Abstract: Based on the Krig gridding method, 4D space-time terrain models of Lingdingyang estuary were constructed for two years of 1990 and 2008 respectively. And then, the Lingyingyang estuary can be divided into 5 regions of Humen region, Qi’ao island region, Lingdingyang shallow shoal region, Lingding waterway region and marginal region of Tonggu waterway, the shoreline migration and scour-and-fill space-time alternation in all these five regions since 1975 were quantitatively analyzed, combining with ²¹⁰Pb dating method. It had found that the land area of whole region had increased 216. 0 km² ,the water area had decreased 84.6 km², and the tidal-flat area had decreased 131. 4 km²,the holding capacity of water area had reduced 19 783.7X10⁴ m³,the mean annual silting quantity had reached 477. 4 X 10⁴ m³,and the whole estuary was silting and atrophying constantly. The annual silting quantities of the 5 regions were-236.6X10⁴,135.3X10⁴, 663.7X10⁴,-452.7X10⁴ and 367.7X 10⁴ m³ respectively, while the mean silting velocity Were-4.46,0.93,1.27,-5.49 and 2.93 cm/a respectively. The total depths in Humen region and Lingding waterway region had increased while those in other regions had decreased. The silting extent in marginal region of Tonggu waterway was significant. The main reason of the increasing water depth in Humen region is natural degradation and manual sand digging while the deepening in Lingding waterway region is the result of artificial desilting. Tonggu waterway is a new digged artificial channel. Influenced by manual dredging mud, water depths at both sides of each channels decreased apparently. But the changes of water depths in other regions were the results of natural evolution of delta. With the fast development of economics at two sides of Lingdingyang estuary, the manual activity had been the main factor for the evolution of seafloor relief and landform in this region.

Key words: Lingdingyang estuary, digital terrain model(DTM), silting change, shoreline migration, artificial factor