Stream cross-sectional areas (A) are required for a number of 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 compute A. An example of a typical stream cross section is shown in Figure. The data points represent locations where a boat was anchored and depth readings taken. Use two trapezoidal rule applications (h = 4 and 2 m) and Simpson’s 1/3 rule (h = 2 m) to estimate the cross-sectional area from this data.

Water surface 1.8 3,6 3,4 2,8 10 20 Distance from left bank, m Depth, m 2.