The Study Of The Characteristic Of Gully System In The Loess Area And Their Effect On Geo-hazards

The landform in loess area are with many ditch and valleys. the valleys with different forms and in different developmental stage will cut the loess plateau into tableland, mound slope and so on different forms of landscape. Gully development not only affects human life and property safety, but also made a great impact on the human engineering activities in loess area. previous make a lot of researches about the formation and development of valleys, mainly concentrated in the development pattern and development stage of valleys, but are short of the study of gully system as a whole.This paper start from the perspective of system theory, based on 973 program "The occurrence, evolution mechanism and control theory of serious disaster and disaster chain to loess", chooses Kong Tong area in Ping Liang as the research area, to make a analysis and research of the formation, characteristics and mechanism of valleys system and disaster-causing effect in a comprehensive system. The main research contents and results are as follows:(1) Development characteristics of gully system. Based on the predecessors’ research of gulch development, make research and investigation of 9 large valleys system in the studied area. the analysis about morphological characteristics and boundary characteristics of valleys system was included, it is found that valleys system in the study area is affected by the uplift of LiuPanShan and internal joint development of loess.We classify them into three types: Straight, bent, and "Y" type according to the form of main ditch, and we made a statistic analysis of the branch ditch‘s extension length on the main ditch’s slope and the altitude difference from the ditch head to the top of the slope.(2) The evolution mechanism of valleys system. some of valleys system’s evolution are cutting the slope from the surface to internal, some are developed along the original joints and fissures in the soil, take underground erosion as development power to grown from internal of slope to the surface, or the complex development that combined with two kinds of evolution model in the same time. On this basis, we put forward the three forms of valleys system evolution model: incised-lateral erosion type, underground erosion-collapse type and complex type, and analyzes the characteristics of the valleys in different mode.(3) The Geo-hazards’ effect of gully system. Through investigation and analysis of the valleys system in the study area, to make the research about the interaction between valleys system and the geological disasters, summarizes the development characteristics of geological disasters in the valleys system.and we discuss the distribution and characteristics of geological disaster in different stages of gully development and in different type of ditch with statistics and analysis.At the same time, the paper analyzes the geological disaster’s influence on gully system development, the research results show that the influence of geological hazards are mainly concentrate in the groove grown direction, the form of groove and the development process.