Abstract:

Based on experimental data of the shallow groundwater samples, the hydrogeological characteristics in Siyang area and spatial distributions of the chemical components were studied,meanwhile, the formation characteristics and influencing factors were discussed. The results showed that the hydrochemical type of shallow groundwater in Siyang area presented some horizontal zoning regularity. In the southwest of the Grand Canal, HCO^-₃ is the predominant anion of the shallow groundwater; total dissolved solids (TDS) is less than 1  g/L; total hardness is less than 450 mg/L, and the water quality is generally good. While in the northeast of the Grand Canal, the predominant anions of shallow groundwater areHCO^-₃,Cl^-and SO^2-₄; TDS usually is within 1-3 g/L; total hardness is more than 450 mg/L; the water is brackish and the quality is bad. In addition, the ammonium nitrogen and nitrate nitrogen contaminations of the shallow groundwater are obvious in Siyang area, and the spatial distributions there have significantly uneven regional differences, ammonium nitrogen and nitrate nitrogen concentrations are high at both sides of the Grand Canal and near the Siyang farm.NH⁺₄-N high-concentration in shallow groundwater is less than that in 18 meters in the vertical, while NO^-₃-N  highconcentration in shallow groundwater is within 8-20 meters. The spatial variations of hydrochemical characteristics of shallow ground-water in Siyang area are affected by the interactive marine and terrestrial deposit, the chemical constituents of the supply source, supply and runoff flow conditions of aquifer medium and human activities.