Retrospective river flows, January to March 2011
What we predicted for the first three months of 2011, and what actually happened.
What we predicted for January to March 2011
River flows were predicted to be normal everywhere.
What actually happened January to March 2011
River flows were normal to above normal in the North Island and much of the South Island, but below normal in the Tasman District.
Interpreting these maps
Percentage chance of above normal, normal or below normal flows.
Mapped quantities for the past month, and the past three months, are based on the position of those flows in a distribution of historical flows from each flow recorder for that month or that season. (A season is any contiguous three-month period). At present the data used to estimate the distribution are flow data from the beginning of each flow record up to the year 2000.
If a catchment is mapped as 'normal' this means that the flows for the period were in the middle tercile (third) of the historic distribution. Catchments mapped as 'far below' or 'far above' normal mean that their flows for the period correspond to the bottom or top 10% of the historic distribution. Catchments mapped as 'below' or 'above' normal had their flows respectively in the bottom or top tercile but not in the most extreme 10% of historic flows.