## 4 Results
### Electrical Resistivity  
The resistivity data collected on 10 July 2019 in Seven Palm Lake and on 15 July 2019 in West Lake were inverted to a two-layer constrained water depth model. In this section, we focus on the spatial\(-\)temporal change in groundwater and surface water.  
In the constrained water depth inversion, the best fit (red color) and [PERSON]'s inversion (olive color) showed a good agreement in estimating the water column resistivity measured using the YSI probe (Figure 9). In the figures, the equivalence analysis (dashed green line) produced a more tightly constrained result in the West Lake system (Figure 9a-j)  
Figure 6: Map of apparent conductivities at West Lake and Seven Palm system: **(A)** 1 KHz in 2016, **(B)** 1 KHz in 2017, **(C)** 4 KHz in 2016, **(D)** 4 KHz in 2017, **(E)** 16 KHz in 2016, and **(F)** 16 KHz in 2017. At West Lake, the data were collected on 25 January 2016 and 10 February 2017. At Seven Palm, the data were collected on 6 February 2016 and 20 January 2017. The star shows the location of the monitoring well.  
compared to the Seven Palm system (Figure 9k-r). In the West Lake system, the surface water resistivity measured using the YSI probe decreased between 0.37 \(\Omega\)\(\cdot\)m and 0.28 \(\Omega\)\(\cdot\)m from west to east. In the Seven Palm system, the resistivity varies from 0.27 \(\Omega\)\(\cdot\)m at the north end to 0.17 \(\Omega\)\(\cdot\)m at the south end (Figures 9a-j and 10A). Similarly, the inverted surface water resistivity in the West Lake system decreased between 0.33 \(\Omega\)\(\cdot\)m at the west end and 0.26 \(\Omega\)\(\cdot\)m at the east end. In the Seven Palm system, the resistivity varies from 0.23 \(\Omega\)\(\cdot\)m at the north end to 0.16 \(\Omega\)\(\cdot\)m at the south end (Figures 9k-r and 10B). Generally, the data showed west to east and north to south decreases in surface water resistivity.  
The lake bottom resistivity in the West Lake system varies between 1.69 \(\Omega\)\(\cdot\)m at the west end and 3.74 \(\Omega\)\(\cdot\)m at the east end. In the Seven Palm system, the resistivity is 32.85 \(\Omega\)\(\cdot\)m in the north and decreases gradually toward the south to 1.5 \(\Omega\)\(\cdot\)m (Figure 10C). The lake bottom resistivity generally increased from west to east while it decreased from north to south.  
Figure 7: The box plot shows the mean (white dot), the median (white line), the interquartile range (IQR blue or red box) (i.e., the range between the 25 th and 75 th percentile), the upper and lower fence (range within 1.5 IQR), and outliers (asterisks).  
Figure 8: Apparent conductivity percent change between 2017 and 2016 in the West Lake and Seven Palm systems. The star shows the location of the monitoring well.  
Figure 9: \(Cont\).  
Figure 9: Constrained resistivity inverse model in West Lake system **(a-j)** and Seven Palm system **(k-r)**. The left panel shows the observed and calculated data (lines), and the right panel shows the inverted model. In the left panel, the square dots indicate the observed data, the purple line indicates the best fit calculated data, and the olive color indicates [PERSON]’s inversion. In the right panel, the red line indicates the best fit model, the green dashed lines indicate the equivalency analysis, and the olive line represents [PERSON]’s inversion model. The outlier measurements represented by asterisks were masked during inversion.  
In the inverse model, the minimum and maximum lake bottom resistivity varied between 1.4 \(\Omega\)-m and 3.7 \(\Omega\)-m at West Lake and between 1.4 \(\Omega\)-m and 32.8 \(\Omega\)-m at Seven Palm. Based on equivalency analysis, at West Lake, the model showed a highly constrained model with the lower and upper limit between 1.1 \(\Omega\)-m and 4.9 \(\Omega\)-m (Figure 11), whereas in Seven Palm, the model showed a poorly constrained model with the lower and upper limit between 1  
with the Seven Palm system (Figure 11). This uncertainty on the upper bound could be due to measurement errors induced by wind or wave action.