Drought analysis in New Zealand using the standardized precipitation index

The present article investigates drought events in New Zealand through the application of the SPI at various timescales (3, 6, 12 and 24 months). First, a temporal analysis has been performed, and the most severe dry episodes have been detected. Then, the spatial distribution of the percentage of data falling within the different level of drought has been evaluated. In addition, a trend analysis has been conducted at seasonal scale, considering the wet and the dry seasons, and at annual scale. Finally, the relationship between drought and ENSO has been investigated. Results show that, in every area currently subject to drought, an increase in this phenomenon can be expected. Specifically, the results of this paper highlight that agricultural regions on the Eastern side, such as the Canterbury Plains, are the most consistently vulnerable areas, as well as other regions in the North Island, including primary industry regions like Waikato. Moreover, a clear link between drought and the two phases of the ENSO has been detected.