The simplest approach to measuring crosssectional area is to locate a number of points on the stream bottom by measuring down from the tagline (or yardstick) at regular intervals (see ``'' in Fig. 3.2. Then draw these locations (and the water surface) to scale on graph paper, and count the squares to determine the area. A second method is to approximate the area by a series of rectangles, as shown in Fig. 3.2 and Table 3.2, Sanders (1998). If you measure depth at regular intervals (e.g. 2 cm), then the width of each rectangle is constant.
