Flooding is expected to increase in the future as the effects of climate change increase. CBO examines how projected flood risk varies in two multiyear projection periods, one centered on 2020 and the other centered on 2050.

In the 2020 period, 9 percent of properties face at least a 1 percent annual probability of experiencing a flood of a depth of roughly 1 foot or more, CBO estimates. A 1 percent annual probability is equivalent to having about a one-in-four chance of experiencing at least one such flood over a period of 30 years. In the 2050 period, 10 percent of properties face that risk. CBO examines how that risk varies across communities with different economic and demographic characteristics.