## 3 Materials and Methods
### Methodology of Dataset Analysis  
#### 3.2.1 Analysis of Morphology and Morphometry  
An orthophotomap and a Digital Surface Model (DSM) were created for every studied hydration landform involving its surroundings. The forms are most commonly domed (e.g., Figure 2b) or tepee-like in shape (e.g., Figure 2c). The basis for distinguishing the tepee-shaped forms is the presence of at least two rock slabs with semi-flat or concave morphology, raised in place of their contact and leaning against each other, \"pressing\" each other from opposite directions, occupying the dominant part of the form, usually in the middle of it. The dome, on the other hand, has a dominant rounded (convex) shape without a sharp crest. The geomorphometric parameters for the characteristics of the studied landforms were adopted from descriptions of the analogous domed forms of relief: hydration forms [18; 48], gypsum tumuli [36; 37; 67], drumllins [82; 83; 92], and granite A-tents [64; 66]. Some parameters were modified and the new ones were also introduced as described below. The geomorphometric description of the landforms was carried out during both field and office work and was adapted to their convex morphology. During the office work, photogrammetric data and data obtained as a result of their further processing, such as 3D and 2.5D models [93], orthophotomaps, point clouds with extension _.las_ and DSMs were collected and elaborated. These works mainly involved ArcGIS, Photoscan, Excel and Corel Draw X9 programs. Work in the ArcGIS program (Esri, Redlands, CA, USA) began with the transfer of the extent line for each of the 74 identified hydration forms to the orthophotomap of the area (3 forms were excluded from the analysis because of the lack of photogrammetric data; see Table S1). Based on the extent of the form, lines of the longest axis (length of the form, a--longer axis; Figure 3) were drawn and measured on the map similarly to [PERSON] et al. [82] and Maclachlan and Eyles [83], as the longest straight line possible within the mapped forms area. Then, the width of the form (b--short axis; Figure 3) perpendicular to the a axis was drawn and measured [82; 83]. The crest lines through the points of maximum curvature of the majority of contours were also marked (Figure 3) [92]. An orientation of the axis a, i.e., elongation of the form, was computed to acquire the azimuth of elongation orientation Az of every form and, on the basis of these measurements, to generate a rose diagram. On the basis of the DSM, the Zonal Statistic as Table tool [94] (pp. 327, 349) was used to measure the values of elevations (in m a.s.l.) marked by h\({}_{\text{max}}\) and h\({}_{\text{min}}\) (Figure 3). Value h\({}_{\text{max}}\) is the peak at the highest elevation point (usually located in the middle of the form) while h\({}_{\text{min}}\) is the lowest elevation point of the hydration form within its extent. The relative height of form h\({}_{\text{r}}\) is understood as the form altitude range and is the result of subtraction h\({}_{\text{min}}\) from h\({}_{\text{max}}\) (see [84]). This value does not take into account the hillslope of the terrain surface, which at Dingwall is generally minimal. When the forms were overgrown with vegetation, the covered part was excluded from the calculation of relative height. As part of the statistical analysis realized in the Excel program for all the calculated parameters (Table 2), a simple linear regression analysis was performed to reveal the possible regular relationships between these parameters [95]. The regression lines were generated and the Pearson correlation coefficient was calculated. For the values: a, b, h\({}_{\text{r}}\), the regression line was fixed at a point (0,0) in the coordinate system to obtain a more realistic equation of their mutual dependence. All the values (a, h\({}_{\text{r}}\), B, C; see below) were used to create their frequency distribution diagrams (histograms).