Comparison of the EDI and RDI meteorological drought indices

In the present study, comparison of two meteorological drought indices, named Effective Drought Index(EDI) and Reconnaissance Drought Index (RDI), are performed, respectively, utilizing precipitation and ratioof precipitation over ET0. Data are collected from stations with different climatic conditions. According toresults, the EDI index provides higher values for the wet periods in comparison with the RDI values, for thestudied stations. This is an indication of the sensitivity of the EDI index to precipitation changes during wetperiods. Furthermore, the RDI values for dry periods are lower than the EDI values. Utilization ofprecipitation over ET0 provides a more critical and realistic evaluation of severe droughts during dry periodsin comparison to the RDI procedure, leading to lower index values. The results also indicate that correlationbetween EDI and RDI improves as the time scale increases, in all of the studied stations.

کلیدواژه ها:

Comparison ، Meteorological drought ، RDI ، EDI