Selects the area for which the force_element_edge_water record with the same index should be applied. By example, -geometry_line 1 can be used in 2D, indicating that the nodes on line 1 get the distributed water pressure force.
Attention: if this force_element_edge_water_geometry option is used INSIDE a FE mesh, then the elements on each side of the geometry will get the force. So you may need to specify only half of the physical force value.