Browsing by Author "Neves, Maria C."
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- Avaliação crítica de mapas ambientais de poluição da água em marinasPublication . Neves, Maria C.Este estudo aplica o modelo PSR (“Pressure-State-Response”) para avaliar e mapear o risco ambiental das marinas ao longo da costa de Portugal continental. Focámo-nos em 27 marinas, classificando-as e avaliando-as em termos de risco ambiental para a qualidade da água. A metodologia integra pressões ambientais, condições do estado e respostas sociais, pro-porcionando aos decisores informação espacial baseada em dados científi-cos. Construímos uma base de dados que abrange dados de navegação, operações portuárias, dragagens, poluição e uso do solo nas regiões adja-centes. Usando Sistemas de Informação Geográfica (SIG), mapeámos e avaliámos a suscetibilidade, valor ecológico e naturalidade de cada mari-na, considerando as estratégias de gestão locais para mitigar as pressões humanas. Os nossos resultados revelam que as marinas com maior risco ambiental estão concentradas na região do Algarve, onde as atividades de navegação contribuem significativamente para o risco. No entanto, as dis-crepâncias entre a classificação de risco e os resultados das análises de da-dos in-situ da qualidade da água destacam limitações na metodologia ba-seada no modelo PSR, sugerindo a necessidade de indicadores adicionais. Os mapas de risco resultantes servem como ferramentas valiosas para pri-orizar planos de intervenção para melhorar a qualidade da água e alcan-çar os objetivos de desenvolvimento sustentável.
- Climatic and geologic controls on the piezometry of the Querença-Silves karst aquifer, Algarve (Portugal)Publication . Neves, Maria C.; Costa, Luis; Monteiro, José PauloKarst aquifers in semi-arid regions, like Queren double dagger a-Silves (Portugal), are particularly vulnerable to climate variability. For the first time in this region, the temporal structure of a groundwater-level time series (1985-2010) was explored using the continuous wavelet transform. The investigation focused on a set of four piezometers, two at each side of the S. Marcos-Quarteira fault, to demonstrate how each of the two sectors of the aquifer respond to climate-induced patterns. Singular spectral analysis applied to an extended set of piezometers enabled identification of several quasi-periodic modes of variability, with periods of 6.5, 4.3, 3.2 and 2.6 years, which can be explained by low-frequency climate patterns. The geologic forcing accounts for similar to 15 % of the differential variability between the eastern and western sectors of the aquifer. The western sector displays spatially homogenous piezometric variations, large memory effects and low-pass filtering characteristics, which are consistent with relatively large and uniform values of water storage capacity and transmissivity properties. In this sector, the 6.5-year mode of variability accounts for similar to 70 % of the total variance of the groundwater levels. The eastern sector shows larger spatial and temporal heterogeneity, is more reactive to short-term variations, and is less influenced by the low-frequency components related to climate patterns.
- Congress session’s synthesis: Geodynamics and marine geological hazardsPublication . Neves, Maria C.CIESM Congress is an event that not only celebrates scientific breakthroughs but also bridges diverse cultures across the Mediterranean and Black Sea regions, by exploring a wide range of marine disciplines such as dynamics of phytoplankton, environmental toxicology, ocean biogeochemistry, marine biodiversity, sea level variability and coastal hydrodynamics, sustainable blue bioeconomy, microbial biotechnology, geodynamics and marine geological hazards, marine litter and nano/microplastics, climate change impacts, deep sea & extreme environments, aquaculture, ocean literacy, assessment of fishery resources, and Mediterra nean Straits.
- Estudo comparativo de índices de avaliação da seca em aquíferos costeirosPublication . Neves, Maria C.Os aquíferos em áreas costeiras áridas e semiáridas, como a região do Algarve, são fortemente impactados por secas, agravadas pela sobre-exploração, que pode levar à degradação da qualidade da água e à intrusão salina. A monitori zação eficaz é essencial, utilizando vários indicadores para prever e gerir os efei tos da redução da precipitação e do aumento da extração. Este estudo compara indicadores de desempenho relativos à seca, como o Índice Padronizado do Nível de Água Subterrânea (SGI) e os tempos ótimos de acumulação do Índice Padro nizado de Precipitação e Evapotranspiração (SPEI). Ao combinar dados de re análise atmosférica com observações dos níveis de água subterrânea, o estudo avalia a memória do sistema de água subterrânea e determina os períodos de acumulação do SPEI mais adequados. O inverso da memória obtido pela auto correlação do SGI ajuda a estimar a capacidade de recuperação de cada furo em condições de seca, indicando a sua resiliência e sustentabilidade. No Algarve, o índice SPEI-12 representa eficazmente a variabilidade regional dos níveis de água subterrânea, mas as memórias dos aquíferos e os tempos ótimos do SPEI variam amplamente (SPEI-5 a SPEI-48). Furos com memórias mais curtas (< 6 meses) demonstram melhor sustentabilidade, enquanto aqueles com memórias mais longas (> 16 meses) apresentam menor resiliência.
- Evaluation of GRACE data for water resource management in Iberia: a case study of groundwater storage monitoring in the Algarve regionPublication . Neves, Maria C.; Nunes, Luís; Monteiro, José PauloStudy region: Iberia, Algarve basin, South Portugal. Study focus: This study evaluates the performance of several GRACE products in Iberia using the closure of the water budget. Then, it focusses on the Algarve region and explores the potential of GRACE as a tool of quantitative groundwater monitoring capable of bridging gaps in the existing ground-based network. Monthly data from GRACE, ancillary datasets from E-OBS, GLEAM, GRUN and ERA5, and groundwater level measurements from 12 karst-porous aquifers in the Algarve basin (5000 km2) are analyzed from 2004 to 2014. New Hydrological Insights for the Region: When considering the closure of the water budget at the Iberian scale, GRACE Mascon solutions perform remarkably well and better than the products based on spherical harmonics. When considering only the Algarve region, the results are similar to the ones obtained for Iberia, but the GRACE solution that performs the best is the average of the CSR and JPL Mascon products. In spite of the Algarve’s extremely small area when compared to the GRACE footprint, the satellite is capable of capturing the regionally averaged seasonal and deseasonalized variations in observed groundwater storage (correlation between GRACE-derived and regionally averaged ground-based measurements is 0.82). For the first time ever at the regional Algarve scale, bounds are placed on the aquifer’s storage properties which vary from 3.65 × 10 3 to 4.92 × 10 2.
- Exploring the interplay between water availability and solar and wind energy potential in the Algarve (Portugal)Publication . Neves, Maria C.; Rui Mendonça NevesThis work falls within the scope of the Energy-for-Water branch of the water-energy nexus and is a contribution to better understand the available water and endogenous energy resources in the Algarve region. Time series for water resource availability, solar and wind power generation potential in the Algarve between 2004 and 2014 are analyzed. Complementarity relations among their trends and seasonal cycles are identified that can improve the efficiency in use of endogenous renewable energies in groundwater pumping.
- Links between extremes in GRACE TWS and climate patterns across iberiaPublication . Neves, Maria C.The Iberian region relies heavily on groundwater and is highly vulnerable to climate variability, making it crucial to understand factors influencing water availability. The aim of this research was to assess how large-scale climate patterns affect total water storage anomalies (TWSAs) in Iberia, particularly in relation to persistent droughts and floods. To address this, I analyzed TWSAs derived from a reconstructed dataset (GRACE-REC) spanning from 1980 to 2019, first at the scale of the entire Iberian Peninsula and then across its main river basins. The links between the North Atlantic Oscillation (NAO), East Atlantic (EA) and Scandinavian (SCAND) patterns, TWSAs, and hydrological extremes were quantified using wavelet and principal component analysis. The results reveal that the NAO exerts the strongest multiyear influence on TWSAs, with periodicities of approximately 10 and 6.5 years, particularly in the southern river basins (Tagus, Guadiana, and Guadalquivir). EA and SCAND have stronger influences in the northern basins (Douro, Minho, and Ebro), driving 2- to 3.5-year cycles. Coupled phases of climate patterns, such as NAO+ and EA- (or SCAND-), correspond to extreme droughts, whereas NAO- and EA+ (or SCAND+) correspond to wet conditions.
- Links between GRACE water storage and NAO-EA-SCAND climate patterns in IberiaPublication . Neves, Maria C.; Neves, Rui G. M.Groundwater drought develops as a smoothed and delayed response to persistent or frequent deficits in rainfall, or as result of a continued negative balance between recharge and extraction. Although not as accurate as in-situ observations, remote sensing has the advantage of providing near real-time and spatially continuous data. GRACE satellite data has been used to show evidence of groundwater depletion in aquifers all over the world (Rodel et al. 2018), and NASA currently generates weakly groundwater and soil moisture drought indicators based on GRACE-FO as part of the United States drought monitoring program. In Europe the Copernicus Global Drought Observatory also uses GRACE total water storage (TWS) anomalies as a proxy of groundwater drought. The use of GRACE satellite data for water resources management, particularly for groundwater systems in the Iberia Peninsula, looks promising (Neves et al. 2020), but its suitability to monitor drought requires further research. On the other hand, large scale atmospheric circulation patterns also known as teleconnections control the interannual to interdecadal natural variability of the climate system. In the Iberian Peninsula, the North Atlantic oscillation (NAO), the East Atlantic (EA) and the Scandinavian (SCAND) patterns are the three main modes of variability driving winter precipitation, river flow and therefore surface and subsurface water storage. These patterns or modes of variability are characterized by indices which measure the strength of atmospheric pressure anomalies. Positive and negative phases of the indices, defined by values above or below given thresholds(e.g. NAO+ is defined for aggregates of winter month indices above 0.5), are generally associated with either wet or dry conditions. Previous studies have shown that wintertime NAO+ and EAphases potentiate droughts in Iberia, the opposite occurring for NAO- and EA+ phases. However, few studies have recognized the importance of interactions amongst climate patterns and only recently did we become aware that their combinations or superpositions, as well as the temporal shifts in their synchronization, may lead to major anomalies in groundwater storage (Neves et al. 2019). The purpose of the present study is to address the question: Do combined NAO-EA-SCAND phases also produce noticeable extremes in GRACE TWS observations? This question is relevant for two main reasons. First, GRACE offers a unique opportunity of fast and reliable large-scale monitorization of groundwater and can be used as an early warning system for groundwater drought or aquifer depletion. Second, the NAO-EASCAND indices provide a potential source of seasonal forecast since their wintertime value determines the availability of water in the following summer. Teleconnections may also be a source of long-term forecasting as they exert periodic controls on groundwater level and are linked to recurrent droughts.
- Mapping environmental risk of marinas in Portugal-mainlandPublication . Neves, Maria C.; Mundt, NeeleThis study applies the Pressure-State-Response (PSR) model to assess the environmental risk of marinas along the coast of mainland Portugal. The goal is to provide decision-makers, such as government agencies and harbour managers, with scientifically-based information that helps to manage marinas and neighbouring waterfronts. The PSR model integrates the evaluation of environmental pressures, state conditions, and societal responses. The steps of the work comprised: (a) build a database with information necessary to determine the environmental impacts of identified pressure activities, such as navigation, port operations, dredging, oil pollution, coastal litter, and nearby industrial activities; (b) identify specific environmental conditions at each marina by mapping and evaluating susceptibility, ecological value, and naturalness using Geographic Information Systems (GIS) tools; (c) consider locally implemented management strategies to mitigate or prevent negative environmental effects from human pressures; and (d) establish risk thresholds, categorize pressures, states, and responses, and map spatial variations of risk factors. The classification and hierarquization of the risk is applied to 27 marinas along the west and south Portuguese coast. The resulting maps can help establish priorities for intervention plans aimed at enhancing water quality.
- Modelling drought classes time series for groundwater drought assessment and prediction in Algarve regionPublication . Moreira, Elsa; Neves, Maria C.Log-linear quasi-association models have been successfully applied to analyze and predict drought class transitions derived from standardized precipitation index (SPI) time series in Portugal. This kind of model proved to be suitable for fitting the SPI drought transitions and is considered a reliable tool for capturing the dynamics of drought severity changes since it models the probabilities associated with transitions in drought severity over specific time periods. In the context of groundwater drought monitoring, the standardized groundwater index (SGI) is used and is computed from groundwater levels available from the SNIRH piezometric network. The aim is to employ similar models to model the transitions between SGI drought classes and use them to analyze and predict transitions in groundwater drought classes one or two months in advance. The purpose is also to evaluate the effectiveness of these tools in predicting short-term transitions in groundwater drought. The findings contribute to improving water management practices and enhancing early warning systems to mitigate the impacts of drought in the Algarve, with potential applications in other parts of the world.