Extraction And Analysis Of Terrace Lands In Loess Plateau

Terrace is one of the most important artificial landscape of the loess plateau,due to the significance role in conserving soil and water.In.soil and water conservation work,terrace plays a really important role.With the development of digital terrain analysis(DTA)technology and remote sensing technology,there is a current and future need for the development of robust,repeatable and cost-effective methodologies for researches on terraces.Also,digital terrain analysis will become an inevitable trend in terrace research.Taking Qingshui gully in Shaanxi Province as the research area,with high resolution remote sensing data and 1m&5m DEM data,I conducted an experiment of extraction and recognition terraces by object-oriented classification method.Moreover,the basic morphological characteristics and quantity features of terraces characteristics are analyzed,in order to achieve a complete understanding of terraced fields,and offer some ideas for future studies on terraces.In this paper,the main research work and conclusions are as follows:1.Determine the best combination of terrain factors for extracting terrace,and implement the extraction experiment which finally has a good resultIn this article,with correlation analysis and Gaucher entropy method method,?determined best terrain factors for extracting terraces in study area.In the secod stage,? used 1 m DEM and the latest WorldView-? high resolution image as data sources to extract terrace,and discussed the segmentation methods in the process.Finally,the extraction result is 94%,it shows a good accuracy and good applicability.2.Propose a method for estimate terrace stages and side slopeBased on lm-resolution DEM and 0.3m-resolution WorldView-3 image data,respectively,? proposed two different methods to estimate the terrace stages.The result shows that these methods can meet the practical requirements.Also,based on 1m-resolution DEM,this paper put forward a new method for calculating the average side slope of terraces.3.Analyze the terrain features and the mathematical features of terraces,and construct a new terrace DEM for validationAccording to above methods,based on the profile lines ? created,the terrain futures and mathematical features are analyzed.For validation,? rebuilt a piece of terrace by the mathematical rule ? proposed in the last chapter.The rebuilt DEM presents a good consistency with the original terrain.4.Put forward a chart to evaluate the terrace quality in study area5.Study terrace's influences to LS factorTo study the disturbance of terrace,I resampled the 5m DEM to a smooth 1m-resolution DEM.Then calculate the L factor,S factor and LS factor on both of them,and compare the values.As result,the presence of terraces decreases the L factor on slope,and makes S factor and LS factor a heavier fluctuation.That shows terraces may reduce the average capability of carrying sands,but may have larger detriment at the high-slope point.This paper studied the terraces in sample area deeply and comprehensively.With the development of hardware and software,the high resolution images and topographic data will be updated really fast,thus the method in this paper would have certain effect to help in the future.