龙羊峡库区威连滩冲沟沟头侵蚀的动态监测

采用Trimble GX 3D激光扫描仪、Trimble 4700和集思宝E718CM差分GPS等测量手段，通过对龙羊峡库区威连滩冲沟南侧支沟的沟头连续4 a（2006-2010年）的地形监测，结合野外调查和气象资料分析，初步探讨了沟头溯源侵蚀量、侵蚀成因以及沟头的发育规律。结果表明：① 2006年沟头边岸形状破碎，为后期的侵蚀提供了有利的地形条件。沟头经过3 a的侵蚀，侵蚀面积显著增加，主要表现在南岸一侧的张裂缝区。从2007-2010年中，2009年沟头侵蚀最严重。② 反复的冻融和干湿交替形成的张裂缝不但加强了雨季的流水侵蚀，同时由张裂缝引起的土体坍塌也增强了沟头侵蚀。③ 研究区沟头严重的侵蚀并不是发生在侵蚀性降水多发的年内，强降雨引发的山洪是沟头发生强烈侵蚀的重要动力。

Dynamic Monitoring on Gully Head Erosion on Weiliantan Terrance in Longyangxia Reservoir Area

The gully head of south branch gully on Weiliantan Terrance in Longyangxia Reservoir area was monitored by laser 3D scanner,Trimble 4700 differential GPS and sub-meter differential GPS.After surveying the gully head erosion for 4 years(2006-2010) in field work and analyzing the meteorological data,this paper estimated primarily the erosion amount,and discussed the erosion causes and the gully head development.The results show that the fragmented form of the bank at the gully head in 2006 provided a favorable terrain for erosion in the following years.After 3 years,the erosion area was enlarged significantly,especially in the tension crack zone of the south bank.The scanning data during the period from 2007 to 2010 revealed that the headward erosion was the most serious in 2009.The tension cracks were resulted in by the repeated alternation of freezing-thawing and wetting-drying process,which not only strengthened soil erosion in rainy season,but also intensified the erosion of gully head through destroying soil structure and causing soil collapse.The obvious increase of gully headward erosion did not occur in the years when there was more frequency erosive rainfall,but it could be easily caused by flood disaster under heavy rainfall,and flood disaster was an important power for the gully head erosion.