Seepage-zone recognition of river water based on Cl(-) spatial difference

Area of Science:

• Environmental Science
• Hydrogeology
• Water Quality Monitoring

Background:

• Chloride (Cl-) is a key indicator for surface-groundwater interactions.
• Understanding river seepage zones is crucial for water resource management and pollution control.
• Spatial variations in Cl- concentration can reveal hydrological processes.

Purpose of the Study:

• To analyze the spatial distribution of Cl- in the Dashi River and its adjacent shallow groundwater.
• To evaluate the retardation strength (pCl-), average retardation strength (pA), and average residual retardation strength (pAR) of Cl-.
• To introduce a new quantitative method (Q) for identifying and characterizing river seepage zones.

Main Methods:

• Collection and analysis of Cl- monitoring data from river water and shallow groundwater samples.
• Calculation of Cl- retardation strength parameters (pCl-, pA, pAR).
• Development and application of the difference (Q) between average and average residual retardation strengths to delineate seepage zones.

Main Results:

• Cl- concentration in the river increased in industrial areas and decreased in non-industrial areas, generally decreasing downstream.
• The parameter Q was developed to distinguish between seepage and no-seepage zones (Q < 0 indicates seepage).
• The parameters pCl-, pA, and pAR were used to classify sampling points into seepage, transition seepage, or no-seepage zones, aligning with field observations.

Conclusions:

• The quantitative method using Q effectively identifies and delineates river seepage and transition seepage zones.
• The retardation strength parameters provide a robust framework for assessing surface-groundwater interaction zones.
• The findings offer valuable insights for managing water resources and mitigating pollution in river systems.