14 resultados para Hypsometry


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Mass loss by glaciers has been an important contributor to sea level rise in the past, and is projected to contribute a substantial fraction of total sea level rise during the 21st century. Here, we use a model of the world's glaciers to quantify equilibrium sensitivities of global glacier mass to climate change, and to investigate the role of changes in glacier hypsometry for long-term mass changes. We find that 21st century glacier-mass loss is largely governed by the glacier's response to 20th century climate change. This limits the influence of 21st century climate change on glacier-mass loss, and explains why there are relatively small differences in glacier-mass loss under greatly different scenarios of climate change. The projected future changes in both temperature and precipitation experienced by glaciers are amplified relative to the global average. The projected increase in precipitation partly compensates for the mass loss caused by warming, but this compensation is negligible at higher temperature anomalies since an increasing fraction of precipitation at the glacier sites is liquid. Loss of low-lying glacier area, and more importantly, eventual complete disappearance of glaciers, strongly limit the projected sea level contribution from glaciers in coming centuries. The adjustment of glacier hypsometry to changes in the forcing strongly reduces the rates of global glacier-mass loss caused by changes in global mean temperature compared to rates of mass loss when hypsometric changes are neglected. This result is a second reason for the relatively weak dependence of glacier-mass loss on future climate scenario, and helps explain why glacier-mass loss in the first half of the 20th century was of the same order of magnitude as in the second half of the 20th century, even though the rate of warming was considerably smaller.

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The aim of this study was to carry out a zoning in the municipal ecological park of Ourinhos, SP, located southwest of São Paulo State, aiming to subsidize the planning and management of this area. With this purpose it was made an inventory of the landscape resources of this park with hypsometry, declivity, use of soil and zoning mappings. From this zoning, we analyzed the possibilities of implementing purposes of use, with the objective of preserving this area, minimizing the negative environmental impacts. Thus, this research was of extreme importance, since it allowed to identify and rank, in the territory, areas or sectors that are priority to the development of activities, as well as contribute to the conservation of natural and socio-cultural heritage.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Planning is an essential instrument for the agricultural occupation of the lands, because it supports the activities of food production and raw materials. It must be driven by techniques that provide the sustainability of these activities, so that also ensures the environmental balance of agroecosystems. Lands misuse can be considered as one of the causes of frustration of agricultural activities. Thus, the occurrence of discrepancies between the effective use (real use) of the land and its agricultural aptitude can compete, in many cases, to the decrease of productivity, as well as for soil degradation. In this way, this research intends to study the relationship between the temporary cultivations, halfperennial cultures, perennial and its developmental environment, determining the edaphoclimatic characteristics of landscapes. From then on, a letter shall be subject to the use and occupation of the soil for agriculture in the municipality of Cristais Paulista-SP, aiming to describe the spatial organization of land use and vegetation cover, and emphasizing management and conservative practices. For that, climatic factors were characterized, fundamentally humidity, temperature and luminosity; edaphics, including parental material, chemical and physical properties, fertility, soil temperature and climatic zoning; biotic, referring to the suitability of different cultures or to be implanted; physical, such as geomorphology, slope, geology, hypsometry and hydrology; socioeconomic, in particular production and marketing seasons; and the way they all, together, affect the adaptation, distribution and production of crops. Using this information, the zoning of the area of study was done based on the 21 nominated groups obtained, in addition to recommendations and suggestions for handling each type of cultivation... (Complete abstract click electronic access below)

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Geological-geotechnical problems affecting escarps as well as embankment and fill slopes of roads and motorways may generate different types of unsteadiness, which are mainly arisen from the deficient knowledge about the physical environment. This results in unsuitable engineering projects and inadequate executions, which can be worsened by an occasional inappropriate maintenance of the construction. A geologically-geotechnically characterization of escarps and slopes is crucial in order to prevent these problems. This work deals with a geological-geotechnical study of 1:10.000 scale mapping in a stretch of a local road (CHQ-40) at the Serra de Itaqueri, Charqueada town, State of São Paulo. The stretch is known by several physical problems as erosion and mass movement. The methods of study were based on an integrative analysis of the diverse elements of the physical environment by using aerial photographs - to obtain the physiographic compartmentalization of terrain units - as well as field work - to accomplish the evaluation of the units by employing sketch lists. To achieve this, we selected several techniques in order to identify and classify different types of existing problems as erosion, landslide in embankments and fill slopes, rockfall, block rolling, among others. We also included the analysis of soil horizon, thickness and composition. The geological-geotechnical mapping resulted in six units: 1- Sandstones in cuesta’s backhill; 2 – Basalts in cuesta’s front; 3- Sandstones in cuesta’s front; 4 – Talus and colluvial deposits at cuesta’s foothill; 5- Sandstones of the Piramboia Formation in hillside; and 6 – Colluvial soil in the hill top. A characterization of the geological-geotechnical units is detailed, coupled to the cartographic material. Other cartographic products elaborated for this study included 1:10.000 maps of hypsometry, slope and curvature

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The development of topography depends mainly on the interplay between uplift and erosion. These processes are controlled by various factors including climate, glaciers, lithology, seismic activity and short-term variables, such as anthropogenic impact. Many studies in orogens all over the world have shown how these controlling variables may affect the landscape's topography. In particular, it has been hypothesized that lithology exerts a dominant control on erosion rates and landscape morphology. However, clear demonstrations of this influence are rare and difficult to disentangle from the overprint of other signals such as climate or tectonics. In this study we focus on the upper Rhône Basin situated in the Central Swiss Alps in order to explore the relation between topography, possible controlling variables and lithology in particular. The Rhône Basin has been affected by spatially variable uplift, high orographically driven rainfalls and multiple glaciations. Furthermore, lithology and erodibility vary substantially within the basin. Thanks to high-resolution geological, climatic and topographic data, the Rhône Basin is a suitable laboratory to explore these complexities. Elevation, relief, slope and hypsometric data as well as river profile information from digital elevation models are used to characterize the landscape's topography of around 50 tributary basins. Additionally, uplift over different timescales, glacial inheritance, precipitation patterns and erodibility of the underlying bedrock are quantified for each basin. Results show that the chosen topographic and controlling variables vary remarkably between different tributary basins. We investigate the link between observed topographic differences and the possible controlling variables through statistical analyses. Variations of elevation, slope and relief seem to be linked to differences in long-term uplift rate, whereas elevation distributions (hypsometry) and river profile shapes may be related to glacial imprint. This confirms that the landscape of the Rhône Basin has been highly preconditioned by (past) uplift and glaciation. Linear discriminant analyses (LDAs), however, suggest a stronger link between observed topographic variations and differences in erodibility. We therefore conclude that despite evident glacial and tectonic conditioning, a lithologic control is still preserved and measurable in the landscape of the Rhône tributary basins.

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Fluctuations in the length of 72 glaciers in the Northern and Southern Patagonia Icefield (NPI and SPI, respectively) and the Cordillera Darwin Icefield (CDI) were estimated between 1945 and 2005. The information obtained from historical maps based on 1945 aerial photographs was compared to ASTER and Landsat satellite images and to information found in the literature. The majority of glaciers have retreated considerably, with maximum values of 12.2 km for Marinelli Glacier in the CDI, 11.6 km for O'Higgins Glacier in the SPI and 5.7 km for San Rafael Glacier in the NPI. Among the 20 glaciers that have retreated the most relative to their size, small (less than 50 km**2) and medium (between 50 and 200 km**2) glaciers are the most affected. However, no direct relation between glacier retreat and size was found for the 72 glaciers studied. The highest percentage retreat in the CDI was by the CDI-03 Glacier (37.9%) and Marinelli Glacier (37.6%). In the SPI, relative retreats were heterogeneous and fluctuated between 27.2% (Amelia Glacier) and 0.4% (Viedma Glacier). In the NPI, relative retreat was very high for Strindberg and Cachet glaciers (35.9% and 27.6%, respectively) but for the remaining glaciers in this icefield it ranged between 11.8% (Piscis Glacier) and 3.6% (San Quintin Glacier). In addition to surface area, the surface slope (calculated on the basis of the DEM SRTM) was also related to the relative retreat and no straightforward relation was found. From a global point of view, we suggest that glacier retreat in the region is controlled firstly by atmospheric warming, as it has been reported in this area. Besides the general increase in temperature observed, no signal of a geographical pattern for the fluctuations in glacier length was found. Consequently, glaciers appear to initially react to local conditions most probably induced by their exposition, geometry and hypsometry. The heterogeneity of rates of retreat suggests that differences in basin geometry, glacier dynamics and response time are key features to explain fluctuations of each glacier.

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"Estr. dagli Atti della Reale accademia delle scienze di Torino, vol. v."

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Forms Appendix no. 6 to the U.S. Coast and Geodetic Survey Report for 1881.