克拜东部黑土区侵蚀沟遥感分类与空间格局分析

近百年来,东北黑土区侵蚀沟的大量发育带来了一系列严重的社会经济问题,弄清侵蚀沟的类型、数量及分布情况是进行水土流失治理和生态环境建设的前提条件。以黑龙江省克拜东部黑土区作为典型研究区,采用2005年SPOT-5高分辨率卫星影象,结合野外调查,根据侵蚀沟的活跃程度,将黑土区的侵蚀沟分为活跃性、半活跃性和稳定性三种类型,阐述了不同类型侵蚀沟的影象特征和遥感分类方法,为利用遥感手段在区域尺度上对侵蚀沟进行快速调查提供了一种新途径。在对侵蚀沟进行信息提取和空间插值后,形成研究区不同类型侵蚀沟密度图,探讨了克拜东部黑土区侵蚀沟分布的空间格局特征及其影响因素,认为地貌发育过程中的“分水岭迁移”现象是造成该地区侵蚀沟密度东西差异的重要原因。

Classification of Erosion Gullies by Remote Sensing and Spatial Pattern Analysis in Black Soil Region of Eastern Kebai

Gully erosion is an important part of the soil erosion process and their occurrence and development may cause serious problems to a region's agricultural sustainable development.Nowadays,wide and deep gullies can be commonly observed in Black Soil Region of Northeast China,owing to unreasonable land use option and human activities in the past 100 years.Some new technology such as Global Position System(GPS),phtogrammetry,and so on,is often used to study the process of gully development at local scale.But the research of gully distributing patterns at larger spatial scale is rarely reported.In this paper,taking black soil region of the eastern Kebai as a case study area,the SPOT-5 high resolution image was used to study the gully types,image character and their distribution on a regional scale.Since more active gullies have sparser vegetation cover,this study classified the gullies into three types(active gully,semi-active gully and stable gully) by their stage of development which can be estimated by fractional vegetation cover at gully bottom.The Normalized Difference Vegetation Index(NDVI) was used to calculate the average fractional vegetation cover of gullies.The image character of the erosion gullies is also described in detail.The gully density maps were made to show the spatial distribution character for each type of gullies.This study revealed that gully distribution is influenced by many factors.Gully density first increases sharply when slope degree increases,then decreases when the slope angle goes beyond 8 degree.Gully distribution is not uniform on each slope aspect,and highest gully density occurs at west and southwest side of the slope.Gully density also varies as altitude increases. It reaches the peak when altitude ranged from 210m to 280m.There is a great difference in gully density on two sides of the ridge between Runjin,Shuangyang and Tongken river systems.Most of the erosion gully occurs on the east side of the ridge,owing to the ridge migration in the natural process of landform evolvement.This result revealed that at local scale,gully occurrence is often influenced by such factors as slope steepness,vegetation cover,farm management,etc.,but at regional scale,the natural process of landform evolvement can not be negligible and may become a significant factor on gully distribution.This result indicates that constructing more reservoirs and dams across valleys is an effective way to control soil loss in Black Soil Region of Northeast China,as it can raise the base level and control the velocity of running water.