Trapezoidal:

\[ A = b \cdot d + z \cdot d^2 \]

Triangular:

\[ A = z \cdot d^2 \]

Parabolic:

\[ A = \frac{2}{3} \cdot t \cdot d \]

Where:

• \(A\) is the cross-sectional area in square meters (m²).
• \(b\) is the base width of the channel in meters (m).
• \(d\) is the depth of water in meters (m).
• \(z\) is the canal slope (h/d), in decimal form.
• \(t\) is the top width in meters (m).