Search

The architectural style found in Wa and Tamale is renowned for its distinctive use of earthen construction, which features square buildings with flat roofs and circular compounds with conical thatch roofs. Recently, there has been a growing inclination towards the use of alternative construction techniques in which nontraditional materials such as cement, bitumen, and used car engine oil are utilised to render wall surfaces. These structures show how the materials and design in northern Ghana have substantially evolved. However, what forces drive the changes in cob construction in this region? Furthermore, how might these changes impact the preservation of cultural heritage in Ghana? To explore the factors that contribute to the departure from traditional earthen building methods that rely on local materials, this study employs a constructivist research approach. Participants in a survey that informed this study revealed that they struggled to access building materials to construct their houses. While most of the people who responded to the survey have resided in buildings constructed with a mixture of beini and dawadawa, they hesitate to use plant-based biostabilisers in new constructions. Factors that hinder the ongoing construction and preservation of earthen buildings include shifting cultural and social norms, environmental changes, difficulties accessing local building resources, flood risks, regular maintenance requirements, and societal influences. Thus, this study concludes that if communities are empowered to take ownership and recognise the value of their cultural heritage, they are likely to be increasingly aware and appreciative of their architectural heritage. Thus, their local heritage will be preserved. [ABSTRACT FROM AUTHOR]

Several damaging tropical cyclones (TCs) have occurred recently over the South Indian Ocean (SIO) region, causing enormous social and economic losses. Yet, while many studies have examined SIO TC characteristics using observations and reanalysis, only a few have assessed these characteristics specifically for this region in climate models, and fewer have investigated their projections under climate change. Here we do this for a historical (1980–2010) and future (2020–2050) period, using multimodel simulations from the High Resolution Model Intercomparison Project, as well as examine biases in the historical period relative to a reanalysis (ERA5). The models have horizontal resolutions of 25–50 km, which has enabled an improved ability to represent tropical cyclones globally in previous studies. TempestExtremes software is employed to detect tropical storm and cyclone tracks. In cases where TempestExtremes cannot be applied due to a lack of requisite variables in a dataset, we instead examine extreme wind speeds in that dataset. For the historical period, we find considerable variation in model biases compared to ERA5, which itself exhibits realistic spatial patterns of tracks and their monthly distribution. Models do at least agree on positive biases in track frequency east of Madagascar and somewhat in the Mozambique Channel. However, the models and ERA5 only produce Category 3 tropical cyclones at best. Wind speeds for 25 km resolution models have much larger positive biases than for 50 km ones, suggesting the former can simulate even higher‐category tropical cyclones. Considerable intermodel variation is also found in track changes between the future and historical periods. No systematic intercategory pattern of change exists, and low signal‐to‐noise may obscure any such patterns in the limited timespan of available data. Thus, no meaningful conclusions can be drawn regarding changes in track intensity. Nevertheless, track frequency broadly decreases across models for the region, as does accumulated cyclone energy. An east‐to‐west shift in track location from east of Madagascar toward the Mozambique Channel is also implied by track frequency and wind speed changes. Our findings provide information to potentially improve storm resiliency in this vulnerable region. [ABSTRACT FROM AUTHOR]

Hydrophobic soils can occur either naturally when particles are coated with plant-derived hydropho-bic organic compounds or if exposed to very high temperatures, or artificially if treated with contaminated water or chemicals in the laboratory. Hydrophobic soils can resist water infiltration, are associated with preferential flow and may lead to increased surface runoff and soil erosion. Traditional understanding of unsaturated hy-drophobic soils suggests that convex water menisci, and so positive water pressures, should form between soil particles, due to contact angles > 90◦. However, experimental results do not support this theory. The objective of this work was to study the changes in meniscus structures in hydrophobic sand specimens, as well as the overall response of the sand to wetting and drying cycles. A very uniform, fine silica sand was mixed with Dimethyldichlorosilane to induce water repellence. Successive images captured in an environmental scanning electron microscope are presented, to examine the response of the sand in two distinct drying and wetting cycles. Preliminary results show that the non-spherical nature of the sand particles prevent or hinder the formation of convex liquid bridges, despite the high contact angles. Rather, water droplets appear to expand only through droplet coalescence, which prevents structures from contracting on drying.