ABSTRACT:

Though levees are a widely used flood mitigation infrastructure in the United States, levees displace inundation, shifting flood risk to nearby areas with substantial environmental and social justice implications. To support research on whole-channel hydraulic and morphologic shifts associated with levee construction, this dataset defines the upstream, downstream, cross-stream, and leveed hydraulic reach of 60 levees constructed between 1995 and 2005 in the USACE National Levee Database 2 ("NLD2", https://ags03.sec.usace.army.mil/server/rest/services/NLD2_PUBLIC/FeatureServer).

Each shapefile is named using the "Levee ID" in the NLD2. Each shapefile contains 4-8 polygons corresponding with different hydraulic reaches (upstream, downstream, adjacent, protected/leveed), with multiple hydraulic reaches of the same class indicating a multi-channel levee. The attribute "Polygon" in each shapefile contains a letter indicating the class of hydraulic reach.
1.P--Protected: the land surface area between the channel center and extended floodplain. The levee was constructed to reduce flood risk in this area.
2. A--Adjacent: the land surface area on the same side of the levee as the affected water body, or across the channel from the water body.
3. S--Setback: a design feature used to reduce along-channel flooding. The land surface area between the levee and channel; the NLD will detail whether or not a setback has been included in design.
4/5. U/D-- Upstream/Downstream: this is the land surface area within the affected channel floodplain and within the upstream and downstream hydraulic reach of the structure where there may be hydraulic impacts (alterations in the discharge/inundation relationship) with levee construction.