# The Impact of Spatial Resolutions on Nature-Based Solution Suitability Mapping for Europe
## 3 Materials and Methods
### Analysis and Validation  
The suitability mapping resulted in three different outputs. Based on these, further analysis and validation was performed to gain a better understanding on the suitability of each LULC layer for the integration into Europe-wide suitability mapping for the NBS Toolkit. For this purpose, the three output suitability layers were quantitatively analysed with cell and patch statistics, and qualitatively validated with satellite imagery.  
Figure 3: This figure presents the Boolean output layers for the study state of Rhineland Palatinate in Germany; (**a–c**) present each of the three LULC layers after the reclassification to Boolean layers: (**a**) LUISA base map, (**b**) OSM, (**c**) CLC; and (**d**) presents the suitable areas where all criteria (except LULC) are indicating suitability.  
Cell statistics._QGIS raster cells statistics were applied to assess the coherence of the three output layers. Comparing these layers on a cell-basis indicates whether the outputs suggest the same suitable areas or not. In particular, a new layer was created in which each cell has a value ranging from 0-3:3, indicating high coherence--meaning that all three suitability mapping outputs suggest suitability; a value of 2 presents areas where two layers (out of the three) indicate suitability, 1 suitability is suggested with one layer only, and those with a value of 0 are non-suitable areas.  
Patch statistics.Statistical analysis, or so-called patch statistics, was used to derive information on the suggested riparian forest buffer sizes and the degree of fragmentation. Patch statistics were performed using the QGIS plugin LecoS 3.0 [48]. This plugin is based on the FRAGSTATS (v4) software [49] commonly used in landscape ecology for patch and landscape analysis. The following metrices were calculated: (1) land cover, to calculate the entire area for potential riparian forest buffers; (2) number of patches, to present the difference in the number of suggested areas; (3) patch density (land cover divided by number of patches), which indicates how dense the suggested riparian forests are to each other; (4) maximum and mean riparian area sizes; and (5) the landscape division index, to analyse the degree of fragmentation of the suggested riparian forest areas with values ranging between 0 and 1, while 1 indicates patchiness, and hence, fragmentation.  
Satellite image validation.Qualitative assessment was used to validate the (thematic) accuracy and appropriateness of the suggested riparian areas. At this point, we define thematic accuracy as the correctness degree of the suggested areas; for instance, considering a LULC layer of 100 m, the resolution cannot present LULC class borders as accurate as in reality, whilst the appropriateness is considered as the actual suitability of a suggested area. For this qualitative validation, the Google satellite images layer (2022) was overlayed with each of the three output maps to assess whether suggested areas are thematically accurate and appropriate. For instance, whether suitable areas are placed inside water areas (due to a lack of accuracy) or on camping sites (which may not be appropriate).