Complex sentence: The River Gade and the Grand Union Canal join the upper River Colne near Rickmansworth's eastern boundary and are joined by the River Chess near the town centre from where the enlarged Colne flows south to form a major tributary of the River Thames.
Split into simpler sentences: The River Gade and the Grand Union Canal join the upper River Colne near Rickmansworth's eastern boundary and are joined by the River Chess near the town centre. The much enlarged Colne flows south to form a major tributary of the River Thames.