7/15&30 11/12 12/13

Particulate Matter (PM 10) Concentration in Cagayan de OroCity, Northern Mindanao (Southern Philippines) in Year 2003

(Arrows indicate dates of typhoons within 150 kms radius)

Particulate Matter (PM 10 - 10 microns in diameter or smaller, in m g/Nm 3) are small solid or liquid particlessuspended in air from diesel vehicles and coal-burning power plants. Dust is also a major source especiallyduring the dry months and it can come from unpaved roads and construction activities.The Philippine National Ambient Air Quality (NAAQ) guideline values for PM 10 should not be more than 150m g/Nm3 average over a 24-hour period and not over 60 m g/Nm 3 average over one-year period.


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5/196/21

7/15&3011/12

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Daily Sulfur Dioxide (SO 2) Concentration in Cagayan de OroCity, Northern Mindanao (Southern Philippines) in Year 2003

(Arrows indicate dates of typhoons within 150 kms radius)

Sulfur Dioxide (SO2 in m g/Nm 3) come from power plants and motor vehicles that burn fuels.

The Philippine National Ambient Air Quality (NAAQ) guideline values for SO 2 should not be more than 150m g/Nm 3 average over a 24-hour period and not over 60 m g/Nm 3 average over one-year period.


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Carbon Sequestration

Study of Choshui River during Typhoon Mindulle by A.Carey & S. Goldsmith of Ohio State University and S.-J.Kao, T.-Y. Lee, & J. Chen of Academia Sinica, Taiwan.

In Choshui River during Typhoon Mindulle of July 2009,the study team quantified that out of 61 million tons ofsediment carried out to sea, about 500,000 tonsconsisted of carbon particles produced by chemicalweathering. The team concluded that this is about 95

percent as much carbon that the river transports duringnormal rains over an entire year.


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.. carbon sequestration

With two to four typhoons events per year in Taiwan, itis plausible that the amount of carbon sequesteredduring these storms could be comparable to the long-term annual carbon flux for the country.

The team pointed out that mountainous islands such asTaiwan, New Zealand, and Papua New Guinea [includingthe Philippines] could produce one third of all thesediments that enter the world oceans annually. Thishas important implications to global carbon balance andthus global climate change.


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Sediment Flushing for River Maintenance

A stable river means river in dynamic equilibrium, notstatic, which undergo periodic river changes due toflow regimes and sediment movement. In order tomaintain dynamic equilibrium, it takes seasonaloccurrence of high flow regimes which can only be

brought by large rainfalls from tropical typhoons.The high flow regimes are generally responsible forremoving or mobilizing sediments by erosion whilethe low flows promote deposition of sediments.During high flows, rivers can flush fine sediments,toxic materials and open clogged pores in thestreambed gravel matrix to promote better aerationand circulation for fish spawning and other biological

activities.


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Conclusions

With proper and better understanding of the nature anddynamics of tropical typhoons, it would be worthwhilerecognizing and taking advantage of their beneficialuses in contrast to their adverse impacts.

To reiterate, the broad benefit one can derive fromtyphoons is that tropical regions of the Earth wouldbe too hot to inhabit, and the sub-polar regions toocold, if we didn't have hurricanes and typhoons (BillNye).

Specific benefits of typhoons has also been discussedearlier, but further studies should be made to establishand provide concrete guidelines as to how, when andwhat it takes to take advantage of typhoons benefits.

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Benefits of Typhoons GQTabios