Study on river regime evolution of Baguazhou Reach of Yangtze River and regulation countermeasures in Nanjing City

Through collecting hydrologic and topographic data in Baguazhou Reach of Yangtze River in Nanjing since 1960s,we analyze the recent river regime evolution characteristics and its evolution trend.At present,the diversion ratio of left branch is reducing slowly,which is a threat to the regular operation of the important wharfs on the left branch.In view of the problems existing in Baguazhou Reach and economic development requirement of the regions on both banks,we discuss the countermeasures for regulating the river reach.The regulation schemes including fish mouth regulation,bend bypassing of the entrance of left branch and dredging and widening are studied using mathematical models.The results show that we should remove the barriers at Shangba and Huangchanghe inside the inlet at the same time,so as to obtain the maximum increase of absolute diversion ratio of the left branch.