*2.2.2 Subsidence/collapse/rock (block) fall*

If site selection is made or construction areas are selected for settlement purposes without getting engineering service, the problems of ground subsidence in gypsum areas, and rockfall in collapse areas and slope areas can be observed (**Figures 2a, b, 3b** and **5b, c**) [3]. They have a negative impact on human life and lead to material and moral losses. For example, subsidence and cracks occur in foundation ground due to dissolution in the gypsum unit (with the contact of leachate water), and this may cause damage to buildings. However, the rockfall constitutes a safety problem (e.g., in road, highway, and railway routes) [13] (**Figure 3b**). Consequently, various structural damages (cracks, dissolution, collapse, sinkholes,

#### **Figure 2.**

*Gypsum-based ground deformations in the southeast Sivas city (Turkey) (photos: Sevda Özel, 2018). (a) As the setting-collapse increases, the cavity (~1.0 × 2.5 m2 ) is filled with fill material (as a temporary measure) and (b) a newly formed dissolution area under the pavement (~0.3 × 0.5 m2 ).*

#### **Figure 3.**

*Gypsum-based karst deformations in Sivas (Turkey) (photos: Sevda Özel 2013, 2015). (a) The collapse area, sinkholes, and the gypsum clastic soils in the east and northeast of Sivas. (b) The rockfalls in the northeast of Sivas.*

doline, erosion, corrosion, rockfall, etc.) arise and are observed in the structures of the building (**Figures 2–5b, c**).

### *2.2.3 Health and living environment of living beings*

Vegetation losses also occur with soil salinization occurring with leachate waters containing the high amounts of dissolved ions mixing into the water from gypsum as a result of the contact of gypsum with water in cover units on the edges or on gypsum. In this case, erosion may occur in these regions over time (**Figures 4a** and **5b, c**). Therefore, all living beings including humans, and their living environments are damaged by these losses. Hence, low water-soil quality decreases and destroys the nutritional sources of living beings; soil-water pollution, as well as inadequate nutrition conditions, affect the health of living beings, and plant species may become extinct or decreased due to erosion (**Figure 4a, b**). Similarly, living beings may have to migrate to living environments where healthier and better opportunities exist. The health and living environments of living beings are impaired with these exposures in the dimension of the environmental problem.

While discussing the dimensions of environmental impacts in terms of the settlement by reviewing the detailed characteristics of the environment, hydrogeological and hydrogeophysical investigations are important in this regard. In particular, it is necessary to perform well-planned field studies that determine shallow and deep geological/geophysical, hydrogeological and environmental impact characteristics of the gypsum karst region. Whether the Environmental Impact Assessment (EIA)/Strategic Environmental Impact Assessment (SEIA)

#### **Figure 4.**

*(a) The erosions in the east of Hafik-Sivas (Turkey) (photo: Sevda Özel, 2013). (b) The gypsum clastic agricultural soils in the east and northeast of Sivas city (Turkey) (approximately 1–2 km away from the city) (photo: Sevda Özel, 2013).*

**117**

listed below:

(**Figure 5a–c**).

*2.2.3.1 Mineral transformations*

*Identification and Assessment of Hazard of Development in Gypsum Karst Regions: Examples…*

is required, the identification of aquifers, the calculation of aquifer hydraulic parameters, and underground water-surface water information (feedingdischarge zones, the rate and direction of the flow of underground water, underground water level, the amounts of seasonal variations, hydrogeochemical properties of underground water and leachate waters, and underground water

of layer limits, geological and geophysical parameters) should be calculated. In the detailed investigation of karst geomorphology, the necessary attention should be paid to the seismic activity status, seismic activity history, and meteorological and morphological characteristics of the region. With these studies, the limits of hazardous areas and the risks can be determined after geological-hydrogeologicalhydrogeophysical characteristics of the environment are determined in site selection. Therefore, it is important to define geological environments well and choose the right calculation method in terms of the environmental impact analysis and the measures to be taken. In addition to these, these regions are also monitored periodically by monitoring network and sampling methods designed based on the success and environmental impact of measures taken according to detailed engineering geology/geophysics and environmental geotechnical inputs, and engineering properties of the field, as a result of the environmental impact assessment [4–7, 32]. Thus, control mechanisms, management style, and other plans/projects can be prepared to take measures against risks and dangers within a scientific framework. Furthermore, site selection, natural hazards, environmental problems, and the monitoring studies of them show that it is necessary to maintain joint research with the relevant engineering and other disciplines and that the increase/improvement of environmental protection laws is important. Therefore, it will be important and useful to ensure that studies are not limited only with the top surface and subsurface studies and that necessary attention will be paid to shallow and deep investigations. Based on this idea, the examples of the creation of living environments that are less affected by gypsum-induced events will increase. Moreover, it should be taken into account that natural hazards and environmental impacts caused by gypsum are not only those that appear on the Earth's surface and that there may also be ongoing problems under the ground. Accordingly, when natural hazards and environmental impacts specific to gypsum areas are examined, environmental problems and natural hazard/risk situations caused by gypsum in the site selection for settlement purposes and in the site selection of other human-made construction structures are

The geological stratification status (thickness, depth, slope, topographic changes

These transformations constitute an important environmental problem for deformations resulting from volume expansion and especially for settlement areas (such as structural damage) and agricultural-water areas. In addition to gypsum (CaSO42H2O), which is one of the minerals of the evaporite group, anhydride (CaSO4) and other minerals of the evaporite group are easily soluble when they contact with water

In the event of the loss of water in the environment, these minerals may be recrystallized, new minerals may be formed by the displacement of ions, or minerals may transform into each other. For example, as gypsum (CaSO42H2O) absorbs heat (as temperature increases) depending on climate conditions, it loses water and may transform into gesso (CaSO4½H2O) and anhydride (CaSO4) units, respectively [3]. On the other hand, the melting temperature of gypsum is very high (about >100°C or about 700–1500°C), the dissolution temperature of gypsum

*DOI: http://dx.doi.org/10.5772/intechopen.83684*

level maps) are necessary.

#### *Identification and Assessment of Hazard of Development in Gypsum Karst Regions: Examples… DOI: http://dx.doi.org/10.5772/intechopen.83684*

is required, the identification of aquifers, the calculation of aquifer hydraulic parameters, and underground water-surface water information (feedingdischarge zones, the rate and direction of the flow of underground water, underground water level, the amounts of seasonal variations, hydrogeochemical properties of underground water and leachate waters, and underground water level maps) are necessary.

The geological stratification status (thickness, depth, slope, topographic changes of layer limits, geological and geophysical parameters) should be calculated. In the detailed investigation of karst geomorphology, the necessary attention should be paid to the seismic activity status, seismic activity history, and meteorological and morphological characteristics of the region. With these studies, the limits of hazardous areas and the risks can be determined after geological-hydrogeologicalhydrogeophysical characteristics of the environment are determined in site selection. Therefore, it is important to define geological environments well and choose the right calculation method in terms of the environmental impact analysis and the measures to be taken. In addition to these, these regions are also monitored periodically by monitoring network and sampling methods designed based on the success and environmental impact of measures taken according to detailed engineering geology/geophysics and environmental geotechnical inputs, and engineering properties of the field, as a result of the environmental impact assessment [4–7, 32]. Thus, control mechanisms, management style, and other plans/projects can be prepared to take measures against risks and dangers within a scientific framework. Furthermore, site selection, natural hazards, environmental problems, and the monitoring studies of them show that it is necessary to maintain joint research with the relevant engineering and other disciplines and that the increase/improvement of environmental protection laws is important. Therefore, it will be important and useful to ensure that studies are not limited only with the top surface and subsurface studies and that necessary attention will be paid to shallow and deep investigations. Based on this idea, the examples of the creation of living environments that are less affected by gypsum-induced events will increase. Moreover, it should be taken into account that natural hazards and environmental impacts caused by gypsum are not only those that appear on the Earth's surface and that there may also be ongoing problems under the ground. Accordingly, when natural hazards and environmental impacts specific to gypsum areas are examined, environmental problems and natural hazard/risk situations caused by gypsum in the site selection for settlement purposes and in the site selection of other human-made construction structures are listed below:
