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• Stream gradient investigation in the Bükkalja using interpolated surfaces

  23-36

  János Vágó

  Views:

  115

  The geological, tectonic settings of an area can be examined with the analysis of drainage network. In the Bükkalja, the Miocene pyroclasts – mainly the welded ignimbrites – had taken decisive part in the evolution of drainage network. For the confirmation of their role, the breakpoints of stream profiles were analysed. However this method provides information only about the direct surroundings of the creeks. In the aim of getting informations about the areas between the streams, surfaces were interpolated from stream gradient data and analysed as stream gradient maps. The stream gradient data were calculated with Hack J.T.’s formula, but due to the false results it was necessary to modify this formula and to recalculate the values. According to the map interpolated from the modified stream gradient values, there is a clearly identifiable relationship between the location of the welded ignimbrites on the surface, and the gradient values. Areas with high values are on the eastern part of the study area, where these pyroclasts can be found, while in the west, where the surface is covered by less resistant rock types, the gradient values are much lower.

• Geomorphologic analysis of drainage networks on Mars

  15-30

  Ákos Kereszturi

  Views:

  46

  Altogether 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.

• Morphometric characteristics of a tropical river basin, central Kerala, India using geospatial techniques

  1-14

  Shabna Sherin

  Arunkumar K.S

  Views:

  228

  The 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.