The RIP: Riparian Evapotranspiration package pane is on the MODFLOW Features tab of the Object Properties dialog box.
The data that can be specified for the Reservoir package are the Starting time, Ending time, Ground Elevation, and fractional coverage (fCov) of each plant group.
Starting time and Ending time are explained in the help for the MODFLOW Features tab.
It is used to define the ground surface elevation and the fractional coverage of each plant group in the cells in the Riparian Evapotranspiration package of MDOFLOW-OWHM.
The ground surface elevation within a cell may be varied by defining multiple objects that either intersect or enclose the center of the cell. Each such object can define a different ground surface elevation. However, it is important to note that formulas that are always evaluated at the centers of objects.
One way to assign the coverages for the plant groups would be to use non-overlapping polygon objects that have both Set values of enclosed cells, and Set values of intersected cells checked. Each polygon object would define a non-zero coverage for just one plant group. The formula "ObjectIntersectArea / BlockAreaTop" would return the proper coverage for each cell. If an object would define non-zero coverages for for more than one plant group, the above formula could be multiplied by the fraction of each plant group within the polygon object.
