Spatial Distribution and Controlling Factors of Groundwater Quality Parameters in Yancheng Area on the Lower Reaches of the Huaihe River, Central East China

Groundwater samples that were distributed across the Yancheng area in lower reaches of Huaihe River collected from phreatic aquifer and first confined water layer during summer 2016. Using quality index, suitability groundwater for drinking irrigation purposes was systematically evaluated. The controlling factors solute formation causes deterioration discussed using Chadha diagram relationship among ions. results showed there a serious lack excellent- good-grade shallow layer. also found to be unsuitable irrigation, with only approximately 70% being good quality. spatial heterogeneity significant, poor-quality discontinuously. high concentration alkali metals due weathering silicate rocks clay subclays replacement Ca2+ Na+ surrounding rocks. Additionally, leaching residues salt industry marine sediment historical periods identified as key leading scattering inland areas. study not significantly affected by seawater intrusion human activities. However, signs activity, such agricultural fertilizer urban sewage, affecting “excellent-” “good-grade” intended purposes.