119 resultados para Watersheds


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Presented here is a study about the capability of a sensing unit to detect changes in river water quality. In order to determine its accuracy, water quality was monitored at 11 points along the Veado River in Presidente Prudente, Brazil. To have a basis for comparison, a water quality index (WQI) was developed following methods previously applied in different watersheds. Results showed an accurate relationship between WQI and electric impedance readings detected by the sensing unit. Principal components analysis (PCA) was used to derive results in a form that can be correlated with WQI calculated for each sample point, which showed the potential application of this device.

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The following soil classes were identified in the studied area: Quartz Sands (AQ), Yellow Red Podzolic, Dusky Red Latosol (LR), 'Terra Roxa estruturada' (TE), Lithosol substrate sandstone (Lia) and Hidromorphic (Hi). The dimensional analysis method allowed: a) to group the watershed whose percentage (60%) are showing predominance of the same soil (Quartz Sands) and which located in the same relief; b) to group watersheds with different soil classes, but with similar percentages. -from English summary

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Annual runoff, loss by interception, transpiration and evapotranspiration of two watersheds in the Amazon rainforest of the terra firme type in central Amazonia, were estimated. The results show the significant importance of the forest to the present ecological balance of the region, which may be seriously altered if uncontrolled and unplanned deforestation continues.-from Authors

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Covers cartographic aspects related to characterization and map-making of watersheds, in surveys relating to agronomic activities. The recommendations, about scales and others specifications of thematic maps, were established in conformity with the dimension and complexity of watershed. -English summary

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Riparian forest restoration projects in the Tropics are complex, demanding longterm research, continuous human efforts and correct use of financial resources. This paper presents an approach to rank priority areas for riparian forest restoration on the upper section of the Pardo River watershed, in São Paulo, Brazil, using remote sensing and GIS techniques. Pardo River watershed is specially important, since it is the major source of drinking water supply for the region and water for domestic and industrial use within Botucatu and surrounding. Results indicated that riparian restoration should involve 81,27% of the protected area and could be made in three phases, allocating resources according to a priority scale.

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A novel and timely ground penetrating radar (GPR) survey has been carried out in Pantanal from Mato Grosso State, west-central Brazil. Fieldwork was carried out on February/2001 and August/2002 in an attempt to understand avulsion processes that are occurring within Taquari alluvial megafan. The main objectives were to map channel, crevasse and floodplain morphology, as well as active sedimentary bedforms. Many GPR profiles were acquired in the medium and lower Taquari River course. Subaqueous megaripples and exposed sand bars were identified in the medium fan area. Similar features were observed in the lower fan channels, where there were many crevasses in the marginal levees. During the flooding seasons, the flow splays out on to the floodplain, where new distributary channels are being formed. GPR data show that the lower fan, Taquari channel is topographically higher than the adjacent floodplain, thus favoring avulsion as a natural process of river course shifting. GPR data obtained during the wet and dry seasons, together with sedimentology information have been very important in characterizing the fluvial dynamics, and avulsion phenomena. © 2005 Springer Science+Business Media, Inc.

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This work had as objective to quantify the reforestation for water retention in the Palmital Stream watershed, County of Jaboticabal, SP, by using the methodology of compensatory forestation for retention of water in watersheds. This methodology esteems the retention of water in watersheds considering the world medium value of destiny of the water in the hydrologic cycle, the use/occupation of the soil (forest, pasture and agriculture) and its permeability. The watershed in this study presents an area of 10,625.21 ha, being 237.75 ha at forest, 467.01 ha in pasture and 9,237.57 ha in agriculture. The medium values of the permeability identified in the soils were of 94.81 mm h -1 in forest, 8.99 mm t -1 in pasture and 36.01 mm h -1 in agriculture (sugar cane). Considering that should infiltrate in the soil 20.55% of the water that precipitates on the watershed, and, that the losses of water in forest areas is considered standard, the total estimated volume to compensate the excessive loss that occur in the areas of pasture and agriculture is 12.21 million of m 3ano. The compensatory forestation to retain that volume of loss should contemplate an area of 942.73 ha (8.87% of the area of the watershed). The reforestation can be priority in permanent conservation area or in areas of Legal Reserve.

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The waters of Corumbataí River in the middle and eastern part of São Paulo State, Brazil, are extensively used for human consumption; their water quality has been modified mainly due to increasing pressure caused by population growth, accompanied by a more accentuated industrial development for the whole São Paulo State in the early 1970s. The Corumbataí River basin has, over time, received significant emissions of municipal waste products and discharges of wastewater, sludge, sewage, sanitary and industrial effluents, but the first effluent treatment plant at Rio Claro city was only inaugurated at the end of the 1990s. Data on river water quality from two widely spaced locations in the Corumbataí River basin are reported in this paper; they indicate the need for continuous initiatives and efforts by decision makers in order to improve and preserve the water quality in the basin for the 21st century. Copyright © 2007 IAHS Press.

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The present study aimed to show the spatial distribution of the Rochas watershed (Avaré-SP, Brazil) soil use capacity using the Idrisi geographical information system in order to contribute to a better territorial organization and the planning of the appropriate soil occupation. The obtained results using this methodology showed that most of the Rocha watershed areas are from the following groups: dystrophic yellow-red latosol (36.64%), eutroferric and distroferric red latosol (30.30%) with sandy texture. There was a predominance of areas with slope classes of 0-12%, plain to wavy relief (61.37% of the watershed area) showing that these areas are appropriate for annual culture plantations with wide use of machinery. Most of these areas were classified as class IV (73.79%) as to use capacity. In the studied area the following subclasses of land use capacity were found: IIe, s; IIIe; IVe; IVs; IVe,s; VIe and VIIe. Capacity subclasses IVe; IVe,s; IVs and Vie were the most significant because they are areas that can be used for agriculture but subject to severe soil impoverishment if there are no special care mainly for annual cultures. The Idrisi geographical information system was efficient to determine soil use capacity of the Rocha's watershed showing that the use of geoprocessing tools makes data analysis easier and faster, allowing digital data storage for future analysis uses mainly for territorial planning and environmental studies.

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The analysis of morphometric characteristics is used to understand the relationship between soil and surface as a result of erosive processes on different structures and lithologies. The objective of this study was to study the morphometric characteristics of Fazenda Gloria watershed from 1983 to 2000, a fourth-order watershed in Taquaritinga Municipality, São Paulo State. The study was based on photointerpretation techniques. Drainage net and the respective watersheds were selected and the morphometric variables were determined. The watersheds consisted of 7 second-order watersheds and 2 third-order watersheds. The morphometric characteristics showed a reduction in the number of segments of first-order rivers and in the length of the drainage net during the study period. These findings could be related to several influences on land development considering occupation and use of land. A different hydrological behavior could also be observed. The analysis of Fazenda Glória Watershed showed that the length of the segment of fourth order river remained constant during the study period.

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The Tanque Grande Reservoir is located at the Serra da Cantereira, Guarulhos (SP), and provides 3% of the municipal drinking water. In the last years, the urban zone has expanded towards the reservoir and has significantly altered the land use. In this work, water samples from three stations were monitored from August/2007 up to July/2008 in terms of the Water Quality Index (IQA) adopted by CETESB. The waters were usually classified in the band Good during the study period. Nevertheless, termotolerants coliforms, BOD and total phosphorus have exceeded the legal limits several times. Such occurrences may be related to the economical activities at the sub-watersheds in addition to changes in the land use of the surroundings of the reservoir.

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In areas where human activities, as agriculture, are developed land use contributes to physical, chemical and biological characteristics of water. This study aimed to identify physical and chemical variations of the water monitoring network in 4 first magnitude watersheds with different land use/occupation in the hydrographic basin of the Glori Farm Creek in the city of Taquaritinga, State of Sao Paulo, from February to July, 2005. The methodology consisted of weekly sample water collections to naalyze turbidity, temperature, dissolved oxygen, pH and electric conductivity. The characterization of the hydrological conditions of the watersheds showed that agricultural activities, including the productive system of the sugarcane cultivation, have affected the quality of water resources.

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The objective of this work was to study the dimensional parameters of the drainage net using 12 third-order ramification hydrological watersheds: 4 watersheds per soil unit (LVA, RL and RQ). The soil distinction was realized using ''t'' test to verify the orthogonal contrast among three soil averages and the grouping analysis and mean components. The results showed that the multivariance analysis was not able to discriminate three soils using the dimensional analysis. The t test of this isolated variable allowed discriminating RQ soil from LVA and RL soil units; but it was not sensitive to discriminate the LVA soil and RL unit.