*5.1. Restrictions*

Topological, ecological, and structural restrictions were specified based on the local and constitutional rules and regulations and recent studies. Sloping and high lands were less considered due to problems in installing turbines, complex and costly repairs, and the maintenance of turbines. Proximity to faults was also avoided due to the dangers it may cause the structures. To ensure security and minimize the problems of turbines for the general public, the permitted distance of turbines from communication routes, fuel, and energy transmission lines, and airports must also be observed. One of the disadvantages of wind turbines is the environmental hazards in the habitats of various animals, particularly birds. Therefore, environmental considerations keep the turbines far from the protected areas and rivers. By applying these restrictions, unsuitable areas for wind farm construction will be identified. These areas will be shown in red on the map and will be removed from the final desired map, which will be investigated by applying the criteria.

#### 5.1.1. Topological Restrictions

The topological restrictions are represented in Table 8. The digital elevation model was used to create a slope map of the province. According to the references mentioned in Table 8, unsuitable areas with an altitude of more than 2000 m and slopes of more than 30% were considered. A distance of fewer than 500 m from the faults was also considered unsuitable. Figure 8 shows the suitable and unsuitable areas based on the topological restrictions mentioned in Table 8. The red areas indicate inappropriate locations, and the green areas indicate appropriate areas.

**Table 8.** Topological restrictions.


**Figure 8.** *Cont*.

**Figure 8.** Topological restrictions (**a**) elevation map. (**b**) slope map. (**c**) faults buffer zone.

5.1.2. Structural Restrictions

The structural restrictions are given in Table 9. According to the latest maps prepared in the planning studies of the Semnan province, carried out by the Planning and Budget Organization of the Ministry of Interior in 2016, the location of roads, oil and gas transmission lines, high voltage power lines, substations, railways, and the airports were identified [74]. The buffer areas are specified based on the mentioned references in Table 9.


Figure 9 illustrates the suitable and unsuitable structural areas according to the buffer zones of Table 9. The red areas are unsuitable buffer zones, and the green areas are suitable according to structural restrictions. The area of Semnan province is equal to 97,491 km2. Based on the calculations made according to Table 9, 3864.2 km2 (3.96%) of the province's total area is among the unsuitable areas.

**Figure 9.** Suitable and unsuitable areas according to structural restrictions.
