522 / 2024-06-28 21:24:12

Characteristics and Storage Law of Weak-Middle Mineralized Groundwater in Mudstone of Suining Formation in Sichuan Basin

Sichuan Basin; Mudstone of Suining Formation; Shallow weak-middle mineralized groundwater; Storage Law

Subtheme 3: Eco-hydraulics and Environment > Topic 3: Eco-environmental Effect of Water Engineering

The mudstone of Jurassic Suining Formation (J₃s) is widely distributed in the hinterland of Sichuan Basin, and the shallow weathered rock mass hosts weak-middle mineralized groundwater. In order to study its spatial distribution, hydrogeochemical characteristics and storage law, based on the resistivity test of 34 borehole fluid and the hydrogeochemical analysis results of 80 groups of groundwater samples carried out by a water diversion project in this area, the relationship between mineralization and apparent resistivity of underground water, storage law and rock weathering, rock chemical composition, as well as vertical zoning characteristics and genetic mechanism were studied. The study shows that the shallow weak-middle mineralized groundwater mainly stored in the pores and fissures of the shallow weathered rock mass of mudstone. There is an inverse hyperbolic relationship between apparent resistivity and mineralization of groundwater. The apparent resistivity is less than 8Ω·m for middle-mineralized water (mineralization is 3～10g/L), and less than 16Ω·m for weak mineralized water (mineralization is 1～3g/L). The hydrogeochemical types are mainly HCO₃·SO₄-Na·Ca and SO₄-Na·Ca for weak-mineralized water, and SO₄-Na·Ca, SO₄-Na, Cl·SO₄-Na for middle mineralized water, which are medium-strong corrosive to concrete. The ionic components are mainly derived from the plaster salt leaching and dissolution of rock containing soluble and easily soluble components such as gypsum and calcareous nodules. The research results can provide guidance for the development and utilization of groundwater resources in red mudstone areas and the engineering layout and engineering treatment related to weak-middle mineralized groundwater.