| Jiuduansha Wetland State Nature Reserve in Shanghai is composed of Jiuduansha Shoal, Jiangyannansha Shoal and the nearby shallow watershed. It possesses important research and conservation value because of the rich bioproductivity and original ecology. In the recent years, Jiuduansha Wetland has been undergoiung erosion or accretion significantly affected by high-intensifed construction projects that were built up near the Yangtze River estuary. Because of the natural and human disturbance, mostly the latter, Jiuduansha Wetland has been undertaking tremendous dynamical changes in these years.Based on a recent data collection of hydrology, sediment, combined with terrain, water and sediment data at Yangtze River basin, this paper utilized fluvial, dynamic geomorphological, physical oceanographic, GIS and other professional knowledge to study the morphological evolution of Jiuduansha Wetland in responds to large water projects. In the end of this paper, the practical methods to protect and enhance Juduansha Wetland were studied in order to provide scientific basis for the planning and management of the Wetland in the future.The main conclusions of this study include:First, the Yangtze River Estuary North Channel Deep Water Channel Project suppressed the head of Jiangyanansha Shoal and Jiuduansha Shoal from moving down, increased the split ratio ebb of South Channel, and in turn accelerated the Jiangyanansha Shoal to move closer to the Jiuduan Shoal. Second, the south jetty weakened the strength of erosion from the north shore of Jiuduansha Shoal and stabilized the northern boundary of Jiuduansha Wetland. Since the jetty blocked the estuarial flood currents which transported sediment from the Jiuduansha Shoal to North Channel, a lot of sediment deposition in Jiuduansha Wetland settled down at the beach side. Therefore, the wetland communities were enhanced and the ecological functions of wetlands were improved. Third, the Nanhui Inning Project which narrowed the width of the South Channel made a great impact on the intensity of the flow, and thus cased the erosion of the south side of Jiangyanansha Shoal and Jiuduansha Shoal.The change of altitude of Jiuduansha Wetland will directly affect the ecological function of the Wetland in a significant way. This paper presented some suggestions based on the research of the effects of water project to Jiuduansha Wetland. |
