Due to climate change, drought-flood alternations have become more frequent and more severe in many countries in the world. However, little research has been done on the relationship between flood and drought. Thus, this research aims to investigate whether a relationship exists between multi-year droughts and the floods that follow in the post-drought period. The hypothesis is that vegetation decreases as a result of long-term drought, which decreases evaporation and increases the proportion of precipitation that becomes runoff, and thus, increases flood.

To test this hypothesis, the United States is chosen as a case study area. Hydrological data and remote sensing data are collected for 671 basins in the case study area, from around 1980 till 2014. A list of criteria is established to detect the occurrence of long-term droughts, verify the water balance, and ensure data availability. 83 basins fulfill all criteria and these basins are investigated further.

These 83 basins are plotted inside the Budyko space and Fu's equation is fitted to find the free parameter that indicates the runoff ratio. It is found that in general, no increase in runoff ratio is detected after drought. However, looking at the basins individually, changes in the runoff ratio do exist. Further investigations into the cause of these changes are carried out by looking at the effects of drought on the partitioning of hydrological fluxes and separating the basins' movements into climate effects and residual effects. Vegetation changes are also investigated to see whether the runoff changes are related to vegetation changes. The results show that although strong correlations exist between the runoff ratio, evaporative index, and residual effects, no relationship is found between the runoff ratio and the vegetation-related variables. It is concluded that using the method in this research, no significant relationship is found between the multi-year droughts and floods that occur after drought. ... Read more

Lithium halide electrolytes with high ion conductivity and good cathode compatibility have shown great potential for solid-state batteries. Li₃YBr₆, with a conductivity of 0.39 mS/cm at room temperature, synthesized by mechanical milling (BM-Li₃YBr₆), which can be further increased by heat treatment. The annealing parameters are tailored to obtain pure Li₃YBr₆ (AN-Li₃YBr₆) with a higher conductivity of 3.31 mS/cm by annealing the BM-Li₃YBr₆ at 500 °C for 5 h. The higher conductivity of AN-Li₃YBr₆ compared to the previously-reported results is due to the lower activation energy. NMR and simulation results show that the lithium ion migration between Li-1 and Li-2 sites along the [001] direction is the major obstacle for lithium diffusion in AN-Li₃YBr₆. The K- and L₃-edge X-ray absorption near-edge structure (XANES) of Y for BM-Li₃YBr₆ and AN-Li₃YBr₆ showed that Y exists with similar local structures. The increased vibrations of AN-Li₃YBr₆ due to increased temperatures increase the rate of lithium jumping from one site to another, yielding higher lithium ion mobility. Lithium nuclear density maps prove that the mobile lithium on the 4g(Li) site is more sensitive to the varying temperatures. Both BM- and AN-Li₃YBr₆ are incompatible with Li, however, an annealing process can improve the electrochemical stability. Both the experimental and simulation results confirm the anode incompatibility between In and AN-Li₃YBr₆. To mitigate the cathode and anode incompatibility with AN-Li₃YBr₆, a LiNbO₃ coating layer and a Li_5.7PS_4.7Cl_1.3 buffer layer are introduced at the cathode side and anode side, respectively, to assemble all-solid-state batteries with improved capacity and cyclability. ... Read more