| The northeast black soil area is an important commodity grain production base in China,which causes serious land degradation and soil erosion due to irrational farming activities.According to the first China census for water,there were 295,663 gullies in the 100-5000 m located in black soil area of Northeast China,which seriously damages cultivated land and reduces grain output.At present,there are few studies on the distribution law and reconstruction of gully in Northeast China.The lack of theoretical basis seriously restricts the scientific and effective prevention and control of gully in this region.The slope is the carrier of the gully.The slope and aspect are the basic attributes of the slope.In order to clarify the relationship between the slope and gully,the paper first studied the distribution characteristics of gully,and then summarized the development law of the gully.After the influence of the distribution and development of the gully,the pre-erosion landform was reconstructed to restore the geographical information of the slope,which provides technical support for the accurate prediction of the gully erosion.In the research on the distribution characteristics of gully,the gully data and digital elevation model(DEM)from the first China census for water were used as data sources.With the help of GIS technology,the distribution characteristics of gully in different slopes and aspect in the sub-region of water and soil conservation were analyzed,and the potential risk of gully was predicted according to the distribution characteristics.According to the potential risk prediction results of gully,two subregions were selected.With the help of remote sensing and GIS technology,the development status and differences of gully in different sub-regions were obtained,and the development rules of gully in different slopes and aspect were defined.After grading the existing gully according to morphology and combining DEM and GIS,the best method of geomorphological reconstruction was selected on the slope without gully.The results showed that under the influence of slope and aspect,there were commonalities and differences in the distribution characteristics of concentration,density and proportion of cutting land in different slope and aspect.Gully density for 5 ° in slope and north aspect,the biggest difference is that although the gully density along with the change of slope up the overall trend was the same,but in rising or falling in the part of the slope fluctuation,and then present two "three peak valley","double peak valley" and "single peak" type three trends;The difference of density distribution of gully in different sub-regions was reflected in the difference of slope threshold.Slope threshold of the Hulun Buir hilly and plain sub-region and the Changbai Mountain-Wanda Mountain sub-region was 8 ° and 3 ° respectively,development of gully slope threshold 8 °,15 ° respectively.The developed gully had exceeded the slope limit of the original stable state of the erosion gully,which has great potential risk of gully erosion.After four years of development,the intensity,density and proportion of cutting land of gully changed with the increase of slope and the slope threshold.When the slope was less than 5°,gully development was given priority to with the new gully,when the slope was greater than 5°,was given priority to with original gully headward erosion and transverse expansion.Slope in 3°~8°,two partitions gully density increment was bigger,growth of 73.97%,51.69% respectively,and the slope of 5° and 4°gully density increased,the biggest and the maximum intensity increment in slope were the same.Affected by gully intensity and density growth rule,When the slope was less than 8° cutting land growth rate was greater than the proportion more than 8° slope classification rate,and the effect of gully fusion and transverse expansion,cutting land proportion increase the highest grade for the 8°.Under the influence of the proportion of different slope area,the growth rate of gully in the two districts was different.When the slope was less than 8°,When the slope was less than 8°,the Changbai Mountain-Wanda Mountain sub-region gully intensity,density and cutting percentage growth rate continues to increase with the decline in slope land,the Liaoning-Around Bohai mountainous and hilly sub-region growth first decreased and then increased.The results of the study on the distribution and development of different slope and aspect to the gully showed that the slope and aspect to the gully according to their own trend to complete the control of the trend and location of gully,and then affect its distribution characteristics;Secondly,different slopes and orientations affect the distribution of gullies by changing the distribution of natural conditions.In addition,distribution was the embodiment of development results,and development was the process of accepting slope and redistribution of external factors on the basis of existing distribution.At the same time,the comparative development results showed that the growth rate of gully area and length in the Changbai Mountain-Wanda Mountain sub-region area was 322.01% and 20.39% respectively,which were both higher than 191.91% and 16.41% in the Liaoning-Around Bohai mountainous and hilly sub-region.In addition,the number of newly developed gullies in the the Changbai Mountain-Wanda Mountain sub-region hilly area was 1772,far more than the 461 gullies in the Liaoning-Around Bohai mountainous and hilly sub-region,which confirmed the conclusion that the potential risk of gully erosion in the Changbai Mountain-Wanda Mountain sub-region is greater.In the study of pre-erosion geomorphological reconstruction,the erosion landforms were first graded according to the length of the gully.Comprehensive data integrity test,Pearson correlation coefficient matrix evaluation,T-test evaluation and error analysis were selected to select the best reconstruction of pre-erosion landforms of different lengths.The method,in view of the fact that there are four levels of best reconstruction methods in the five gradings,the same process was used for the non-hierarchical reconstruction.By comparing the grading and non-grading reconstruction accuracy,it was proved that the grading reconstruction according to the length of the eroded ditch is necessary.The optimal reconstruction method and stability test of different levels of pre-erosion landforms were carried out.Finally,the pre-erosion landform reconstruction equation constructed has high fitness and stability.The main innovative idea of this paper was to study the distribution and development characteristics of different slopes and slope to gully,and to find the influence of slope and slope to gully from the static and dynamic parameters of gully.The potential risk of gully was predicted by slope threshold of developing gully and stabilizing gully.The main innovative findings in this paper were that the gully on the gentle slope has the highest growth rate.The results of gully potential risk predicted by slope threshold are similar to those predicted by other methods.In the process of topographic reconstruction before erosion,the accuracy of grading reconstruction is much higher than that of non-grading reconstruction. |
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