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• Prioritizing Watersheds for Flood Risk Assessment in Uttarakhand Himalayas using Geospatial Techniques and TOPSIS Method

  54-71

  Abhishek Kumar

  Pardeep Kumar

  Views:

  28

  Uttarakhand has a highly diverse topography, with snow-covered peaks, deep canyons, roaring streams, and dusty plains, all drained by various rivers of the Ganges system, India. The present study prioritizes watersheds in the Uttarakhand Himalayas for flood susceptibility using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method, supported by GIS and remote sensing data. ALOS PALSAR Digital Elevation Model (DEM) with 12.5-meter resolution was utilized to map topographic features and to analyze 18 morphometric parameters of 28 watersheds. The TOPSIS method prioritized sub-watersheds using AHP criteria weights, which are classified into five priority levels ranging from very low to very high. The Sarju, Ram Ganga, and Song watersheds were identified as having the highest flood risk, placing them in the “Very High” priority class. These watersheds exhibited high drainage density (Dd), stream frequency (Fs), and bifurcation ratio (Rb), indicating a dense and complex drainage network prone to rapid runoff and increased flood potential. The watersheds such as Bandagarh, Parry, and Chandra Bhaga were placed in the “Very Low” priority class due to lower closeness coefficient (Cci) values, suggesting simpler drainage systems and reduced flood risk. The AUC (Area Under Curve) value of 0.789, indicates a good predictive accuracy for the TOPSIS model. The classification helps in pinpointing high-risk areas that require urgent flood management interventions.

• Remnant surfaces in the Tárkány Basin

  20-30

  Péter Pecsmány

  András Hegedűs

  János Vágó

  Views:

  320

  The terraces of the Tárkány Basin, located in the SW part of the Bükk Mountains are known since the beginning of the 20^th century. Based on field surveys, six morphological levels were delineated and described in 1936. During the later geological mapping surveys, three gravel terraces had been mapped in the basin. Since then, no comprehensive morphological mapping has been made in the Tárkány Basin. Our study aimed to validate the results of these early studies using a digital elevation model. We delineated the remnant surfaces of the basin by morphometric and GIS techniques. Then, based on field surveys and former geological maps; we characterised these remnant surfaces, and their area was measured as well. The results of this study contribute to a better understanding of the surface evolution of the basin and its surroundings.

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

  1-14

  Shabna Sherin

  Arunkumar K.S

  Views:

  339

  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.

• Morphometric changes of the River Bodrog from the late 18th century to 2006

  28-40

  Nikoletta Mecser

  Gábor Demeter

  Gergely Szabó

  Views:

  173

  The river regulations of the 19th century have affected each of our rivers to a different degree. In the case of the River Bodrog it was stronger than the average. In our paper a section of the river between Bodroghalász and Szegi was examined, the extent and intensity of river channel changes was intended to be determined. The applied series of maps and aerial photos was georeferred and the river channel was vectorized. The morphometric parameters of the channel were measured and the changes were evaluated using the created database. From methodological aspect we concluded that the 9 variables can be grouped into 3 factors therefore most of the indexes can be substituted. We measured the changes of length and lateral shift of the channel using GIS methods. Three development periods were identified based on our results. In the first period the development of the river was characterized by natural processes. Then, the development of the river altered owing to the antropogenic impacts. In this transient phase the average shifting of the channel was 7.43 m/y. In the third term this value reduces to 0.2 m/y as the river is getting to reach the equilibrium stage.