# Improvement of Subsurface Thermal Characteristics for Green Parks
## 4 Discussion  
Heat waves produced by the sun and daily temperature changes dissipate rapidly and generally influence the upper 1.5 to 2 m levels below ground. Temperature variation at deep levels or, for example, below the vadose level, is negligible. This is mainly attributed to the type, moisture, voids, and porous nature of the soil [25]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Clay Percent** & **0\%** & **10\%** & **20\%** & **30\%** \\ \hline T\({}_{\text{5 GG}}\) & 0.03 & 0.13 & 0.20 & 0.37 \\ \hline T\({}_{\text{9 GG}}\) & 0.2 & \textgreater{}24 & \textgreater{}24 & 0.5 \\ \hline T\({}_{\text{50L}}\) & 0.2 & 0.3 & 0.3 & 0.1 \\ \hline T\({}_{\text{90L}}\) & 22.5 & 2.8 & 3.3 & 4.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Exposure to 30 \({}^{\circ}\)C temperature and time in hours to reach 50% and 90% levels. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Clay Percent** & **0\%** & **10\%** & **20\%** & **30\%** \\ \hline T\({}_{\text{5 GG}}\) & 0.2 & 0.3 & 0.6 & 0.7 \\ \hline T\({}_{\text{90G}}\) & \textgreater{}45 & 9.5 & 24.0 & 10.0 \\ \hline T\({}_{\text{50L}}\) & 0.3 & 0.3 & 0.4 & 0.4 \\ \hline T\({}_{\text{90L}}\) & 6.0 & 7.2 & 7.3 & 13.3 \\ \hline \hlineSoil-moisture interaction is a very complex phenomenon, but with the recent introduction of digital sensors capable of recording moisture and electrical conductivity, it has become more convenient and has helped researchers, geotechnical engineers, and landscape industries to conduct more useful studies. It has also been useful in predicting soil behavior and monitoring temperature and moisture at any time under different weather conditions. When soil becomes dry, or when there is not enough water for plants, automatic irrigation pumps can be started. When included in clay-sand liners, these sensors can provide information that is useful to environmental engineers. The trends and temperature profile variations in clay-sand mixtures used as cover liners for landscing or landfills are the main subjects of this study. Three components make up unsaturated soils: solids, air, and water. According to [PERSON] [26], an aqueous solution is the only conducting phase for apparent electrical conductivity. This made it possible to employ this to assess volumetric water contents (\(\theta\)). The soil density, porosity, particle shape and orientation, cation content, and temperature are just a few of the variables that might affect how the electrical conductivity is determined. The electrical resistance of the soil can also decrease as the temperature rises. The profiles presented in Figures 7-9 indicate three levels of heat gain and heat loss. The time required to reach 50% of the exposure temperature (T\({}_{50}\) gain) is estimated as half an hour to one hour for all exposures, and this seems to be independent of the soil composition and clay content; however, the time to reach 90% exposure temperature (T\({}_{90}\) gain) is variable. The rate of heat gain is low in pure sand compared to sand enhanced with clay additives. The variation in the time necessary to achieve a 90% level gain for a high temperature gradient (50 \({}^{\circ}\)C) is small when comparing the 10%, 20%, and 30% clay admixtures. The results of elevating the temperatures to low and medium gradients (40 \({}^{\circ}\)C and 30 \({}^{\circ}\)C) are not consistent. This can be attributed to other factors influencing the gain of heat, namely, air and fluid within the system. It is important to note that these results cannot be compared because the field and lab settings have different clay contents. Therefore, if a comparison is to be made, these variations must be taken into account. Lower clay content gains heat faster than the than higher clay content. Therefore, it can be useful to adopt a higher clay content in order to make the morning cool last longer before the hot weather of midday in summer prevails.