An Enhanced Effective Reconnaissance Drought Index for the Characterisation of Agricultural Drought

The drought phenomenon is directly associated to the agricultural production and it is considered as one of the major water-related hazards in this sector. Conventionally, the magnitude of drought impacts on crops, taking into account the susceptibility of the plants to the meteorological and hydrological conditions, is referred to as agricultural drought. The accurate and timely assessment of agricultural drought can provide the means for taking the appropriate proactive and relief measures for the protection of the farmers’ income and supporting food security. The Reconnaissance Drought Index (RDI), incorporating the key parameters of precipitation and potential evapotranspiration, has been widely and successfully used worldwide for drought characterisation during the last decade. In this paper, a modification of this index is proposed, namely the Effective Reconnaissance Drought Index (eRDI), aiming at improving the ability to assess agricultural drought. The main aspect of this modification consists in the substitution of the total precipitation with the effective precipitation, which represents more precisely the amount of water that is productively used by the crops. Further, the estimation methods of effective precipitation and the modification of other aspects of RDI, such as the selection of the appropriate reference period, are analysed and discussed.