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- Influência da seca severa em indicadores de águas superficiaisPublication . Sequeira, Mário; Tavares, Alexandre; Lopes, Ana Maria Aguiar Castilho Ramos; Dinis, PedroRESUMO: Durante a seca que afetou Portugal no ano hidrológico de 2021/2022, foram realizadas cinco campanhas de monitorização das águas superficiais na bacia hidrográfica do Rio Mondego. A amostragem ocorreu de março a novembro de 2022 e os indicadores de qualidade da água medidos foram comparados com um fundo geoquímico criado a partir de dados abertos. Durante o período de seca, as águas superficiais parecem tendencialmente mais alcalinas potencialmente devido à menor diluição ou a uma influência bicarbonatada proveniente de águas subterrâneas. No mesmo período as concentrações de NO2 tenderam a aumentar, quase sempre acima de teores normais. No início do ano hidrológico seguinte, com eventos de chuva intensa, e um aumento do escoamento, erosão e transporte de partículas do solo, notou-se um aumento da turbidez, com valores acima do normal, associado a concentrações excessivas de Al, Fe e Mn, enquanto se verificou o regresso aos valores normais de pH e NO2.
- The influence of rural fires in surface water qualityPublication . Sequeira, Mário; Dinis, Pedro; Lopes, Ana Maria Aguiar Castilho Ramos; Tavares, AlexandreABSTRACT: This study focuses on the impact of rural fires on water quality in the Mondego River basin in Portugal. An analysis of water quality was conducted to assess the interaction between fires, land use, geology, and precipitation. Data from a monitoring program conducted over two hydrological years were statistically analyzed and compared to a geochemical background. The results reveal substantial increases in the concentrations of Ca, K, Mg, NO3, SO4, and As in surface waters after the fires. These changes are accompanied by an increase in electrical conductivity. While some parameters returned to normal concentrations in the following months, As kept with elevated grades in some sites, which appear to reflect complex interactions between post-fire processes and geology.
- 1926 – 2021 flood impacts in Mozambique from a local database incidencePublication . Nganhane, Helio Vasco; Tavares, Alexandre; Santos, Pedro Pinto; Dgedge, GustavoABSTRACT: Due to its geographical location, Mozambique has been frequently affected by climatic events, in particular depressions, storms and tropical cyclones that often cause flooding processes. In the last 10 years, the frequency of these events has increased and consequently the social and economic losses have also been amplified. This work presents results from ongoing research to create a database, using local incidence analysis, collecting and evaluating impact associated with flooding processes. The database - relying on hemerographic information and cross-checking data from official reports and international databases - shows, for the period encompassing 1926 and 2021, 996 flood occurrences, where 3237persons lost their lives, 1510 people were injured, 2.821.639 people were displaced, and 10.604.520 were only materially affected. The southern and central Mozambique have been the most exposed regions to flood process. The analysis of these outputs improve the disaster risk management system in Mozambique.
- Tropical cyclone meteorological extreme events and their large impacts in Mozambique during the period 1926 to 2021Publication . Nganhane, Helio Vasco; Tavares, Alexandre; Santos, Pedro Pinto; Fernández Sánchez, AdriánABSTRACT: The monitoring and prediction of tropical cyclones in Mozambique rely on short databases that sometimes lead to inadequate interpretations due to the lack of precision in equipment and limited human resources. Misinterpretations are also related to the notoriously unstable climatic conditions in the oceanic domain, especially in the Mozambique Channel region, particularly in recent years. It is essential to have a better understanding of the history of these events, as Mozambique has been frequently devastated by tropical cyclones. In this paper, we present our contribution to reconstructing the historical record of these events, their human and material impacts on Mozambican territory from 1926 to 2021. In this interval, 33 tropical cyclones were highly destructive, causing severe human, material and environmental impacts. The research has shown that extreme meteorological events of the tropical cyclone type cause greater human, material and infrastructure damage, mainly because of their duration after landfall and because they are associated with heavy rainfall after energy dissipation.