Scientists have produced a preliminary map of the flooding in Houston from Tropical Storm Harvey.
The
map doesn't yet represent all the flooded areas, and for technical
reasons, it likely understates the extent of flooding. But even this early analysis shows that flooding from Harvey extended well beyond the traditional flood plains mapped out by the federal government.
The map above was drawn with data from flood experts at the University of California, Davis Center for Watershed Sciences.
The researchers used radar imagery from two polar orbiting satellites
taken on August 29. That imagery likely underestimates flooding because
trees and buildings on the ground can obscure the view of flooding from
space. The map should not be used for emergency services or insurance
purposes.
But what it does show is how much of the flooding occurred outside
government-drawn flood zones. Two-thirds of the flooding was outside
the 100-year flood zone, as defined by the Federal Emergency Management
Agency (FEMA). And more than half the flooding was outside all flood
zones — 100-year, 500-year or minimal hazard.
Team member Nick Santos
points out that Houston has had several floods in recent years that
qualify as 100-year or 500-year events. Harvey appears to have topped
even those. Santos says this suggests the flood zone maps may no longer
represent true risk for property owners. "So we need to rethink the
total risk map for areas like this," he says.
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