Water budget is determined by both hydrological and thermal processes, characteristics often represented by so called ‘‘drought indices’’ to manifest the actual hydrological conditions in a single number. According to their characteristics, drought indices can be sorted as: precipitation indices, water budget indices, soil moisture indices, hydrological and various aridity indices, all of them meant to indicate from different points of view moisture conditions, deficiency or surplus of water, for a given area. One of the most common indices is the Palmer Drought Severity Index (PDSI), introduced by Palmer (1965) to simulate moisture content of the soil month by month and to compare its monthly anomalies at regions having totally different climate and seasons. Source: Relevnt PDFs...