Improvement of contaminant plume estimation by a geostatistical method considering groundwater flow and non-negativity

Takai, Shizuka; Shimada, Taro; Takeda, Seiji; Koike, Katsuaki*

no journal, , 

For underground contamination by such as radioactive nuclides and chemicals, the contaminant plume distribution needs to be clarified accurately for effective remedy. However, once a pollutant reaches an aquifer, the transport will be affected by groundwater. In such case, only spatial interpolation of measurement data may be unable to reproduce the contaminant plume. In this study, we considered the estimation method integrated transport information into geostatistical analysis. To gain physically feasible solution, we also considered the non-negativity constraint by Gibbs-sampling. The applicability of the method was confirmed for both hypothetical model and actual contamination case (Gloucester landfill, Canada). As the hypothetical model, we assumed that H is leaked for 300 days with 2 peaks. The two peaks of plume could not be reproduced by spatial interpolation (Kriging with a Trend). However, the plume was reproduced well by the geostatistical method with the mean average error (MAE) of 2.8E-9. In the Gloucester landfill, the contamination by 1,4-dioxane in the aquifer (300 300 40m) was evaluated using 69 points measured in 1982. By the geostatistical method considering groundwater flow and nonnegativity constraint, the large spill in 1978 could be reproduced well compared to previous research by other methods such as minimum relative entropy. The plume was also evaluated well with the MAE of 2.8E-2 mg/L; therefore, the applicability of the method was confirmed.