Pearland (Brazoria County), TX Flood Zone & Drainage Map

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Overview

Where does rainwater drain in Brazoria County? This interactive map shows surface drainage patterns across Pearland, Lake Jackson, Angleton, and surrounding areas based on terrain shape - where gravity directs rainwater based on elevation and slope. For official flood risk information, see the FEMA flood zone layer on the Hazards tab.

Brazoria County sits at the terminus of the Brazos River watershed, with extremely flat terrain averaging just 25 feet above sea level. Heavy clay soils resist infiltration, forcing nearly all rainfall into surface drainage channels. The Brazos River, San Bernard River, and Chocolate Bayou are the primary drainage conduits to the Gulf of Mexico. Choose a location to see surface drainage analysis and water flow direction based on terrain shape. The first three locations are free.

Interpretation

Select a location on the map or enter an address to see terrain analysis.

3D Terrain Visualization
Where does rainwater flow based on terrain shape? Blue areas show where water collects and drains downhill.
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Terrain drainage map of Brazoria County, TX: modeled paths where rainwater runs and collects, from USGS 3DEP elevation data, with the county boundary Click any spot on the map to analyze it
4.0× Horizontal:Vertical
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Brazoria County flood history

FEMA records 21,436 flood insurance claims in Brazoria County since 1978, with about $628 million paid. 45% of the claims with a rated flood zone came from moderate- or low-risk zones (X, B or C), outside the high-risk areas on FEMA’s flood maps.

Bar chart of FEMA flood insurance claims per year in Brazoria County, TX, 1978 to 2026, highest in 2017 (Hurricane Harvey) with 5,120 claims.

Biggest flood years

  1. 2017 · Hurricane Harvey · 5,120 claims
  2. 1979 · Tropical Storm Claudette · 3,849 claims
  3. 2008 · Hurricane Ike · 1,867 claims
  4. 2001 · Tropical Storm Allison · 1,200 claims
  5. 1998 · 1,091 claims

ZIP codes with the most claims

ZIPClaimsShare
775413,83917.9%
775113,47516.2%
775813,14114.7%
775152,47511.5%
775841,9949.3%
774221,4306.7%
775661,0675.0%
775317083.3%

How to read this. These are National Flood Insurance Program claims, so they count only insured buildings and miss flooding where owners had no flood insurance. FEMA publishes them without names or addresses: they show which years and areas flooded, never whether a particular house did. ZIP codes are as reported on the claims, and a ZIP code can extend beyond the county. The “rated” flood zone is the one used to price the policy and may come from an older map. Data as of 2026-09-08, from FEMA OpenFEMA.

Next: look up the flood zone for an address · how to check whether a specific house has flooded · why Zone X can still flood · how to read the drainage map

Sunlight and soil in Brazoria County

Sunlight. Ground here gets about 4.9 kWh of sunlight per square meter per day on average (4.8 to 5.1 across the map), above the middle of the lower 48 (4.5). South-facing slopes get more, north-facing ones less.

Soil. The ground is mostly swelling clay (Vertisols 89%). Rain soaks in slowly, so more of it runs off. Swelling clay also shrinks and cracks as it dries, which can move slabs and foundations.

The Solar and Soil tabs on the map above show both for any address. Read more: how much sun does my property get? · what soil type is my property, and how it affects drainage

Sunlight: long-term average on flat ground from the National Solar Radiation Database (National Laboratory of the Rockies, formerly NREL). Soil: most likely soil types from ISRIC SoilGrids, a 250 m model, not a survey of any lot. Both cover the map area above.

Explore more flood and drainage maps

Browse all 64 flood and drainage maps · Flood insurance claims in the 50 largest cities · How Terreflow uses terrain and FEMA data