Water flows and land use – a very complex business

A recent international conference entitled ‘Integrating Multiple Aquatic Values’, mainly focused about rivers and streams and what is in them.

Attended by hundreds at the Claudelands Event Centre in Hamilton, including scientists from all round the world, the oral presentations filled four full days in five contiguous 15 minute sessions.

These revealed the broad spectrum of ways in which water flows are seen and understood by humans.

As a farming and science writer and catchment committee member, who inveigled her way into being allowed to attend, I focused on the sessions describing research into land use and water quality in New Zealand and which related to the Waikato and its catchments.

A keynote presentation delivered by Catherine Knight, author of ‘New Zealand’s Rivers – An environmental history’ (published last year by Canterbury University Press) provided an eye-opening background to Maori and Pakeha settler attitudes to water flows, which went a long way to revealing both how our streams ended up less than pristine, and why the battles over values continue now.

Rights to pollute

While Maori treasured awa as food supplies and ancestors, early Pakeha regarded all moving water as drains, into which anything could be tipped.

A battle between early gold mining and farmers was won by mining interests, as representing the most ‘economically favourable’ industry at the time.

I saw some irony in the current state of affairs where farming is ‘the economic backbone of the country’ and rights to pollute are still being fought.

We see so much these days about ‘intensification’, its likelihood and dangers that it was fascinating to attend a number of linked sessions where ‘land use suitability’ was the overall focus.

Much of this research has come about because of the Our Land and Water National Science Challenge, coupled with the National Policy Statement for Freshwater Management in New Zealand.

River strategy

In the Waikato, we have the Waikato River Restoration Strategy which looks at what local problems to tackle in which order, to spend the huge amount of funding which came with the river settlement.

A broader concept which is looking at systems which can be applied nationally to inform land use, and catchment planning and assessment, has been involving science people from all over the country.

It aims for a basic ‘shift from the traditional focus on production, to a broader view that accounts for effects of land use on environmental, social, cultural and economic values at multiple spatial and temporal scales’ and is known as LUS.

Its three components involve:

(1) The potential of individual parcels of land for long-term primary production;

(2) The inherent contribution of each land parcel to the delivered load of potential pollutants to a critical point in a receiving environment;

(3) A measure of the pressure on an environment that can be ameliorated by on-farm mitigations or interventions at receiving environments such as rivers and estuaries.

Critical points

A paper which followed looked at where ‘critical points’ might occur, and the requirements for the variety of upstream sources to ‘over achieve’ to ensure that the critical points were not exceeded.

An example given was Porirua Estuary, where a single point was fed by multiple watercourses in the surrounding hill country.

A matter which concerned me (and seemingly many others) was the final outcome of the Healthy Rivers Plan Change, where various interested parties are working on a change to a sub-catchment basis, where decisions on discharges would be made locally, and the resulting overall effect on the river quality, if these were not restrained by their positions of being at different upstream and downstream points on the Waikato River.

Other science groups have been working on computer based analysis of spatial and mapping systems to provide the multiple layers of data to be used to effect the overall changes in approach planned by LUS, and the system is known as the Land Use Suitability Spatial Explorer.

Tipping points

A further group has been investigating the realities and potential effects of ‘tipping points’, a phrase which has been much used of late, but for which explicit definitions have been somewhat lacking.

What has unexpected effects in different situations, and what might be the results on future land use suitability?

On my second day I listened to a session on the effects of land use changes to create ‘integrated catchment management’, using tree planting, extensive wetlands and animal management changes.

Our recent change of Government and its focus on tree planting may yet have significant effects on land use.

Some regional councils are already attempting to view their catchments in an integrated way, but with limited ability to make significant changes in farms.

One session, which I found of great interest, was the discovery that NIWA and the University of Minnesota have done joint work on measuring eight nutrient level indicators at 17 sites in the Waikato River Catchment from Taupo to the sea for a whole year.

Flow and light

It focused mainly on nitrogen, phosphorus and phytoplankton (chlorophyll), particularly the effects of flow and light on the latter and its growth.

The data collected must surely be of value, both to other groups of researchers and to councils attempting to achieve significant plan changes in the search for less pollution and more sustainability.

I left the conference wondering how much of that expensive and useful research would get to be shared with all the parties (not just scientists), whose interests and lifestyles could be affected, by being able to incorporate such knowledge into their own understandings.

It is now there, but how much will it be shared and used?


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