5:15 PM - 6:45 PM
[AHW17-P05] Estimation and Verification of the Hydraulic Coupling Changes in Hydrogeological Parameters affected by Subsidence
Keywords:Subsidence, Hydrogeological Parameters
According to the theory of Lo et al. (2002), the porosity and hydraulic conductivity parameters after soil compaction were first corrected and applied to the Choshui River alluvial fan area to evaluate the possible impact of stratigraphic subsidence on hydraulic conductivity parameters as a correction method. Determined reference. A total of 26 stratigraphic subsidence magnetic ring monitoring well data in Changhua and Yunlin stations and the hydraulic parameters of standard groundwater observation wells at the same site were selected for calculation. In addition to the same site in space, both subsidence wells and observation wells must also be considered. The same time background is used to avoid doubts about different time and space distributions. Therefore, there are 5 stations in Changhua and 11 stations in Yunlin that can be calculated. The calculation results show that the change rate of the hydraulic conductivity coefficient in the Changhua is about 4 to 11%, with the 11.1% of XinJie Elementary School (Fang Yuan) being the largest. The change rate of the hydraulic conductivity coefficient of the Yunlin area is about 2 to 12%, with YuanChang Elementary School (Yuan Chang) being the largest.
We further selected two stations, Xigang (4 wells) and Kechuo (3 wells), to conduct pumping tests to verify the results of the theoretical calculations. Comparing the theoretical estimation and pumping test results, the maximum difference between the Xigang station estimated value and the original well setting value is 10.0% for Xigang #3, and the difference between the parameters obtained from the pumping test and the original well setting value is 35.5%. Except for Xigang #2, the difference between the pumping test and the original well setting value of the other wells is about 25% to 35%. The difference between the Kecuo Station pumping test parameters and the original and theoretical estimates is 92.1%. The differences between the parameters obtained in the Kecuo #2 and Kecuo #3 pumping tests and the original well setting values were 44.4% and 39.7% respectively.
In summary, the above results show that the parameters obtained in the pumping test are smaller than the original values of the wells and the estimated values after subsidence, which can confirm that the subsidence of the formation does have an impact on the hydrogeological parameters. The current hydrogeological parameters are different from the estimated values or original data. In addition to factors caused by formation subsidence, this difference is also caused by the decline of the well condition after decades. Secondly, it is estimated by the theoretical model. It is also worth exploring whether changes in porosity are linked to changes in soil properties such as bulk modulus and effective particle size. Therefore, hydrogeological parameters need to be re-examined in the future to meet current needs.
We further selected two stations, Xigang (4 wells) and Kechuo (3 wells), to conduct pumping tests to verify the results of the theoretical calculations. Comparing the theoretical estimation and pumping test results, the maximum difference between the Xigang station estimated value and the original well setting value is 10.0% for Xigang #3, and the difference between the parameters obtained from the pumping test and the original well setting value is 35.5%. Except for Xigang #2, the difference between the pumping test and the original well setting value of the other wells is about 25% to 35%. The difference between the Kecuo Station pumping test parameters and the original and theoretical estimates is 92.1%. The differences between the parameters obtained in the Kecuo #2 and Kecuo #3 pumping tests and the original well setting values were 44.4% and 39.7% respectively.
In summary, the above results show that the parameters obtained in the pumping test are smaller than the original values of the wells and the estimated values after subsidence, which can confirm that the subsidence of the formation does have an impact on the hydrogeological parameters. The current hydrogeological parameters are different from the estimated values or original data. In addition to factors caused by formation subsidence, this difference is also caused by the decline of the well condition after decades. Secondly, it is estimated by the theoretical model. It is also worth exploring whether changes in porosity are linked to changes in soil properties such as bulk modulus and effective particle size. Therefore, hydrogeological parameters need to be re-examined in the future to meet current needs.