Critical droughts extracted from dry periods

Differently from common definitions, we distinguish droughts from dry periods in this study. From the dry periods, we extract subperiods of various durations changing from one month to the dry period length. Each subperiod is called a drought, and the most severe drought (with maximum severity or intensity) of each duration is defined critical drought. These newly defined concepts of this study were tested based on the 12-month timescale standardized precipitation index calculated from monthly precipitation data of two meteorological stations in Seyhan River Basin, Turkey. Frequency analysis was applied on the critical drought intensity for each drought duration separately. Results showed that statistical characteristics (duration, severity, intensity and frequency) of dry periods and critical droughts were different from each other. Critical droughts were more intense than the dry periods and their intensity increased as their duration decreased. The Generalized Extreme Value was confirmed as the best-fit probability distribution function of the critical drought intensity in majority. By extracting droughts from the dry periods instead of taking a dry period as one single drought, high number of short and intense critical droughts were deciphered that are masked otherwise within dry periods. These frequent droughts may have higher negative impact on water-dependent economic sectors and society if their timing of occurrence coincides with the season when the water demand is peaking. Therefore, extraction of critical droughts from dry periods is a substantial achievement of this study as the negative impact of drought is often related to its intensity along with its severity and duration.