Analysis on morphologic features of the peak-cluster depression in Qiubei, Southeast Yunnan

Qiubei peak-cluster depression in southeast Yungui Plateau, about 40km2 in area , is chosen as the sample region for karst landform fractal geometry analysis. Statistical method is used to analyze the characteristic parameters of 48 karst depressions and peaks; fractal theory is chosen to calculate fractal dimensions at different elevation contours and surface water network. The results indicate that: (1) the average area of the depressions is 0.8 km2, the mean boundary-namber is 5.6 and the average perimeter is 3.4km; (2) depressions grow in breadth and in depth near-synchronously, and the development of corrosion surface is restricted by the elevation of initial surface; (3) fractal characteristics of peak-cluster depression are well response to the karst evolution, and the average fractal dimension of contour in limestone region and non- limestone region is 1.30 and 1.16 respectively, and the dimension of surface water network is 1.07, which reflect topographic change are complicate, underground hydrographic net are quite developed and the relative degree of karst development is high in this karst region; (4) the karst in Qiubei is in the young or mature stage, and will continue to develop slowly.