Many estuarine deltas in the world are densely populated areas. This is because deltas are alluvial plains in estuarine areas. The terrain is flat, the land is fertile, the temperature is suitable, the river is close to the sea, and the waterways are convenient, making them very suitable for human habitation, survival and reproduction. In addition, abundant freshwater resources, land resources, shipping resources, oil and gas resources, biological resources, tourism resources, etc. have attracted more people to migrate to the estuary delta. Many deltas have gradually developed into large cities and urban agglomerations with concentrated populations. For example, China's Yangtze River Delta has a living population of more than 75 million, and has a Yangtze River Delta urban agglomeration composed of 22 cities led by Shanghai; the Pearl River Delta region has a total registered population of 86.79 million, and is now building a world urban agglomeration of Guangdong, Hong Kong and Macao.
At the same time, the ecological environment of the delta region is relatively fragile and is extremely vulnerable to river basins, local human activities and global climate change. Therefore, the estuary delta region has also become one of the areas with the greatest ecological crisis pressure.