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Geomorphology

Volume XIX |

The occurrence of the armored mud balls during the flash flood phases of the streams from the Meledic Plateau – the Curvature Subcarpathians, Romania

Abstract: Armored mud balls that form in fluvial environments were observed on the river bed of two small streams from South-East Subcarpathians Bend, in the area of Miocene deposits with salt dia-pirs. Pieces of well-rounded clay mate-rial but with coarse surface were found on the gravel banks as well as partially submerged into stream channel and embedded in soft sediments of stream banks. The surfaces of mud balls, nearly spherical and ranging from 5 cm to 17 cm in diameter, were studded with sand grains and gravel that collected during flash floods as a result of bedload transport. The main source material of the armored mud balls consists of dark clay material detached from the cap rock of the salt massif that is crossed by the two streams. The newly formed armored mud balls, which were found among the gravels on the stream bed following the summer flash flood event from June 2019, supports the fact that these particular sedimentary features form during exceptional floods when pieces of clay material are rolled by the high-energy water flow, which results in acquiring of their spherical shape and the pebble shell. This paper represents the first report on the occurrence of modern armored mud balls formed in a fluvial environment, located in the Curvature Subcarpathians, Romania.

Volume XIX |

Gross chemical analysis of the turf and podzolic soils on glacial deposits, laid by dense carbonate rocks

Abstract: Gross analysis allows us to reveal issues concerning the genesis of soils and to identify the peculiarities of elementary soil processes. The article summarizes the results of the study of gross chemical analysis of the turf and podzolic soils on alluvial and glacial deposits, laid by dense carbonate rocks. Features and relationships of oxides content in soils and soil-forming rocks are considered, that will make possible to justify important issues of the nature of these soils and to study the dependence of their natural properties with dense carbonate rocks.
It is established that oxides of silicon, ferum, aluminum and calcium form the basis of gross chemical composition of the turf and podzolic soils on alluvial and glacial deposits, laid by dense carbonate rocks. The maximum content of the first component is observed in the upper humus-eluvial horizon (90–94%), aluminum and ferum oxides – in iluvial accumulative horizons, where their content in total is 7–15%. Calcium oxide content in soil profile of studied soils, naturally increases from 0.36% in the upper horizons to 0.95% in the transitional, and in the laid carbonate rocks its content can reach up to 35%. This confirms the fact that laid carbonate rocks have a significant influence on the flow of all soil elementary processes, and gross analysis confirmed the presence of carbonates in the entire soil profile, which could not be determined during field or macromorphological studies. Oxides of alkaline-earth metals are mainly accumulated in the upper humus horizons of all soils, their content decreases down the profile. Potassium and phosphorus oxides, although pliable to washing, however are delayed in the soil and included in the biological cycle and partially fixed in secondary minerals. The content of biologically important components such as P2O5, MnO, S, N in the upper horizons of the studied soils is closely related to the accumulation of humus.

Volume XVIII |

Climate parameters relevant for avalanche triggering in the Făgăraș Mountains (Southern Carpathians)

Abstract: The climate conditions may contribute significantly to the generation of several hazards in mountain areas, such landslides, wildfires, flash floods and avalanches. This study examines the variation of the main meteorological parameters with impact on avalanche triggering conditions at Bâlea-Lac Meteorological Station. At the best of our knowledge, this is the first overview of the basic climate parameters which are potentially avalanche triggers in the Făgăraș Mountains (Southern Carpathians). The study is based on data from only one weather station (Bâlea-Lac) from the period 1979-2017, assuming it is consistently relevant from climatic point of view for avalanche occurrence in the area. The results demonstrate that the theoretical circumstances for avalanche triggering (e.g. snow pack, fresh snow or wind) can be captured. This paper briefly describes the nivologic monitoring system run by the National Meteorological Administration and emphasises its utility for avalanche forecasting and alerts.

Volume XVII |

Study of Landscape Evolution in North Koel River Basin, Jharkhand, India: Tectonic and Structural Implications Based on Hypsometric Analysis

Abstract: Hypsometry is widely used for inferring tectonic effects and erosion status of landscapes. Tectonics, structural inhomogeneity, lithologic differences, and climatic variations lead to topographic undulations discerned into discrepancies in the values. Hypsometric index (and curve), indicative of frequency distribution of proportional elevation with the respective proportional area, is used as a tool to describe characteristics of landscape morphology, lithological variability, and degree of fluvial dissection. Many workers have used to infer comparison of rates of erosion with tectonic uplift rates. However, there are many other factors reported to influence topographic undulations other than tectonics which lead to a variety of hypsometries. Morphotectonic index, hypsometric integral, calculated using digital elevation models (DEMs) in GIS environment has been widely used for inferring tectonic effects, status of erosion, and structural controls. The present study is conducted in the North Koel River basin. This river rises in the Ranchi plateau and joins the Son River a few miles north-west of Haidarnagar, is the right bank tributary of the Son River. Along its entire course of flow, North Koel river (260 km) flows through plateau region mostly formed of metamorphic rocks. Hence, structural control seems to be the primary control on the landscape evolution of this sub-basin. In this study, hypsometric integral (and curve) has been calculated for third order and upper order streams to look whether this morphotectonic index shows any sign of tectonic, structural, or lithologic control on the landscape evolution in the North Koel River basin.

Volume XVII |

Lateral migration of the Jiu river course between 1864 and 2018. Case study: Craiova – Zăval sector

Abstract: During the last 154 years, the Jiu river course that stretches from its confluence with the Amaradia down to the outlet has undergone serious lateral and length changes. The main purpose of this article is to highlight these changes, to determine their magnitude, and to understand the future evolution of the Jiu course.
The results of our analysis showed that from 1864 until 2018, the Jiu river became shorter in the lower section, decreasing with 38.1 km, from 134 km to 95.9 km. The shorten-ing of the course happened gradually. Thus, between 1864 and 1910, the length of the course decreased by 25.6 km, from 134 km to 108.4 km. From 1910 until 1970 there was a shortening of 11.9 km and between 1970 and 2018, the river shortened its course by about 0.6 km. The greatest lateral distance between its historical and present channels showed a maximum of 11.22 km on the outlet.