Abstract: The vertical closure difficulty can be divided into three key problems such as dumped rock-block stability, river closure scale and safety degree of river closure. Dumped rock-block stability involves several hydraulic parameters, such as closure gap, river foundation and closure materials, human elements etc. River closure scale involves the river hydrology peculiarity and diversion condition etc. Degree of safety primarily relates to the embankment head collapse etc. In this article, by analyzing all influencing factors and their correlation degrees, the measures to reduce the difficulty of vertical closure are summarized such as the optimization of diversion capacity, head fall distribution and control of river closure with double embankments, wide banch effect and application, strengthening anti-scour stability of closure blocks, enhancing closure safety degrce by dumping cushion layer on the river bed, as well as cascade reservoir regulation, dumping method optimization and increasing dumping intensity etc. In addition, related problems and countermeasures of vertical closure under the condition of deep soft-foundation coverage layer are discussed.

Key words: vertical closure   , difficulty of river closure  ,  , hydraulic parameter  ,    material peculiarity  ,   bed surface roughness  , deep thick covering layer  , bottom protection technology