Fig.7 Hydroelectric power station on Yuhong subterranean stream.
Huaihua county, Hunan province.
1. upper part of upper Permian; 2. lower part of upper Permian; 3. limestone and dolomite;
4. siliceous rock; 5. carbonaceous shale; 6. subterranean stream; 7. underground arch dam;
8. pipe line and HE power station.