Integrated catchment management—a decade of research in the Motueka River catchment

The need for more holistic approaches to land and water management has long been recognised (Cullen 1990). These approaches have a common focus on research and management, which recognises that land use and land cover are inextricably linked with water resources and they seek to mobilise resource management towards an integrated systems view of the landscape. One such approach, integrated catchment management (ICM), highlights the river basin or catchment as the ecologically appropriate spatial unit within which to apply good management (Ferrier & Jenkins 2010). For the purpose of the papers in this special issue, we define ICM as follows:

A process that recognises the catchment as the appropriate organising unit for understanding and managing ecosystem processes in a context that includes social, economic and political considerations, and guides communities towards an agreed vision of sustainable natural resource management in their catchment.

In New Zealand, a continuing decline in water quality and increasing competition for water have led to calls for more collaborative approaches to land and water management (e.g. Land and Water Forum 2010). This challenge was at the heart of a place-based, 10-year, cross-disciplinary and inter-agency research programme focused on the Motueka River catchment and Tasman Bay. An integrated approach was taken, recognising that land, water and social systems are interlinked. The programme brought together research on biophysical (water, sediment, nutrient and contaminant fluxes and aquatic organisms), economic and social sciences alongside research on social processes (social learning, community engagement, Māori values, policy relevance), across land and water (including coastal waters).

This special issue illustrates the breadth and the diversity of learning that has occurred throughout this 10-year journey. Each of the 15 papers is backed up by a substantial body of previously published work (see Table 1, in Fenemor et al. (2011) and at http://icm.landcareresearch.co.nz/). This work shows the importance of connecting resource management issues, taking a holistic approach to managing natural resources from the mountains to the sea, and engaging stakeholders in the science of improved catchment management.

The first paper is an overview by Fenemor et al. (2011), which describes the context for the ICM programme and for the papers that follow in this special issue. These papers describe how research insights support systems-based management of catchments. More importantly, these papers describe how the research agenda was driven by critical stakeholder needs. Thus, the research journey included not only scientists, but policy makers, farmers, fishermen, foresters, artists and a range of other technical and non-technical stakeholders. The Motueka ICM programme addressed the primary issues of concern to these stakeholders by taking an inclusive view of the landscape that encompassed the mountains to the sea. A fundamental basis of the framework was that social processes should guide the research and implementation agendas to achieve acceptable catchment scale outcomes.

Basher et al. (2011) describe the importance of large floods in controlling sediment delivery and transport within river systems, and document the flow versus sediment concentration relationship in the Motueka River, which was substantially altered by a 1-in-50-year flood in 2005, prompting a need for changes in how sediment yields are calculated. One method of controlling delivery of sediment and other contaminants to river systems is to enhance riparian vegetation. Smaill et al. (2011) report results from a riparian planting trial in the Sherry River, a sub-catchment of the Motueka. They conclude that seedling robustness and weed control are critical factors affecting the success of riparian planting efforts. Wilkinson et al. (2011) simulate faecal bacteria transport in the Sherry River and at the Motueka River mouth and show how flow, temperature and sunlight are key drivers for bacterial transport and die-off. Despite representing <4% of the catchment area, the intensively modified Sherry River catchment—including four dairy farms—contributes around 8% of the faecal bacterial load from the Motueka River to Tasman Bay.

Water, nutrients and sediment move downstream within catchments, but aquatic organisms also move throughout river networks (upstream and downstream), a fact that should be reflected in water policy, for example when setting environmental flow regimes. Two papers examine fish movements. Olley et al. (2011) demonstrate how the microchemistry of trout otoliths (ear bones) can be used to infer patterns of fish movement within catchments and the potential power of this technique for determining critical spawning areas that contribute to the main-stem fishery. Doehring et al. (2011) test an acoustic camera for describing juvenile galaxiid (whitebait) movement through tidal floodgates near the river mouth. A comparison of a gat ed culvert and an un-gated culvert demonstrates how tidal floodgates can restrict fish passage and also make whitebait more vulnerable to predation on their journey from the sea, upstream to their adult habitat.

The importance of land use in controlling river health is clearly demonstrated by Shearer & Young (2011), who found invertebrate communities indicative of healthy conditions at sites dominated by native forest, whereas invertebrate communities in pastoral streams were indicative of poor health. Exotic forest streams fell between these extremes. Differences in stream invertebrate communities among geology types were weaker than among different land uses. However, the geologies within a catchment should not be overlooked when considering the consequences of land development on river and stream ecosystems.

Biophysical monitoring such as that described by Shearer & Young (2011) is of course fundamental to understanding whether our rivers meet acceptable scientific standards for river health, and for understanding trends in river health. However, it is increasingly recognised that assessments of the state of the environment should also include a strong cultural perspective. Harmsworth et al. (2011) review the philosophies behind cultural and scientific monitoring of river health and compare two approaches used in the Motueka and Riwaka catchments. Biophysical and cultural indicators both suggested a decrease in river health in relation to increased land-use pressure. Using biophysical scientific approaches in conjunction with culturally based monitoring provides a wealth of insight and understanding, and harnesses the benefits of two different but complementary knowledge systems and perspectives.

One of the major outcomes from this ICM research has been the clear demonstration that land use can directly and substantively impact water quality, coastal productivity and shellfish harvesting. Building on the work of Basher et al. (2011), Gillespie et al. (2011a) found that the unique chemical signature of sediment from the upper reaches of the Motueka River is a natural tracer for delineating the depositional footprint of the river within Tasman Bay. The strong connections found also demonstrate that the river plume ecosystem beyond the river mouth is influenced by land use. Consequently, catchment management must extend to considering impacts in offshore areas. Indeed, Cornelisen et al. (2011) in their paper show that faecal bacteria from bovine sources can travel at least 6 km offshore from the Motueka River mouth and are found within shellfish growing in aquaculture management areas. Gillespie et al. (2011b), later in the issue, demonstrate large temporal variations in nutrient loads from the catchment into coastal waters, and discuss how these may affect the productivity within the river plume (e.g. shellfish aquaculture) while having little potential to cause the problems associated with eutrophication.

Economics is an important driver of land use, and changes in land use potentially affect water demand. In an analysis of groundwater use in the neighbouring Waimea Plains, White (2011) found that most irrigated land moved to higher value uses over a 5-year period from 2003 to 2008, with dairying being replaced by horticulture and market gardening, which provided a three to seven times boost in revenues per hectare. These changes resulted in a reduction in groundwater use, as dairying generally used more water per hectare than horticulture or market gardening.

The social science conducted in the ICM programme was the sinew that bound much of the work together. Successful ICM requires the ongoing participation of different groups of stakeholders in an adaptive management process. This is difficult to achieve in practice because we often fail to address the underlying social processes required to design successful engagement. Allen et al. (2011) begin by introducing the social and political context in the Motueka catchment. They go on to document emerging lessons about how to engage stakeholders in integrated research and development initiatives to support social learning. They identify factors that will help project leaders to move beyond multidisciplinary work, to support effective interdisciplinary and transdisciplinary efforts. Complementing this paper, Kilvington et al. (2011a) outline three social frameworks for understanding and managing ICM projects. These frameworks can help the design of strategies that support improved communication, engagement and measurement of progress towards long-term outcomes. In the final paper describing the Watershed Talk project, Kilvington et al. (2011b) explore the benefits of creative approaches, which stimulate participants to reflect on care and responsibility for their local environment, including the innovative use of participants’ photos. The authors show how developing engagement based on principles such as respect, diversity, empowerment, reflection, generosity and active cultivation enables ICM practitioners to move towards more constructive and enduring engagement.

Some important research themes from the Motueka ICM research were not included in this journal issue. Among these is research on the IDEAS (Integrated Dynamic Environmental Assessment System) modelling (e.g. Dymond et al 2010), the primary factors influencing the fluctuations in trout numbers, a new method for assessing changes in fine sediment on riverbeds, potential improvements to water governance in New Zealand, and the setting of water allocation limits based on scenarios from a transient river–aquifer model. Much of this work has been published previously. Information and links to these publications can be found on the ICM website (http://icm.landcareresearch.co.nz).

The studies described in this special issue illustrate what we have come to know as ICM—both the process and its outcomes. The special issue demonstrates how connecting biophysical and social science with community engagement can provide the foundation for sustainable land and water use. Integrating these dimensions is intellectually challenging but necessary to address environmental issues of pressing social concern.