GIS (Geographic information System) techniques, characterized by high accuracy of mapping and measurement, prove to be a competent tool in morphometric analysis. The main goal of the study is to analyze the hydrographic network in linear form (vector) by overlaying databases from different periods (vector layer made in 2003 and layer made in 2017) for a regional case study within Southwestern Romania. The database organized in layers aims to reproduce characteristics of the drainage network: the cartographic maps scale 1: 100.000, Geo-referenced in ArcGIS 10.4); the first version of the hydrographic network used in the first River Basin. The results of this analysis will be concentrated on the length of the river network correlated with the two layers and also on the relief based on a DTM (cell size 5×5 m) within the study area. The relevance of the discussions lies in highlighting the differences appeared over time regarding the hydrographic network spatially using GIS based quantitative morphometric analysis.
There are analysed the variability and trends of pluvial continentality over the Oltenia Plain for the period 1961 to 2018. The datasets cover monthly precipitation amounts from seven meteorological stations, based on which there were calculated five specific continentality indices: Vemičs index of precipitation and seasonal precipitation quotients (RShy/RWhy, RWin/RSum, RWin/RSpr, RAut/RSpr). In terms of spatial distribution, continentality generally increases eastwards. The variability of the pluvial continentality was analysed by the mean of ten-year intervals, while linear regression and the non-parametric Mann-Kendall test were used to emphasize any trend present in the datasets. Linear regression did not highlight a significant upward or downward trend, while Mann-Kendall test illustrated a monotonic upward trend all over the analysed region for RAut/RSpr mainly induced by the increase of the precipitation amount during autumn. The results are statistically significant for the eastern and western extremities of the plain.
The interannual and decadal variability and trends of winter (December to February) air temperature over the Oltenia Plain area is analysed for the period 1961 to 2010. The datasets cover monthly temperatures from six meteorological stations. The variability of the temperature data was analysed by means of standard deviation, the mean of three distinct sub-periods (1961-1990, 1971-2000, 1981-2010), as well as the mean of ten-year intervals. Linear regression and the non-parametric Mann-Kendall test were used to emphasize any trends present in the datasets. From the temporal variations viewpoint, an increase in temperature is observed particularly in the third and fourth decades, as the average values for the last decade mark a slight decrease in temperature. From the spatial distribution viewpoint, the most significant positive deviations characterize the northern and western part of the plain. Mann-Kendall test illustrates a monotonic upward trend all over the analysed region, but the results are not statistically significant except for the aforementioned parts of the plain for the entire winter season and February.