Reduced Leakage with Multi-cell OL

The Surface-Subsurface Leakage Coefficient is used if it is specified. How­ever, it is used differently if the option to use it only in ponded areas is selected (this option is only available if the Multi-cell OL is turned on.

Thus, the two mechanisms are:

·         Reduced contact only in ponded areas (activated). Leakage coefficient is only used in the ponded areas and not in the non-ponded areas.

·         Reduced contact only in ponded areas (not activated). Leakage coeffi­cient is used in both the ponded and the non-ponded case.

The two infiltration calculations (for the ponded and the non-ponded case) result in two infiltration rates from which an area weighted infiltration rate, QinfAWghtd, is calculated:

(25.3)   QinfAWghtd = Qinfntpd x (1 - PAreaFrac) + Qinfpd x (PAreaFrac)

where Qinfntpd is the infiltration rate from the non-ponded area, and Qinfpd is the infiltration rate for the ponded area. The area weighted infiltration rate is then used in the final UZ calculation (when reduced contact is not used).