Ice jam flood in heilongjiang and the songhua river in 1957年黑龙江及松花江区域性冰坝凌汛初步分析
2.
Firstly , inner mongolia reach lies in the top north of the yellow river . it flows from south to north 黄河内蒙段几乎每年产生凌汛，这是由于它的特殊的地理位置、水文气象条件、河道特性决定的。
3.
Freezing is a general phenomenon in the cold area . ice flood is a rise of water when ice is hindered in river course 冰冻是寒冷地区普遍存在的一种自然现象，而凌汛则是河道里的冰凌对水流的阻力作用而引起的一种涨水现象。
4.
Because of the location and river characteristics , in winter , the ice flood is very serious and often cause ice flood disaster in inner mongolia reach of the yellow river , so it is one of the most important reaches of preventing ice flood 黄河上游内蒙古河段，由于其所处的地理位置及河道条件等因素，冬季冰情严重，经常产生凌汛灾害，为黄河上重点防凌河段之一。
5.
During the melting ice flood season , any reservoir upstream a river or lake responsible for the control of melting ice flood must obtain the consent of the relevant flood control headquarters and be subject to its supervision when discharging its flow down stream 在凌汛期，有防凌汛任务的江河的上游水库的下泄水量必须征得有关的防汛指挥机构的同意，并接受其监督。
6.
In recent years it is more severe because of temperature changes , mankind activities , scouring and silting . the special geographical position , hydrometeorological condition , river course characteristics are main reasons for ice flood 由于近几年来气温的变化、人类活动、河床冲淤等流域环境的变化，使得凌汛的威胁不仅依然存在，而且发生冰害的河段有所增多，影响范围随之扩大。
7.
Thirdly , there are many river bends and shoals in the inner mongolia reach . ice flood will occur in these places at the break - up time . it is valuable and meaningful to make factor analysis for ice flood and model research for freeze - up time and break - up time 第三，内蒙段成几字型大弯曲，其间浅滩弯道叠出，坡度变缓，逶迤曲折，河中多夹心滩，分流窜沟，解冻开河时，常在河道的曲湾或山宽变窄的狭窄段产生凌汛。
8.
The thesis reviews the historic and present situations of the yellow river , makes factor analysis for ice flood , simulates and forecasts freeze - up time and break - up time on the basis of fuzzy set theory . the results are reasonable and precise . in the end , the knotty problems are given to obtain feedback information for the future researches 因此，在研究影响河流冰情的热力因素、动力因素、河势因素的基础上，进行凌汛成因分析并对封河日期、开河日期的预报模型做深入探讨，既有理论价值，也有应用意义。
