Large

What this scale means

Large scale covers a river basin, a region or a national territory. The decisions taken at this level are not about individual measures but about where measures should be promoted, which areas qualify for support, and how a national or basin authority allocates a budget across a territory far too large to assess site by site.

Two things change at this scale. The first is that the assessment has to be screening rather than appraisal: it identifies where a detailed assessment is worth its cost, using data that exists everywhere rather than data that exists somewhere. The second is that the relevant institutions are national or basin-level bodies, and the intervention is made through instruments — subsidy rules, planning requirements, funding criteria — rather than through projects.

What to use

Satellite-supported mapping is the appropriate instrument for the screening stage. One mapping establishes the physical potential for hazards across a region, and a parallel mapping establishes the socio-economic exposure within it. Both work at large extent and moderate resolution and require no local survey, and their output is a ranking of where an intervention is likely to be worthwhile.

The mapping of insurance-relevant natural capital adds the layer that makes the screening useful to a financing decision: which ecosystems in the region change the probability or the severity of a loss, and what else they deliver. The institutional analysis establishes which bodies at national and basin level would have to act and what instruments they hold, which is often what determines whether a promising area can be addressed at all.

For a basin authority comparing sub-catchments, the multi-criteria toolkit allows the comparison to be made against several objectives at once — flood risk, water quality, ecology, cost — with the trade-offs visible and the sensitivity to the weighting stated.

Where it is used at NAIAD

The large-scale screening methods were developed for application beyond the demonstration areas and were tested against them, with the Medina del Campo aquifer, the Thames basin, the La Brague basin and the Lower Danube basin providing the full range of settings from a heavily regulated national basin to a small cross-border one. The country-level insurance systems comparison extends the same logic to the national policy scale.