THE WARNING could hardly be more literal: Iloilo is sinking.
For a city that has spent billions of pesos on roads, bridges, drainage systems, buildings and other infrastructure, the revelation that parts of Iloilo City are experiencing measurable land subsidence should trigger a fundamental rethink of how Iloilo obtains, manages and conserves its water.
Marine scientist Dr. Fernando Siringan has warned that excessive groundwater extraction, particularly through deep wells, can aggravate land subsidence at precisely the time climate change is pushing sea levels upward. “If we continue extracting groundwater, the land will continue to subside,” he said.
That is the frightening equation confronting Iloilo: the sea is rising while the land is sinking.
And there are numbers behind the warning. A PSInSAR study covering 2014 to 2016 recorded subsidence of as much as 8.8 millimeters per year in Barangay San Rafael in Mandurriao and 8.1 mm in Buntatala, Jaro. Subsidence was likewise measured in Calahunan, Mandurriao; in adjacent Ungka I in Pavia town; Alibay Norte in Oton; and Leganes.
A few millimeters may sound insignificant. But cities are built to last decades, even centuries. Millimeters accumulated year after year can eventually translate into centimeters of elevation lost. For low-lying communities already struggling with flooding, storm surges, clogged waterways and increasingly intense rainfall, every centimeter matters. This makes groundwater extraction an urban-planning, infrastructure, climate-resilience and disaster-risk issue.
Iloilo’s development has been remarkable. But development also means greater demand for water. If that growing thirst is satisfied substantially by pumping water from beneath the ground, the city risks undermining the very land on which that development stands. We cannot boast about building upward while ignoring what is happening downward.
Authorities should determine how much groundwater is actually being extracted, where extraction is concentrated, whether present withdrawal rates are sustainable, and how much land subsidence has occurred since the measurements cited from 2014 to 2016. Government cannot manage what it does not continuously measure.
The long-term answer must include reducing excessive dependence on deep wells and developing reliable and sustainable surface-water sources. But this transition must be carefully planned. Water security cannot simply be sacrificed in the name of groundwater conservation. Iloilo needs alternatives capable of providing households and businesses with sufficient, affordable and dependable water.
The solution must also go beyond finding another source of water. Siringan’s proposals for detention ponds, reforestation, terracing, hedges and mixed native trees point toward a broader philosophy: instead of treating rainwater merely as something to drain rapidly into rivers and the sea, Iloilo must learn to capture, store and allow more of it to infiltrate the landscape.
Authorities should begin treating groundwater as a finite strategic resource rather than an invisible reservoir beneath our feet. Deep-well extraction must be properly inventoried, monitored and regulated. Subsidence monitoring must be institutionalized. Surface-water alternatives must be accelerated. Rainwater retention must become part of urban development. River easements must be protected.
Most importantly, these measures should be integrated into Iloilo’s long-term development plans before further urbanization makes corrective action vastly more expensive.
The warning has already been given. “If we fail to address this, we will face two problems — rising sea levels and sinking land,” Siringan said.
Iloilo cannot control the global rise of the oceans by itself. But it can certainly stop making the problem worse by unnecessarily sinking the ground beneath its own feet.
