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

Abstract

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 because of the inherent complexity of drought phenomena, different hydroclimatic conditions, and different catchment characteristics. A few studies in which the suitability of some of the existing DIs was evaluated for different parts of the world have been cited in the literature. However, no such study has been 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. The evaluation was conducted to determine how well these indexes modeled historical droughts. Five decision criteria, namely, robustness, tractability, sophistication, transparency, and extendability, were used to compare the performance of these DIs. The results showed that the ADI was superior to other indexes for drought management within the Yarra River catchment.