It is like a yearly ritual. This is the time of the year when torrential rains start bringing havoc to many parts of the country. The monsoon rains lash down, turning streets into raging torrents and communities into islands. Again. As headlines scream of “unprecedented” flooding, a familiar narrative emerges: clogged drains, mountains of garbage, and the sheer volume of water. As part of the ritual, citizens are once again demanding accountability from the government regarding the allocation and use of the billions of pesos in annual flood control budgets.

Beyond the obvious problem of indiscriminate waste disposal, the Philippines, especially its expanding metropolitan centers, faces a more sneaky foe in its battle against perpetual flooding. A significant piece of this watery puzzle is buried beneath our feet, forgotten and paved over.

Yes, the very arteries of our land, the natural rivers and streams designed to carry excess water away, have vanished, swallowed by unchecked urban sprawl and governmental negligence. It sounds like fiction—but it’s not. Hidden beneath concrete homes, shanties, commercial buildings, and paved streets lie the ghosts of flowing rivers and creeks. They have not dried up naturally. They’ve been swallowed by urban expansion, leaving cities vulnerable to flash floods and worsening calamities. In Metro Manila alone, countless waterways—once vital to draining rainfall—are now locked away under structures that should never have been built there. The question begs to be asked: Where have all the rivers gone?

I recall my college days in the university belt in the early 70s. Floods were even worse than they are now. To get to the other side of España, I will have to wade through waist-high floodwater. The floods there today may not be as high as they were before, but one still has to wonder where the money intended to solve the problem completely went.

For centuries, Philippine life revolved around its rivers. They were highways for commerce, sources of sustenance, and natural drainage systems. From the winding Pasig River, once the lifeblood of Manila and other surrounding communities, to the countless smaller streams and esteros that crisscrossed them, these waterways were integral to the landscape and the rhythm of daily life. However, with rapid urbanization and a seemingly insatiable demand for land, many of these vital arteries have been systematically encroached upon, filled in, or built directly over.

Squatter settlements, often born out of desperation and a lack of affordable housing, have proliferated along riverbanks, exacerbating the problem and eventually consuming the waterways themselves. What were once flowing streams are now narrow, stagnant canals, if they exist at all, choked by refuse and hemmed in by makeshift structures. The irony is stark: the very places meant to channel water away now serve as barriers, trapping it and thereby exacerbating the destructive power of the floodwaters.

The government's role in this environmental tragedy cannot be overstated. A lack of foresight in urban planning, coupled with weak enforcement of environmental laws and, at times, outright negligence, has allowed this encroachment to persist and even flourish. The result is a landscape where natural drainage is severely compromised, and when the rains come, there is nowhere for the water to go but up and into homes, businesses, and public spaces. This negligence transforms what should be natural, albeit intense, weather events into full-blown humanitarian crises, displacing thousands and costing the economy billions.

So, how do we begin to reclaim these lost waterways and restore their vital function? The first and most crucial step is to identify exactly where they are. This is where technology can play a transformative role, including the use of satellite data. Geographic Information Systems (GIS) can be employed to overlay old maps with current satellite imagery and ground-level surveys. This would allow for the precise mapping of former riverbeds and stream paths.

Furthermore, remote sensing technologies like LiDAR (Light Detection and Ranging) can be incredibly effective. LiDAR uses pulsed laser light to measure distances and create detailed 3D maps of the terrain, even beneath dense vegetation or urban structures. By analyzing variations in elevation and historical flow patterns, LiDAR can reveal the faint imprints of forgotten waterways, even if they are now buried under layers of development.

Finding the rivers is only the first step. What comes next is much more complex—but essential. It will involve clearing obstructions, demolishing illegally built structures, and relocating encroachments. We need to integrate restored natural waterways into urban planning and enforce existing laws meant to protect them.

Restoring natural waterways is not just about flood control. It's about giving nature the room to breathe in our cities. It's about honoring the geography of the land, designing more innovative urban systems, and planning for the future—not patching the past.

(The author is an executive member of the national Innovation Council, lead convener of the Alliance for Technology Innovators for the Nation (ATIN), vice president of the Analytics and AI Association of the Philippines, and vice president of UP System Information Technology Foundation. Email: [email protected])