THE VULNERABILITY OF THE CIBIN HYDROGRAPHIC BASIN FOR PRECIPITATIONS SURPLUS AND DEFICIT PUBLISHEDSimona Spânu, Iuliana Antonie
This paper aims first of all to analyse the periods with precipitations surplus and deficit in Cibin hydrographic basin, in a causal liaison with the synoptic situations that generate floodings or droughts, but also the effect they have on the geographic environment. The periods with precipitations surplus represent a risk that usually has a local prevalence, unlike the periods with precipitations deficit, where the areal spread is large, and the onset and evolution are slow. The perception in the case of periods with pluviometric surplus is that of a major hydrological risk, because of the violent and progressive way of manifestation, while droughts are perceived as being less dangerous phenomena. Precipitations are the main natural source of water supply in Cibin hydrographic basin. The complexity of the factors that determine the regime of precipitations imprints the studied area with special climatic characteristics that have an impact on the geographic landscape. The analysis of the annual regime of precipitations in Cibin hydrographic basin for the interval 1961-2009 and that of the frequency with which precipitations have been registered on different risk classes denote that in Sibiu only a low risk of surplus and deficit is manifested, in Agnita the extreme values with medium and major risk are of deficitary nature, and in Păltiniş the extremes of medium and major risk are characteristic to the surplus quantities. The quantity of precipitations fallen in the area of Cibin hydrographic basin has been grouped according to deviation classes (one normal class and five classes for each of the quantities that are higher and lower than the normal) and to pluviometric domains (where there have been gathered the values of all the classes with positive and negative deviations, comparing them to the normal domain). Then there have been established groups of pluviometric risk through surplus and deficit, to these being added the group with no pluviometric risk. The ensemble and unitary analysis highlights the relations that are being realized between precipitations and the other components of the geographic environment and underlines the local hallmark of Cibin hydrographic basin. The major imbalances that are being generated on the environment by the excess of precipitations or, on the contrary, by the lack of precipitations, justify the interest of climatologists for these phenomena. This analysis has in view both the direct, determinant effect of precipitations on the components of the geographic environment, and the indirect effect, favouring or limitative, induced by precipitations.
vulnerability for precipitations; precipitation surplus and deficit pluviometric risk