东北典型黑土区侵蚀沟形态及分布特征

Morphology and distribution characteristics of erosion gully in the typical black soil region of Northeast China

东北黑土区是中国最重要的粮食生产基地之一,同时也是中国四大水蚀区之一,其中沟道侵蚀是水蚀发生的主要形式,掌握东北黑土区沟道侵蚀的基本情况,剖析其形态及分布特征,对于分析东北黑土区沟道侵蚀的成因及水土流失治理至关重要。该研究以典型黑土区嫩江县为研究区域,利用航空遥感影像及1∶5万DEM对区域内侵蚀沟进行普查统计,并分析侵蚀沟的沟宽、沟长、纵比降等形态特征,以及海拔、坡度、坡向等地形因素对侵蚀沟分布的影响,为黑土区侵蚀沟的治理提供理论依据。研究结果表明:1)沟道侵蚀主要分布在丘陵区,沟道类型以切沟为主,冲沟影响面积仅次于切沟,研究区以小于500 m的侵蚀沟为主,数量及面积分别占总数的96.67%、61.99%;2)侵蚀沟的沟宽与沟长为正相关,纵比降与沟宽、沟长为负相关;3)坡向对各类型侵蚀沟的分布影响较小,坡度对侵蚀沟的分布有一定影响,细沟和浅沟主要分布在2~6°和6~15°的坡面上,而切沟和冲沟则主要分布在0~2°、2~6°的坡面上,90%以上的细沟和浅沟、80%以上的切沟、冲沟发生在耕地上;4)嫩江县冲沟地形阈值模型拟合表明嫩江县冲沟发生的临界坡度较小,较小的坡度就能对坡面形成冲刷,出现冲沟的发生发育,而模型中主导径流过程的参数数值较小,表明嫩江县冲沟的产生可能受到地下过程的影响。

The black soil region of Northeast China is one of the most important grain production bases in China.It is also one of the four major water erosion areas in China,in which the erosion gully is the main form of water erosion.In order to analyze the causes of gully erosion and evaluate the basic situation of gully erosion in the northeast black soil area,it is necessary to analyze its morphology and distribution characteristic of gully erosion.In this paper,Nenjiang County was taken as the study area,which is located in the northwest of Heilong province,China.The aerial remote sensing images with ground resolution of 0.2 m and 1:50000 Digital Elevation Model(DEM)were used to carry out census and statistics on the erosion gully,and the morphological characteristics such as the gully width,gully length and longitudinal slope of the erosion gully were analyzed,as well as the influence of terrain factors such as elevation,slope and aspects.The results of the second land use survey in China were used to obtain the land use situation around the erosion ditch.The results showed that:1)The number of erosion gullies in Nenjiang County was 38426,and the whole area of the erosion gullies were 16277095 m^2.The erosion gully mainly occurred on hilly area,and was dominated by gully erosion,accounting for 74.50%and 51.05%of the total number and area,respectively.The next type was modern incised valley.Erosion gullies were mostly less than 500 m.2)The width and length of the erosion gullies were positively correlated,and the slope was negatively correlated with the width and length.3)Compared with slope,aspects generally had a little effect on the distribution of erosion gullies.Rills and ephemeral gullies mainly distributed on slopes of 2~6°and 6~15°,and gullies and modern incised valleys mainly distributed on slopes of 0~2°and 2~6°.More than 90%of rills and ephemeral gullies,and 80%of gullies and modern incised valleys were occurred on cultivated land.4)Although the topographic threshold model of gulley in Nenjiang County was not fitted well,it could still be used to analyze the process of gully erosion.The model showed that the critical slope of the modern incised valley was small,the parameter which expressed the gully erosion process reflected the occurrence and development of the gullies might be influenced by the underground process.