Like any surgical procedure, a gastrojejunostomy could result in infection or another complication. A gastrojejunostomy connects the stomach to the jejunum, bypassing the duodenum, the beginning of the intestine at the bottom of this image.
One more thing: Don't make your turtle's water temperature too warm. For most adult aquatic turtle species, 78 F. (25.5 C.) is the highest you want unless you're treating them for an illness and a veterinarian has told you to raise the temperature. Otherwise, too-warm water can encourage bacteria growth in the tank. It also discourages turtles from basking sometimes.
The water depth in this should also be as deep as the turtle is long (carapace length), and a land area is not necessary unless the turtle has been bred or is sick. Instead a flat stone or other item should be placed in one area of the tank to provide a shallower place to rest.