Research On The Relationship Between Landslide Development And Water System Evolution In Northern Shaanxi

Northern Shaanxi is located in the Loess Plateau,with broken terrain and ravines.Most human settlements are located in wide valleys.The geological environment is fragile,landslides,collapses and other geological disasters occur frequently,seriously endangering the lives and property of local residents.Landslide is the main geological hazard in the study area.Field investigation shows that landslides are mostly developed in river valleys or river valley slopes,and pebble layers with different thickness and good roundness are often developed on river valley slopes.As a sign of river terraces,it is proved that there are perennial or intermittent water flow here,and it is also indirectly proved that there is a direct correlation between the development of landslides and the evolution of rivers.The evolution of rivers is mainly reflected in the distribution and characteristics of terraces.The terraces of terraces not only record the evolution history of rivers,but also record the crustal tectonic movement,regional climate change and erosion base level change.After a long period of tectonic movement,the crust of the study area was uplifted and the valley was cut.There are different levels of river terraces in each basin,with obvious characteristics.The terrain is constantly divided,and the external dynamic erosion also produces landslides.So,what is the relationship between the development of landslide and the evolution of river? This article takes this as the starting point,has carried on the discussion in the article.This paper mainly through the collection of data and field investigation,analyzes the geological conditions,landslide types and landslide distribution law of landslide development in the study area,and uses the fractal theory to analyze the influencing factors of landslide disaster,and discusses the influence degree of each influencing factor on landslide disaster.Taking the typical rivers in the study area as the research object,the types and distribution characteristics of river terraces are discussed,the spatial distribution pattern of river terraces is constructed,the formation time and cutting rate of terraces are calibrated,and the response of river evolution to mountain uplift is discussed through the evolution characteristics of river terraces.According to the evolution characteristics of river terraces,the interaction between river evolution and landslide development is analyzed.The main results and conclusions are as follows(1)The influencing factors of landslide development in Northern Shaanxi include:elevation,slope,slope height,slope type,slope aspect,lithology grouping,cutting depth,river distance,precipitation,etc.The fractal theory is used to discuss the influence of various factors on the development of landslide.The results show that: rock group > elevation > slope type >River distance > cutting depth > slope height > rainfall > vegetation coverage > slope aspect.(2)In the investigation of river terraces,there are no five terraces t1-t5 in Wuding River,Yanhe and Luohe,and four terraces T1-T4 in Qingjian River.Taking Yanhe River as an example,the spatial distribution pattern of river terraces was constructed,and the formation time and cutting rate of terraces were calibrated.The formation time of each terrace is 0.01 ma,0.24 ma,0.4ma,0.9ma and 1.2m A respectively.The results show that the cutting speed is the fastest in T5 formation period,and then gradually decreases,indicating that the current crustal movement is relatively slow.(3)In terms of time,under the influence of tectonic movement in the crustal stage,large and small landslides developed intensively and showed a certain periodicity,and the tectonic movement uplifted.Small landslides are developed,while large landslides are relatively developed in the period of relatively stable tectonic movement.From the perspective of space,the greater the density of the river,the closer the distance,the more developed the landslide.