Late last year we published the inaugural HMD on the EMI website. We are grateful to those participants who assisted us by providing data, feedback and advice.

The HMD replaces the so-called Spectra dataset that the Authority previously published every two years. More importantly, it extends the available data beyond inflows. For example, the HMD includes information on storage, spill, and resource consents. Timely hydrological information is important for making well-informed investment and operational decisions, policy, and for monitoring security of supply. The latter is particularly topical given the recent and proposed thermal plant closures. 

We are also progressing standardisation and alignment of key parameters, such as plant factors, across the various uses of hydrological data, e.g. the determination of hydro risk curves by the system operator and the conversion of flow rates to energy in the NZX Hydro (NIWA) dataset.   

We have retained OPUS International Consultants to undertake an interim update to append 2015 data to the dataset we published last year. Accordingly, we have once again requested assistance from the relevant participants. In the future, we propose to undertake an interim update annually with a full update, including a review of the historical correlations series, every two or three years.

We would welcome your feedback, so please post below or contact if you have any questions or comments.