Analysis of navigation hindering characteristics and regulation principle of shoal group reaches of mountain rivers

The shoal group reach distributes widely in the southwest mountainous river.Compared with a single shoal reach,the navigation environment of the shoal group reach,which consists of a lot of shoals or rapids sections close to each other,is complex and more difficult to be regulated.By analyzing the sketch features,navigation hindering characteristics and regulation experiences of different shoal group reaches,the navigation hindering features and the general regulation principles which should be followed are summarized.Though the navigation hindering characteristics of each shoal section are different,the characteristics of the shoal group reach are generally associated with the river regime characteristics of the long reach where the shoal group exists.The regulation of the complex shoal group should conform to the river regime,consider the influence of adjacent shoal section,and focus on improving the navigation environment of the controlled shoal section.For sand pebble shoal group,the sediment transport balance of shoal reaches after regulation should be considered too.