堰塞湖定义
堰塞（sai）湖
堰塞湖是由火山熔岩流，或由地震活动等原因引起山崩滑坡体等堵截河谷或河床后贮水而形成的湖泊。由火山溶岩流堵截而形成的湖泊又称为熔岩堰塞湖。
必须强调说明，堰塞湖的堵塞物不是固定永远不变的，它们也会受冲刷、侵蚀、溶解、崩塌等等。一旦堵塞物被破坏，湖水便漫溢而出，倾泻而下，形成洪灾，极其危险。
堰塞湖一旦形成威胁，必须事先以人工挖掘、爆破、拦截等方式来引流或疏通湖道，使其汇入主流流域或分散到水库，以免造成洪灾。
堰塞湖形成过程
1、原有的水系。
2、原有水系被堵塞物堵住。堵塞物可能是火山熔岩流，可能是地震活动等原因引起的山崩滑坡体，可能是泥石流，亦可能是其他的物质。
3、河谷、河床被堵塞后，流水聚集并且往四周漫溢。
4、储水到一定程度便形成堰塞湖。
堰塞湖多见地区
由山崩滑坡所形成的堰塞湖多见于藏东南峡谷地区，且年代都很新近，如1819年在西姆拉西北，因山崩形成了长24-80km，深122米的湖泊。藏东南波密县的易贡错是在1990年由于地震影响暴发了特大泥石流堵截了乍龙湫河道而形成的，波密县的古乡错是1953年由冰川泥石流堵塞而成，（实则也属冰川湖）。八宿县的然乌错是1959年暴雨引起山崩堵塞河谷形成的。
台湾地震活动频繁，1941年12月，嘉义东北发生一次强烈地震，引起山崩，浊水溪东流被堵，在海拔高度580m处溪流中，形成一道高100m的堤坝，河流中断，10个月后，上游的溪水滞积起来，在天然堤坝以上形成一个面积达6.6km2，深160.0m的堰塞湖。
最新的堰塞湖是2008年5月12日汶川大地震导致的堰塞湖。
堰塞湖的危害
堰塞湖的堵塞物不是固定永远不变的，它们也会受冲刷、侵蚀、溶解、崩塌等等。一旦堵塞物被破坏，湖水便漫溢而出，倾泻而下，形成洪灾，极其危险。堰塞湖,是指地震等原因引起的山崩滑坡体,堵截河谷或河床后贮水而形成的湖泊。
灾区形成的堰塞湖（海子）一旦决口后果严重。
伴随次生灾害的不断,堰塞湖（海子）的水位可能会迅速上升,随时可发生重大洪灾。
堰塞湖（海子）一旦决口会对下游形成洪峰,破坏性不亚于灾害的破坏力。
Cypriot Weir (sai) Lake
Yan Sehu by the lava flow, or by seismic activity such as landslides caused by landslides, such as the interception of the river valley or after the formation of the lake water. Karst flow from the volcano which formed the interception of the lava lake is also known as Yan Sehu.
Must be stressed that Yan Sehu the plug was not fixed will never change, they will be subject to erosion, erosion, dissolved, collapse, and so on. Once the plug of the destruction, it Manyi out of the lake, and caving in under the formation of the floods, extremely dangerous.
Yan Sehu Once a threat, prior to artificial excavation, blasting, such as ways to block or clear the drainage Lake Road, into the mainstream so that the reservoir basin or distributed, so as to avoid floods.
Yan Sehu formation process
1, the original water system.
2, the original water system was plug-block. Plug may be of volcanic lava flows, may be caused by seismic activity such as the landslides landslide, mud-rock flow may be, may also be other material.
3, Valley, the river was blocked, and to gather around the water Manyi.
4, water to a certain extent it formed Yanse Hu.
Yan Sehu多见region
Landslide by landslides formed by Yan Sehu more common in southeast Tibet Gorge region, and the very recently, such as the 1819 Simla in the Northwest, because of landslides formed a long 24-80 km, the lake 122 meters deep. Bomi County, southeast Tibet is wrong Yigong in the 1990 outbreak of the seismic impact of the large landslides blocked Pottinger-long river formed by Qiushui, Bomi County, the ancient township is wrong in 1953 by the landslides blocked from glaciers, (also a reality Glacier Lake). Basu County, the Ukrainian contingent is wrong in 1959 rainstorm caused a landslide blocked the river valley.
Taiwan's frequent earthquakes, in December 1941, Chiayi a strong earthquake in the northeast, caused landslides, Choshui River east Pidu, 580 m above sea level in the river, forming a 100 m high dam the river suspended, 10 months after , The upper reaches of the river lag plot, in forming a natural dam over an area of 6.6 km2, the Yan Sehu 160.0 m deep.
Yanse Hu is the latest on May 12, 2008 earthquake led to the Wenchuan Yanse Hu.
Yan Sehu hazards
Yan Sehu the plug was not fixed will never change, they will be subject to erosion, erosion, dissolved, collapse, and so on. Once the plug of the destruction, it Manyi out of the lake, and caving in under the formation of the floods, extremely dangerous. Yan Sehu, refers to earthquakes and other causes landslides landslide, or the interception of the river valley after the formation of lakes and water.
Formation of the disaster areas Yanse Hu (Haizi) once the breaches serious consequences.
With the continuous secondary disasters, Yan Sehu (Haizi) the water level may be rising rapidly, major floods can occur at any time.
Yan Sehu (Haizi) Once a crevasse on the downstream flood peak, the devastating disaster of not less than destructive.
