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Archive: Waiology June 2014

What causes didymo blooms (“rock snot”) in NZ rivers?

Waiology Dec 19, 2012

By Cathy Kilroy Ever since the alga Didymosphenia geminata was discovered growing prolifically in a South Island river, scientists have puzzled over how “blooms” (unusually large algal growths) of this alga can form. Rivers below lakes and dams in the South Island have been especially severely affected. Massive, persistent mats of didymo in these rivers have changed their character, reduced … Read More

Map: Projected effects of climate change on New Zealand freshwaters

Waiology Nov 27, 2012

By Daniel Collins Maps are helpful tools in communicating and understanding the potential implications of climate change. We have national maps of projected changes in temperature that show faster warming in the north, and in precipitation that show more rain in the south and west and less in the north and east. We also have national maps of … Read More

Waiology moving from water cycle to freshwater sciences

Waiology Nov 26, 2012

By Daniel Collins After over a year serving New Zealand as a source of information and discussion on hydrology and the water cycle, I am pleased to announce that Waiology is expanding its scope to freshwater sciences and allied disciplines more generally. This includes all things hydrological, as before, but also aquatic ecology and chemistry, fluvial geomorphology, hydraulic engineering, and … Read More

Water allocation and limit-setting in a changing climate

Waiology Nov 20, 2012

By Daniel Collins Last week, the Land and Water Forum released its third and final report on water management in New Zealand. It is a substantial piece of collaborative work with 67 recommendations. Number 29 is that allocation limits be set by taking into account “any flow and water level fluctuations caused by seasonal or other climate variations”. While … Read More

Canterbury does not have 70% of New Zealand’s freshwater, it has 12%

Waiology Oct 29, 2012

By Daniel Collins In the Christchurch Press today there is an article about the race to irrigate Canterbury. In it is the following statement: “Canterbury had 70 per cent of New Zealand’s fresh water resource, and 34 per cent of its hydro-generation capacity.” Unfortunately the 70% is an error that has appeared in the past and it is … Read More

Climate change and NZ’s freshwaters: NIWA presentation, Friday

Waiology Jul 26, 2012

By Daniel Collins For those of you in or around Ōtautahi/Christchurch, I will be giving a presentation on climate change and the future of New Zealand’s freshwaters on Friday (tomorrow), 3:30 pm, at NIWA’s Kyle St site. I’ll talk about what we know and what we don’t know about the potential implications for the freshwater system, including water quantity … Read More

Predicting river flows in ungauged catchments, from New Zealand to the world

Waiology Jul 13, 2012

By Ross Woods Our knowledge of the water cycle is imperfect – for example we don’t have data for all rivers across the landscape, and yet so often we want river flow information for resource and hazard management purposes. In the absence of direct data, then, we turn to models and seek to make hydrological predictions in these ungauged … Read More