Dr Daniel Collins is a hydrologist at NIWA. He formed the Waiology blog to bring together commentary on New Zealand's freshwater systems. The blog features commentary from numerous contributors.

‘Twas the post before Christmas: 2011 in review - Waiology

Dec 19, 2011

By Daniel Collins ‘Twas the post before Christmas, when all through the ‘sphere Bloggers reflected on happ’nings this year. Here at Waiology we’ll do so too. Two thousand eleven: The year in review. It started in June with a mission to share The science of water flows from here and there. It’s part of our programme, with MSI dough, To chart and to model the Waterscape’s flow 3000 visits and thirty posts hence Much have we offered to help you make sense Of the wonderful watery world that we boast So gather round all as I recap our posts! How much freshwater do we get each year? More than enough to submerge our two ears. But if you look closely you’ll certainly see That … Read More

Water footprints – What do they mean for us in New Zealand? - Waiology

Dec 12, 2011

Guest post by Dr Sarah McLaren, Associate Professor at Massey University and Director of the NZLCM Centre. This article originally appeared in the Summer 2011 (December) issue of IrrigationNZ News. Have you heard that the water footprint of 1 kg beef is 15,500 litres, and of 1 kg cheese is 5,000 litres? Did you know that Unilever has set itself a target of halving consumer use of water associated with its products by 2020? Or that Walmart is in the process of asking all its 10,000 suppliers to provide information on total water use in their facilities, and their water use reduction targets? These activities all reflect an increasing concern about the limited availability of freshwater for use in economic activities. Although there is plenty of water in the world, only 2.5% of it is freshwater — and … Read More

Where to get information on NZ hydrology - Waiology

Dec 08, 2011

By Daniel Collins While we’re building up Waiology to be a useful reference for those of you who are interested in New Zealand’s hydrology and freshwaters, I thought it would also be good to mention some other useful resources available. BOOKS Freshwaters of New Zealand. Edited by Jon Harding, Paul Mosley, Charles Pearson and Brian Sorrell. Jointly published in 2004 by the NZ Hydrological Society and the NZ Limnological Society. Forty-six chapters by New Zealand experts on topics ranging from precipitation to lacustrine food webs — an excellent reference. Groundwaters of New Zealand. Edited by Michael Rosen and Paul While. Published in 2001 by the NZ Hydrological Society. Floods and Droughts. Edited by Paul Mosley and Charles Pearson. Published in 1997 by the NZ Hydrological Society. JOURNALS Journal of Hydrology (New Zealand). Published biannually by the … Read More

More on climatic shifts and river flows - Waiology

Dec 02, 2011

By Daniel Collins For those with an interest in how decadal shifts in climate affect our rivers, as Ross wrote about previously about the IPO, NIWA has a press release on the same work: In 2000, the IPO changed back to the negative phase (as for 1945-77). ‘The whole of South Island is drier now. If you had to make a guess about the coming 10 years, expect a slightly drier South Island. It certainly affects Canterbury and has implications for the design of irrigation and hydro power schemes,’ says Dr Woods. Ross will be presenting his work on Wednesday afternoon at the HydroSoc conference at Te Papa. Read More

Hydrologists to flood into Wellington for annual conference - Waiology

Dec 01, 2011

By Daniel Collins If you notice groups of people in Wellington next week using such vernacular as ‘discharge’, ‘piezometric’ or ‘A block’, then they’re probably attending the NZ Hydrological Society’s conference at Te Papa. It’s the society’s 50th conference, and many of the talks will be on the history of hydrology in New Zealand. If you’re there, tell us how awesome Waiology is, and give us some feedback! For my part, I’m giving two talks and presenting one poster. (Yes, I’m a masochist, but I do like to get the science out as you might have noticed.) Fellow Waiologist, Ross Woods, is giving a keynote address on his journey as a hydrologist, having won the Society’s Outstanding Achievement Award last year. He’s also giving a regular talk on our Waterscape programme and the decadal variations of river flow. Read More

Where does NZ take its water from? - Waiology

Nov 28, 2011

By Daniel Collins I mentioned previously how much water we are allowed to use in NZ. The amount varies markedly from region to region, and is growing over time, with Canterbury and Otago accounting for well over half of the consumptive takes (excluding the Manapouri hydro scheme). But seeing as Kiwis seem to know less about our aquifers than our rivers, I’d like to turn now to the issue of where we can take our water from — rivers, lakes, aquifers or reservoirs (or storage lakes). About two thirds of the water NZers are allowed to take is from surface water — rivers and lakes. This is for all non-hydro schemes and other non-consumptive uses; the data come from a 2010 report from Aqualinc Research for MfE. About a third comes from groundwater. Five percent comes … Read More

Recent NZ research from climate change to tussock | Journal of Hydrology (NZ): 50(2) - Waiology

Nov 24, 2011

By Daniel Collins For those of you who don’t receive New Zealand’s own hydrology journal, or for those who want to save some time, here’s an overview of this month’s edition — the journal’s 100th. 1. Barry Fahey (Landcare Research) et al. use their water balance model, WATYIELD, to assess whether tussock in Otago’s uplands can really intercept appreciable amounts of fog, turning it into runoff. Their conclusion: no. This is actually one in a long line of studies that have considered the same question, a question that has turned out to be a veritable controversy, with different papers firmly coming down on opposing sides. 2. Suzanne Poyck (formerly NIWA) et al. use their catchment hydrology model, TopNet, to forecast the impacts of climate change on the Clutha River basin, with a particular focus on changes to … Read More

Sea level fall and floods due to massive evaporation - Waiology

Nov 21, 2011

By Daniel Collins On average, about 87% of the Earth’s evaporation takes place over the oceans. 9% of this water then makes it over the land and falls as precipitation, the rest falls back to the sea. But this is just an average. Over much of 2010, there was so much evaporation from the oceans that the global average sea level actually dropped 6 mm. With more water circulating in the atmosphere, some parts of the planet received much heavier rainfalls, triggering the floods in Australia, Pakistan and Venezuela. This extra water can be detected by its effect on the gravitational pull around the Earth, as measured by GRACE (Gravity Recovery and Climate Experiment). (GRACE figure courtesy of NASA/JPL-Caltech.) These changes were associated with a dramatic shift from El Nino to La … Read More

Long-term fluctuations in river flow conditions linked to the Interdecadal Pacific Oscillation - Waiology

Nov 17, 2011

By Ross Woods Within the Waterscape research programme, we’re doing some case studies on the potential effects of climate change on water resources, in water-limited parts of New Zealand, such as Canterbury and Hawkes Bay. In effect, we’re asking how these water resources might look in the future. In another post, I’ll look into the results of a couple of the climate change studies we’ve done that relate to water resources in Canterbury, as part of wider team efforts. Before thinking about climate change, it’s a good idea to understand the variations in water resources that are happening already. The weather is different from one year to the next, and one decade to the next, so water resources also vary on these various time scales. Understanding those variations will let us put any potential future changes in the … Read More

The importance of groundwater - Waiology

Nov 14, 2011

By Tiejun Wang Groundwater is one of the most important natural resources in New Zealand, which by one estimate accounts for about 80% of the water present at any one time across and beneath the country. According to a 2010 review of water allocation [2], the number of groundwater consents accounts for 68% of all national consents. In terms of the allocated volume for consumptive use, groundwater allocation is about 12% (3.3×109 m3/year; equivalent to 6% of the water in Lake Taupo) of the total annual allocation (26.9×109 m3/year). Over the last decade, the demands for groundwater have increased dramatically in New Zealand, which is manifested in the volume of groundwater allocated and the percentage of groundwater allocation in the total allocation [2]. Most of the groundwater resources have been allocated to irrigation purposes in NZ. For example, … Read More