严重淤积 meaning in English

damaging deposition
damaging sedimentation

By the analysis and study , it is showed that : 1 ) the lower weihe river main channel was at a balanceable state between aggradation and degradation and floodplain of the lower weihe river is a tiny aggradation state before the construction of the sanmenxia dam ; 2 ) the severe aggradation of the lower weihe river bed is mainly caused by the increasing riverbed elevation at tongguan after the construction of the sanmenxia dam ; 3 ) the main reason leading to the increasing riverbed elevation at tongguan is the unreasonable operation of the sanmenxia reservoir ; 4 ) the rate of the riverbed aggradation at tongguan reach and the lower weihe river reach are speeded by adverse condition of incoming water and sediment recently
然后以实测资料为基础分析研究了三门峡建库前后潼关高程的变化规律以及渭河下游河道的冲淤演变规律，分析研究表明：建库前渭河下游主槽处于动态冲淤平衡状态，滩地处于微淤状态；建库后，渭河下游河道发生严重淤积主要是由于潼关高程的抬升造成的；潼关高程的抬升主要是由于三门峡水库的不合理运用造成的，近期不利的水沙条件加剧了潼关河床的抬升速度和渭河下游的淤积。