The development and control of the seawater intrusion in the eastern coastal of Laizhou Bay, China

Seawater intrusion was observed in China’s coastal aquifers as early as 1960s. At present, it covers an area of more than 2,000 km² in China. In 2002, the seawater intrusion area was increased to 1773.6 km² in Shandong Province, China, and it is continuing to extend in the coastal area of Laizhou Bay. In order to study the characteristic of the seawater intrusion and the pattern of the saltwater/freshwater interface, we set the China’s first three-dimensional seawater intrusion observation network in Longkou City of Shandong Province in 1989. In order to control the development of the seawater intrusion, in 1995, a continuous underground concrete wall, by the method of high-pressure jet grouting, was constructed in the downstream plain area of the Huangshuihe river in Longkou City. The average depth of the 5,842 m long concrete wall is 26.7 m, and the maxim depth is 41 m. It forms a coastal underground reservoir with the total storage capacity of about 5,359 × 10⁴ m³. In the past 10 years, the reservoir obtained great economic benefit, social benefit and ecosystem benefit.