I have drainage basins shapefile, some basins pour water to the east in the Sea and others to the west in the river.

I would like to create the drainage divide line that divides those pouring to the east from those to the west. Just like the red line in the attached picture.

My objective is to get a polygon of the area with a line that run along the polygon dividing the area into to halves; eastern half pour water to the east the other to the west.

Thanks

I have drainage basins shapefile, some basins pour water to the east in the Sea and others to the west in the river.

I would like to create the drainage divide line that divides those pouring to the east from those to the west. Just like the red line in the attached picture.

My objective is to get a polygon of the area with a line that run along the polygon dividing the area into to halves; eastern half pour water to the east the other to the west.