40年来长江九江河段河道演变及其趋势预测

利用地理信息系统(GIS)与数字高程模型(DEM)技术定量模拟40年来九江河段冲淤演变过程,结果表明: 1963~1972年总体表现为淤积,淤积量为6.505 hm³,平均淤积速率为0.65 hm³/a。1972~2002年总体表现为冲刷,冲刷量为20.720 hm³,平均年冲刷率为1.036 hm³/a。1963~2002年九江河床总体表现为冲刷,冲刷量为14.977 hm³。2003年与1963年比较,河床淤积区域主要分布在九江河道上段近南岸区域,中下段河道的中间区域;冲刷区域主要分布在九江河道上段的中间及近北岸区域,中下段河道两岸的近岸区域。中下段南岸的不断刷深和南偏对九江的防洪带来更大的压力。

Evolution and Developing Trend of the Jiujiang River Course of the Yangtze River in Recent Forty Years

Jiujiang is one of the best import business and tour center in Jiangxi Province. However, more and more flood disasters from the Yangtze River have been occurred since the last century. The Jiujiang River course evolution has huge impact on flood discharge, shipping and the sustainable development of Jiujiang City. This thesis adopts DEM (Digital Elevation Model) and GIS (Geographic Information System) technology, and rationally simulates the Jiujiang River course evolution in recent forty years on the basis of the Yangtze River Lower Reaches Relief Map in 1963,1972 and 2002 (map scale is 1∶10000). It quantitatively expresses spacial-temporal distribution of riverbed erosion-deposition such as cross section, vertical section, isobaths and erosion-deposition volume. From 1963 to 1972, the Jiujiang River course was generally characterized by deposition, and the total deposition volume was 6.505×10⁶m³, average annual deposition load was 0.65×10⁶ m³/a, and the main deposition area is located in the south bank area of upper-middle course and the middle area of lower course, the main erosion area is situated in the north bank area of the course; From 1972 to 2002, Jiujiang River course was generally characterized by erosion, total erosion volume was 20.720×10⁶m³, average annual rate of erosion was 1.036×10⁶ m³/a, and the main deposition area is located in the south bank area of upper course, the middle area of middle-lower course and a piece of north bank area, the main erosion area is located in north bank area of the course and the south bank area of middle-lower course; From 1963 to 2002, the Jiujiang River course was generally characterized by erosion, and the total erosion volume was 14.977×10⁶ m³, and the main deposition area is located in the south bank area of upper course and the middle area of middle-lower course, the main erosion area is located in the the north and the south bank area of middle-lower course.The course change is relative multi-factors such as suspend sediment load and runoff load from upper reaches, geological basis and crust motions, human activities and river evolution of lower reaches. The deposition from 1963 to 1972 is directly the result of Hankou suspended sediment load increase from 1955 to 1969, which relates to deforestation activity; the erosion form 1970 to 2002 is directly the result of Hankou suspend sediment load decrease and runoff increase, which because that lots of reservoirs quickly increase in upper and middle reaches since the 1970S. In conclusion, Jiujiang course evolution is the result of the course borderline conditions, runoff, suspend sediment load and human activities. In addition, the paper gives a river evolution trend in the future, and points out the continual erosion of the south bank area in middle and lower course will bring the more pressure for preventing flood. The government should pay attention to constructing the protecting bank project, monitoring the riverbed evolution. These measurements are essential to Jiujiang City's future.