Abstract:The main purpose of this study is to identify the major factors affecting groundwater quality by means of multivariate statistical analysis of the physico-chemical compositions. Cluster analysis results show that the groundwater in the study area is classified into four groups (A, B, C and D), and factor analysis indicates that groundwater composition, 81Ð9% of the total variance of 17 variables, is mainly affected by three factors: seawater intrusion, microbial activity and chemical fertilizers. These results might be related to the geographical characteristics of the study area. The main influence on groundwater in groups B, C and D, which are close to the Yellow Sea and contain reclaimed areas, is the seawater intrusion by the present seawater, the trapped seawater, and microbial activity. Group A, however, has been used for agriculture for a long time, and thus groundwater in this group has been largely affected by chemical fertilizers. As groundwater flows from group A to group D according to its path, the governing factor of the groundwater quality gradually changes from chemical fertilizers to microbial activity and seawater intrusion.

No abstract

This paper presents the hydraulic interaction between aquifer and river related with bank storage. A convolution equation was used to analyze the aquifer response, discharge, and bank storage due to river stage fluctuation. River stages were generated to describe flood peak, asymmetry, and duration. The simulation results suggest that the geometry of flood hydrograph can play an important role in affecting the discharge and bank storage. The presented model was applied to a field data, and the site is a floodplain aquifer of the Mangyeong River. Aquifer responses for the various flood duration and flood peak were observed at the site, which is well matched with the simulated results. A model parameter, the riverbed leakance was determined from calibration with the simulated and observed groundwater levels. After the determination of each parameter, the discharge and bank storage can be calculated. The presented method is a good tool to assess the hydraulic interaction between the aquifer and the river, as arbitrary river stage fluctuations are used. The limitation of the method is that the actual discharge and bank storage can be different from the calculated ones, when significant regional groundwater gradient exists. It also can be a useful tool before applying more complex numerical models.

No abstract

No abstract