The following figure represents two alternative selections of points for the line approximation in the Surface Area LP Param table. The linear approximation represented by the dashed line corresponds to the selection of points near the extremes of the Volume Area table. This approximation will tend to result in an under-estimation of Surface Area, and thus an under-estimation of Evaporation and Precipitation Volume. Evaporation losses in the post-optimization rulebased simulation would be greater than the losses approximated in the optimization solution. The linear approximation represented by the solid line corresponds to the selection of points closer together in the Volume Area Table, and is more similar to the Tangent approximation. This approximation would tend to result in an over estimation of Surface Area, and the losses due to Evaporation in the post-optimization rulebased simulation would be less than the approximation in the optimization solution.

Surface area vs storage relationship with two alternative line approximations. Not drawn to scale.