Minimum Flow Regulations for Water Management (2011)

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Water Management In Aotearoa

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By international standards fresh water in New Zealand is both abundant and clean. We generally have plenty of rain which replenishes our streams, rivers, lakes and groundwater. However, protecting the country’s freshwater bodies is a growing challenge. For example, water quality in New Zealand varies considerably, and in some areas water shortages can be felt at certain times of the year (Ministry for the Environment, 2011). <ref></ref>

Conflict between water uses and water management has become an increasing issue due to advancing agricultural practices, which brings the need for irrigation water to sustain intensive yield growth. The demands on New Zealand’s fresh water resources have intensified in recent years due to a boom in intensive agriculture throughout New Zealand. This is due to factors such as the increasing demand of water for irrigation. With a rise in modern technology and irrigation systems, water extraction from streams and rivers has become an easier, more accessible process for the agricultural and horticultural industries. As a consequence, the nation's water resources have diminished at the expense of the growing abstraction rates. Hence, the introduction of minimum flow regulations have been required to protect the natural and physical characteristics of New Zealand's natural water resources.

Water allocation planning is a multidisciplinary process that requires a diverse range of skills and information. An integral part of this management is the establishment of "minimum flow" regulations. A minimum flow is a vital part of an in stream flow regime that essentially sets a minimum level of environmental protection for the ecological values of the region. Minimum flow definitions vary depending upon activity that is being undertaken and the region in which it occurs. There are various methods which are used to use to predict minimum flow regulations - hydraulic, ecological, hydrological, and holistic. In practice, each of these methods seek to protect and address the adverse effects of natural water extraction in New Zealand. However, the methods still remain criticised for their lack of "real world" applicability and ambiguous standards.

Methods used throughout New Zealand

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New Zealand Legislation

The Resource Management Act 1991 (RMA) is the main environmental act that oversees and establishes the framework for water use management throughout New Zealand. It passes most of the responsibility for water management onto individual regional councils, allowing them to cater their goals and methods according to their regional ecological and commercial requirements. Under this Act there are a series of steps that must be followed when applying for a resource consent for the abstarction of water as seen in Figure 1. Section 14 of the RMA states that the taking of water from rivers, lakes and aquifers (groundwater) must either be authorised by consent or hold a permitted activity in a plan (this excludes the taking of water for stock drinking and domestic purposes, which are specifically permitted by Section 14). An important component of water management involves the planning of water allocation from rivers and groundwater resources. In addition to Section 14, Section 9 and Section 31 provide for the management of adverse effects on the use of land on water quantity and control the use of land for the maintenance of water quantity in district plans.

Figure 1: Steps to be followed when applying for water abstarction reosurce consent.

In terms of the RMA planning, water policy may be established at a number of levels from national policy statements (potentially), regional policy statements (necessarily), and regional and district plans (optionally). In addition, water allocation plans can help to provide very important frameworks for managing the take and use of water from rivers, lakes, or aquifers <ref></ref>. Each region is required to address water management either as an individual water management plan or through there regional policy statement. Due to the broadness of the RMA framework that each Regional Council must comply with, there are many variations amongst regions with regards to the methods they use to workout minimum flow regulations.For example Hawkes Bayand Otagowhich both have little pressure from intensive agriculture, tend to use an Ecological based methods, identifing eco-systems survival as their benchmark indicators and giving clear outlines as to how minimum flows are derrived. On the other hand Canterburyand Manawatu-Wanganuireigons which have substantial amounts of intensive agriculture mention ecosystems but show little indication as to how these are incorperated in the minimum flow process.

The Ministery for the Environment minimum flow guidelines report 2011

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Minimum Flow Regulations of Selected Regions in New Zealand

Minimum Flow Regulation used in New Zealand shows water regulations by region.

Due to the economic, ecological, and climatic variability between regions in New Zealand, water management frameworks vary greatly throughout the country. Regions such as Canterbury, which relies heavily on intensive agriculture, have a high demand for water extraction for irrigation. This places a large pressure on the regional council to appropriately manage water sources. In contrast, regions such as Hawkes Bay and Otago, where irrigation is less feasible, and the water demand for irrigation decreases. In addition, regions such as Otago and the Manawatu-Whanganui utilize a large amount of natural power production through the use of dams on the major river system - for example the Clutha River in Otago. Whilst this is economically advantageous to the region, the council frequently leaves only the minimal amount to the discharge of the river bed causing a major shift in the ecosystem of the diverted section <ref></ref>.

Moreover, fishing and water sports are an embedded cultural activity in New Zealand adding another further demand to the use of New Zealand's water resources. For example, regions such as Southland are renowned for its brown trout fishing, as well as Waikato which has established a reputation as a world class rowing venue. In contrast, regions such as the Manawatu-Whanganui region is largely agricultural with less recreational pressures.

Lastly, some regions, such as Hawkes Bay, are more prone to summer droughts than regions such as Southland which tends to maintain moderate levels of rainfall over summer. As a consequence, this places some regions in higher demand of water extraction than others, which is reflected in their water management policies. In addition, the effects of climate change have the potential to impact heavily on regions prone to drier periods, further adding to the importance of effective water management in the future.

Case Study regions for assessment of minimum flow regulations:

  1. . Northland Dominantly Hydrolic
  2. . Waikato Dominantly Holistic
  3. . Hawkes Bay Dominantly Ecological
  4. . Manawatu - Whanganui Does not clearly define their method
  5. . Tasman Hydraulic but doesn't define
  6. . Canterbury Dominantly Holistic
  7. . Otago Holistic with ecological values being dominant
  8. . Southland Dominantly Ecological

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Recommendations for Setting Minimum Flow Regulations in Aoeteroa

Overall we believe that the most appropriate method for setting minimum flow regulations is the holistic approach, as this incorporates an interdisciplinary approach to water management. It identifies the cultural, recreational, economic and ecological value of water resources in order to reach a rational conclusion. Within the analysis of these factors, the hydraulic and ecological conditions lay the foundation for the decision making process for setting the minimum flow requirements.

The future of New Zealand's water regulation agrees with this recommendation. According to the Ministry of the Environment’s Draft Guidelines for the Selection of Methods to Determine Ecological Flows and Water Levels, regional councils are recommended to set their minimum flows based on the most appropriate method with the holistic method being the primary technique where possible. With this comes difficulty as the holistic approach requires a great deal of historic evidence and data in order to determine the ecological, recreational, economic and cultural needs of a region.

Despite this, each method for determining minimum flows in New Zealand can be thought of only as a theoretical model framework - whereas environmental management must address and comply with "real world" situations. That is to say, these methods have a limit to addressing the dynamic and interconnected relationships in the natural environment. There is no "magic number" that can maintain healthy water flows, just as there is not a single correlation between the success of species and water regulation. In short, methods must be redirected to address realistic issues that the natural world presents rather than simply theoretical policies.

Furthermore, as mentioned in Minimum Flow Regulations of Selected Regions in New Zealand, methods for minimum flow regulation can often only leave a minimal amount to the original discharge of a main river bed, which can cause a range of shifts in the nature of ecosystems. This range is a function of natural hydrological conditions, the river gradients and transport mechanisms of sediment, substrata and morphology, and the sensitivity of the ecosystem <ref></ref>

Lastly, minimum flow regulations are inextricably linked with an essential ambiguity in water management. In other words, policies cannot explicitly state "bottom line" figures or concrete values. This is because it is difficult to quantify a single overriding figure that caters to the diversity of water resources throughout New Zealand. Consequently, this allows for human subjectivity, which can often be linked to financial interest and land use exploitation. Although it is not possible to identify "all encompassing" quantifiable values for water management - methods for water management must be aware of human interest and financial advancements that are often at the expense of the natural ecosystem.

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