Geohazard assessment of landslides in south Brazil: Case study

Slope instability phenomena such as mudslides represent a major geohazard in Brazil, which has caused devastation in many states and affected the lives of people, particularly in self-built settlements on steep slopes. This paper presents and discusses slope stability issues encountered in Caxias do Sul in the State of Rio Grande do Sul, which exemplifies the existing situation of landslide risk assessment in southern Brazil. Local geology and ground conditions of the area in relation to slope instability were reviewed and gaps in information required for mitigating risk were identified, such as inadequate geotechnical information and lack of full inspection and continuous monitoring of active landslides. Although risk assessment has been developed for the city and regarded as a fundamental management tool in the mitigation of landslide hazards, the study showed that the risk assessment works are outdated and not effectively considered for the development of the city. With significant unplanned urban expansion (where houses have been self-built on very steep terrains without geotechnical assessment of the ground and slope conditions), new geohazard mapping is essentially required. Several key recommendations were provided for mitigating the destructive effect of landslides and improving their management in mountainous urban settings.Newton Researcher Links (Ref. NRCP1617/6/182) administrated by the Royal Academy of Engineering (RAEng)

Climate change impact and adaptation: Lagoonal fishing communities in west Africa

Lagoons are a common feature of the low-lying West African coastline. These lagoons are resource-rich and biodiverse. The small-scale fishing communities, which border them, are dependent on the resources and ecosystem services for their livelihoods and well-being. Climate change has had significant and diverse effects on both the lagoons and their surrounding communities. Sea level rise has caused erosion of the coast and increased the risk of floods. Changes to rainfall patterns have caused shifts in lagoon ecosystems and physical cycles. Of particular relevance to lagoon fishing communities is the fluctuation in quantity and distribution of fish catch that they rely upon for economic livelihood. Understanding the vulnerability of these communities to the effects of climate change is critical to supporting and developing successful adaptations. Using a case study from Ghana, sustainable livelihoods approach (SLA) and vulnerability framework are used to characterize the community vulnerability, giving insight into the temporal and spatial dynamics of vulnerability and how subsections of the community may be identified and prioritized for adaptation interventions. A scalar analysis of the relevant coastal and environmental frameworks and policy to support climate change adaptation in coastal communities reveals the common challenges in implementing adaptation interventions and strategies in the region. A policy gap exists between high level, institutional coastal, and climate directives and implementation of climate adaptations at the local level. That gap might be bridged by a participatory approach that places coastal communities at the center of creating and enacting climate change adaptations.Internal GCRF (seed corn) funding partially supported this research

The impact of freshwater mussels (order Unionoida) on river bed characteristics and sediment flux: A flume-based study.

Unionoid mussels are considered keystone species due to their ability to modify and link pelagic, benthic and hyporheic environments in freshwater systems, [1,2,3] yet empirical data to determine their influence on river bed dynamics and sediment flux is lacking. A recirculating flume-based study using fifty individuals of the unionoid species Anodonta anatina investigated the impact of this species on bedform development and particle flux of a polymodal substrate representative of the grain size distribution of the mussel's river habitat. River seston was added to the flume at weekly intervals, and water and substrate conditions were monitored for the eight-week duration of the study. The control experiment had mussels absent from the flume. It was found that the presence of A. anatina increased the organic content of the substrate through deposition of pseudofaeces, and led to significant reductions in near-bed velocity, boundary shear-stress and the amount of suspended and dissolved solids in the water column. However, despite these impacts a greater quantity of sediment and a larger range of grainsizes entered the flume's sediment trap compared to the control experiment when mussels were absent. The impact of mussel bioturbation appears to outweigh any sediment stabilisation effects arising from the increased organic content of the substrate and the reduced near bed velocities. Additionally, sediment grainsize and longitudinal wetted profile measurements indicate that the mussels increased bed roughness and heterogeneity of the substrate. Given that freshwater mussels can exist at very high densities within rivers, [3] increased mixing and mobilisation of bedload, improved habitat heterogeneity and the transferral of material from the water to the substrate by mussels implies they constitute a critical element in the sediment and nutrient dynamics of fluvial systems. References: 1. Vaughn, C.C., Nichols, S.J. & Spooner, D.E., 2008. Community and foodweb ecology of freshwater mussels. Journal of the North American Benthological Society, 27(2), pp.409-423. 2. Gutierrez, J.L. et al., 2003. Mollusks as ecosystem engineers: the role of shell production in aquatic habitats. Oikos, 101(1), pp.79-90. 3. Aldridge, D.C. et al, 2007. Freshwater mussel abundance predicts biodiversity in UK lowland rivers. Aquatic Conservation-Marine and Freshwater Ecosystems, 17(January), pp.554-564.University of Derby ESR

Characterising the vulnerability of fishing households to climate and environmental change: Insights from Ghana

Rural coastal communities in the global south are mostly natural resource-dependent and their livelihoods are therefore vulnerable to the impacts of climate and environmental changes. Efforts to improve their adaptive capacity often prove mal-adaptive due to misunderstanding the dynamics of the unique socioeconomic factors that shape their vulnerability. By integrating theories from climate change vulnerability and the Sustainable Livelihoods Approach, this study draws upon household survey data from a fishing community in Ghana to assess the vulnerability of fishing households to climate change and explore how their vulnerability is differentiated within the community. The findings suggest that household incomes in the last decade have reduced significantly, attributable to an interaction of both climatic and non-climatic factors. Analysis of the characteristics of three vulnerability groups derived by quantile clustering showed that the most vulnerable household group is not necessarily women or poorer households as expected. Rather, it is dynamic and includes all gender and economic class categories in varying proportions depending on the success or failure of the fishing season. The findings suggest furthermore that the factors that significantly differentiates vulnerability between households differ, depending on whether households are categorised by economic class, gender of household-head or vulnerability group. Consequently, the study highlights the importance of looking beyond existing social categorizations like gender and economic classes when identifying and prioritizing households for climate change adaptive capacity building.Internal REF PhD studentshi

Climate, dust, and fire across the Eocene-Oligocene transition, Patagonia

The Eocene-Oligocene transition (EOT) is typically interpreted as a time of drastic global cooling and drying associated with massive growth of a glacial icecap in Antarctica and the shift to an “icehouse” climate. The effects of this transition on the terrestrial environments, floras, and faunas of the Southern Hemisphere, however, have been unclear. Here we document simultaneous changes in fire regime and plant community in Patagonia, Argentina. Decreases in the concentration of magnetite in loessites from the Eocene-Oligocene Vera Member of the Sarmiento Formation correlate with decreases in the fraction of burnt palm phytoliths as well as more consistently palm-dominated phytolith assemblages. Association of magnetite and burnt palm phytoliths suggests intense wildfires, which appear to have been suppressed for ~200 k.y. shortly after the EOT. The disappearance of fire-related characteristics near the EOT is possible if changes in regional wind patterns—consistent with observed changes in sediment particle sizes—caused changes in seasonal precipitation. These results imply a more important role for fire in structuring Eocene-Oligocene landscapes than previously though

Shoreline change and sea level rise at the Muni-Pomadze coastal wetland (Ramsar site), Ghana

Lagoon-wetland systems are common along low-lying coastlines. They provide rich species habitats, multiple ecosystem services and socio-economic activities. They are particularly susceptible to the impacts of sea level rise (SLR), especially in less developed countries (LDCs) where economic and development constraints limit adaptation. The Muni-Pomadze lagoon is one of five coastal Ramsar sites in Ghana and one of many along the country’s coastline. It is an intermittently closed lagoon with extreme seasonal hydrological and physico-chemical variation. Field observation, digital mapping and GIS analysis of the shoreline has enabled an understanding of coastal change and SLR at the lagoon. From 1972 to 2014 the high water mark has shifted landwards with an average retreat rate of 0.22 m/year. Evidence of erosion and sediment washover indicate loss of and a shift landward of the sand barrier separating the lagoon from the ocean. Creation of an inundation map for a one-meter rise of sea level reveals fragementation and breaching of the barrier and an increasingly permanent connection to the ocean. A more open lagoon system stabilises hydrological and physico-chemical conditions, leading to increases in biodiversity and aquatic productivity. The lagoon currently has no consideration of SLR in its management plan. The results of this analysis and the limited development of the Muni-Pomadze lagoon support a no intervention approach to coastal management that allows SLR to transform the closed lagoon to an open estuary. A similar approach at comparable coastal wetland systems in Ghana and in other LDCs could prove an effective management option.Sheffield Hallam University Department of Natural and Built Environment professional development funds. University of Virginia