Sinking Deltas: The Pampanga Delta, Philippines
“Our primary school was permanently shut down after it was submerged, now students have to travel half an hour by boat for their daily commute. Also our church is permanently flooded. The water gets high, up to the window level. Sometimes it reaches the altar. We can even see oysters growing on our church grounds already. Masses are now being held with churchgoers in their boats.”
The Pampanga delta, located in northern Manila Bay, has been experiencing human-accelerated subsidence for several decades, predominantly driven by groundwater overextraction, with present sinking rates locally reaching up to 15 cm/yr (Sulapas et al., 2024). As a result large parts of the delta have been lost to the sea in only a few years time, causing population displacement and irreversible landscape changes with attendant impacts of delta livelihoods. Entire villages have already been abandoned due to permanent inundation as crop lands disappear. In recent years larger inland towns (~20 km away from original coastline) have also sunk into the tidal zone and now experience daily tidal inundations, disrupting all daily life and activities of an estimated 2 to 3 million people. The speed of change is so fast that large-scale adaptation measures have not been put into place, while small-scale, makeshift adaptation efforts, like elevating roads (1-1.5 meters in places), raising floor levels, complete abandonment of ground floors, and tide-adjusted school hours illustrate the limits of short-term adaptation.
A: Drowned Pampanga delta. Former rice fields are now permanently inundated. Feb 2025; B: Drowned landscape with makeshift walkway to reach houses. In the left corner, abandoned school building Feb 2025. C: Permanently inundated house with makeshift boardwalk, many people now exclusively live on the upper floor. D: Inundated school-yard during low tide. During high tide classrooms flood and school schedules are altered to match tides. Sept. 2024 (Images copyright: Philip S.J. Minderhoud).
While the drowning Pampanga delta may be the forerunner in widespread delta drowning and system collapse, deltas around the world are increasingly facing the interconnected threats of accelerated land subsidence, relative sea-level rise and groundwater overextraction. To avoid other deltas from undergoing the same fate, the UN Convention on River Deltas will help to raise awareness on unique existential threats to delta systems, such as accelerated land subsidence, and facilitate inter-delta knowledge exchange and best-practice learning.
What would a UN Convention on River Deltas do?
A grassroots-driven UN Convention would create a platform that enables the exchange of knowledge across disciplines and communities of individual deltas and thereby allows them to learn from the trajectories and states of other deltas. It would give the institutional frame needed to successfully address the deltas’ challenges in a targeted way, being rooted in the international law of the United Nations. Through connections to other UN bodies such as the UNDRR, UNFCCC and UNESCO’s Land Subsidence International Initiative (LaSII), the UN Convention for River Delta will create strong synergies to tackle the compound threats and specific needs of deltas effectively. Consequently, a delta UN Convention will help to: (1) identify and understand delta trajectories, (2) accelerate the design and implementation of strategies for sustainable delta development and disaster risk management through benefitting from other deltas’ experiences, and therefore (3) increase the window of action in view of human-environmental pressures and impacts of delta subsidence and sea level rise .
Contributed by: Philip Minderhoud and Katharina Seeger, Drowning Deltas project, Wageningen University and Research, The Netherlands
