What do cross sections describe in relation to floodplain mapping?

Cross sections in floodplain mapping refer to the detailed vertical profiles of the landscape at specific locations. They illustrate the shape and dimensions of the floodplain by showing how the ground rises and falls across a given area. This information is crucial for understanding how water might flow during a flood event and how the topography can impact flood risk. By analyzing the shape of the floodplain through these cross-sections, planners and engineers can better assess flood vulnerabilities, design flood mitigation measures, and create effective emergency response plans. This foundational understanding of the floodplain's geometry is integral to accurate floodplain management and development planning.