Distribution and Characteristics of the Phreatic Water in Tianjin Binhai Core Area

Taking Tianjin Binhai core area as an example, the engineering characteristics of phreatic water in coastal area were studied. The lithological composition, spatial distribution and permeability of the phreatic water-rich aquifer and phreatic aquifer in Binhai core area were investigated, and the status and dynamic change of the phreatic water level were analyzed. The range values of water quality analysis indexes such as Cl⁻, SO₄²⁻ were provided, and their water quality was evaluated. The results show that: (1) The phreatic water level in the Binhai core area is shallow and mainly distributed in silts layers of Q₄^3Nal, Q₄¹al and Q₄²m and other phreatic water-rich aquifer, with a thickness of less than 6 m. The permeability coefficient of phreatic aquifers is generally 0.1～0.6 m/d, indicating weak permeability. (2) The annual dynamics of the phreatic water level in Binhai core area show a certain law with seasonal changes. The annual variation range is generally 0.22～0.72 m in the past five years, and the maximum water level in the past five years has an overall upward trend, which is about 0.3 m. The main indicators of phreatic water quality in the past five years have the trend of decreasing first and then increasing, and the water quality is poor.