中文摘要：

流域地貌和水系结构对流域的水生态功能起支撑作用。本文运用地理信息系统方法,将东江流域15m空间分辨率DEM与1：100万地貌图和1：25万水系图等相结合,分析了东江流域上游地貌特征,提取了东江上游水系结构特征与流域面积-高程积分值,探讨了地貌特征与水系结构对生态系统的影响。结果显示,东江上游的地貌以200～500m高程、坡度〈8°的丘陵和中小起伏山地为主;本文将东江上游地区水系划分为10级结构,河网总数目33.81万条,总长度8.12万km,沟谷密度5.29km/km2,河网频度22条/km^2,平均分支比为3.86;东江上游面积-高程积分值为0.23,整体地貌发育阶段处于晚年期。东江上游流域整体水土流失为轻度,但局部为中度到重度。在地势比降平坦,人口密集的新丰江水库、浰江、船塘河三个流域,河网密度和频度相对较小,水生态与水环境相对脆弱。

英文摘要：

Using GIS tools and combining high resolution DEM data （pixel resolution at 15m） with regional geomorphologic and river system maps （scales 1 ： 100 0000 and 1 ： 25 0000）, the relationship between the characteristics of stream network structure and regional geomorphologic features in the upper stream area of the Dongjiang River basin are analyzed. Geomorphic features such as elevation, gradient and relief amplitude were used. By using the Strahler stream order method with our improved approach to extracting river networks, we developed a l O-order stream network structure for the area. Stream network structure variables such as stream length, stream length ratio, drainage density, bifurcation ratio, stream frequency and gradient ratio were used to show characteristics of the stream network structure. We found that geomorphic types of the upper stream area in Dongjiang River basin consist of rolling hills and undulated low mountains, ranging mainly between 200m and 500m in elevation, with maximum gradient below 8°. The divided 10-level stream network structure contains 33.81 × 104 brooks, rivulets and rivers, stretching a total length of 8.12 × 10^4kin. The stream network structure in the area has some unique features characterized by a drainage density of 5.29 krn/km^2, a stream frequency of 22/km^2, and an average bifurcation ratio of 3.86. The area-altitude curve integral reaches to 0.23, implying the area phasing into the old age in geomorphic development stage. Soil erosion is light in the area as a whole, with a few exceptions of strong erosion on some steep slopes. The Xinfengjiang reservoir, Lijiang River and Chuantanghe River are subject to heavier human disturbances and unfavorable geomorphic backgrounds and are therefore comparatively more fragile than other sub-watersheds in our focal area.