The following figure shows the correction coefficient as a function of the angle of face inclination (θ). A zero angle corresponds to a vertical facing.

Correction coefficient for cos2(teta) and Corn et al. (1988)

For the distribution according to the Cos2(teta) method, the coefficient is calculated according to the following formula:

USBR (1987) considers the following for inclined faces (see figure below):

For dams with a combination vertical and sloping face, the procedure to be used is governed by the relation of the height of the vertical portion to the total height of the dam as follows:

• If the height of the vertical portion of the upstream face of the dam is equal or greater than one-half of the total height of the dam, analyse as if a vertical throughout.
• If the height of the vertical portion of the upstream face of the dam is less than one-half of the total height of the dam, use the pressures on the sloping line connecting to the point of intersection of the upstream face of the dam and reservoir surface with the point of intersection of the upstream face of the dam and the foundation.

USBR (1987) slope correction for an inclined upstream face