凌汛危害及其防护措施

Harmfulness of Ice Flood and Protection Measures

凌汛是在冬春季节江河水流受冰凌阻碍而引起的涨水现象。凌汛的发生与江河所处的地理位置密切相关，由于河流下游段的纬度高于上游段，因而产牛封冻时下段早于上段，解冻时下段迟于上段，再加上江河中一些河段弯曲狭窄，在封冻流冰期，易形成冰塞洪水；在解冻流冰期，易产生冰坝洪水，其结果轻则漫滩，重者决堤成灾，造成很大灾害。我国在防凌汛洪水措施方面积累了较丰富的经验，在实践中逐步认识到凌汛的产生是由于热力和动力因素共同作用的结果。除采用人工打冰、破冰船破冰、炸药爆破、群炮轰冰以及飞机投炸弹破冰等一系列措施外，还可利用上游水库控制下泄水量，利用江河沿岸水闸宣泄槽蓄水量，以减少开河期上游来水量及河道槽蓄水量，均可减免凌汛洪水灾害。

Ice flood is the phenomenon of river rising caused by water flow blocked with ice in winter and coming spring, and ice flood is closely related to the geographical location of the river. Suppose a river is with higher Lantitude in its lower reaches than that of its upper reaches, the lower reaches will be iced earlier and thawed later than the uppers, and especially in some narrow and meandering reaches which are easy to form ice block and water rising in frozen period, and as well as form ice dam causing flail in thawing period. The results are either overbank or broken bank to cause significant disaster. In order to protect the ice flood, the method of ice broken by men, ice-breaking-ships, explosion, drop bomb by aircraft, etc, besides, such measures can be also employed to alleviate the harmfulness of ice find as controlling the coming water flow upper reaches through the upper reserviors to reduce water intake and discharging the river storage flow through the gates along the river to deduct the flow storage in river channel.