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Distribution Pattern of Trees in a Hydrological Gradient below the paraná-Paraguay River Confluence

American Journal of Plant Sciences 2013年第3期4卷 663-673页

作者： Sylvina Lorena Casco Juan José Neiff Centro de Ecología Aplicada del Litoral Consejo Nacional de Investigaciones Científicas y Técnicas Universidad Nacional del Nordeste Corrientes Argentina

Riparian and riverine aquatic plant species have evolved within the context of flowing water habitats for which the flooding and droughts are the forcing factors that shape the community features, either through a positive or negative effect on the ecosystem’s function, according to the timing, frequency and magnitude of such events. In the paraná floodplain landscape, topographic position is a crude indicator of the position along the complex gradient, but it also includes information about flood/drought periods and trees’ resilience to extreme hydrological phases. We present the occurrence of major tree species in riparian forests of the paraná River on islands of different topographies in a section of the paraná River downstream from the confluence with the Paraguay River. Our results suggest that each tree species had a preferred position in the topographic gradient, sites where the observed counts were more frequent. This trees species were more frequent between 2 and 8 m in the topographic position and were affected by 5 and 202 hydrosedimentologic pulses between 1949 and 1999. We suggest that knowledge of the distribution curves of the vegetation species present can help draw possible future scenarios of the river landscape. Future engineering works to alter the hydrological dynamics of paraná should pay more attention to the distribution of riparian forests because they are indicators of changes at the landscape level and they are the support for the wildlife of the river.

关键词： Riverine Forests River Pulse paraná Floodplain Ecohydrology Fluvial Landscape

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2D TEM Modeling for a Hydrogeological Study in the paranáSedimentary Basin, Brazil

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International Journal of Geosciences 2017年第5期8卷 693-710页

作者： Emerson Rodrigo Almeida Jorge Luís Porsani Fernando Acácio Monteiro dos Santos Cassiano Antonio Bortolozo Universidade de Sã o Paulo Instituto de Astronomia Geofísica e Ciências Atmosféricas Departamento de Geofísica. Rua do Mat&atilde o Butant&atilde S&atilde o Paulo Brazil Universidade de Lisboa-IDL Lisboa Portugal

This work uses 2D TEM (Transient Electromagnetic) modeling for a hydrogeological study in the paraná sedimentary basin. The study area is located at the northern region of the state of S?o Paulo, Brazil, where groundwater is exploited from two aquifer systems: one sedimentary, shallow, and the other crystalline, deep. The interest in applying the TEM method in this area owes to the high exploitation rates of groundwater from the crystalline aquifer system for irrigation, which is triggering considerable seismic activity locally. This aquifer system is composed of fractured basalt within the Serra Geral Formation and is about 120 m deep. Eighty-six TEM soundings were acquired at this location, but in nine cases the data did not fit the modelled curve for 1D geoelectrical models due to the geological complexity of the area. This paper shows 2D geoelectrical modeling results based on the FDTD (Finite Differences in Time Domain) method to explain the lateral resistivity variation within the geological setting. A 2D model was generated for each sounding and compared with 1D inversion models as well as with direct information from wells. The results show some vertical variations of about 10 to 30 meters on the upper interface of the basalt layer from Serra Geral Formation. They are located at approximately 60 meters from the center of the soundings. The existence of these 2D structures in the subsurface can be related to the drainage system in the study area. The presence of these structures may indicate a connection between the shallow and deep aquifer systems, acting like a conduit that may contribute to the seismic activity reported.

关键词： Transient Electromagnetic (TEM) 2D Modeling Hydrogeophysics paraná Basin Brazil

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Pre Impoundment Studies in Monday River, Eastern Paraguay I: Soils and Submerged Soils

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Journal of Chemistry and Chemical Engineering 2019年第2期13卷 82-92页

作者： Juan F Facetti-Masulli Carmelo López Amado González Hydroconsult SRL-Laboratory Asunción Z12 – Paraguay

Monday River, at Eastern Paraguay is located south of the Itaipu Dam, and discharges into the paraná River. At the point of discharge it has been projected to build a Hydroelectric power Plant and the reservoir will extend upstream the Monday. As a result of the impoundment of a river, the flooded soil can provide a certain amount of nutrients into the aqueous medium setting new conditions for aquatic life and affecting to a greater or lesser degree the ecosystems. The aim of this work is the assessment of the impact on the water quality of the incorporation of major nutrients into the water body after damming Monday River. Samples from soil profiles were taken at selected sites on both banks of the river;the amount of phosphorus, nitrogen, potassium, calcium and magnesium as well as other parameters as pH, organic matter, exchangeable bases were determined using standard procedures. Granulometric analysis was also performed. Phosphorus availability was determined by isotopic exchange. In addition the samples were submitted to submersion/incubation experiments along 60 days, and the concentration of elements incorporated into the water analyzed. Results show that flooded soils are low in phosphorus and nitrogen which is scarce in some cases;so does other nutrients. Submersion experiments also indicate generally limited incorporation of such nutrients into the water body. Significant negative impact of these soils on the water quality of the reservoir cannot be expected.

关键词： Alto paraná Dpt Monday River Soils E-value Incubation experiments

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