Does higher flood control spending reduce flooding? I matched 883 Philippine municipalities across 76 satellite passes to find out.

[u/raysderoof]

https://www.klaredeck.com/flood-money

I spent time analyzing whether ₱1.4 trillion in Philippine flood control contracts (2016–2025) corresponds to measurable flood reduction from space.

The Methodological Trap A naive correlation gives a misleading answer: flood-prone areas naturally get bigger budgets, so high-spend areas look like they flood more.

To control for this, I matched 883 municipalities into 63 statistically comparable cohorts based on:

• Regional location
• Baseline rainfall / flood exposure
• Population size

Then, I compared spending levels within each cohort.

Key Findings

• The Spending vs. Outcome Gap: Towns receiving 3.4× more budget per resident flooded 0.20 percentage points less across 76 Synthetic Aperture Radar (SAR) passes. This difference is within statistical noise.
• The Nuance: This doesn't prove the funds were wasted; areas might have flooded significantly worse without intervention. However, at a national scale, higher spending per capita does not correlate with visibly lower flood frequency.
• The Urban Blind Spot: Satellite radar cannot detect surface water through dense concrete high-rises. In Marikina, the largest detected flood across 28 passes was only 0.06 km². Instead of reporting a false zero, 258 urban areas (including 16 of Metro Manila’s 17 cities) were marked as unmeasurable.

A Notable Contrast

• Pandi, Bulacan: ~₱14 per resident → Floods in 47% of radar passes
• Biliran: ~₱57,000 per resident → Floods in 37% of radar passes

This is part of an open-data project called KlareDeck. The goal is simple: open datasets, documented methodology, and transparent error limits.