海南岛主要入海河流流域地貌演化

GEOMORPHOLOGICAL EVOLUTION OF MAJOR CATCHMENT BASINS OF HAINAN ISLAND, SOUTHERN CHINA

河流入海物质的输出特征不仅与流域的构造、岩性、自然地理特征相联系,还与水系流域所处的地貌演化阶段密切相关.基于海南岛13条主要入海河流流域的SRTM数据,分别计算流域HI值、河流纵剖面拟合曲线和S-A双对数曲线图,旨在探讨海南岛主要入海河流流域地貌演化阶段、均衡态和未来动态以及对沉积物入海通量的指示意义.结果表明：海南岛主要入海河流流域处于地貌发育的老年阶段,其HI值为0.09～0.29,指示入海河流沉积物通量总体处于较低水平.海南岛在东南亚河流入海通量环节处于极低值区域,侵蚀模数低于东南亚其他岛屿一个数量级.结合河流地貌均衡态和河流纵剖面曲线拟合函数的结果,可推断河流地貌下一阶段地貌演化将遵循继承型、回春型和演化型的方向,河流入海通量将表现为稳定、增大和减小趋势.

Sediment discharges from rivers are not only related to the geological structure, lithology and geographical conditions of the catchment basin, but they are also influenced by the geomorphological evolutionary state. Using the SRTM data, we analyze the evolutionary stage, morphological equilibrium and the trend of future development of the major （13, i.e. rivers of Nandujiang, Changhuajiang, Wanquan, Lingshui, Ningyuan, Zhubijiang, Wenlan, Wanglou, Beimengjiang, Longwei-longshou, Chunjiang, Taiyang and Wenjiao） river catchment basins of Hainan Island, together with their significance to the sediment flux. The HI values, longitudinal river bed profiles and standard logarithmic slope-area plots of the major rivers were obtained. The results show that all the catchment basins in consideration have reached their old stage of geomorphological evolution, with their HI values ranging between 0.09 and 0.29, which suggests that the sediment flux of the rivers in Hainan Island should be generally low. The sediment flux of Hainan Island represents a depression region of southeastern Asia, which has a lower order of magnitude of erosion modulus （ 118t/km2 · a） than the other inlands （ 1600～ 13815t/km2 · a） （ in Table 3）. Combined with the analysis of the equilibrium status and the best-fit curves for the longitudinal river channel profiles, it can be inferred that the future development of these basins will follow the different directions of inheritance （i.e. rivers of Nandujiang, Changhuajiang, Ningyuan, Wenlan, Taiyang and Wenjiao）, rejuvenation （ i.e. rivers of Wanquan, Lingshui, Beimengjiang, and Chunjiang） , or ageing （ i.e. rivers of Zhubijiang, Wanglou, Longwei-longshou） , which are associated with stable, increasing and decreasing sediment fluxes, respectively.