PROPOSED INDEX FOR DROUGHT ASSESSMENT: MODIFIED RECONNAISSANCE DROUGHT INDEX (mRDI)

Many drought indices have been developed for drought analysis, one of which is the Reconnaissance Drought Index (RDI) that is widely used all over the world due to its inherent capability of sensitivity and resilience. Since the RDI takes into account both the cumulative precipitation and the potential evapotranspiration that is marked as the main advantage. In this study, a modified version of RDI (mRDI) is proposed to evaluate RDI time series by reliability-resilience-vulnerability-max extent metrics. The use of these performance indices incorporates the frequency, recovery period, probable severity and extremity of droughts. As in many sustainability indexes, the high (low) values of mRDI indicate being in a good (bad) status of the region with respect to drought conditions. The application of mRDI is illustrated for four different provinces of Turkey with different precipitation and temperature regimes. The long-term (between 1970-1971 and 2015-2016 water years) monthly precipitation and mean temperature data were used in the study. The 12 months-RDI time series, which used for calculations of mRDI, were obtained by the use of DrinC software. The study revealed that the mRDI is a valuable index, and it allows evaluating not only the recent conditions, but also the historical droughts in a single metric. It provides additional insights for the studies dealing with socioeconomic droughts, ecologic droughts, moreover, mRDI can be used as an efficient indicator in water resources management and agriculture insurance issues.