Boundary Rhine runs parallel with the King Sedgemoor Drain, although controlled by sluices water from the Rhyne is allowed to flow into the drain at a number of places, this shot is of the outfall at Greylake on King's Sedgemoor.

The Somerset Levels have an area of about 160,000 acres (650 km2) and are bisected by the Polden Hills; the areas to the south are drained by the River Parrett, and the areas to the north by the rivers Axe and Brue. The Mendip Hills separate the Somerset Levels from the North Somerset Levels. The Somerset Levels consist of marine clay "levels" along the coast and inland peat-based "moors"; agriculturally, about 70 per cent is used as grassland and the rest is arable. Willow and teazel are grown commercially and peat is extracted. (Wikipedia)

To give an idea of the drainage system on the levels I have added a previously posted screen grab from openstreemap,

Large view perhaps,,,,,,,,,,,, Wish you all a nice Friday and a good weekend