The River Bourne then by a manmade channel turns east instead of running the final 100m into the Upper Chertsey Reach; joining the River Thames below the southern weir of Shepperton Lock and its many islands, which due to the barraging of the Thames provides (as was possible before the Thames weirs were built) a greater fall.
The River Bourne then by a man-made watercourse turns east instead of flowing into the Upper Chertsey Reach; merging with the River Thames below Shepperton Lock and its many islands, which due to the creation of the Thames dams enables (as was possible before the construction of the weirs) a steeper incline.