Background River crossâ€sectional areas are required for several tasks in water resources engineering, including flood forecasting and reservoir designing. Unless electronic sounding devices are available to obtain continuous profiles of the channel bottom, the engineer must rely on discrete depth measurements to estimate the river crossâ€sectional areas. An example of a river cross section is shown in Figure 5 below. The data points represent locations where a boat was anchored, and depth of the river was taken. Numerical methods can be used to estimate the crosssectional area from this data. The sectional volume of the river can be estimated if multiple crossâ€sectional areas are obtained along the length of the river.