Archive December 2011

‘Twas the post before Christmas: 2011 in review Waiology Dec 19

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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 this amount varies ‘tween windward and lee.

The variability doesn’t stop here
You also will see it between year and year
And if you wait long enough data will show
That even ‘cross decades our streams change in flow.

Looking ahead as temperatures rise
And more or less rainfall descends from the skies
Kaitaia’s river flow’s likely to fall
But how could we know the future at all?

To understand this is to understand science
Building models of nature with healthy reliance
On data you gather, like snow in the alps
Or snow in your yard; really, everything helps.

And how much freshwater may we take and use?
2% overall, eight do some choose.
This we take mainly from land surface sources
From streams and from lakes and from fluvial courses.

Some of this water we save up for later
Storing in dams when rains they are fainter.
But reservoirs don’t give you gains without loss
For somewhere downstream you’ll have shifted a cost.

And under the ground, where aquifers lie,
The much-valued groundwater flows by and by.
The part of the cycle that moves e’er so slow
Sneaking through fractures and pores down below.

But back to the surface, our focus moves higher,
To roots and to leaves and to water transpired.
This water is often embodied in crops
Exported to markets and sold in your shops.

Thus water has value, a means to an end,
But not so financial, as many contend.
Rivers do much more than normally thought,
By offering services that can’t be bought.

With that, my dear readers, I end this review.
So look forward to next year as we write for you
On New Zealand’s freshwaters, and shed much more light.
Happy Christmas to all, and to all a good-night!

Water footprints – What do they mean for us in New Zealand? Waiology Dec 12


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 most of this freshwater is stored as glaciers or deep groundwater. Therefore only a small proportion is available for use in human economic activities and by ecosystems. This freshwater becomes available to us via precipitation, and its collection in rivers and lakesa. The increasing demand for this water is a result of population growth, economic development, changes in lifestyles (mainly related to increasing demand for certain agricultural products), and climate changeb.

Much of the media coverage of this issue has focused on calculations of the virtual water content of different products. According to this approach, pioneered by the Water Footprint Network (WFN), volumetric water use at the different life cycle stages of a product is added together to give a total volumetric result for water used by a product. For example, the volumetric water use associated with a merino jumper would be the total of the water used for irrigation on a merino farm, washing and dyeing the wool, and washing by the consumer throughout the jumper’s lifetime (plus water use in associated activities such as electricity generation and fertiliser production).

However, there is a problem with this approach. Assessment of water use, and its environmental significance, is complicated by the fact that the significance of water use depends upon where water is extracted and used. Most people assume that the significance of using one litre water in central Africa is quite different from using one litre water in New Zealand — at least from an environmental perspective. But how can this difference be represented when comparing water use by alternative products and processes?

Water stress index for different regions of the world

Water stress index for different regions of the world c

This type of question has led to recent interest in water footprinting using a Life Cycle Assessment (LCA) framework. LCA is a technique for assessing the environmental impacts of products, processes and activities along their life cycles from extraction of raw materials, through processing, manufacture, distribution, use and on to final waste management. According to this approach, the environmental significance of water use may depend upon factors such as: water scarcity at the location where water is withdrawn from a water body; whether water is rainwater, surface water in a river or lake, or fossil water located in an underground aquifer; and whether water use ‘counts’ when the water is returned to the location of withdrawal within a short time period. Degradation of water due to pollution is also relevant. These types of issues are currently being addressed by the International Organisation for Standardisation (ISO) which has set up a Working Group to produce a standard (ISO 14046) on ‘Water Footprint: Requirements and Guidelines.’ Interested organisations in New Zealand are invited to become members of the International Review Group (IRG) that discusses and submits comments to this ISO Working Group; contact Sarah McLaren for more details.

Does any of this matter for New Zealand? The answer is yes for two main reasons: (1) we live in a globalised economy with a ‘virtual water trade’ of about 1000 km3/yeara, and so water shortages elsewhere in the world can potentially be compensated by water used in production processes in New Zealand where products are then exported, and (2) we can position our exported products for competitive advantage by measuring their water footprints, driving improvements, and demonstrating their water footprint credentials. The five partners in the New Zealand Life Cycle Management Centre (Massey University, AgResearch, Landcare Research, Plant and Food Research, and Scion Research) have all worked in this area and are able to assist with measuring and reducing the water footprints of our exported products.

a Oki, T., & Kanae, S. (2006). Global hydrological cycles and world water resources. Science, 313, 1068-1071.
b UNESCO-WWAP (2009). The United Nations world water development report 3: Water in a changing world. Paris, France: The United Nations Educational, Scientific and Cultural Organization.
c Pfister, S., A. Koehler, & Hellweg, S. (2009). Assessing the environmental impacts of freshwater consumption in LCA. Environmental Science & Technology, 43(11), 4098-4104.

Where to get information on NZ hydrology Waiology Dec 08

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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.


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.


Journal of Hydrology (New Zealand). Published biannually by the NZ Hydrological Society. Includes research articles predominantly by NZ scientists. Articles become open-access when 4 or so years old.

NZ Journal of Marine and Freshwater Research. Published four times a year by the Royal Society of NZ. Includes research articles predominantly by NZ scientists. Open-access content from 1994-2006.


Water Physical Stock Account: 1995—2010. Prepared by NIWA for Statistics NZ, 2011. Provides information on NZ’s national and regional water balance.

Update of Water Allocation Data and Estimate of Actual Water Use of Consented Takes 2009—10. Prepared by Aqualinc Research Ltd for the Ministry for the Environment in 2010.


Regional council hydrometric data collections. Each regional council and unitary authority has its own set of monitoring sites and archives of data: climatic, river flow, groundwater, and lake level.

Environmental Data Explorer NZ (EDENZ). An online collection of data including measured river flow and climatic conditions are particular sites. Provided by NIWA.

Water Resources Explorer NZ (WRENZ). An online interactive map of rivers, hydrological stations, and estimates of river flow, sediment yield and water quality around the country. Provided by NIWA. [Ed (23/4/2015): This service has been discontinued. A partial replacement (flood frequencies in small basins) may be found here: NIWA Stream Explorer

MetService. Weather forecasts around New Zealand.

Seasonal Climate Outlook. NIWA’s seasonal forecasts of temperature, precipitation, soil moisture and river flow around the country.

Of course, there are many more reports from the various CRIs (NIWA, GNS, Landcare Research), regional councils or unitary authorities, and central government agencies (MFE, MAF), but I’ll leave it there for now. If there are some resources you’d like to recommend, please leave a comment.

More on climatic shifts and river flows Waiology Dec 02

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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.

Hydrologists to flood into Wellington for annual conference Waiology Dec 01

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By Daniel Collins

hydrosocIf 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. Over a dozen other NIWA scientists will also be giving talks and posters.

My first talk is on the history of terrestrial ecohydrological research in New Zealand — where hydrology meets plant physiology and ecology. This has been a fascination of mine for years. I will be giving a few vignettes of the research from across the scientific fields, but because I am taking an historical approach, I will also describe the social context of this research. There’ll even be a couple of controversies.

The second talk will be on the hydrological effects of climate change in New Zealand. While it’s easy to find information on how climate change may affect how weather, what is arguably more important to most of us is how climate change may affect our freshwater resources and ecosystems. So I will be presenting a review of research to date. A peer-reviewed review article is also in the works, but it will likely be many months away.

The third presentation — the poster — looks at the relationships between groundwater levels (specifically, piezometric heads) and stream flows around Te Waihora/Lake Ellesmere, Canterbury. The novel development in this piece of work is a physically plausible model that links regional groundwater conditions to local surface water conditions. I also offer advice on how to set up observation networks in order to get the necessary data to create such a model.

I’ll cover each of these presentations more fully on Waiology at some later stage, so if you’re not in the conference audience then stay tuned.

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