An analysis of satellite imagery and property data shows at least $US23 billion ($A29 billion) worth of property has been affected by flooding from Hurricane Harvey in parts of two counties in Texas alone.
Reuters have analysed satellite imagery of areas in the Harris and Galveston counties to come up with the figure, which represents property market values, not storm damage, which was not possible to discern from the images.
The satellite pictures were compiled by researchers at the University of Colorado and show flooding across 600 square kilometres of Harris County and 132 square kilometres of Galveston County, about one-eighth of each county's land area.
Reuters overlaid the flood imagery on property parcel maps and found floodwaters had encroached on at least 30,000 properties in the two counties, with a total market value of $US23.4 billion, putting Hurricane Harvey among the most damaging in US history.
Of that, 26 per cent is land value with the rest made up of buildings and other improvements. In Harris County, where Reuters was able to determine the property's use, about 18 per cent of the affected property is residential.
The tally omits much of Houston's dense urban centre as a satellite specialising in urban imagery has not yet taken enough images. Floodwaters have inundated the area, like surrounding regions, and thousands of homes are damaged. Many roads, including vital highways and parkways, were submerged and businesses flooded and shuttered.
