*2.4. SEA Methods and Techniques*

The methods and techniques used in SEA procedures are undefined, in comparison to the exact, practical tools used in other scientific fields [41]. This ambiguity is due to the fact that there are, as of yet, no strictly defined methods and techniques at every step of SEA. Furthermore, the prevailing attitude views these as a collection of tools, of which users are encouraged to select those most suitable for each situation [42].

According to the general prerequisites [43,44], SEA methods and techniques should:


These prerequisites ought to be considered more as general principles, rather than criteria for the selection, in each individual case, of the most suitable SEA methods and techniques. According to Therivel [4], the factors which determine which of these are most appropriate for each individual case are the scale (international, national, regional, local), the "strategic-ness" (policy, plan, program) of the strategic actions, the type of decision, the audience who would use the outputs, the context in which SEA is conducted, the availability of time, resources, personnel, and equipment, as well as the types of data required by the methods and techniques. Finally, a common defining factor is the tradition and mindset of each individual state, researcher, or practitioner.

A large number of methods and techniques is available for use in SEA processes. According to Lee [5], a study carried out in the early 1980s on behalf of two Dutch ministries compiled descriptions of 350 different methods and techniques in North American andWestern European literature. Nevertheless, of this wide array, only a small number were utilized in practice [43–45]. Although an in-depth analysis goes beyond the scope of the present paper (see in greater detail [2,4,43,44,46–49]), Table 2 presents methods and techniques which are extensively referenced in international literature, and categorizes them into two modules. In the first (methods and techniques works for), the methods and techniques are determined according to the level and scope of their implementation (PPP, large–small area, land use plan, sectoral plan). In the second (methods and techniques copes with), the categorization pertains to the quality of utilized data (incomplete or not, uncertain or not), their nature (qualitative or quantitative), and the resources required for their processing.

**Table 2.** Extent of application of SEA methods and techniques ([44] (p. 351), and own processing based on: [2,4,43,46–49]).


The first conclusion is that the majority of methods and techniques can be utilized, either comprehensively or in part, at all levels and scales, regardless of the quality of the utilized data and required resources. The column titled Qualitative data, in which the methods and techniques are categorized as either qualitative or quantitative, is indicative of both their potential and their limitations. In particular, the qualitative methods and techniques are applicable at all levels of PPP, with the exception of the multi-criteria analysis, in contrast with numerous quantitative methods and techniques, which cannot be applied at the policy level, such as cost-benefit analysis, modeling, etc. The qualitative methods and techniques are applicable even in cases of incomplete or uncertain data and, due to not requiring specialized equipment, can even be utilized when there are limited available resources. Notable examples are expert judgment, guiding questions, and literature/case review. In other words, the qualitative methods and techniques contribute to improve certain SEA steps, making the process more simple and rapid, require little in the way of equipment, and can utilize both qualitative and quantitative data, while simultaneously taking into account existing political sensitivities. By contrast, the quantitative methods and techniques are, in their majority, time-consuming, complicated, and expensive, due to requiring large volumes of data and specialized equipment. However, they are objective, scientifically sound, and produce comprehensible results, while also being useful for application at the planning and programming level, regardless of extent and design. Notable examples are the cost-benefit analysis and the land use partitioning analysis.

Table 3 distinguishes the methods and techniques depending on the extent to which they are applicable at the various steps of SEA. Due to the fact the SEA Directive, and consequently the SEA JMD, both refer to the EIA-like SEA analysis of the steps of SEA, this was chosen as the means of analysis. The differences between this and the figure of Therivel and Wood [44] lie in the addition of the screening column, which aims to pinpoint every element used in the process of preliminary environmental screening, and in the identify alternatives column, with the objective of identifying all those which define alternatives.

Initially, and in contrast with Table 2, it becomes evident that the majority of the methods and techniques cannot be implemented at every step of SEA. Notable exceptions are the participatory methods, which are applicable, either comprehensively or in part, to the entirety of SEA steps. Furthermore, there are methods and techniques which are applicable to the majority of SEA steps, such as expert judgment, guiding questions, indicators, GIS, etc. The majority of these methods and techniques manage primarily qualitative data, exhibit particular advantages, and are noted for their ease of use. On the other hand, the qualitative methods and techniques, due to their various inherent disadvantages, which were previously described, are not suitable for application at the steps of preliminary environmental screening, description of the current status, and monitoring of environmental impacts. Nevertheless, due to their scientific approach and the objectivity of their results, they are notably effective, and are commonly applicable in the identification, description, and evaluation of the environmental impacts of PPP. Indicative examples of such methods and techniques are cost-benefit analysis, modeling, and scenario/sensitivity analysis.



*Sustainability* **2020**, *12*, 3310
