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Geomorphology

Volume [:ro]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 [:ro]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.

Volume XIX |

Landslide-susceptibility Analysis, Mapping and Validation in the Bălăcița Piedmont (South-West Romania)

Abstract: This work presents the results of applying the GIS matrix method (GMM) to the mapping and validation of landslide-susceptibility analysis in different sectors of the Bălăciţa Piedmont. The main objective of the paper concerns the achievement of landslide-susceptibility maps based on the inventory, classification and description of the landslides within the study area. The starting point was represented by the DEM and, subsequently, based on the lithological data, other determinant factors were analyzed and reclassified in a vectorial format: slope angle, slope elevation and slope aspect. After the factors that determine instability were identified for each type of mechanism, susceptibility maps were drawn. In the resulting landslide-susceptibility map a model for the validation is presented (based on the determination and calculation of a set of landslides not included in the susceptibility analysis). The landslide-susceptibility maps of the Bălăciţa Piedmont are preventive tools intended to minimize risks in the threatened areas, especially near the settlements that are located on the left slope of the Jiu river and witness the reactivation of old landslides.

Volume XIX |

Assessment of Soil Erosion by RUSLE Model using Remote Sensing and GIS – A case study of Ziz Upper Basin Southeast Morocco

Abstract: cause many environmental and socio-economic problems on -and off-site: loss of biodiversity, reduced productivity of agricultural land, siltation of dams, increased risk of flooding. The quantification of soil erosion is essential in the management and conservation of the soil and water resources. Modeling soil erosion can provide a lot of information to estimate soil loss and sediment yields at large-scale. In this study, the Revised Universal Soil Loss Equation (RUSLE) integrated into a GIS was used to quantify soil losses in the large upper watershed of Ziz (4435 km2) in southeastern of Morocco. The RUSLE parameters were estimated based on data from satellite imagery, DEM-SRTM and national watershed management plan studies. The results show that annual average of the potential soil erosion is 489.5 t. ha-1. yr-1 and the specific sediment yield is 36.4 t. ha-1. yr-1. The main sources of sediment are in the watershed upstream parts and some deposition zones are located before the catchment outlet. These soil losses contribute to the annual siltation of the Hassan Eddakhil dam by a rate of 3.5%. The application of principal components analysis to soil erosion factors shows an important influence of the soil erodibility factor (K) followed by the topographic factor (LS) then crop management factor (C). These modeling results will provide data within the Moroccan southeastern High Atlas that can constitute a road map for future soil erosion projects and it can be a useful tool for proposing soil conservation strategies.

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.