def setOutlet(self, col, row, outslope=None):
        """
        Sets the outlet grid cell information in the project file.

        Parameters:
            col(float): 1-based column index.
            row(float): 1-based row index.
            outslope(Optional[float]): River slope at outlet.
        """
        #OUTROW, OUTCOL, OUTSLOPE
        gssha_grid = self.getGrid()
        # col, row = gssha_grid.lonlat2pixel(longitude, latitude)
        # add 1 to row & col becasue GSSHA is 1-based
        self.setCard(name='OUTROW', value=str(row))
        self.setCard(name='OUTCOL', value=str(col))
        if outslope is None:
            self.calculateOutletSlope()
        else:
            self.setCard(name='OUTSLOPE', value=str(outslope))