关键词: 横沙通道;冲淤变化;地形演变;ArcGIS;数字高程模型;长江口;

Abstract: The Hengsha Passage in the Yangtze Estuary is an important connecting passage between the North and South Channel. It is of great significance to study the erosion-deposition and topographic evolution of the passage for mastering the hydrodynamic conditions of the passage and ensuring the safety of production and operation. In this paper, the measured underwater topographic data from 2005 to 2020 in the Yangtze Estuary were used to establish a digital elevation model with an accuracy of 20 m×20 m in ArcGIS. By drawing maps about topographic, erosion-deposition change, contour and cross-sectional of the passage, the evolution characteristics of the whole landform and the formation mechanism of local pit of the passage were analyzed quantitatively and qualitatively. The results indicated that a pit with a length of 1.85 km from north to south and a maximum depth of 56.1 m, appeared at the north entrance of the Hengsha Passage recently. The pit expanded by about 3.8×106 m3 and extended to the south by about 770 m, suggesting that it may evolve into a deep trough. The passage presented a evolution mode of ‘erosion-deposition-erosion’ on the whole, which was dominated by erosion. There was local deposition on both sides, and the accumulated scouring was 2.88×107 m3. The main reason for the continuous expansion of the pit was that under the influence of reclamation engineering performed in North Changxing and the construction of the Qingcaosha reservoir, the hydrodynamic force in the north of the passage was enhanced, and the flow of the ebb current was increased, which further accelerated the development of the pit.

Key words: Hengsha Passage; erosion-deposition; topography evolution; ArcGIS; digital elevation model; Yangtze Estuary