Navigating Water Resource Management: A Forecasting Framework for Interannual Drought Projections

Can CMIP6 decadal projections be effective for multi-decadal water resources planning? This is the underlying question that motivates the present research, investigating what are the key deficiencies that limit their direct use for applications, and whether cleverly formulated mathematical alternatives can be used as effective postprocessors. This study focuses on the development of a robust framework for predicting droughts over interannual to decadal scales to enhance water resource management. The proposed framework utilizes the Wavelet System Prediction (WASP) methodology, which refines the spectral attributes inherent to climate indices to improve the skill of drought forecasts. Further improvement in forecasting capability is achieved through the Hierarchical Linear Combination (HLC) logic, which incorporates forecasts from ten climate indices. These indices, including ENSO-related sea surface temperature anomalies and other climate drivers closely linked to Australian rainfall, are derived from decadal predictions of the Decadal Climate Prediction Project (DCPP). The results of projected drought indices across various scales in Australia demonstrate the substantial potential of the integrated HLC-WASP framework to significantly improve the forecast skills of medium to long-term drought scenarios. This advancement enables the water industry to adapt their strategic plans and optimize reservoir operations effectively. By providing more reliable near-term projections of water availability, this research contributes to effective water resource management, facilitating informed decision-making for water allocation and conservation initiatives.