This specification is formulated with a view to standardizing the content, methods, and technical requirements of the reservoir area engineering geological investigation of hydropower projects, to ensure the investigation quality.　This specificationis applicable to the reservoir area engineering geological investigation of large-sized hydropower projects or the medium-sized hydropower projects with complex geological conditions.　In addition to this specification, the reservoir area engineering geologicalinvestigation of hydropower projects shall comply with other current relevant standards of China.