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Monthly riverflow and rainfall summary

We monitor river flow and rainfall levels throughout Otago. These reports summarise monthly rainfall, river flow and lake levels across the region.

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Riverflow and rainfall levels last month

In brief

February rainfall totals were generally below normal in the Dunedin area, Central Otago, Queenstown lakes district, and lower and Strath Taieri. The Alexandra basin received around one third of its normal rain, with just 11mm recorded in Alexandra, and 15mm at Clyde.  Most of North Otago received normal rainfall, with the exception of the Shag Valley and lower Kakanui, which were 25% below normal. Southwest Otago rainfall totals were also close to average, except for the Moa Flat area, where 30% more rain than normal was recorded.

With the exception of a few small flow events, river flows remained below normal for the entire month across almost all of Otago. The following flow monitoring sites had average monthly flows less than half of normal for February:
The Shag River at The Grange in North Otago
The Water of Leith at University Footbridge in Dunedin,
The Waitahuna at Tweeds Bridge, and Pomahaka at Glenken sites in Southwest Otago.
All sites in the Taieri catchment, including all Taieri main stem sites, and Silverstream, Nenthorn and Deep Stream tributaries. In particular, the Silverstream and Taieri River at Outram and Waipiata had average monthly flows 75 to 85% below normal.

Smaller streams such as the Silverstream on the Taieri Plains, the Shag River in North Otago, and Dunstan Creek in the Manuherikia are now particularly susceptible to extended periods of low rainfall like those experienced during February. Water temperatures can rise dramatically in small shallow streams, and periphyton growth is promoted by low velocities and a shallow water column. The cumulative effects of drier than normal conditions that have dominated since mid 2005 mean that base flow is now well below normal. Rainfall events that would normally have increased river flow for a reasonable length of time, instead result in only very brief ?freshes?, with a rapid return to low flow conditions. Above normal rainfall over a period of several months is needed to increase flows back to average levels in these rivers.   

The few small rainfall events that did occur in February, along with precise management of consumptive water use from rivers, has generally helped to keep river flows above the level where restrictions begin to take effect. Restrictions on permits for consumptive water use in rivers such as the Kakanui, Shag and Taieri have been only infrequent this summer.

>> Download the complete monthly report (PDF - 165KB)

Reports from previous months

 

>> Riverflow and rainfall summary report January 2006
>> Riverflow and rainfall summary report December 2005
>> Riverflow and rainfall summary report November 2005
>> Riverflow and rainfall summary report October 2005
>> Riverflow and rainfall summary report September 2005
>> Riverflow and rainfall summary report August 2005
>> Riverflow and rainfall summary report July 2005
>> Riverflow and rainfall summary report June 2005
>> Riverflow and rainfall summary report May 2005
>> Riverflow andrainfall summary report April 2005
>> Riverflow and rainfall summary report March 2005

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