The cross-section of a river can be determined by measuring the width of the river and riverbank as well as the depth of the water. This data can be used to create visual representation of what the river looks like.
People can use hand tools such as a tape measure and surveying pole to measure the cross-section of a river. However, organizations such as the United States Geological Survey use modern methods. These include GPS data, laser range-finders and echo sounders. The information compiled from multiple river cross-sections can be used for research projects to determine hydraulic flow and fish populations.