where l denotes seasons (l=1forwet season, l=2 for normal season);
p denotes type of groundwater (p=1 for alluvial aquifer and p = 2 for
karst aquifer); CW is cost of surface water supply (RMB ¥/m3); EFil is
irrigation efficiency of crop i in season l;eR il is water demand of activity
i in season l (m3/km2); and TGpl are decision variables representing
groundwater withdrawal from aquifer p in season l (m3). The total
cost of groundwater supply can be presented by: