Preferential flow and soil strength degradation induced by desiccation cracks are important causes for expansive clay slope instability. The cyclic opening and closing of desiccation cracks during drying-wetting processes incessantly alters preferential flow paths and soil strength. Quantify the impact of desiccation crack dynamics on slope hydrology and stability remains a major unresolved challenge. To bridge this gap, we developed the first slope-scale hydro-mechanical model that couples weather-driven crack evolution with preferential flow while incorporating the deterioration effect on soil strength. This unified approach is a major contribution to our capacity to model the integration of hydrological processes and mechanical degradation of soil strength induced by dynamic cracks. The hydrological part adopted a dynamic dual-permeability model (dynamic DPM) and was validated by a physical slope model test. The dynamic DPM was then integrated into a set of numerical slope stability analyses under one-year atmospheric conditions. The groundwater level, water balance, pore water distribution, crack evolution and slope stability were investigated in the case of dynamic cracks and fixed cracks. The hydrological results showed that the slope model with dynamic cracks retained more water and higher groundwater level than that with fixed cracks. The narrowing of desiccation cracks slows down slope drainage process, resulting in a rapid build-up of pore water pressure due to preferential flow, which emerges as an often overlooked and significant factor contributing to slope instability. Conversely, fixed and well-connected cracks in soils enhance water drainage and thus benefit slope stability. The mechanical results revealed that the irreversible deterioration effect induced by crack dynamics on soil strength persistently degrades long-term slope stability. These findings provide new insights into failure mechanisms in cracked soil slopes, and show the importance of the integration of dynamic crack properties into climate-resilient slope design. Also, our results underscore the importance of understanding and quantifying the physical behavior of soil structures for soil hydrological response and slope stability assessment.

The coronavirus disease 2019 pandemic has posed severe threats to humans and the geoenvironment. The findings of severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) traces in waste water and the practice of disinfecting outdoor spaces in several cities in the world, which can result into the entry of disinfectants and their by-products into storm drainage systems and their subsequent discharge into rivers and coastal waters, raise the issue of environmental, ecological and public health effects. The aims of the current paper are to investigate the potential of water and waste water to operate as transmission routes for Sars-CoV-2 and the risks of this to public health and the geoenvironment. Additionally, several developing countries are characterised by low water-related disaster resilience and low household water security, with measures for protection of water resources and technologies for clean water and sanitation being substandard or not in place. To mitigate the impact of the pandemic in such cases, practical recommendations are provided herein. The paper calls for the enhancement of research into the migration mechanisms of viruses in various media, as well as in the formation of trihalomethanes and other disinfectant by-products in the geoenvironment, in order to develop robust solutions to combat the effects of the current and future pandemics.