Volume XXII |

Influence of climate conditions on maize yield in Oltenia (1990-2021)

Abstract: Maize, the most important cereal crop at global level, is a climate-sensitive plant. Consequently, the changes of the key meteorological parameters, namely temperature and precipitation amount, determine low yields, especially in rain-fed regions. The dependency of maize yield on climate conditions was assessed based on monthly values of the considered meteorological parameters (data from 14 meteorological stations for the period 1990-2021). The mean values of the analysed interval generally reveal proper conditions for the development of maize. However, starting with June until September, mean temperatures are 1 to 2°C above the optimum thermal threshold, as mentioned in the specialized literature. The growth degree days index (GDD) emphasizes Oltenia as a region with a very good thermal potential for maize, all mean values exceeding 1600°C, but the southwestern sector of the plain area has already exceeded 2000°C, underlining the increase in heat stress. The water deficit generates dry conditions, especially in Mehedinți, Dolj, and Olt, mainly in the interval July-August, which also corresponds to the maximum water requirements of maize. Drought prone areas were determined based on Selyaninov’s hydrothermal coefficient (HTC), which indicates slightly dry conditions in the growing season in the plain area, while northwards, in the piedmont and Subcarpathians, the climate is slightly humid, respectively moderately humid, drought risk decreasing gradually in this direction. At monthly level, August is the most problematic period as, except the northeastern part (Polovragi and Râmnicu Vâlcea), the entire region displays dry, moderately dry, and slightly dry conditions. The lowest maize yields correspond to the years 1993, 2000, 2002, 2007, and 2012. If in the first three years, the drastic yield reduction was mostly determined by a severe water deficit registered during the entire life cycle of the plant, in the last two years, the main restrictive factor was represented by temperature, mean monthly values exceeding 27°C and mean maximum values 35°C, especially in the plain area. Taking into account the projected increase in temperature and water deficit, the impact of climate conditions on maize crops may also be gradually higher in Oltenia and certain adaptation measures should be taken.

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 X |

Indicators of the Human Pressure on the Environment in the Bălăciţa Piedmont

Abstract: The Bălăciţa Piedmont represents the western subdivision of the Getic Piedmont, being located in south-western Romania. The unit under study is an early inhabited space and, at the same time, an area of active development of numerous geodynamic phenomena. The man-induced changes had significant influences upon the environment and especially upon the relief, the increased vulnerability of the terrains to the dangerous geomorphologic phenomena being one of the most important problems that the local communities have to face nowadays. The present study aims to assess the human influence upon the emergence of environmental unbalances and especially the human actions that influence the risk geomorphologic processes. A relevant means in the process of evaluating the type and dimension of the human intervention within a given territorial unit concerns the computation of certain synthetic indicators that characterize the degree of landscape transformation. The assessment has been realized through the analysis of statistical data at the level of the administrative-territorial units that overlap the Bălăciţa Piedmont. The general research regards an interval of thirty years (1977 – 2007), while the focus was laid upon the transition period (1992, 2002, and 2007).

Volume X |

Human-Induced Environmental Changes and Floodplain Restoration Necessity along the Danube, on the Drobeta-Turnu Severin – Bechet Sector

Abstract: The present paper aims at analysing the human-induced transformations that took place in the Drobeta-Turnu Severin – Bechet sector of the Danube Floodplain during the last two centuries. The research started from the need to obtain a real and comprehensive database concerning the extension, the nature and the characteristics of the topographic-hydrographical, edaphic and biologic structures appeared or modified under human influence, their relation with the changes occurred at the level of the land use and their present functionality. Special attention was paid to the latter transformations occurred after 1989. The primary types of topographical and hydrographical changes resulted from the geomorphic human activity in the Danube Floodplain are analysed in relation with the land use within this unit. The analysis of the environmental transformations in the floodplain sector started from cartographic and statistical materials that are relevant for the 19th-21st centuries. For the post-communist period, the valorisation of the Corine Land Cover database allowed for a more detailed analysis of the land use dynamics. The data thus obtained was checked and updated with field observations and measurements, which are mandatory given the fact that the cartographic database shows deficiencies and it is partially outdated.

Volume IX |

The Analysis of the Relief Fragmentation Features within the Bălăciţa Piedmont

Abstract: Within the Bălăciţa Piedmont there are to be distinguished two areas with specific features, which correspond to the Danube catchment and to the Jiu drainage area. Both in the case of the drainage density, as well as in that of the relief energy, the distribution of the value classes correlated with the two catchments underlines major differences, but also certain resemblances, situation which is explained by the evolution time, the base level, the flow direction in relation with the structure and the lithological and climatic homogeneity. The analysis of the data enabled the quantification of the relief energy and of the drainage density within the Bălăciţa Piedmont, as well as the correlation of the two parameters in report to the main catchments. The computation and representation methods for the two indicators of the relief fragmentation (i.e. the depth and the density) allowed for a quantitative interpretation (the identification of five value classes), as well as for a spatial interpretation (the grouping of the values depending on the two collecting rivers: the Danube and the Jiu). The aggregation of the influence factors on the two main drainage areas is mostly due to the fact that the Danube catchment extended its area in the detriment of the Jiu catchment, the three more important tributaries (the Blahniţa, the Drincea and the Desnăţui) catching sectors within the upper course of the tributaries of the Jiu. The analysis of the relief fragmentation within the Bălăciţa Piedmont shows that this unit is on different evolution stages. The complexity of the fragmentation is closely connected to the maturity degree of the valleys and to the morphogenetic complexes imposed by the paleogeographical evolution.