Faculty of Water Conservancy Engineering;
North China University of Water Conservancy and Eleetric Power;
Zhengzhou 450011;
P. R. China;
College of Planning and Architectural Engineering;
Henan University of Science and Technology;
Luoyang 471003;
P. R. China;
College of Water Conservancy and Hydropower Engineering;
Hohai University;
Nanjing 210098;
P. R. China;