*3.1.2 Results of topography analysis of the study area*

The results of the topographic analysis (morphology, elevation and slopes degree) of the study area are illustrated in **Figures 2**–**4**.

From the topographic analysis of the study area, we find that the group of mountains and plateaus that surrounding the study area made it semi-closed. Therefore,

**Figure 1.** *Location of the study area [17].*

the north-west corner of the study area formed the outlet for the runoff network as shown in **Figure 5**. According to the digital elevation model of the study area that was obtained from the NASA site and topographic analysis, the elevations in the study area concentrated in the south and southwest, where the height of the mountain of Sabir was up to 3000 m above sea level, whereas Jabal Habashi has a maximum height of 2400 m above sea level. The lowest elevation is located in the north-west and is 872 m above sea level, and in the east, elevations are between 1200 and 1600 m above sea level (**Figure 3**). **Figure 4** shows the map of the degrees of slope in the study area. The degree of slope determines the flow intensity of the floods and, therefore, the extent of water (or water and pollutants) infiltration into the ground.

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer…*

The results of the hydrological analysis [the hydrological limits, direction of surface runoff and then the flow direction of pollutant at the surface (hydrology system) and the hydrological level (main valleys and its tributaries)] of the study

*3.1.3 Results of hydrology analysis of the study area*

**Figure 3.**

**Figure 4.**

**127**

*The slope degree in the study area.*

*The elevation in the study area.*

*DOI: http://dx.doi.org/10.5772/intechopen.91329*

**Figure 2.** *Topography of the study area.*

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer… DOI: http://dx.doi.org/10.5772/intechopen.91329*

**Figure 3.** *The elevation in the study area.*

**3. Results**

*Resources of Water*

**Figure 1.**

**Figure 2.**

**126**

*Topography of the study area.*

*Location of the study area [17].*

*3.1.1 Location of the study area*

**3.1 Results characteristics analysis of the study area**

third largest and important cities in Yemen (**Figure 1**).

degree) of the study area are illustrated in **Figures 2**–**4**.

*3.1.2 Results of topography analysis of the study area*

The study area represents the southern part of the Upper Wadi Rasyan catchment area, Taiz governorate, Yemen. The study area is estimated at 472 square kilometers which is densely populated and includes Taiz city which represented the

The results of the topographic analysis (morphology, elevation and slopes

From the topographic analysis of the study area, we find that the group of mountains and plateaus that surrounding the study area made it semi-closed. Therefore,

**Figure 4.** *The slope degree in the study area.*

the north-west corner of the study area formed the outlet for the runoff network as shown in **Figure 5**. According to the digital elevation model of the study area that was obtained from the NASA site and topographic analysis, the elevations in the study area concentrated in the south and southwest, where the height of the mountain of Sabir was up to 3000 m above sea level, whereas Jabal Habashi has a maximum height of 2400 m above sea level. The lowest elevation is located in the north-west and is 872 m above sea level, and in the east, elevations are between 1200 and 1600 m above sea level (**Figure 3**). **Figure 4** shows the map of the degrees of slope in the study area. The degree of slope determines the flow intensity of the floods and, therefore, the extent of water (or water and pollutants) infiltration into the ground.
