## 2 Geological Setting of the Study Basin  
A significant portion of the Arabian plate is occupied by Saudi Arabia, and to the west of it is the Red Sea. The geodynamic processes that have led to the Red Sea's opening and present enlargement have a significant impact on and control over the geology and tectonics of western Arabia. The study basin is located along the eastern side of the Red Sea basin in northwestern Saudi Arabia. Geologically, major rock groups are assigned from Cambrian to Tertiary [21]. The lithology of the study basin includes several types of rock units (Figure 2). Syenogranite, syenite, monzogranite, and gabbro units were recorded as small units at the southern part of the study basin nearing Heelan (Figure 2). Within the area between Al henakiyah and Heelan, shale, siltstone, arenite, conglomerate, and felsic tuff lithologies were recorded. Also, a long strip of sand, silt, gravel, evaporites, and coral limestone is observed in the middle part of the study basin. Granite, granite gneiss, granodiorite gneiss nylonite, and gabbro were observed in several sites in the study basin (Figure 2). Basalt, andesite, dacite, rhyolite, felsic tuff, volcaniclastic arenite, and limestone cover most of the study basin, and they are mainly concentrated in Khaybar in the middle part. Alkali-feldspar granite and monzogranite are recorded at the northeastern part of the study basin. More lithological details are illustrated in Figure 2. According to certain geologists, the shield has been impacted by multiple cycles of metamorphism, tectonism, and plutonism of varying strengths, all of which have an impact on the study basin situated in western Arabia [22; 23; 24]. The NW and NE faults are the two main Tertiary tectonic features that dominate the western Arabian and Red Sea regions. The NE-trending faults in the Red Sea region can be divided into two groups: newly developed transverse faults associated with the opening of the Red Sea and ocean floor spreading, or faults controlled by older Precambrian ones that were reactivated during the Tertiary [22]. There is likely a connection between the grouping of NE-trending faults in the west-central Arabian region and the center Red Sea and preexisting Precambrian faults in this area [23].  
The study basin offers a variety of morphological features because of the influence of tectonics and various types of rocks. Generally, variations in morphological features, such as variations in locations and altitudes, are what directly produce the variances in climatic conditions within the same season. In terms of topographic effects, the study basin landscape's surface elevation recorded its highest values at the north, east, and southwestern parts by 2359 m a.s.l., whereas the eastern sections of the study basin show the lowest topographic values (Figure 3a). Consequently, the study basin's overall surface elevation can be summed up as a significant landscape with a high elevation in the east that progressively descends towards the Red Sea (Figure 3a). Additionally, ArcGIS 10.4 is used to generate slope maps from the DEM. After analysis, the slope data produced values ranging from 0 to 36 (Figure 3b). The highest slope values are often found along the upstream basins, and the basin mouths are indicated by the lowest values [11]. As a result, topographical variation signals govern changes in the study basin's overall slopes.  
Figure 2: Lithological map of the study basin.