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Mean monthly river flows for the year compared against the previous year and the long-term average/range. Hover over charts to see specific values and click on legend entries to show/hide that series.
Kāpiti Coast
Te Awarua-o-Porirua
Te Whanganui-a-Tara
Ruamāhanga
Wairarapa Coast
Maximum recorded river flows with return periods derived by flood frequency analysis of annual peak flows recorded at each site. Sites highlighted in blue indicate a flood flow in excess of a 5-year return period. Click on table headers or the arrows next to them to sort the data by that column – holding the shift key allows sorting over multiple columns.
Note that for all frequency analysis results (high or low flows and rainfall) a return period expressed as 100 years can be assigned a probability of occurring being 1/100, or 1% in any one year. Similarly, a 5-year return period event equates to 1/5 or a 20% chance of occurring in any one year.
Minimum recorded river flows (averaged over 7- and 28-day periods). Significant flow events (5-year return period or greater) are shaded blue. Click on table headers or the arrows next to them to sort the data by that column – holding the shift key allows sorting over multiple columns.
Note that for all frequency analysis results (high or low flows and rainfall) a return period expressed as 100 years can be assigned a probability of occurring being 1/100, or 1% in any one year. Similarly, a 5-year return period event equates to 1/5 or a 20% chance of occurring in any one year.
GWRC has defined low flow thresholds on several rivers and streams across the Region to signify when restrictions on abstractions should begin (restriction thresholds) and when all abstractions shall stop (minimum flows). These are defined in the GWRC Freshwater Plan). The table below summarises the number of instances that the first restriction threshold was reached for rivers and streams as specified in the Regional Freshwater Plan. Values for the current year are in bold and results from the previous three years are included for comparison. Click on table headers or the arrows next to them to sort the data by that column – holding the shift key allows sorting over multiple columns.
As part of its flood warning and response service, GWRC sets high river level alarms on many of its monitoring sites to provide early warning of rising river levels and possible flooding. Below shows the rivers and sites where flood warning alarms were triggered. Hover over the chart to see which site/s exceeded alarm levels.
Click on table headers or the arrows next to them to sort the data by that column – holding the shift key allows sorting over multiple columns.