An increasing number of dams have been constructed on sites marked by complex geological conditions, requiring detailed geological investigations not only of the dam site, but also of the slopes around its reservoir, Quaternary faults, and dam body materials, etc., but these investigations must be efficiently carried out in order to appropriately lower costs. Thus, the Japan Dam Engineering Center makes advanced technological judgments by applying the most sophisticated investigation technologies such as high-quality sampling, and bore-hole televisions, improving the efficiency of geological investigations and analyses.

By systematically compiling data on faults, joints, hydrothermal alterations, weathering and other geological phenomena that severely impact the construction of dams, and nationwide cases of geological investigations and design, and by proposing survey and design methods adapted to geological conditions and hydrogeological structures at the dam sites, the JDEC contributes to the construction of dams at sites which have unsuitable geological and/or hydrogeological conditions.

For example, as shown by the following diagram, at sites where multiple pyroclastic flow deposits are complexly distributed and it has been extremely difficult geologically to construct dams, appropriately clarifying their distribution and properties permits rational design such as artificial abutments or a reservoir impervious blanket and the construction of dams. At sites where large-scale deteriorated zones are distributed, clarifying the hydrogeological structure permits the effective use of a deteriorated zone as an impervious layer and greatly reduces the cost of foundation treatment.