## 4 Impact of Climate Change and Practical Implications  
The stability of an embankment supporting a roadway is strongly related the increase in water content or reduction of matric suction in the subgrade soil and embankment fill materials. The magnitude of the changes in moisture content are in turn related to the weather conditions (e.g., rainfall, temperature, humidity, infiltration/evaporation potential), and their impact is directly associated with the soil properties (e.g., plasticity, water retention and thermal properties). The impact climate change is twofold, i.e., (a) increase in temperature and extensive periods of droughs and (b) different rainfall patterns, which are expected to become few and far between but having a high intensity leading to rapid flooding. In other words, dry summer periods remove water that leads to shrinkage and cracking; prolonged and intense rainfall events cause swelling and increased pore water pressures. Figure 9 illustrates the effects of seasonal climatic variation on a typical roadway embankment. As it can be observed, the increase in temperature caused by atmospheric conditions will cause evaporation to take place and hence a reduction in water content (dry season). This may cause a change in the soil properties as well as the onset of cracking caused by desiccation and soil shrinkage which can propagate through the pavement layers. This is particularly important in locations with soils that have potential for volume changes (e.g., swelling and shrinkage), especially because repeated shrink-swell cycles can lead to accumulation of shear strains resulting in strain softening and progressive failure [29]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Spectrum Element Label** & **C** & **O** & **Na** & **Mg** & **Al** & **Si** & **K** & **Ca** & **Ti** & **Fe** \\ \hline Unstabilised Average (\%) & 7.19 & 47.99 & 0.42 & 1.38 & 9.26 & 25.52 & 1.06 & 1.29 & 0.69 & 5.43 \\ \hline HL & 14.12 & 47.36 & 0.1 & 1.21 & 5.45 & 14.72 & 0.56 & 12.51 & 0.85 & 3.65 \\ \hline HL/SFS Average (\%) & 7.26 & 45.92 & 0.23 & 1.40 & 6.09 & 20.32 & 0.57 & 4.94 & 0.54 & 7.95 \\ \hline PC & 15.09 & 44.89 & 0.47 & 0.66 & 8.60 & 15.57 & 1.24 & 14.79 & 0.45 & 3.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: EDS spectrum results presented as an average percentage. Figure 9: Diagram of a roadway embankment subjected to seasonal climatic variations. For constant suction conditions [30] reported that the contribution of suction to soil strength and stiffness may be reduced due to thermal loading. In addition, [31] reported that an increase in temperature from 20 to 60 \({}^{\circ}\)C under approximately the same level of suction results in a reduction in the soil shear strength and resilient modulus due to the differences in surface tension values at these temperatures. Nonetheless, it should be noted that temperature changes induced by climatic action as illustrated in Figure 9 are likely to be accompanied by a variation of moisture and suction. The soil thermal regime can be characterized by periodic changes in response to the natural periodicity in atmospheric conditions. There is a diurnal (daily) cycle, as well as a superimposed seasonal cycle (Figure 9). In the diurnal cycle, the temperature variation in the soil tends to be shallower (20-50 cm, e.g., [32]) whereas in the seasonal cycle temperature variations can go up to 10m depth [33]. This is mainly because much of the heat conducted through a soil profile is utilized to change the local temperature of the soil and there is a decrease in energy flux with depth. Thus, the phenomenon of amplitude damping, or a reduction in the magnitude of these temperature cycles with increasing depth is observed. As the annual average atmospheric temperatures continue to rise as well as the prevalence of drought conditions, it is likely that the seasonal temperature cycles are shifted to larger temperatures.