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Periphery Dichotomy and its Investigation by GIS Methods
131-136Views:164Centre-periphery dichotomy can be regarded as one of the crucial issues in human geography and regional science. The definition of periphery is far from unambiguous due to its relative expression and its content. This is the reason why can significant number of studies be found focusing on the delimitation of central and peripheral areas. The revolution of computer technology and the rapid development of GIS cause the more and more extended usage of these techniques in the human geography as well. These related studies were categorised by their approaches – namely the locational or developmental centreperiphery concepts – and their GIS tools. Application of spatial parameters with extended datasets and complex GIS based calculations mean the most precise and complicated use of GIS and computer tools in the delimitation of peripheral (and central) areas.
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Morphometric characteristics of a tropical river basin, central Kerala, India using geospatial techniques
1-14Views:232The Thutapuzha watershed (TW) is one among the major tributaries of Bharathapuzha – the largest west flowing river in Kerala, India. Morphometric analysis was carried out to determine the spatial variations in the drainage characteristics and to understand the prevailing geologic variation, topographic information and structural setup of TW using Survey of India topographic maps and ASTER-DEM. Geoprocessing techniques has been used for the delineation and calculation of the morphometric parameters of the watershed. The TW sprawled over 1107Km2 and the study revealed that the watershed includes a sixth order stream and lower order streams mostly dominate the basin with a drianage density of 1.36 m/Km2 exhibiting highly resistant subsoil, dense vegetation, and low relief of surface nature . The study indicate that rainfall has a significant role in the drainage development whereas the drainage pattern is controlled by structure and relief. The watershed of TW is moderate to well-drained and exhibited a geomorphic maturity in its physiographic development. The shape parameters revealed the elongated nature of TW having less prone to flood, lower erosion and sediment transport capacities and drainage network development in the watershed. This study strongly brings to light that the drainage morphometric parameters have the enormou spotentiality to unveil the hydro-morphologicalcharacteristics of the river basins. Integrating hydro-morphological characteristics with conventional watershed assessment methods would have a beneficial effect on judicious watershed management, which helped to formulate a comprehensive watershed management plan.
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Geomorphologic analysis of drainage networks on Mars
15-30Views:57Altogether 327 valleys and their 314 cross-sectional profiles were analyzed on Mars, including width, depth, length, eroded volume, drainage and spatial density, as well as the network structure. According to this systematic analysis, five possible drainage network types were identified such as (a) small valleys, (b) integrated small valleys, (c) individual, medium-sized valleys, (d) unconfined, anastomosing outflow valleys, and (e) confined outflow valleys. Measuring their various morphometric parameters, these five networks differ from each other in terms of parameters of the eroded volume, drainage density and depth values. This classification is more detailed than those described in the literature previously and correlated to several numerical parameters for the first time. These different types were probably formed during different periods of the evolution of Mars, and sprung from differently localized water sources, and they could be correlated to similar fluvial network types from the Earth.
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Spatial pattern of soil erosion using RUSLE model and GIS software at the Saf Saf watershed, Algeria
31-47Views:125Soil erosion is one of the problems threatening the Algerian environment. In agriculture, soil erosion leads to the thinning of the topsoil under the effect of the natural erosive forces of water, or under the effect of agricultural activities. The present study aims to estimate average soil loss rate and to identify vulnerable zones. Through the integration of RUSLE model at the Saf Saf watershed, various parameters are utilized such as the rainfall erosivity factor (R), soil erodibility factor (K), slope length - slope factor (LS), crop management factor (C) and practice management factor (P). All these parameters are prepared and processed through a geographic information system (GIS) and remote sensing using various database sources. The results reveal that the river basin has an average annual soil loss of 3.9 t ha−1 yr−1, and annual soil loss of 4.53 million tonnes for the period 1975-2017. Meanwhile, eighty five percent of the study area is experiencing acceptable rate of soil erosion loss, which is ranging between 0 to 5 t ha−1 yr−1. The present study of risk assessment can contribute to understand the spatial pattern of soil erosion in order to use appropriate conservation practices for sustainable soil management.
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Spatial and temporal pattern of soil pH and Eh and their impact on solute iron content in a wetland (Transdanubia, Hungary)
34-45Views:47Land mosaics have direct and indirect influence on chemical reaction and redox condition of soils. The present paper deals with the relationship between some environmental factors (such as soil and vegetation patterns, micro-relief, water regime, temperature and incident solar radiation) and the pH, Eh of soils and solute iron in a headwater wetland in Transdanubia, Hungary. Measurements have been taken in four different patches and along their boundaries: sedge (Carex vulpina, Carex riparia, three patches and two species), horsetail (Equisetum arvense), common nettle (Urtica dioica). The spatial pattern of the studied parameters are influenced by the water regime, micro-topography, climatic conditions and by direct and indirect effects of vegetation. The indirect effect can be the shading, which has influence on soil temperature and on the incident solar radiation (PAR). Root respiration and excretion of organic acids appear as direct effects.. There have been measured individual pH and Eh characteristic in the studied patches. Soil Eh, pH and solute iron have shown seasonal dynamics. Higher redox potentials (increasingly oxidative conditions) and higher pH values were measured between late autumn and early spring. The increasing physiological activity of plants causes lower pH and Eh and it leads to higher spatial differences. Although temperature is an essential determining factor for Eh and pH, but our results suggest it rather has indirect effects through plants on wetlands.
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Analysis of the connection between urban land cover and census districts using geoinformatical methods
52-67Views:50Remote sensing resources are usually used in research to better understand urban built-up density, spatial structure and the processes of change. Based on results of image segmentation, landscape metrics indexes, texture and pattern may be analyzed beside the spatial changes in urban reflectance. Social processes within the settlement can be analyzed efficiently, although the census data may also be connected to the urban land cover data through geoinformation systems. On the research project different parameters of urban segments, i.e. patch number, mean patch area, total patch area, total patch perimeter, patch density and edge density, formations that make up the urban pattern were analyzed. Urban functional districts of different built-up density were separated using appropriate indexes, and extending the database with spectral content made it possible to review district boundaries and to mark new boundaries due to these changes.