The Research Of The Relationship Of Area-height Difference Base On Yuan Mou DEM

The study area, Yuanmou dry-hot valleys area is located in subtropical climate zone, and the most typical characteristics of this area is the dry and hot climate in the basin-liked region. The prevailing southwest monsoon from Indian ocean brings amount of rainfall in rainy season which mainly concentrates from June to October, while the tropical continental air plays the biggest role in the dry seasons. The frequent severe drought and flood disasters lead up to the region’s ecologically fragile. Influenced by natural causes and human disturbance, gullies are widely distributed in the region, resulting in serious soil and water erosion. The production and living in the area are greatly affected, which have a major impact on sustainable development. The morphology of the gullies is the research object, and different methods, such as geomorphology, statistics, 3S technology etc. are used to probe the relationship between area and height difference(A-H) of Yuanmou gullies. The main research content and results are as follows:1. When we review the related research of gully topography and Yuanmou gully, we find that most research focuses on vegetation, precipitation, morphological characteristics of the gullies, also on the relationship of the gully length and gully area etc. Few research has been reported on A-H of Yuanmou gullies. Whether there is a link between gully area and height difference, and whether this relationship can reflect the difference of gully development remains to be discussed. This study will show its important practical significance on soil and water conservation, also will help to put forward measurement on fragile ecological management.2. The main gully length, average width, slope, area, elevation in Yuanmou gullies have been analyzed. The extracted results show that the size of gullies in Yuanmou have big differences. The average gully length reaches to 60 m, and the gully width is approximately 25 m. Steep slope and extreme steep slope are the main type of slope in Yuanmou gullies.3. The statistical characteristics of area and height difference(A-H) of Yuanmou gullies have been analyzed. The analysis results show that the elevation difference of whole basin and the first order basin have high consistency, ranging from 10 m to 30 m. There are large gaps between area of the whole basin drainage and area of the first order basin, the area of the whole basin range from176.83m~2 to 2000m~2, the area of the first order basin change from 53.61m~2 to 900m~2.4. The relationship between area and height difference of Yuan Mou gullies has been discussed.1) The data of Area-height difference of whole basin and the first order basin in Yuanmou gullies are fitted respectively. The results show that the fitting effect of whole basin is better than the first order basin, while the fitting coefficient of whole basin is 0.6726, but the first order basin is 0.5453. Fitting results show that area and height difference(A-H) of Yuanmou gullies have better curve relationship.2) The relationship between area and height difference of Yuanmou gullies has been discussed on two dimensions. For all gullies in the study area, When height difference increases, the area has been increased synchronously. The logarithmic fitting function of area-elevation difference is better with the fitting coefficient 0.9739, 0.9704 and 0.8961 respectively(after three scenarios, similarly hereinafter). The fitting coefficient of area and height difference of five groups are 0.6222, 0.9699, 0.9346, 0.9072 and 0.8871 respectively. The result indicates that there is a good relationship between area and elevation difference inYuanmou gullies. In the first order basin, area increases along with the increase of elevation difference. The fitting coefficient are 0.9529, 0.9262, 0.8197 respectively. The consequent of correlation analysis and cluster analysis show that the correlation coefficient of the first order basin is 0.626227, which means a clear "hold together" gathering characteristics. The correlation coefficient of aggregate data is 0.801177, which indicates that area and height difference of the first order basin has good correlation in some aggregates range.5. The characteristics of area and height difference of Yuanmou gullies in different development stages has been investigated.1) According to the degree of vegetation covering of gully and other factors, we can preliminary judge the developmental stages of gullies, and analyze the characteristics and relationships of area and height difference in different developmental stages. The analysis results show that the height difference of Yuanmou gullies changes from 20 m to 30 m in monadnock phase, from 10 m to 30 m in the mature phase, and from 10 m to 20 m in the youthful stage. The area of monadnock phase range from 286.35m~2 to 1000m~2, and the mature stage’s are between 337.55m~2 and 2000m~2, and that the youthful stage change from 192.02m~2 to 3000m~2.2) The data fitting has been investigated for the area-height difference of gully on the different development stage. The best fitting function appeared in youthful stage, which fitting coefficient is 0.9019. The second is gullies in mature stage, and its fitting coefficient is 0.731. The third is monadnock phase gullies, and its fitting coefficient is 0.6216. The results show that the distinction of the fitting effect of area-elevation difference of gullies on different development stages is large, while they all show the obvious nonlinear relationship between the area and the height difference.