of the Verde Island Passage, Philippines - weADAPT

chapter 1 • vulnerability assessment of marine ecosystems and fisheries to climate change: exposure
Figure 30. Changes in shoreline position along Malaylay-Baco
coast.
Malaylay-Baco
Erosion of as much as 300-m occurred
along the Baco-Malaylay delta between
1953 and 2001 (Figure 30). From 2001
to 2009, this coastline remained stable.
The erosion prior to 2001 may have been
triggered by liquefaction caused by the
magnitude 7.1 earthquake on a segment
of Lubang Fault, south of Verde Island
on November 15, 1994. This earthquake
also generated a tsunami that inundated
the northeastern coast of Mindoro from
Puerto Galera to Pinamalayan, Baco
islands, and Verde Island (Phil. Insti. Vol.
Seis. 1994). The tsunami also traveled
northwards affecting Batangas Bay and
Lobo (Imamura et al. 1995). Coastal
lowlands along the Calapan Bay including
Malaylay, Baco, Wawa, and Baco islands
were hardest hit by the tsunami of at least
6 m high, flooding areas 50 to 200 m landward. Highest wave run-up of as high as 8.5 m occurred in Baco
Island. The steep coastal gradient also facilitated the strong rundown that caused beach erosion of about 20
m. On the other hand, in the gently sloping delta plains of the Malaylay-Wawa coast, aggradation occurred.
Strong incoming waves scoured sands along the foreshore area and deposited the sediments inland forming
a ridge, which was preserved because of the weakened backflow in relatively flat areas. The rest of Calapan,
San Teodoro, and Puerto Galera experienced tsunami ranging from 2 to 3 m high. Low run-up heights of 0.5
m, 0.9, and 1.2 were respectively observed in Pola, Pinamalayan, and Naujan (Phil. Insti. Vol. Seis. 1994).
Figure 31. Changes in shoreline position along Mag-asawang Tubig-
Naujan coast.
Mag-asawang Tubig
From 1950s to 2009, there was a net
land loss at the mouth and net land gain
along the flanks of the Mag-asawang
Tubig River in Naujan, Oriental Mindoro
(Figure 31). This trend is possibly due
to river switching upstream which may
have been induced by differences in
river discharge and amount of sediment
load. The 1977 topographic map
shows that Mag-asawang Tubig directly
drained into the Verde Island Passage
just north of Bgy. Estrella in Naujan. But
recent Google Earth® images indicate
that at present, Mag-asawang Tubig
joins the Bucayao River upstream,
before emptying to the Verde Island
Passage through the Silonay River in
Calapan.
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