( 4 ) by five terraces surrounding the ancient barrier lake , presuming that destroyed process of the ancient barrier lake is at least divided into five phases at the time span of two thousand years to three thousand years , and it reflects the five times flood in the course of the destroying of the ancient barrier lake ( 4 )依据古堰塞湖湖相沉积中存在的五级阶地，说明古堰塞湖至少分为明显的五个阶段突发性消亡的，消亡的平均周期为2 3千年，并且反映了古堰塞湖消亡过程中五次洪水事件的发生。
The paper analysed transformation on hydrology factor after ningxia meili paper mill used its waste water to irrigate its fast - growing forestry , i . e . , groundwater level raised after long irrigation , lake ' s area enlarged and soil became sauna where transition in highland irrigation and lowland irrigation 摘要分析了美利纸业速生林基地用废污水灌溉后引起附近水环境的变化，即随着灌溉水量增加，地下水位升高，湖泊湿地范围扩大；低位灌区与高阶地交接带产生土壤盐渍化。
This theme selected weihe river round tianshui , jinhe river round binxian , bahe river round lantian and luohe river round luochuan to study the evolutionary model of river terraces in the mid - tail of weihe river . we have built the cross - section of each river , and analyzed the evolution of each river terrace in the mid - tail of weihe river according to the velocity of downcuting and lateral erosion 本论文以天水渭南镇段渭河、彬县段泾河、蓝田段灞河和秦家河段洛河为例建立渭河中下游河流阶地演化模式，以阶地形成年代为标尺，根据下切速度和侧蚀速度对渭河中下游各河谷阶地的演化过程进行了分析。
