A summarised monthly flow dataset, denominated in GWh rather than cumecs for users' convenience, 
is included alongside the Spectra Update.

The data is divided into seventeen hydro systems (Waikato, Waikaremoana, TPD, Matahina, Mangahao,
Kaimai, Aniwhenua, Wheao/Flaxy, Patea, Waitaki, Clutha, Manapouri, Cobb, Coleridge, Waipori,
Highbank, Branch).

The conversion to GWh is necessarily approximate. Use the original cumec data for any analysis
where high precision is needed. The conversion factors are based on the current hydro system;
they would not be correct for past or future time periods where the system was configured
differently.