坡耕地增长对沟谷发育的影响——以四川西昌大箐梁子为例

为了研究近50 a来土壤加速侵蚀的状况和原因,收集了四川西昌大箐梁子1957年、1979年、2000年航空影像,应用立体像对获取高程信息生成DEM,并利用DEM纠正航片获取正射影像。同时,利用三期正射影像获取土地利用变化和沟谷变化信息,通过野外调查与验证,分析了沟谷形成、发育特点及与坡耕地增长的密切关系。研究表明,西昌大箐梁子沟谷发育,到1957年已形成部分稳定或半稳定冲沟,1970年代后期,大量草地被开垦为耕地,且多为坡耕地,土壤抗蚀能力降低,土壤侵蚀由此加剧,沟蚀增强,人为加速了沟谷侵蚀的发育。

Study on the Responses of Gully Develop to Plough Land Changes——Taking Daqingliangzi of Xichang in Sichuan Province as Examples

Gully erosion is one of the serious ecological and environmental issues in the lower reaches of Jinsha river.Because of gully erosion land resources was destroyed and sediment in the river was increased.In order to protect land resources and decrease sediment from this area,it is necessary to discuss causations of rapid development of gully erosion.Land use types have been changed in the last 50 years at Daqingliangzi of Xichang in Sichuan province.Aerial photos of this area in 1957,1979 and 2000 are obtained.DEM is generated from these aerial photos.Orthophotos are made with the DEM and photos.Then the information of land use and gully in three period are obtained from these orthophotos.It is analysed the consanguineous relation between gully and land use.It is showed that some gullies had formed before 1957 and they had been steady or near steady.But many sidehill grass land were dig up to plough land in 70s' of twenty century,the soil erosion resistant ability was receded.Soil erosion,especially gully erosion,was intensified.Some old gullies expand fast.Some new gullies formed rapidly.Land resources are destroyed.