The Philippine Star

Bay recla­ma­tions prone to dis­as­ters

- By JARIUS BONDOC Weather · Disasters · Ecology · Natural Disasters · Manila · Cavite · Metro Manila · Bataan · Pampanga · Bulacan · University of Illinois at Urbana-Champaign · Illinois · Philippines · California · San Joaquin Valley · Navotas, Metro Manila · Dagupan City · Cabanatuan City · Japan · Ōsaka · Facebook · Pasay · Capiz · Cabanatuan · Kansai International Airport · Kansai

(We have in­ad­ver­tently picked the wrong copy of this col­umn which ap­peared on March 10. My apolo­gies. – RML)

The gov­ern­ment has lined up 102 shore recla­ma­tions cov­er­ing 38,272 hectares na­tion­wide. A third of those are in Manila Bay. Four are about to com­mence: two in Manila City, one in Pasay, and one in Cavite. The new real es­tate would bring mega-prof­its to the pro­po­nents. But wait, warns earth and en­vi­ron­ment sci­en­tist Kelvin Rodolfo. Those recla­ma­tions also would cause floods, storm surges, and liq­ue­fac­tion. Mil­lions of coastal res­i­dents in Metro Manila, Bataan, Pam­panga, Bu­la­can, and Cavite would be left in mis­ery.

The NGO Save Our Shores re­cently pre­sented the study of Rodolfo, a Filipino-Amer­i­can PhD at the Univer­sity of Illi­nois in Chicago and a Ba­lik-Sci­en­tist of the Philip­pine gov­ern­ment. Three loom­ing dis­as­ters were ex­plained:

• Sea­wa­ter will flood coastal com­mu­ni­ties. Due to sea tem­per­a­ture warm­ing, sea lev­els are ris­ing, es­pe­cially near the equa­tor. In the Philip­pines the rate of rise is as much as 14.7 mm a year, or just below an adult's calf in ten years. At the same time, the bay area is fast sink­ing. Un­bri­dled ex­trac­tion of ground­wa­ter is caus­ing the sur­face to sub­side. The rate of sub­si­dence in Greater Manila is about 19.2 mm a year, or mid-leg deep in ten years. (Rodolfo likens that sub­si­dence to the sink­ing of Cal­i­for­nia's San Joaquin Val­ley by eight me­ters, or a three-story house, due to ground­wa­ter overuse in the 1920s to 1970s.)

The Manila Bay coastal plains slope up in­land very gen­tly. Ten to 20 kilo­me­ters of land from the shore are only one me­ter above sea level. The com­bi­na­tion of ris­ing sea lev­els and land sub­si­dence would make sea­wa­ters ad­vance in­land. Large swaths of the bay area per­pet­u­ally would be in knee-deep sea­wa­ter in ten years.

Recla­ma­tions, be­ing soft earth, would be sus­cep­ti­ble to the com­bi­na­tion of ris­ing sea lev­els and sub­si­dence. They would even has­ten and deepen the flood­ing in other parts of the bay area as nat­u­ral out­flows of rivers and high tides would be clogged. Rodolfo cites the ex­pe­ri­ence of Da­gat-Da­gatan in Navotas, Metro Manila. Start­ing in the 1970s the gov­ern­ment poured bil­lions of pe­sos for land­fill and dikes – all for naught. More ar­eas of the city are flooded to­day than be­fore.

• Storm surges would lash the coastal com­mu­ni­ties.

Typhoons are be­com­ing stronger than ever due to cli­mate change. Most at risk from storm surges and gi­ant waves are coastal plains that slope up very grad­u­ally, like the Manila Bay area. His­tory has shown ev­i­dence of typhoon de­struc­tion. Ships have be­come un­chained from an­chors and crashed against each other or onto Roxas Boule­vard due to strong waves. Recla­ma­tions ar­ti­fi­cially would change the coastal con­tour, mak­ing them prone to storm surges and de­struc­tive waves.

• Liq­ue­fac­tion would sink the coastal ar­eas into the bay wa­ter in case of earth­quake.

Liq­ue­fac­tion is when loose, sat­u­rated soil and sed­i­ments lose co­he­sion and tem­po­rar­ily be­have like liq­uid. That’s what hap­pened when build­ings in down­town Dagu­pan City, be­side the

The new real es­tate would bring profit to the pro­po­nents, and mis­ery to the pop­u­la­tion.

Lin­gayen Gulf, sank as deep as one me­ter from the 1990 Lu­zon earth­quake. Yet the epi­cen­ter was one hun­dred kilo­me­ters to the east, near Ca­banat­uan City. In case the Big One strikes when Greater Manila's West Val­ley Fault moves, the re­claimed ar­eas could suf­fer liq­ue­fac­tion. Struc­tures could col­lapse.

Rodolfo warns against the recla­ma­tion of San­g­ley Point in Cavite, at the south­ern tip of Manila Bay, for a new air­port. Such earth-fill­ing could sink large parts of the heav­ily pop­u­lated ur­ban­ized prov­ince due to has­tened sea­wa­ter rise, land sub­si­dence, storm surges and waves, and earth­quake liq­ue­fac­tion. Rodolfo cites Japan's en­gi­neer­ing fi­asco with the Kan­sai Air­port, built on a re­claimed is­land off the bay coast of Osaka. More than $20 bil­lion – 40-per­cent over-bud­get – was spent to re­claim land from the sea, pave two run­ways, build the ter­mi­nals – and try­ing to out­pace the sink­ing. Still it sunk, by 11.9 me­ters, or a four-storey build­ing. Ten per­cent of the cost went to wa­ter­proof­ing alone to save base­ments. The is­land con­tin­ues to sink to this day.

* * * Catch Sapol ra­dio show, Satur­days, 8-10 a.m., DWIZ (882-AM).

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