Slope stability and land use – improving planning practice

Technical Abstract

This study adopted a two-fold approach to researching current land use practice, and comparing this with what may be considered good practice.

Firstly, documentation held by two case study councils, Far North District and Hutt City, was examined in order to ascertain the influence that available tools and their application have had on improving professional practice and, second, a series of surveys and workshops were held in order to provide context to the relationships between the different disciplines contributing to the land use decision process.

The lessons from these two work streams have then been synthesised into a ‘process map’ illustrating how slope stability information gets incorporated into the decision-making process, and the ways in which these sources of information can contribute to improved understanding and a higher quality of decision making.

Key findings of this study are that:

• There is a view that all land can be safely engineered to make it suitable for development. This view is not consistent with reality;
• While the understanding of how to reduce landslip risk has increased over time, many professionals employed by developers and councils have not kept up with these advances;
• Geotechnical information pertaining to various regions is held by a number of organisations without all parties being aware of, or having access to it;
• Accountability for ensuring effective decision making methods of the consenting process does not always lie where the advice that the process depends upon is given;
• A raised awareness that slope stability is an issue, and improved education and information sharing, is a prerequisite to improved land use planning.

Observations made by the project team during the course of this study, and direct contributions from planners and related professionals through the workshops and survey have identified a range of opportunities for improvements to the planning process. Foremost amongst them is the need for an integrated approach to the problem and better coordination to improve communication and collaboration.

Recommendations are made for both near-term and medium-term implementation.

The recommendations focus on three key areas for action:

• Improved information sharing;
• Raising the profile of slope stability risk, and;
• Extending accountability.

Adoption or action upon these recommendations is not the responsibility of any single organisation or profession. Instead the report suggests a framework for going forward that encourages all stakeholders to take a proprietary interest in dealing with and improving approaches to slope stability risk throughout the country.