Changes of evolution models of China's large river deltas since Holocene and their responses to anthropogenic activities

As a key component of the global environmental system, deltas are located in the specific areas suffering strong land-sea interaction. Generally, the deltaic regions are rich in natural resources, densely populated, highly urbanized and active in human activities, but they are fragile in terms of ecological conditions. The China’s large deltas, i.e the Yellow River Delta, the Yangtze River Delta and the Pearl River Deltas, have played important roles in the economic development of the country and contributed much to global environmental changes. Therefore, it is significant to reveal the deltas’ evolution processes and depositional models to ensure the sustainable development of the deltas and utilization of their resources. In this paper, we summarized synthetically the evolutionary models of these deltas based on the data from regional marine geological surveys and their precious results. Since Holocene, the evolution of China’s large river deltas has suffered three stages of evolution in three time-scales with their exclusive features. By these models, the factors influencing the delta evolution are discussed on millennium, centennial, interannual time scales respectively. The evolutionary models have changed from the natural factor dominated to human factor dominated owing to the stronger anthropogenic activities. It is an urgent need to strengthen the study of estuary delta evolution under the influence of human activities, so as to provide more scientific support for the sustainable development and full use of deltaic resources in these regions.