Trapezoidal:

\[ t = b + 2d \cdot z \]

Triangular:

\[ t = 2d \cdot z \]

Parabolic:

\[ t = \frac{A}{0.67d} \]

Where:

• \(t\) is the top width in meters (m).
• \(b\) 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.
• \(A\) is the cross-sectional area in square meters (m²).