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311.
312.
Assessing the physical,geographic,chemical,and geological aspects are important to understand environmental impacts as well as health concerns in view of building a more sustainable planet with circular economies that would last for the foreseeable future.In the recent years,the significance of incorporating ecosystem,anthropogenic activities,and climate has fortified from being an academic concern(e.g.,WEF,2011)into a broadly societal concern as the forecasted realities of environmental deterioration and global climate change come to pass. 相似文献
313.
Marquis Henrique Campos de Oliveira Nilza Maria dos Reis Castro Olavo Correa Pedrollo 《水文科学杂志》2017,62(13):2120-2138
Soil water content (SWC) is an important factor in transfer processes between soil and air, contributing to water and energy balances, and quantifying it remains a challenge. This study uses artificial neural networks (ANNs) to analyse spatial and temporal variation of SWC in a Brazilian watershed, based on climate information, soil physical properties and topographic variables. Thirty eight input variables were tested in 200 models. The outputs were compared with 650 gravimetric moisture measurements collected at 26 points (25 field studies). The results show that it is possible to estimate SWC efficiently (Nash-Sutcliffe statistic, NS = 0.77) using topographic data, soil physical properties and rainfall. If only climate information is considered, modelling is less efficient (NS = 0.28). Using many variables does not necessarily improve performance. Alternatively, SWC can be estimated by simplified models using rainfall and topographic maps information, although the performance is less good (NS = 0.65). 相似文献
314.
Ramos Claudete Gindri dos Santos de Medeiros Diego Gomez Leandro Oliveira Luis Felipe Silva Schneider Ivo André Homrich Kautzmann Rubens Muller 《Natural Resources Research》2020,29(3):1583-1600
Natural Resources Research - This study was focused on physical, petrographical, mineralogical, and chemical characterization of a volcanic-rock mining by-product (dacite rock), as well as on... 相似文献
315.
Helen Michelle de Jesus Affe Fernanda Reinhardt Piedras Lucineide Maria Santana Gleyci Aparecida Oliveira Moser Maringela Menezes Jos Marcos de Castro Nunes 《Marine Ecology》2019,40(4)
Functional groups have become an important tool for characterizing communities of marine and estuarine environments. Their use also holds promise for a better understanding of the temporal dynamics of phytoplankton. This study aimed to evaluate the contributions of phytoplankton size fractions and functional groups characterizing short‐term variation throughout tidal cycles and between dry and rainy seasons in a tropical estuarine system. Camamu Bay is an oligotrophic estuarine system that is under strong influence from tropical shelf waters and is characterized by high salinity and low concentrations of dissolved nutrients. Surface‐water samples were collected at nine sampling sites distributed among the three hydrodynamic regions of the bay, and at a mooring, at 3‐hr intervals during tidal cycles (12 hr each) in both the rainy and the dry season. Although the abundances of the phytoplankton fractions (pico‐, nano‐, and micro‐) were higher in the rainy season and during periods of higher tide, they were not significantly higher. The phytoplankton community in the bay comprises three functional groups: GI = “colonial” (i.e., chain‐forming diatoms and filamentous cyanobacteria); GII = “GALD >40” (i.e., pennate and centric diatoms with MDL >40 µm), and GIII = “flagellates” (i.e., species with motility via flagella). Nanoflagellates were the most abundant form in the bay, while chain‐forming diatoms, in particular, contributed to the microphytoplankton fraction during both the rainy and dry seasons. Functional groups, as defined by cluster analysis, reflected ecological strategies compatible with the high hydrodynamics of Camamu Bay, which is characterized by processes of tidal‐forced intense mixing, mainly during periods of spring tides. The phytoplankton of the bay was found to possess a series of attributes (functional traits) that endow them with some resistance to sinking. Functional diversity indexes (FEve, FDiv, and FDis) indicated a stable community without significant short‐term variation due to low variability in the environmental conditions of the system during the study period. 相似文献
316.
The uncertainty associated with simulations of process-based coastal area morphodynamic models is assessed through numerical experimentation. Appropriate metrics of uncertainty are defined based on the standard deviation of the model results at each location and each time step. Uncertainty is examined using a set of realistic one year morphodynamic simulations of the evolution of a highly dynamic tidal inlet. Results indicate that uncertainty increases linearly with time, and suggest that its rate grows with increasing sediment fluxes. Hence, the limits of predictability of morphodynamic model applications are higher for slowly varying systems. Attempts to reduce uncertainty by aggregating model results at larger spatial scales met with limited success. Ensemble simulations are suggested as a possible avenue to investigate the long-term evolution of tidal inlets using process-based models. 相似文献
317.
Felício Cassalho Samuel Beskow Carlos Rogrio de Mello Maíra Martim de Moura Leroi Floriano de Oliveira Marilton Sanchotene de Aguiar 《水文研究》2019,33(7):1101-1116
Due to the severity related to extreme flood events, recent efforts have focused on the development of reliable methods for design flood estimation. Historical streamflow series correspond to the most reliable information source for such estimation; however, they have temporal and spatial limitations that may be minimized by means of regional flood frequency analysis (RFFA). Several studies have emphasized that the identification of hydrologically homogeneous regions is the most important and challenging step in an RFFA. This study aims to identify state‐of‐the‐art clustering techniques (e.g., K ‐means, partition around medoids, fuzzy C‐means, K ‐harmonic means, and genetic K ‐means) with potential to form hydrologically homogeneous regions for flood regionalization in Southern Brazil. The applicability of some probability density function, such as generalized extreme value, generalized logistic, generalized normal, and Pearson type 3, was evaluated based on the regions formed. Among all the 15 possible combinations of the aforementioned clustering techniques and the Euclidian, Mahalanobis, and Manhattan distance measures, the five best were selected. Several watersheds' physiographic and climatological attributes were chosen to derive multiple regression equations for all the combinations. The accuracy of the equations was quantified with respect to adjusted coefficient of determination, root mean square error, and Nash–Sutcliffe coefficient, whereas, a cross‐validation procedure was applied to check their reliability. It was concluded that reliable results were obtained when using robust clustering techniques based on fuzzy logic (e.g., K ‐harmonic means), which have not been commonly used in RFFA. Furthermore, the probability density functions were capable of representing the regional annual maximum streamflows. Drainage area, main river length, and mean altitude of the watershed were the most recurrent attributes for modelling of mean annual maximum streamflow. Finally, an integration of all the five best combinations stands out as a robust, reliable, and simple tool for estimation of design floods. 相似文献
318.
Hugo Oliveira François Louf Estelle Hervé-Secourgeon Fabrice Gatuingt 《国际地质力学数值与分析法杂志》2020,44(1):19-39
In numerical models, the connections among component members are crucial for the prediction of structural behaviour under different types of solicitations. In reinforced structures, the connections are often assumed rigid, what may not be realistic in many practical cases. As alternative, a semi-rigid behaviour depending on a set of independent parameters can be proposed. In this case, a new difficulty arises, which is finding the appropriate values for those parameters. The present study proposes a numerical strategy for identification of the connection parameters based on the constitutive relation error (CRE). To include all available information, an augmented version (Modified CRE) is implemented. The parameters search is iterative and require large amount of system response analysis. To increase the computational efficiency, a reduced order model is adopted. The proposed approach shows low-sensitivity to limited lack of information and also to support condition variability, both of them verified numerically. In this work, experimental tests for a real 1:4 scale structure is utilized for finding the parameters corresponding to the first three modal shapes. A good agreement between numerical predictions and observations is verified, what highlights the accuracy and stability of the proposed numerical approach. The present study may also find applications in the domain of design of experiments. 相似文献
319.
Vinícius dos Santos Marcelo Dias de Oliveira Jan Boll Ricardo Snchez‐Murillo Amauri Antonio Menegrio Luiz Felippe Gozzo Didier Gastmans 《水文研究》2019,33(4):647-660
Equatorial Pacific sea surface temperature variations interact with processes of atmospheric circulation, creating conditions for the occurrence of El Niño–Southern Oscillation (ENSO). ENSO events represent the most important interannual phenomena affecting climate patterns worldwide and causing significant socio‐economic impacts. In the Brazilian territory, ENSO leads to an increase in drought episodes in the north‐eastern region and an increase in precipitation in the southern region, whereas the effects over the south‐east region are yet not well understood. The main goal of this study is to compare variations of isotopic composition in precipitation across the south‐east portion of the Brazilian territory during two very strong ENSO events: 1997–1998 (ENSO 1) and 2014–2016 (ENSO 2). Daily isotopic records, available from the Global Network of Isotopes in Precipitation database for ENSO 1, and samples collected during ENSO 2 were used to compare the influence of both events on the isotopic composition of precipitation. Seasonal variations indicated more depleted precipitation during the wet seasons (δ18O = ?5.4 ± 4.0‰) and enriched precipitation during the dry seasons (δ18O = ?2.8 ± 2.3‰). Observed rainfall variations were associated with atmospheric large‐scale processes and moisture transport from the Amazon region, whereas extreme values (enriched or depleted) appear to be associated with particular convective and stratiform precipitation events. Overall, more depleted isotopic composition of precipitation (δ18O = ?4.60‰) and higher d‐excess (up to +15‰) were observed during the dry season of ENSO 1 when compared with ENSO 2 dry season (δ18O‰ = ?2.80‰, d‐excess lower than +14‰). The latter is explained by greater atmospheric moisture content, particularly associated with recycling of transpiration fluxes from the Amazon region, during dry season of ENSO 1. No significant differences for δ18O and δ2H were observed during the wet season; however, d‐excess from ENSO 2 was greater than ENSO 1, due to the slightly greater atmospheric moisture content and very strong upward motion observed. Our findings highlight the opportunity that environmental isotopes offer towards understanding hydrometeorological processes, particularly, the evolution of extreme climatic events of global resonance such as ENSO. 相似文献
320.
Field relationships, geochemistry and U–Pb zircon and Sm–Nd whole-rock geochronology are used to constrain the genesis of Palaeoproterozoic massive amphibolites and orthogneisses of the Algodões Sequence, Central Ceará Domain, Northeastern Brazil. The 2236 ± 55 Ma-old Algodões amphibolites show trace element geochemical signature and positive εNd(t) values similar to Phanaerozoic oceanic plateau basalts and less often to back-arc basalts. The amphibolites are intruded by tonalitic to quartz-dioritic gneisses of the Cipó unit which were dated at 2160–2170 Ma and 2130 Ma. Neodimium isotope data and whole-rock geochemistry for these gneisses show they are akin to juvenile arc plutonics of the adakitic suite. The likely occurrence of Palaeoproterozoic plateau basalts and arc plutonics in this part of northeastearn Brazil render comparisons with similar terranes elsewhere in South America and Africa, which in turn indicate a significant contribution of accretionary orogens in the early assembly of the Columbia Supercontinent. 相似文献