Gates are defined in the domain as a line section specified as list of points (a minimum of two points is required). The section is composed of the sequence of line segments. The line segments are straight lines between two successive points. The cross section in the numerical calculations is defined as a section of the nearest element faces. The face is included in the section when the line between the two element centers of the faces crosses one of the line segments. The geographical coordinates are taken from the dialog or from an ASCII file. The file format is two space separated floats (real numbers) for the x- and y-coordinate on separate lines for each of the points. The faces defining the line section are listed in the log-file.
You must also select the map projection (Longitude/Latitude, UTM, etc.) in which you want to specify the location of the line section for the gate.