**4.1 Rainstorm occurred on January 26, 2011**

The data recorded by the rainfall station located at the headquarter of the Saudi Geological Survey shows that the precipitation began at 10:56 am on Saturday, January 26, 2011; continued until 12:27 noon, for ~91 min; and remained after a short break until 3:38 pm. The total precipitation is ~112.0 mm. It is difficult


**23**

**Figure 4.**

*Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts*

period of ~78 min. The first phase is shown in **Figure 4b**.

**4.2 Rainstorm occurred on November 22, 2014**

**4.3 Rainstorm occurred on November 17, 2015**

period of ~27 min. The first storm is shown in **Figure 6b2**.

*total storm. (b) Distribution of cumulative rainfall intensity of the first phase.*

Khulays, Station J134, and Wadi Qaws.

storm is shown in **Figure 5b**.

to distinguish two separate storms, but this rainstorm can be separated into two phases. The first phase of rainfall was ~54 mm, while the second one was ~58 mm. **Figure 4a** shows the rainfall recorded plotted against the whole rainfall time (4.7 h), which shows ~48% of the rainfall depth is fallen in the first phase for a

This event was recorded in one rainfall station located at the headquarter of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 0:22 am on Saturday, November 22, 2014; continued until 1:03 am, for ~41 min; then resumed at 9:53; and stayed until 10:19 am. The total precipitation is ~42.87 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~33 mm, while the second one was ~9.61 mm. **Figure 5a** shows the rainfall recorded plotted against the whole rainfall time (10 h), which shows ~77% of the rainfall depth is fallen in the first storm for a period of ~41 min. The first

This event was recorded in four rainfall stations including Radwa farms, Wadi

The data recorded by the rainfall station at Radwa farms shows that the precipitation began with a slow rate at 8:44 am on Tuesday, November 17, 2015; continued until 9:51 am, for ~67 min; and remained with a moderate rate until 11:25 am of the same day. The total precipitation is ~21.7 mm. The main storm in this event lasted ~41 min and reached a precipitation amount of ~19 mm. **Figure 6a1** shows the rainfall recorded plotted against the whole rainfall time (2.7 h), which shows ~88% of the rainfall depth is fallen at a period of ~41 min (the main storm; see **Figure 6a2**). The data recorded by the rainfall station at Wadi Khulays shows that the precipitation began at 9:18 am on Tuesday, November 17, 2015; continued until 9:45 am, for ~27 min; and continued intermittently until 12:00 noon. The total precipitation is ~20.6 mm. The main storm in this station lasted ~27 min and reached a precipitation amount of ~18 mm. **Figure 6b1** shows the rainfall recorded plotted against the whole rainfall time (2.7 h), which shows ~87% of the rainfall depth is fallen at a

The data recorded by rainfall station J134 (located in the old Jeddah airport) shows that the precipitation began at 10:00 am on Tuesday, November 17, 2015; continued until 12:20 am, for ~140 min; and continued intermittently until

*The rainstorm on January 26, 2011, at SGS station. (a) Distribution of cumulative rainfall intensity of the* 

*DOI: http://dx.doi.org/10.5772/intechopen.86774*

#### **Table 1.**

*Rainstorms occurred between 2011 and 2017 in the Jeddah area and the stations' names.*

#### *Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts DOI: http://dx.doi.org/10.5772/intechopen.86774*

to distinguish two separate storms, but this rainstorm can be separated into two phases. The first phase of rainfall was ~54 mm, while the second one was ~58 mm. **Figure 4a** shows the rainfall recorded plotted against the whole rainfall time (4.7 h), which shows ~48% of the rainfall depth is fallen in the first phase for a period of ~78 min. The first phase is shown in **Figure 4b**.

## **4.2 Rainstorm occurred on November 22, 2014**

*Rainfall - Extremes, Distribution and Properties*

**4. Characteristics**

longitudes 39°06′ and 39°31′E (**Figure 3**). From the latitude point of view, the Jeddah area is considered to be in the arid zone (Köppen's climate classification). The Jeddah area has different geomorphological features. It represents a part of the Red Sea coastal zone. Jeddah drainage system comes from the east (a series of hills) toward the city which is located to the west. The catchment areas have a variety of landforms such as low- and midsize hills and flattened foothills in some places followed to the west by the floodplain areas. The monthly average relative humidity ranges between ~85% from September to October and ~34% from April to June. The Jeddah area is characterized by scarce rainfalls with high variability, which occur most often in November–December–January (the winter season). Additionally, monsoonal rainstorms take place in March and April due to the moist air currents from the Indian Ocean and the Arabian Sea. The average annual precipitation is ~52.5 mm/year. The maximum rainfall was recorded in 1996, with ~284 mm/year. Recently these thunderstorms increased in their frequencies and

intensities causing flash floods and inundation events within Jeddah city.

has a list of different storms that will be considered in this study.

**4.1 Rainstorm occurred on January 26, 2011**

4 November 17, 2015 Khulays, Ad

5 November 17, 2015 Old Jeddah

In this study, all the current stations have automatic rain gauges that can record the intensity of the rainfall events (minute-base). This technique did not occur before, and most of the hydrological studies were depending on the daily rainfall data analysis which brings some uncertainty to the hydrological results. The stations used in the current study are shown in **Figure 3**. In the present work, trend and pattern analysis is based on intensity rainfall values for each rainfall station. Detailed analysis and discussion of the different recently occurred storms will be carried out in the following sections. This analysis and comparison work will give us the ability to deduce the general pattern prevailing in the storms in the city of Jeddah. **Table 1**

The data recorded by the rainfall station located at the headquarter of the Saudi

**No. Date Location Name Total rainfall (mm) Duration (h)** January 26, 2011 SGS site SGS 112.0 4.7 November 22, 2014 SGS site SGS 43.0 10.0 November 17, 2015 Radwa farms Radwa 21.7 2.7

6 November 17, 2015 Wadi Qaws Qaws 61.0 1.77 7 December 02, 2016 SGS site SGS 44.91 2.75 8 November 21, 2017 SGS site SGS 88.04 15.75

Khulays 20.6 2.7

J134 79.0 3.2

Geological Survey shows that the precipitation began at 10:56 am on Saturday, January 26, 2011; continued until 12:27 noon, for ~91 min; and remained after a short break until 3:38 pm. The total precipitation is ~112.0 mm. It is difficult

Daff

airport

*Rainstorms occurred between 2011 and 2017 in the Jeddah area and the stations' names.*

**22**

**Table 1.**

This event was recorded in one rainfall station located at the headquarter of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 0:22 am on Saturday, November 22, 2014; continued until 1:03 am, for ~41 min; then resumed at 9:53; and stayed until 10:19 am. The total precipitation is ~42.87 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~33 mm, while the second one was ~9.61 mm. **Figure 5a** shows the rainfall recorded plotted against the whole rainfall time (10 h), which shows ~77% of the rainfall depth is fallen in the first storm for a period of ~41 min. The first storm is shown in **Figure 5b**.

#### **4.3 Rainstorm occurred on November 17, 2015**

This event was recorded in four rainfall stations including Radwa farms, Wadi Khulays, Station J134, and Wadi Qaws.

The data recorded by the rainfall station at Radwa farms shows that the precipitation began with a slow rate at 8:44 am on Tuesday, November 17, 2015; continued until 9:51 am, for ~67 min; and remained with a moderate rate until 11:25 am of the same day. The total precipitation is ~21.7 mm. The main storm in this event lasted ~41 min and reached a precipitation amount of ~19 mm. **Figure 6a1** shows the rainfall recorded plotted against the whole rainfall time (2.7 h), which shows ~88% of the rainfall depth is fallen at a period of ~41 min (the main storm; see **Figure 6a2**).

The data recorded by the rainfall station at Wadi Khulays shows that the precipitation began at 9:18 am on Tuesday, November 17, 2015; continued until 9:45 am, for ~27 min; and continued intermittently until 12:00 noon. The total precipitation is ~20.6 mm. The main storm in this station lasted ~27 min and reached a precipitation amount of ~18 mm. **Figure 6b1** shows the rainfall recorded plotted against the whole rainfall time (2.7 h), which shows ~87% of the rainfall depth is fallen at a period of ~27 min. The first storm is shown in **Figure 6b2**.

The data recorded by rainfall station J134 (located in the old Jeddah airport) shows that the precipitation began at 10:00 am on Tuesday, November 17, 2015; continued until 12:20 am, for ~140 min; and continued intermittently until

#### **Figure 4.**

*The rainstorm on January 26, 2011, at SGS station. (a) Distribution of cumulative rainfall intensity of the total storm. (b) Distribution of cumulative rainfall intensity of the first phase.*

**Figure 5.**

*The rainstorm on November 22, 2014, at SGS station. (a) Distribution of cumulative rainfall intensity of the total storm. (b) Distribution of cumulative rainfall intensity of the first storm.*

#### **Figure 6.**

*The rainstorm on November 17, 2015, at Radwa, Khulays, J134, and Qaws stations. (a1, b1, c1, d1) Distribution of cumulative rainfall intensity of the total storm. (a2, b2, c2, d2) Distribution of cumulative rainfall intensity of the first storm.*

**25**

**Figure 8.**

**Figure 7.**

*Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts*

fallen at a period of ~53 min. The first storm is shown in **Figure 6d2**.

**4.4 Rainstorm occurred on December 2, 2016**

43 min (the second storm).

1:10 pm. The total precipitation is ~79.0 mm. The main storm in this station lasted ~140 min and reached a precipitation amount of ~60 mm. **Figure 6c1** shows the rainfall recorded plotted against the whole rainfall time (3.2 h), which shows ~76% of the rainfall depth is fallen at a period of ~140 min. The first storm is shown in

The data recorded by the rainfall station at Wadi Qaws shows that the precipitation began at 10:48 am on Tuesday, November 17, 2015; continued until 11:41 am, for ~53 min; halted at 12:09; and then continued intermittently until 12:34 pm. The total precipitation is ~61.0 mm. The main storm in this station lasted ~53 min and reached a precipitation amount of ~58.7 mm. **Figure 6d1** shows the rainfall recorded plotted against the whole rainfall time (1.8 h), which shows ~96% of the rainfall depth is

This event was recorded in one rainfall station located at the headquarters of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 7:18 am on Friday, December 2, 2016 and continued until 7:38 am, for ~20 min; then it resumed at 8:11 and stayed until 8:43 am, followed by a precipitation of 0.25 mm at 10.03 am. The total rainfall is ~44.91 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~12.43 mm, while the second one was ~31.47 mm. **Figure 7a** shows the rainfall recorded plotted against the whole rainfall time (2.75 h), which shows ~28% of the rainfall depth is fallen in the first storm for a period of ~20 min and the second storm which lasted 43 min shows 70% of the total rainfall depth. **Figure 7b** shows the main storm which lasted

*The rainstorm on December 2, 2016 at SGS station. (a) Distribution of cumulative rainfall intensity of the* 

*The rainstorm on November 21, 2017, at SGS station. (a) Distribution of cumulative rainfall intensity of the* 

*total storm. (b) Distribution of cumulative rainfall intensity of the second storm.*

*total storm. (b) Distribution of cumulative rainfall intensity of the first storm.*

*DOI: http://dx.doi.org/10.5772/intechopen.86774*

**Figure 6c2**.

#### *Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts DOI: http://dx.doi.org/10.5772/intechopen.86774*

1:10 pm. The total precipitation is ~79.0 mm. The main storm in this station lasted ~140 min and reached a precipitation amount of ~60 mm. **Figure 6c1** shows the rainfall recorded plotted against the whole rainfall time (3.2 h), which shows ~76% of the rainfall depth is fallen at a period of ~140 min. The first storm is shown in **Figure 6c2**.

The data recorded by the rainfall station at Wadi Qaws shows that the precipitation began at 10:48 am on Tuesday, November 17, 2015; continued until 11:41 am, for ~53 min; halted at 12:09; and then continued intermittently until 12:34 pm. The total precipitation is ~61.0 mm. The main storm in this station lasted ~53 min and reached a precipitation amount of ~58.7 mm. **Figure 6d1** shows the rainfall recorded plotted against the whole rainfall time (1.8 h), which shows ~96% of the rainfall depth is fallen at a period of ~53 min. The first storm is shown in **Figure 6d2**.

### **4.4 Rainstorm occurred on December 2, 2016**

This event was recorded in one rainfall station located at the headquarters of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 7:18 am on Friday, December 2, 2016 and continued until 7:38 am, for ~20 min; then it resumed at 8:11 and stayed until 8:43 am, followed by a precipitation of 0.25 mm at 10.03 am. The total rainfall is ~44.91 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~12.43 mm, while the second one was ~31.47 mm. **Figure 7a** shows the rainfall recorded plotted against the whole rainfall time (2.75 h), which shows ~28% of the rainfall depth is fallen in the first storm for a period of ~20 min and the second storm which lasted 43 min shows 70% of the total rainfall depth. **Figure 7b** shows the main storm which lasted 43 min (the second storm).

#### **Figure 7.**

*Rainfall - Extremes, Distribution and Properties*

**24**

**Figure 6.**

**Figure 5.**

*rainfall intensity of the first storm.*

*The rainstorm on November 17, 2015, at Radwa, Khulays, J134, and Qaws stations. (a1, b1, c1, d1) Distribution of cumulative rainfall intensity of the total storm. (a2, b2, c2, d2) Distribution of cumulative* 

*The rainstorm on November 22, 2014, at SGS station. (a) Distribution of cumulative rainfall intensity of the* 

*total storm. (b) Distribution of cumulative rainfall intensity of the first storm.*

*The rainstorm on December 2, 2016 at SGS station. (a) Distribution of cumulative rainfall intensity of the total storm. (b) Distribution of cumulative rainfall intensity of the second storm.*

#### **Figure 8.**

*The rainstorm on November 21, 2017, at SGS station. (a) Distribution of cumulative rainfall intensity of the total storm. (b) Distribution of cumulative rainfall intensity of the first storm.*

#### **4.5 Rainstorm occurred on November 21, 2017**

This event was recorded in one rainfall station located at the headquarters of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 8:19 am on Tuesday, November 21, 2017; continued until 10:50 am, for ~152 min; then resumed at 11:30 pm; and continued until 12:01 night. The total precipitation is ~88.04 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~76 mm, while the second one was ~12.0 mm. **Figure 8a** shows the rainfall recorded plotted against the whole rainfall time (15.75 h), which shows ~85% of the rainfall depth is fallen in the first storm for a period of ~152 min. The first storm is shown in **Figure 8b**.

## **5. Comparison of different storms**

In the current work, a comparison between the storms which occurred in the Jeddah area during the period (2011–2017) was carried out. The results indicated that there is some similarity in the behavior of these storms. The presence of the two main storms characterizes most of them during the rainfall time which is usually separated by a period of partial cessation. The most substantial amount of rainfall always exceeding 70% of the recorded rainfall appears in the first storm. Also, it was found that there is one exception in this rule which seems in the storm recorded on January 26, 2011, at the Saudi Geological Survey Station, which is different from other storms in terms of the amount of precipitation where the rain value reached 112 mm. **Figure 9a** shows a comparison of the major storms that have been occurred in the Jeddah area. **Figure 9b** shows comparison between storms which exceeded a rain value (50 mm). The results also indicated that based on the rainstorm that hit the city of Jeddah on November 21, 2017, with the storms that had a definite impact in the Jeddah city, we find that all these storms exceeded the amount of rainfall 50 mm during the first 100 min (**Table 2**).

The storm recorded at Wadi Qaws station on November 17, 2011, is the highest intensity, followed by the storms occurred at J134 on November 17, 2015; then the station at the headquarters of the Saudi Geological Survey on November 21, 2017; and then the storm recorded at the station at the headquarter of the Saudi Geological Survey on January 26, 2011. However, the storm occurred on January 26, 2011, left a massive damage and problems to the Jeddah area. It caused failure of the Umm al-Khair dam and paralyzed traffic in the province. Maybe the reason for that

#### **Figure 9.**

*A comparison between different rainstorms occurred in the period between 2011 and 2017: (a) all storms and (b) storms recorded rainfall more than 50 mm (the first 100 min).*

**27**

**Figure 10.**

*Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts*

**6. Prevailing patterns of precipitation in Jeddah**

is related to the duration time of the storm on January 26, 2011. The impact of the storm on November 21, 2017, was within the city of Jeddah and led to the flooding of a large number of roads and tunnels, although considers moderate intensity, however, the storm was concentrated in the center of the city, where almost urban areas are located. The lack of a proper drainage system inside the city has increased

To deduce the characteristic patterns of rainfall in the Jeddah area, we need a large number of reordering storms which are not available in the whole KSA. However, in the current work depending on the storms collected in the Jeddah area from the new installed automated rainfall stations, some suggestions can be made to understand the behavior of storms in the Jeddah area. To achieve this, the data available for each storm were converted to dimensionless data (**Figure 10**). The behavior of all possible storms was compared with the SCS-type II distribution curve. It is noticed that these storms can be divided into two groups. The first group represents the storms, which exceeded 50 mm of precipitation (**Figure 11a**). This group is represented by the storms recorded at the headquarters of the SGS station on November 21, 2017; January 26, 2011; and November 17, 2011, in both the Wadi Qaws and J134 stations. The second group represents short-term storms which recorded precipitation quantities less than 50 mm (**Figure 11b**). This group includes the storms registered at the headquarters of the SGS station on November 22, 2014, and December 2, 2016. For both groups, the average curves of each storm set were derived. To verify that these two storm groups are different from each other and have different behaviors, a distribution histogram of the average curve for each storm group was extracted

*DOI: http://dx.doi.org/10.5772/intechopen.86774*

and simplified as shown in **Figure 12**.

*Cumulative dimensionless hyetographs for rainstorms occurred in the period 2011–2017.*

the impact of this storm.

*Statistical Analysis of Rainfall Patterns in Jeddah City, KSA: Future Impacts DOI: http://dx.doi.org/10.5772/intechopen.86774*

*Rainfall - Extremes, Distribution and Properties*

**5. Comparison of different storms**

50 mm during the first 100 min (**Table 2**).

*(b) storms recorded rainfall more than 50 mm (the first 100 min).*

**4.5 Rainstorm occurred on November 21, 2017**

period of ~152 min. The first storm is shown in **Figure 8b**.

This event was recorded in one rainfall station located at the headquarters of the Saudi Geological Survey. The data recorded by this station shows that the precipitation began at 8:19 am on Tuesday, November 21, 2017; continued until 10:50 am, for ~152 min; then resumed at 11:30 pm; and continued until 12:01 night. The total precipitation is ~88.04 mm. This rainstorm can be separated into two storms. The rainfall of the first storm was ~76 mm, while the second one was ~12.0 mm. **Figure 8a** shows the rainfall recorded plotted against the whole rainfall time (15.75 h), which shows ~85% of the rainfall depth is fallen in the first storm for a

In the current work, a comparison between the storms which occurred in the Jeddah area during the period (2011–2017) was carried out. The results indicated that there is some similarity in the behavior of these storms. The presence of the two main storms characterizes most of them during the rainfall time which is usually separated by a period of partial cessation. The most substantial amount of rainfall always exceeding 70% of the recorded rainfall appears in the first storm. Also, it was found that there is one exception in this rule which seems in the storm recorded on January 26, 2011, at the Saudi Geological Survey Station, which is different from other storms in terms of the amount of precipitation where the rain value reached 112 mm. **Figure 9a** shows a comparison of the major storms that have been occurred in the Jeddah area. **Figure 9b** shows comparison between storms which exceeded a rain value (50 mm). The results also indicated that based on the rainstorm that hit the city of Jeddah on November 21, 2017, with the storms that had a definite impact in the Jeddah city, we find that all these storms exceeded the amount of rainfall

The storm recorded at Wadi Qaws station on November 17, 2011, is the highest intensity, followed by the storms occurred at J134 on November 17, 2015; then the station at the headquarters of the Saudi Geological Survey on November 21, 2017; and then the storm recorded at the station at the headquarter of the Saudi Geological Survey on January 26, 2011. However, the storm occurred on January 26, 2011, left a massive damage and problems to the Jeddah area. It caused failure of the Umm al-Khair dam and paralyzed traffic in the province. Maybe the reason for that

*A comparison between different rainstorms occurred in the period between 2011 and 2017: (a) all storms and* 

**26**

**Figure 9.**

is related to the duration time of the storm on January 26, 2011. The impact of the storm on November 21, 2017, was within the city of Jeddah and led to the flooding of a large number of roads and tunnels, although considers moderate intensity, however, the storm was concentrated in the center of the city, where almost urban areas are located. The lack of a proper drainage system inside the city has increased the impact of this storm.
