10:45 〜 12:15
[AHW19-P11] Evaluation of Water Quality in the Choushui River Alluvial Fan and Analysis of the Difference Between Wet Season and Dry Season
キーワード：groundwater salinization Piper diagram Hydrochemical Facies Evolution diagram Base Exchange Index, Choushui river alluvial fan, Piper diagram, Hydrochemical Facies Evolution diagram, Base Exchange Index
When the contents of dissolved solids in groundwater in a place is varied highly from the background, we could regard it as groundwater salinization (Van Weert et al., 2009). Because of the steep terrain and precipitation in Taiwan, water can hardly be preserved on the surface. Therefore, groundwater play a major role in most kinds of water usage. However, groundwater in Choushui river alluvial fan could be not conducive to use according to groundwater salinization. This study aims to evaluate the water quality in Choushui river alluvial fan and discuss changes between wet and dry seasons.
In this study, we discuss historical data of the Choushui river alluvial fan with statistical analysis such as correlation analysis, principal components analysis, and factor analysis. Then, we narrow the target to Yunlin, the south part of the Choushui river alluvial fan. Since 2021, we collect water samples in wet and dry seasons and analyzed the hydrochemistry component of the samples. Data then plotted on the Piper diagram, Hydrochemical Facies Evolution diagram, and calculate their Base Exchange Index to determine if the sample has been salinized (Giménez-Forcada, 2010; Piper, 1944; Stuyfzand, 2008).
First, we sort historical data from 2015 to 2019 from Water Resources Agency and Environment Protection Administration (Fig. 1). 219 and 321 data from WRA and EPA respectively were selected to do statistical analysis. The correlation between parameters (Fig. 2) shows that Ca, sulfate, EC, Na, Cl, K, and Mg have a higher correlation to groundwater salinization.
If we plot PCA results on the map (Fig. 3), cluster 3 has a high relationship with salinization and is located in the coastal region.
We have collected 3 batches of samples and measured their concentrations since 2021. Then, we plot those data in the Piper diagram and HFE diagram (Fig. 4). Data from 3 batches shows that most parameters in the dry season have a higher concentration than those in the wet season. However, we can see that the ratios between parameters in the wet season slightly tend to salinization than in the dry season.
while the lighter plots represent the wet season. (b) HFE diagram BEX can tell the state of the samples (Stuyfzand, 2008). When BEX is less than 0, it means the water was salinized. Using ArcGIS to map the BEX value of the EPA groundwater wells (Fig. 5), we can clearly observe that in the wet season, the area that is salinized is slightly larger than in the dry season. It reveals that the source of salinity might come from the surface, and transport into the aquifer through leaching in the wet season.
In this study, we discuss historical data of the Choushui river alluvial fan with statistical analysis such as correlation analysis, principal components analysis, and factor analysis. Then, we narrow the target to Yunlin, the south part of the Choushui river alluvial fan. Since 2021, we collect water samples in wet and dry seasons and analyzed the hydrochemistry component of the samples. Data then plotted on the Piper diagram, Hydrochemical Facies Evolution diagram, and calculate their Base Exchange Index to determine if the sample has been salinized (Giménez-Forcada, 2010; Piper, 1944; Stuyfzand, 2008).
First, we sort historical data from 2015 to 2019 from Water Resources Agency and Environment Protection Administration (Fig. 1). 219 and 321 data from WRA and EPA respectively were selected to do statistical analysis. The correlation between parameters (Fig. 2) shows that Ca, sulfate, EC, Na, Cl, K, and Mg have a higher correlation to groundwater salinization.
If we plot PCA results on the map (Fig. 3), cluster 3 has a high relationship with salinization and is located in the coastal region.
We have collected 3 batches of samples and measured their concentrations since 2021. Then, we plot those data in the Piper diagram and HFE diagram (Fig. 4). Data from 3 batches shows that most parameters in the dry season have a higher concentration than those in the wet season. However, we can see that the ratios between parameters in the wet season slightly tend to salinization than in the dry season.
while the lighter plots represent the wet season. (b) HFE diagram BEX can tell the state of the samples (Stuyfzand, 2008). When BEX is less than 0, it means the water was salinized. Using ArcGIS to map the BEX value of the EPA groundwater wells (Fig. 5), we can clearly observe that in the wet season, the area that is salinized is slightly larger than in the dry season. It reveals that the source of salinity might come from the surface, and transport into the aquifer through leaching in the wet season.