Runoff response of a small agricultural basin in the argentine Pampas considering connectivity aspects

Our manuscript analyses the surface runoff variability, and its controlling factors in a small basin with gentle slopes, at the headwaters of a flat catchment, to improve the knowledge of the hydrology of plain areas under agriculture. We study runoff, rainfall and antecedent conditions in the argentine Pampas region. We use correlations, regressions and quantitative and qualitative descriptive information of the system: erosion signs, ground cover by crops, groundwater depth data and temporal changes in the drainage network, to discuss and understand the complexity of the runoff process by frameworks to study (dis)connectivity. The analysis of 56 events evidenced a nonlinear rainfall–runoff relationship. In contrast with other works, we identified clear upper limit events, under which hydrological responses emerge, as a result of combinations of antecedent wetness, rainfall erosivity, ground cover and preferential drainage paths. We separated the nonlinear rainfall–runoff response in three linear relationships according to differences in antecedent wetness conditions. We found differences in runoff responses under wet and dry antecedent conditions, but complex responses under medium antecedent conditions. The analyses of the inputs, the structural and the functional elements of the (dis)connectivity frameworks, were key in the understanding of the temporal changes of runoff, and its complex responses. Temporal coincidences of connectivity components and their feedbacks appear to be strongly associated with the runoff dynamics. High-magnitude hydrological responses occur with complete coincidences, while partial coincidences between the components reduce connectivity and low magnitude and/or heterogeneous responses prevail. Thus, these analyses suggest that runoff is controlled by (dis)connectivity in this basin with gentle slopes. Our work contributes to the understanding of the process of surface runoff in the context of humid flatlands under agricultural land use, by the identification of the complex combinations of factors which regulate/control the (dis)connectivity that helps to interpret the nonlinearities of runoff.Fil: Ares, María Guadalupe. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff". - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff". - Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff"; ArgentinaFil: Varni, Marcelo Raúl. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff". - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff". - Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto de Hidrología de Llanuras "Dr. Eduardo Jorge Usunoff"; ArgentinaFil: Chagas, Celio Ignacio. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Ingenieria Agricola y Uso de la Tierra. Cátedra de Manejo y Conservación de Suelo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Spatial and seasonal variation of microphytoplankton community and the correlation with environmental parameters in a hypereutrophic tropical estuary - Maranhão - Brazil

O estuário do rio Bacanga apresenta um comportamento hidrodinâmico com fluxo de marés limitado por uma barragem. Ele é considerado como um ambiente hipereutrófico que recebe diariamente altas cargas de esgoto doméstico sem tratamento. Este trabalho teve como objetivo avaliar a variação espaço-sazonal da comunidade fitoplanctônica e suas relações com parâmetros ambientais. Amostragens bimestrais foram realizadas em seis pontos fixos entre 2012 e 2013, obtendo valores dos parâmetros físico-químicos e biológicos (clorofila a, composição e abundância do fitoplâncton) para realização das análises estatísticas. Os resultados indicam que a comunidade fitoplanctônica é representada por diatomáceas, sendo Skeletonema costatum a espécie dominante responsável por pulsos de florações em abril e junho de 2012. O predomínio dessa espécie está relacionado aos elevados teores de silicato, pH e turbidez da água. Outros eventos de florações como da Euglena gracilis e Chlamydomonas sp. foram registrados em fevereiro de 2013, quando os teores de fósforo total estiveram elevados e as taxas de oxigênio dissolvido foram superiores. Os dinoflagelados, cianobactérias e a diatomácea Thallassiosira sp. apresentaram ampla distribuição no período de estiagem e estão altamente correlacionados com a salinidade, transparência da água e nutrientes. Desta forma, a distribuição da comunidade fitoplanctônica é mais definida sazonalmente que espacialmenteThe Bacanga River Estuary has a hydrodynamic behavior and its tidal flow is limited by a dam. It is considered as a hypertrophic environment that receives daily high loads of domestic sewage without treatment. This study aimed to evaluate the spatial and temporal variation of phytoplankton community and its relationship with environmental parameters. Bi-monthly sampling campaigns were carried out at six fixed sites between 2012 and 2013. Physical-chemical and biological parameters were collected (chlorophyll a, phytoplankton composition and abundance) to perform the statistical correlations. The results indicate that phytoplankton community is mostly represented by diatoms, with Skeletonema costatum being the dominant species responsible for bloom in April and June of 2012. The dominance of this species is related to the high silicate concentrations, pH and turbidity. Other blooms events as well as the Euglena gracilis and Chlamydomonas sp. were recorded in February 2013, when the total phosphorus concentrations were high and the dissolved oxygen concentrations were higher. Dinoflagellates, cyanobacteria and diatom Thallassiosira sp. were widely distributed in the dry period and highly correlated with salinity, water transparency and nutrients. Hence, the distribution of phytoplankton community is more defined seasonally, rather than spatially

Impianto Vibrant approccio transcanalare

Impianto Vibrant approccio transcanalar