Multicriterial compensation : Consideration of soil quality in compensation mechanisms of spatial planning

Pressure on access to land in Switzerland has increased in recent years, driven by the country’s social and economic growth between 2005 and 2015. Moreover, changes in land-use planning legislation have considerably restricted the scope for expanding building zones and have reduced the amount of building land for many municipalities too. As a result, all new land-use projects now require stakeholders to reconcile multiple constraints that are dramatically limiting their room to manoeuvre. Under these circumstances, the ideal scenario – avoiding impacts, striving to minimise them and, seeking to compensate them – is very often confined to the ultimate phase, that of compensation.p>

Because soil quality is an increasingly critical component, the aim of the project was to better consider soil quality in the choice of compensation measures. Indeed, negotiations concerning compensation measures are currently typically limited to equivalent area of agricultural land, for example, without considering potential differences in soil quality.

The project’s findings showed that even when spatial planners generally share concerns about soil quality, they feel at a loss to take soil quality into account into their projects and decisions. This difficulty derives from the very limited room to manoeuvre, as well as real difficulty in understanding the concept of soil quality. Given these circumstances, the project developed a decision-support tool based on three principles: 1) it should help in implementing the projects, including but not only in terms of maintaining soil quality; 2) it should facilitate interactions among experts in land use and soil science by enabling both sides to stay within their field of expertise; 3) it should enable inexpensive, incremental collection of data targeted to soils posing the most immediate challenges.

Two research outputs are worthy of note. The first concerns the proposal for an operational measure of soil quality adapted to the context of land compensation. This new indicator has the advantage that it is simple, transparent and suited to taking local expertise into account. The second output is of an interdisciplinary nature and entails the conception and validation of a decision-support tool.

The findings suggest that simply making data on soil quality available may not be sufficient for integrating it into spatial planning projects. We believe that it may be preferable and more effective to adopt an approach where a smaller set of data is acquired incrementally and made available using a decision-support tool that can be integrated directly into spatial planning practice.

From Areal to Multi-criterial Compensation: How to Integrate Soil Ecosystem in Compensation Mechanisms Applied in Land Use Planning?