I am using r.watershed to create watershed basins using a 25*25m dem.
The problem I have is that basins are not always created at coast lines. I am experimenting with the parameter "minimum size of exterior watershed basin", which controls the minimum number of pixels required to make a basin. If i set this value to say 1-50 I get basins created at coastlines but they are very narrow. If I choose a large value 400+ i get reasonable sized basins but they are are not always created at coasts.
Image - the yellow shaded area is a basin, but the area immeadiately to the left is not a basin.
Is there a way to get basins that cover all areas on the DEM? or is this the correct "behaviour"?