Flooding is the most common and most costly natural disaster in the country. In the last two years, more than 8.5 billion in damages more than 130 lives lost How many are there of you? - There's about 40 In the bus? The question, is what can we do to mitigate this destruction? a FIRM, as they call it, a Flood Insurance Rate Map is a panel which depicts flood zones and these flood zones give an idea of specific risk. How likely you may or may not be to encounter a flooding event within a given period of time These maps need to be updated because the factors upon which the engineering is based change over time. You have changes in the composition of the ground material, you may have an increase in the impervious area. You may have better flood study methods available. One of the ways to keep these FEMA maps up to date is by tracking urban change using satellite imagery. Take this suburb of Atlanta, Georgia If we look at Landsat images spanning a 27 year period we can pinpoint areas of the earth's surface that have changed. usually because of construction. Like here, where the Mall of Georgia was built. A product called NUCI help to mine these images. Well, NUCI is especially important when considering risk, because it allows us to identify trends in urbanization. Now if you identify areas where urban change is accelerating, there are consequences. That increase in impervious area are going to mean altered flood characteristics likely, and increased risk, because people are probably building houses there. Impervious area essentially means ground cover which has been changed from the natural state to, say, a paved area, which is going to be concrete or asphalt. The infiltration characteristics of that ground material have been altered significantly, such that the ground is no longer able to hold water which means that local flooding sources are going to receive more water and the flooding characteristics are going to change. Tracking urban change from space helps everyday people understand their flood risk, and take action You can't see them, or hear them, but since 1972 Landsat satellites have been sending us data and today, that data helps us manage the high cost of flooding here on earth.