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Geomorphology

Volume XXI |

Geodiversity Assessment by Application of Geoinformation Approach (on the Example of Golo Bardo Mountain, Western Bulgaria)

Abstract: Geodiversity is considered as a complex indicator of the abiotic environment. On the example of information about Golo Bardo Mountain (Western Bulgaria), the article emphasizes the need to develop methods for quantitative assessment of the geodiversity of an area to minimize the subjective nature of the assessment by defining clear criteria that can be quantified. The complex geodiversity assessment of the investigated area was made based on the analysis of lithology, soils, topographic features and drainage network. The analysis is done in a GIS environment. Topographic settings are analysed on the base of digital elevation model with a cell size of 30 m using Spatial Analyst Tools. The elevation model is used for calculating the terrain roughness, slope gradients and aspects of the slopes. Geological component is evaluated considering the petrographic composition of the area. The variety of the abiotic components is calculated by application of grid method (cell size 1000 x 1000 m), using Focal statistics tool, neighborhood type “Variety”. Fuzzy logic is suggested to be used for comparison of areas located in different regions and with different landscape conditions.
The results of the geodiversity assessment show that most of the area of the Golo Bardo mountain has moderate geodiversity index. The method used in the article gives reliable results with minimal subjectivity, that can be used for assessment of the distribution of the geodiversity on a particular area and allow to compare different territorial units. The results obtained in the current study show good correlation between areas with high and moderate geodiversity index, and areas with high biodiversity values. The applied methodology and the visualization of the geodiversity index allow for easy understanding of geodiversity by a wide range of stakeholders, even non-geoscientists, and can be successfully applied in the planning of geotourism activities.

Volume XX |

Combining geomorphological approach and thermal monitoring for permafrost research in Rodna Mountains, Northern Romanian Carpathians

Abstract: This paper aim to investigate the possibility of permafrost occurrence in the alpine area of Rodna Mountains by describing the rock glaciers distribution and characteristics and by monitoring the ground surface temperature and spring water temperature during late summer. Rock glaciers have a rather scarce distribution between 1670 and 1960 m a.s.l., their morphology is completely relict even at the highest altitudes which indicate they are inherited landforms. Thermal regime indicates improbable permafrost at Bila talus slope (1844 m a.s.l.) and an ambiguous outcome at Curmătura Buhăescului talus slope (1980 m a.s.l.) where average temperature during the BTS period was warmer than the -2°C threshold only in one year of the two monitored. Alpine spring water temperatures are above 3°C indicating absence of permafrost and they are moderately correlated with altitude. Iezeru Pietrosu cirque headwall is affected only by seasonal frost at 2100 m a.s.l. for almost 9 months. It seems that in Rodna Mountains the past and present climate conditions were and are milder in comparison to Southern Carpathians as the latitude increase does not compensate the lower altitudes.

Volume XX |

Research regarding soil erosion and its effects in the Balota area, Dolj County

Abstract: The research presented in this paper was carried out during three years of study (2018-2020) and aimed at studying soil erosion and losses of humus and major macroelements (nitrogen, phosphorus, potassium) based on the precipitation regime that produced runoff on the slope. The research was carried out on a stagnic vertic preluvosoil with a slope of 4%, with a moderate acid reaction and a medium supply of nitrogen and potassium, and weak supply of phosphorus from Balota de Sus area, Dolj County, comprising 3 crops practiced in the area: wheat, corn, alfalfa compared to the field black (uncultivated) and spontaneous vegetation (natural).
Following the researches, it was found that the most significant runoff on the slope was recorded in black fallow 471.98 mc/ha and corn 252.62 mc/ha, and the lowest were recorded in wheat 183.43 mc/ha and alfalfa 118.87 mc/ha (25.14% compared to the black fallow).
Soil erosion, or soil losses, recorded high values also in the case of corn cultivation 6.84 t/ha (39.42%) and in the case of black fallow 17.35 t/ha (100%).
The humus in the soil was lost in the largest quantities also in the corn crop 198.19 kg/ha (40.56%) and black fallow 488.58 kg/ha (100%) and in quite small quantities in the case of alfalfa 89.20 kg/ha (18.25 %).
Nutrients in the soil have been lost, both by runoff water on sloping soil and by eroded soil, with higher amounts lost through eroded soil.

Volume XX |

Risk of Dynamics of the River Stream in Tectonic Areas. Case studies: Curvature Carpathian – Romania and Maghrebian Chain – Algeria

Abstract: The tectonic characteristics of the Alpine orogeny highlight some similarities in the genesis of landforms over large areas. This paper analyses the role of tectonic processes in two subsiding areas with uplift movements. The overall tectonic activity implies the formation and evolution of the hydrographic network and its correlation with the major relief structure, thus forming streams parallel to the high-altitude lines, as well as consistent, transversal, and subsequent streams.
These tectonic processes are accompanied by antecedents and/or epigenesis common in the Eastern Carpathians, Romania. Hence the Bistrița River is longitudinal compared to the Bistrița and the Stânișoara Mountains, but also transversal in other sectors. In Algeria, the Northeast, especially the Zighoud Youcef zone (NE of Constantine), is characterized by a particular morphography and morphometry of the river basins which reveals reorganizations of the river network through their transversal or longitudinal characteristics compared to the structure and tectonics of the region. In areas with imminent catchments, the regressive erosion amplifies the slope dynamics and slope processes vulnerability.
The uplift and subsidence movements impose reorganizations of the hydrographic network of the catchments with the alternation of the erosion and sedimentation processes it creates a certain fluvial style pattern. In the subsidence of the Întorsura Buzăului depression, the longitudinal profile of the Buzău River has a very low slope and its meanders create islets. This is subject to frequent floods which imposed the riverbed regularization. However, in Zighoud Youcef, the Oued Smendou River also indicates some similarities with the Buzău River structure due to subsiding areas of the Mila-Constantine basin.

Volume XX |

Estimating Soil Erosion Exerted by Water in the Lower Sector of the Jiu River Floodplain and Băilești Plain

Abstract: This paper aims to identify the main areas prone to soil erosion exerted by water within the Băilești Plain and in the lower section of the Jiu River Corridor, a region with a very high agricultural potential. The study is concerned with rainfall erosion. Computing this type of erosion helps us to give better solutions for mitigating topsoil loss rate. For quantifying the amount of soil eroded, we used and adapted RUSLE equation. The obtained values we computed for RUSLE within our area range between 0 and 8.89 t-1/ha-1/yr-1. The most exposed areas to soil erosion exerted by water are located on the steep slopes, in the North-East of our study area, where the rainfall erosivity factor has the highest values, soil erodability factor (K-factor) is also very high, and cover-management factor (C) has the biggest value.