Drought assessment and forecasting: a case study on the Yarra River catchment in Victoria, Australia

Drought is a natural phenomenon, and has widespread and significant impacts on the world's economy, environment, industries and the wider community. Early detection of droughts helps to implement drought mitigation strategies and measures before they occur. Therefore, drought forecasting plays an important role in the planning and management of water resources systems, especially during dry climatic periods. However, drought assessment and forecasting are not always easy tasks. In this paper, an approach that was developed and tested for drought assessment and forecasting is presented together with a case study on the Yarra River catchment in Victoria (Australia). An evaluation of existing drought indices was first conducted in this study, which led to the development of a new non-linear aggregated drought index (NADI). The NADI defines a broad perspective of dryness within the catchment rather than the traditional individual meteorological, hydrological and agricultural subcategories. Thereafter, a novel drought forecasting modelling approach was developed using the NADI time series. The results show that the developed forecasting models are capable of forecasting drought conditions well up to 6 months ahead forecasts which were statistically significant at 1% level. The outcomes of this study will be useful for water resources managers to assess droughts effectively and forecast future drought conditions, which will allow them to plan ahead the future water management activities especially during drought periods