A typical method of redeveloping an existing dam by expanding its reservoir capacity is raising the height of the dam body. Improving its function in this way effectively lowers the costs and permits the use of the effective capacity obtained by raising the dam height to control flood discharge or to supply water. Work to increase the height faces different technological challenges from those when constructing a new dam, because the work is done while the dam is operating and requires that the existing and new parts of the dam body be appropriately integrated. The Japan Dam Engineering Center provides technological assistance with dam height raising projects from specialized perspectives ranging from design and execution planning to execution methods.

Completed in 2006, the redevelopment of the Shimonohara Dam operated by the Water Bureau of Sasebo City in Nagasaki Prefecture is an example of raising the height of the dam body. The Shimonohara Dam redevelopment faced problems such as integrating the existing and new parts and ensuring the safety of the existing dam during execution while maintaining the reservoir water level, so the Japan Dam Engineering Center provided advice regarding these and other technological challenges that arose as the work progressed.