## 3 Materials and Methods  
### Monitoring Systems  
The field test site included three monitoring systems [12]: a meteorological monitoring system, a soil monitoring system, and a groundwater monitoring system. The ground con \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Stratum** & **Depth** & **Elevation** & **Sand** & **Silt** & **Clay** & **Soil Texture** & **Bulk** & **Hydraulic** & \\
**Symbol** & **(m)** & **(m)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(lithology)** & **Density** & **Conductivity** & **Permeability** \\ \hline  & 0–0.20 & 33.20 & 10.40 & 67.60 & 22.00 & & 1.49 & \\  & 0.20–1.20 & 32.20 & 12.13 & 71.62 & 16.25 & Slity loam & 1.51 & \\  & 1.20–2.60 & 30.80 & 8.90 & 74.17 & 16.90 & 1.48 & & \\  & 2.60–4.40 & 29.00 & 0.93 & 72.44 & 26.63 & 1.60 & \(10^{-7}\)–\(10^{-5}\) & Extremely low—weak \\  & 4.40–5.70 & 27.70 & 1.20 & 62.15 & 36.65 & Slity clay & 1.66 & & \\  & 5.70–11.60 & 21.80 & 3.00 & 79.42 & 17.58 & Slity loam & 1.63 & & \\  & 11.60–13.00 & 20.40 & 4.60 & 61.49 & 33.91 & Slity clay & 1.41 & & \\  & 13.00–14.00 & 19.40 & 45.10 & 41.54 & 13.36 & Loam & 1.67 & & \\  & 14.00–15.00 & 18.40 & 66.17 & 26.43 & 7.40 & Sandy loam & & \\  & 15.00–18.00 & 15.40 & \(\backslash\) & \(\backslash\) & Sand-gravel & \(\backslash\) & \(1.3\times 10^{-2}\) & Strong \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Geological structure and soil texture information of test site. ditions were all bare land during the monitoring period from 1 January 2018 to 4 November 2020. Equipment models, factors, and monitoring frequency of the field test site are shown in Table 2.  
The soil monitoring system was aimed at monitoring the volume of soil moisture and soil water potential at different layers of the east side profile of WELL 3 (\(\varphi\) = 2 m) (named 3E) in the unsaturated zone (0-6 m) above the micro-confined groundwater level. The depths of the monitored layers in profile 3E were 0.2 m, 0.5 m, 0.9 m, 1.4 m, 2.0 m, 2.5 m, 3.0 m, 3.5 m, 4.0 m, 4.5 m, 5.0 m, and 6.0 m (Figure 1). The surface heat flux of the soil was also monitored at a depth of 0.1 m. The meteorological monitoring system was located at the northeast side of the site, and was mainly aimed at normal meteorological factors (Table 2) monitoring in order to evaluate the amount of moisture and energy received. The groundwater monitoring system was located at the southwest side of the field test site and was aimed at monitoring the dynamic changes in the micro-confined groundwater level. The electrical energy to support the operation of the meteorological monitoring system and soil monitoring system was provided by a battery, which was charged from solar panels equipped by the meteorological monitoring system (Figure 1). The groundwater monitoring system had its own battery inside the probe. In situ monitoring data (soil volume water content, soil water potential, surface heat flux) of the soil monitoring system were measured from probes, which were buried horizontally in different monitoring layers in profile 3E. The CS257 probe measured the resistance value (\(R\)) when the water potential between the sensor and the soil reached an equilibrium state. The CS650 probe measured the soil bulk dielectric permittivity (\(Ka\)) by using the time domain reflectometry (TDR) method. Finally, the program self-contained inside the CR1000 data collector transformed them to soil water potential and soil volume water content. The relationship between dielectric permittivity and volume water content in mineral soils has been described by the Topp Equation (1980) in an empirical fashion using a third-degree polynomial, and it works well in most mineral soils, so a specific soil calibration of the CS650 sensor is usually not necessary. To obtain reliable data, we performed specific soil volume water content calibrations in the laboratory to confirm the equation relating \(Ka\) to \(\theta_{\rm{v}}\).