Operators of dams that control flood discharge using gates have recently faced high demand for dam reconstruction by removing the gates to introduce the natural regulation method, or for an end to the preliminary discharge system at dams which use this method, in order to reduce the risk of a delayed gate operation caused by the narrow area of the river basin, reduce the number of management workers, and cut the cost of gate maintenance and renewal.

The Japan Dam Engineering Center is responding to such demands by studying plans to remove the gates from gated dams to transform them to natural regulation dams and to increase the height of the dam body to increase the reservoir capacity, eliminating preliminary discharge system. The JDEC also studies and evaluates the preliminary design of dam upgrading.