【摘要】 陕西华县于1556-01-23(明嘉靖三十四年十二月十二日)深夜,发生里氏814级地震,死亡83万人,成为世界罕见的特大灾难。地震期间和地震以后,由于震动荷载作用,地震区岩石破碎,发生了大范围崩塌灾害,为水石流发育提供了丰富的固体物质。震后450 a(1556~2006年)以来,这些碎屑物质在暴雨激发下,多次暴发水石流,在山前洪积扇和平原地区,造成了严重灾害和巨大损失;同时,也形成了地形上的淤积,改变了局部地形条件,使得该区容易遭受洪水灾害。1960年三门峡大坝建成蓄水之后,渭河下游淤积了大量泥沙,河床抬升,成为地上河,与从秦岭北坡沿溪流出山口向下发育的洪积扇共同作用,形成了地形相对下凹的"二华夹槽",这里常受洪水侵袭,损失巨大,严重危害人民生命财产安全,影响经济发展。更多还原

【Abstract】 On the night of January 23,1556,an earthquake of 8.25 Richter magnitude hit Huaxian,Shanxi Province,with 830 thousands people died. In addition,the earthquake induced widespread rockfalls and landslides,providing tremendous quantity of materials for debris flows.In the last 450 years after the earthquake,these fragments of materials often turn into debris flows at the triggering of rainstorms,which have caused serious disasters and large losses in the alluvial fans and plains in the mountain front.Moreover,debris-flow depositions have changed the local landform which is favoring flood.Since the construction of the Sanmenxia dam in 1960,a great deal of sediment has deposited in the lower Weihe River,causing the silt up of riverbed.And combining the fluvial fan developing in the outlets of valleys on the north slope of Qingling mountain,there formed a depression which is often attacked by calamities of flood.更多还原