Comparative Evaluation of Drought Indexes: A Case Study on the Yarra River Catchment in Australia

Drought Indexes (DIs) have commonly been used to quantify drought conditions around the world. Most DIs are developed for specific regions and therefore may not be directly applicable to other regions due to inherent complexity of drought phenomena, different hydro-climatic conditions and different catchment characteristics. There had been few studies cited in the literature where suitability of some of the existing DIs was evaluated for different parts of the world. However, no such study was conducted in Australia where droughts are more frequent than elsewhere in the world. In this paper, five DIs namely Percent of Normal (PN), Deciles, Standardized Precipitation Index (SPI), Surface Water Supply Index (SWSI) and Aggregated Drought Index (ADI) were evaluated for the Yarra River catchment in Victoria (Australia). Evaluation was conducted based on how well these indices modeled the historical droughts. Five decision criteria, namely robustness, tractability, sophistication, transparency, and extendability were also used to compare the performance of these DIs. The results showed that the ADI was superior to other indices for drought management within the Yarra River catchment