The analysis shows Texas flood standards have been underestimated
The National Oceanic and Atmospheric Administration (NOAA) released an updated analysis of rainfall trends across Texas, which suggests that flood standards have been underestimated. NOAA analyzed decades of rainfall data leading up to Hurricane Harvey coming to the conclusion that instead of expecting the predicted 12 to 14 in. in a day during a 100-year storm, Harris County, Texas, should expect 15 to 18 in.
The study shows that the amount of rain that defines a 100-year storm— a storm that has a 1% chance of occurring in a given year— has increased by 3 to 5 in. in Harris County since 2002. While the NOAA analysis is still undergoing peer review, the results would mean development regulation changes to compensate for the higher runoff anticipated. The final NOAA data will be published May 2018 after peer review and will mark the first statewide update to the administrations rainfall estimates since 1961.