Leaves.PH

METHOD · FLOODING AND THE CANOPY

Does losing trees flood a barangay?

Bumabaha ba ang barangay dahil sa nawalang puno?

A fair question, and a tempting story: less canopy, more runoff, more flooding. So we tested it. We laid the per-barangay canopy series next to how much of each Metro Manila barangay the radar actually saw under water in the July 2025 monsoon flood, and asked what really predicts where it flooded. The answer is honest and a little against the grain.

Patas na tanong, at kaakit-akit na kuwento: kaunting puno, mas maraming tubig, mas maraming baha. Kaya sinubok namin. Pinagtabi namin ang canopy kada barangay at kung gaano kalaki ng bawat barangay sa Metro Manila ang nakitang lubog ng radar noong baha ng Hulyo 2025, at tinanong kung ano talaga ang humuhula kung saan bumaha. Tapat ang sagot, at bahagyang salungat sa inaasahan.

WHAT THE DATA SHOWS

ANG IPINAPAKITA NG DATOS

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Read this carefully. Radar (Sentinel-1) sees standing water as smooth and dark, but it under-sees flooding between buildings in dense areas. So the observed inundation here is a lower bound, and it is cleanest in open, low-rise, and floodplain barangays. This page lines up flooding and canopy so they can be checked together. It does not claim trees cause or prevent a barangay flood.

Basahin nang maigi. Nakikita ng radar (Sentinel-1) ang nakatayong tubig bilang makinis at madilim, ngunit hirap itong makita ang baha sa pagitan ng mga gusali sa siksik na lugar. Kaya ang nakitang baha dito ay pinakamababang tantiya, at pinakamalinaw sa mga bukas at mababang barangay. Pinagtatabi ng pahinang ito ang baha at canopy para masuri nang magkasama. Hindi nito sinasabing puno ang sanhi o lunas ng baha sa barangay.

So what does flood a barangay?

Ano nga ba ang nagpapabaha sa barangay?

Each bar shows how much one thing pushed flooding up or down across the — barangays, after taking the others into account. Bars to the left made flooding less likely, bars to the right more likely. Tree cover is the short one.

Ipinapakita ng bawat bar kung gaano nito itinaas o ibinaba ang baha sa — barangay, matapos isaalang-alang ang iba. Ang nasa kaliwa ay nagpapababa ng baha, ang nasa kanan ay nagtataas. Maikli ang sa puno.

tree canopypuno other factorsibang salik

 

 

barangays checked

barangay na sinuri

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flooded in July 2025

binaha noong Hulyo 2025

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those, with few trees

doon, kulang sa puno

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tree cover's effect

epekto ng puno

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Where the radar saw water

Saan nakakita ng tubig ang radar

Each shape is one barangay, shaded by how much of it the radar saw underwater on 2025-07-23. The outlined barangays are the ones to watch: they flooded and have few trees. Tap any barangay for its numbers.

Bawat hugis ay isang barangay, kulay ayon sa kung gaano kalaki nito ang nakitang lubog ng radar noong 2025-07-23. Ang may guhit-hangganan ang dapat bantayan: binaha at kulang sa puno. Pindutin ang alinmang barangay para sa mga numero.

Loading the map…

share of barangay flooded

bahaging binaha

0% 3%+
priority barangaypriority na barangay

Inundation: Sentinel-1 SAR (COPERNICUS/S1_GRD) change detection, 2025-07-23 against a May to June dry reference. Permanent water and steep ground are excluded. A radar lower bound: dense built-up flooding is under-counted.

Baha: Sentinel-1 SAR (COPERNICUS/S1_GRD) change detection, 2025-07-23 laban sa tuyong sanggunian noong Mayo hanggang Hunyo. Hindi kasama ang permanenteng tubig at matarik na lupa. Pinakamababang tantiya: kulang ang bilang sa siksik na lugar.

Where to act first

Saan unang kumilos

The useful list: barangays that both flooded and have few trees. Planting trees will not stop the flood, but these are the places where fixing drainage and planting trees both make sense, and where a tree-cutting permit deserves a closer look. It is a list of where two problems overlap, not proof that trees stop floods.

Ang kapaki-pakinabang na listahan: mga barangay na binaha at kulang sa puno. Hindi mapipigil ng pagtatanim ang baha, ngunit dito may saysay ang sabayang pag-aayos ng drainage at pagtatanim, at dito dapat suriing mabuti ang permiso sa pagputol ng puno. Listahan ito ng pagsasanib ng dalawang problema, hindi patunay na pinipigil ng puno ang baha.

# barangaybarangay flooded %binaha % canopy %canopy %

 

Most flood-exposed barangays

Pinaka-binahang barangay

The barangays where the radar saw the most water, regardless of canopy. Notice many are not tree-poor: open, low-lying ground is what the radar reads best, which is exactly why a raw canopy correlation misleads.

Ang mga barangay kung saan pinakamaraming tubig ang nakita ng radar, anuman ang canopy. Marami ang hindi kulang sa puno: bukas at mababang lupa ang pinakamadaling mabasa ng radar, kaya nga nakakalito ang hilaw na ugnayan ng canopy.

# barangaybarangay flooded %binaha % canopy %canopy % low groundlapit-tubig

What this can and cannot tell you

Ano ang masasabi at hindi masasabi nito

It can

Kaya nito

  • Show where radar saw standing water in one severe Metro Manila flood, by barangay.
  • Test the trees-and-flooding link properly, after accounting for low ground, concrete, and distance to water.
  • Point to the barangays that both flooded and have few trees, for combined drainage and tree-planting work.
  • Show that the simple "fewer trees, more floods" link actually runs backwards here, and why.
  • Ipakita kung saan nakakita ng tubig ang radar sa isang malubhang baha sa Metro Manila, kada barangay.
  • Subukin nang tama ang ugnayan ng canopy at baha, habang nakapirmi ang mababang lupa, gusali, at layo sa tubig.
  • Tukuyin ang mga barangay na binaha at kulang sa puno, para sa sabayang drainage at pagtatanim.
  • Ipakita na baligtad ang hilaw na ugnayan ng canopy dito, at kung bakit.

It cannot

Hindi kaya nito

  • Say trees cause or prevent a barangay flood. This is a pattern we measured, not a controlled test.
  • Catch every flood. Radar under-sees water inside dense built-up cores, so figures are a lower bound.
  • Stand on one storm. It reads the July 2025 event, the most severe recent flood with clean radar.
  • Resolve a single street. Below about 30 m, inundation is not independently visible.
  • Sabihing puno ang sanhi o lunas ng baha. Ugnayan ito, hindi eksperimento.
  • Mahuli ang bawat baha. Hirap makita ng radar ang tubig sa siksik na lugar, kaya pinakamababang tantiya.
  • Umasa sa isang bagyo lamang. Binabasa nito ang baha ng Hulyo 2025, ang pinakamalubha kamakailan na may malinis na radar.
  • Suriin ang isang kalye. Sa ilalim ng mga 30 m, hindi nakikita nang malinaw ang baha.

Data and method

Datos at paraan

Flooding is measured from Sentinel-1 radar: we compare 2025-07-23 against a dry May to June baseline and flag the ground that turned to standing water, leaving out rivers, the bay, and steep slopes. We then compare flooding against tree cover and the main flood causes (how low the ground sits and its drainage, how built-up it is, and how close it is to water) and measure how much each one matters. We ran the check two ways and confirmed nearby barangays did not skew the result. Low ground comes from MERIT Hydro, built-up share from Dynamic World, water from JRC Global Surface Water. Per-barangay figures: flood_canopy_barangay.csv. Map polygons: flood_canopy_barangay.geojson. Both regenerable with make compute-flood. CC-BY-4.0.

Sinusukat ang baha mula sa Sentinel-1 radar: inihahambing ang 2025-07-23 sa tuyong baseline noong Mayo hanggang Hunyo at tinutukoy ang lupang naging nakatayong tubig, hindi kasama ang ilog, look, at matarik na lupa. Inihahambing namin ang baha sa puno at sa pangunahing sanhi ng baha (gaano kababa ang lupa at drainage, gaano kasiksik, at gaano kalapit sa tubig) at sinusukat kung gaano kahalaga ang bawat isa. Sinuri namin ito sa dalawang paraan at tiniyak na hindi ito nililihis ng magkakalapit na barangay. Ang mababang lupa ay mula sa MERIT Hydro, dami ng gusali sa Dynamic World, tubig sa JRC Global Surface Water. Datos kada barangay: flood_canopy_barangay.csv. Polygon ng mapa: flood_canopy_barangay.geojson. Mabubuo muli gamit ang make compute-flood. CC-BY-4.0.

Official modeled flood-hazard layers (DOST GeoRiskPH, Project NOAH) would be a useful second lens, but their data is auth-gated or has no addressable download, so we measure inundation directly instead. Pairing the two is on the roadmap. The canopy model behind the rest of the site is on methodology.

Magandang pangalawang lente ang opisyal na flood-hazard (DOST GeoRiskPH, Project NOAH), ngunit naka-auth-gate o walang ma-download na datos, kaya direktang sinusukat namin ang baha. Nasa roadmap ang pagsasama ng dalawa. Ang canopy model ng buong site ay nasa methodology.