The flood control regulation line in the downstream part of Wanquan River is a control line to keep the flood passing safely and to stabilize the river regime. The regulation line is the fundamental basis for the development and management of the river, is the control line at the outer edge to develop and construct the Zone, as well as the control conditions of the overall plan in the Zone. The conflicts between land development and flood passing safely could be coordinated by the flood control regulation line. Then under the premise of keeping the flood passing safely, the land resources on the beach could be reasonably protected, developed and utilized, promoting regional sustainable development of economic society.
The plan on the two banks of the river in the Zone stipulates the flood control standards as appearing once every 20 years (it could be up to appearing once every 30 years under the regulation of Hongling reservoir)., and the standard in Lecheng Island is appearing once every 50 years.