JKAU: Met., Env. & Arid Land Agric. Sci., Vol. 22, No. 2, pp: 59-78 (2011 A.D./1432 A.H.)
DOI: 10.4197/Met. 22-2.4
Analysis of Rainfall over Saudi Arabia
A. Mashat and H. Abdel Basset
Department of Meteorology, Faculty of Meteorology, Environment,
and Arid Land Agriculture, King Abdulaziz University,
Jeddah, Saudi Arabia
Abstract..In this study, rainfall over the Kingdom of Saudi Arabia
(KSA) is analyzed using data from available meteorological stations.
The analysis of these data shows that the highest amount of rainfall
occurs during the spring over the southwest, middle and east of KSA.
The second highest amount of rainfall occurs during winter over the
east and northeast of KSA. The season of the lowest amount of
rainfall over KSA is summer, when, except in the mountainous area in
the southwest region, the amount of rainfall is very small. While the
horizontal distribution pattern of rainfall during autumn is somewhat
similar to that during spring, the amount of rainfall in autumn is
smaller than that in spring. The most significant synoptic feature
appears in spring when the cold air associated with secondary
Mediterranean depressions meets the moist hot southerly air
associated with Red Sea trough over KSA.
1. Introduction
The amount of rainfall that falls over an area is an important factor in
assessing the amount of water available to meet the various demands of
agriculture, industry, and other human activities. Study of the distribution
of rainfall over time and space is therefore very important for the welfare
of a national economy. Many applications of rainfall data are enhanced
by knowledge of the actual distribution of rainfall over a specified area
rather than relying on simple summary statistics. In recent years, several
studies have been devoted to the interannual and decadal variability of
precipitation on regional, national and international scales. Different
methodological approaches have been used, such as temporal analysis of
59
60
A. Mashat and H. Abdel Basset
rainfall (Serrano, et al., 1999; De Luís, et al., 2000; Estrela, et al., 2000;
Agnese, et al., 2002; Turkes, et al., 1996), analysis of extreme events in
regional daily precipitation series (Brunetti, et al., 2002 and 2004), and
use of the standardized precipitation index (Delitala, et al., 2000; Lana, et
al., 2001; Bordi, et al., 2001; and Lloyd-Hughes and Saunders, 2002).
Several researchers have analyzed hydro-meteorological time series in
West Africa from Niger to Senegal (Carbonnel and Hubert, 1985 and
1994; Snijders, 1986; Hubert and Carbonnel, 1987; and Paturel, et al.,
1997). They pointed out the non stationarity of the series and suggested a
climatic change between 1965 and 1972, with the majority of the shifts
appearing between 1969 and 1970. Precipitation in the Great Plains of
the United States also changed significantly with an increase since the
late 1960s and the last two decades of the twentieth century being the
wettest of that century (Garbrecht and Rossel, 2000). A report from the
Office of Technology Assessment (1993) pointed out that the anticipated
intensification of the hydrological cycle would increase global rainfall by
7 to 15 % and evapotranspiration between 5 and 10%. An increase in
extreme events that will be disruptive to natural and human systems is
likely to occur (IPCC, 1995). However, whereas in certain areas an
increase of rainfall is expected, other areas will suffer from decreased
rainfall.
The aim of this study is to analyze the climatology of monthly and
annual rainfall over the Kingdom of Saudi Arabia (KSA). The remainder
of this paper is organized as follows: In Section 2, data from
meteorological stations in KSA and the homogeneity of these data are
described. Section 3 presents the results of an analysis of monthly, annual
and horizontal distributions of rainfall over KSA. Finally, conclusions are
offered in Section 4.
2. Data from KSA Meteorological Stations
Because of its low annual precipitation, KSA is commonly
regarded as a dry country. This is a climatic simplification; however,
because precipitation varies over space and time and of the amounts of
precipitation over particular regions of KSA are diverse. Besides spatial
differences, interannual variations of precipitation also occur. The
complexity of the rates of precipitation over KSA derives from the vast
area of the country (about 2,250,000 km2), its wide latitudinal expanse
(15.5°N - 32.5°N) and its pronounced topographical relief. Monthly
Analysis of Rainfall over Saudi Arabia
61
precipitation records are compiled for 28 stations managed by the KSA
Meteorological Organization. The stations are distributed across KSA,
although their spatial density is low and uneven in some parts of the
country. Table 1 gives the name, position, elevation and the available
period of data from each KSA meteorological station.
Studies on data homogeneity are essential to climatology.
Homogeneity is manifested differently depending on the climatic
element. The values of climatic measures of these climatic elements
could be used in estimating daily and monthly averages. Artificial lakes
and reservoirs and other man-made changes to the local environment
produce sources of inhomogeneity in historical records of climatic data.
Homogeneity in rainfall over cities in KSA has been examined by means
of the Bartlet test.
Table 1. The name, position, elevation and the available data period for each KSA
meteorological station.
No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Name
Turaif
Gurait
Arar
Aljouf
Tabouk
Hail
Wejh
Rafha
Alqusoma
Hafrbaten
Dhahran
Ahsa
Gassim
New Riyadh
Old Riyadh
Wadi Aldwaser
Madina
Yenbo
Jeddah
Makkah
Taif
Baha
Bisha
Abha
Khamis Mush
Najran
Sharura
Gizan
Lat
31.68
31.40
30.90
29.78
28.37
27.43
26.20
29.62
28.31
27.90
26.25
25.29
26.30
24.92
24.71
20.50
24.54
24.14
21.71
21.43
21.48
20.29
19.99
18.23
18.29
17.61
17.46
16.90
Long
38.73
37.28
41.14
40.98
36.60
41.69
38.47
43.49
46.13
45.53
50.16
49.48
43.76
46.72
46.73
45.25
39.69
38.06
39.18
39.79
40.55
41.64
42.61
42.66
42.80
44.41
47.10
42.58
Elevation
852.44
503.90
548.88
668.74
444.10
768.11
357.60
413.00
1001.52
646.71
16.77
23.73
178.17
613.55
619.63
635.60
3.58
1452.75
240.35
701.02
614.39
1651.88
1161.97
2055.93
2093.35
1212.33
724.65
7.24
Available Data
1978 --- 2003
1985 --- 2003
1979 --- 2003
1978 --- 2003
1978 --- 2003
1970 --- 2003
1978 --- 2003
1978 --- 2003
1978 --- 2003
1985 --- 2003
1970 --- 2003
1985 --- 2003
1978 --- 2003
1985 --- 2003
1970 --- 2003
1978 --- 2003
1970 --- 2003
1978 --- 2003
1970 --- 2003
1985 --- 2003
1970 --- 2003
1985 --- 2003
1970 --- 2003
1978 --- 2003
1970 --- 2003
1978 --- 2003
1985 --- 2003
1970 --- 2003
Years
26
19
25
26
26
34
26
26
26
19
34
19
26
19
34
26
34
26
34
19
34
19
34
26
34
26
19
34
62
A. Mashat and H. Abdel Basset
Table 2 presents Bartlet test (short-cut) results for mean annual
rainfall at each station. The mean annual rainfall seems to be
homogeneous except at the Tabouk and Sharorah stations when
2
2
) is used with 95% significance as discussed by Mitchell et al.
( S max
/ S min
(1966). The mean annual rainfall amounts at the Aljouf and Abha
stations indicate some inhomogeneities.
Table 2. Bartlet test (short- cut) result for the KSA stations (n is the number of terms in
each subperiod k, and k is the number of the subperiod).
Station
N
k
Turaif
Guriat
Arar
Aljouf
Rafha
Tabouk
Alqaisoma
Hail
Qassim
Dhahran
Alwajh
Alahsa
New Riyadh
Old Riyadh
Madinah
Yanbo
Jeddah
Taif
Makkah
Albaha
Bisha
Khamis Moshet
Abha
Najran
Sharorah
Gizan
13
9
13
13
13
13
13
11
17
15
13
9
9
17
17
13
17
17
9
9
11
11
13
8
9
11
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
2
3
3
2
3
2
3
95%
Significant point
3.28
4.43
3.28
3.28
3.28
3.28
3.28
4.85
2.76
3.16
3.28
4.43
4.43
2.76
2.76
3.28
2.76
2.76
4.43
4.43
4.85
4.85
3.28
6.94
4.43
4.85
Homogeneity
1.56
2.17
3.25
3.36
1.48
6.23
1.55
1.68
2.69
2.33
3.17
3.25
3.52
1.32
1.59
2.59
1.73
2.77
3.96
1.85
1.92
3.62
3.31
1.15
6.32
1.57
3. Results and Discussion
3.1 Monthly Average Rainfall
Figure 1(a) shows the average monthly amounts of rainfall for each
month of the year at the Arar, Turaif, Guriat, Aljouf, Tabouk and Hail
stations. The maximum amount of rainfall at these stations occurs in
January, and the average amounts of rainfall in January at all stations
Analysis of Rainfall over Saudi Arabia
63
exceeds 10 mm except for Tabouk. The second rainiest month at these
stations is December. Hail and Turaif receive the highest amount of
rainfall during the rainy months of the year. The months from June to
September are the dry months of the year, while the winter and spring
months are the wet months at these stations.
Figure 1(b) presents the average monthly amounts of rainfall for
each month of the year at the Alwajh, Rafha, Alqaisoma, Hafr Albaten,
Dharan and Alahsa stations. The maximum amount of rainfall at these
stations occurs during the winter season excluding November, March and
April. These stations do not receive any rainfall during the June to
September period. The averages of the monthly rainfall at the Hafr
Albaten and Dharan stations are more than 30 mm in January and March,
respectively. The period from May to October is the dry period at these
stations.
Figure 1(c) shows the average monthly rainfall amounts for each
month of the year at the Qassim, New Riyadh, Old Riyadh, Wadi
Aldwaser, Sulayel and Madinah stations. This figure indicates that the
maximum amount of rainfall at the Qassim, New Riyadh, and Old
Riyadh stations occurs in March and April. The maximum amounts of
rainfall received at the Sulsyel station are at April. The Wadi Aldwaser
and Madinah stations recived less than 10 mm of rain during the rainy
months of the year. The period from June to October is the dry period at
these stations.
Figure 1(d) presents the average monthly rainfall amounts for each
month of the year at the Yanbo, Jeddah, Makkah, Taif, Abbaha and Bisha
stations. It is clear that the mountain stations (Taif, Abbaha and Bisha)
received the maximum amount of rainfall of this group of stations. The
highest values of rainfall at these mountain stations occur during the
spring especially in April. Considerable amounts of rainfall at the
Makkah and Jeddah stations occur in November, December and January.
The three mountain stations received rainfall throughout the year with
lowest values in February.
Figure 1(e) shows the average monthly rainfall amounts for each
month of the year at Abha, Khames Moshet, Najran, Sharorah and Gizan
stations. It is clear that the maximum amount of rainfall at these stations
occurs at the Abha and Khamis Moshet stations in March, April, May
and August. The mountain station of Abha received the greatest amount
of rainfall in KSA (more than 55 mm). The minimum amount of rainfall
64
A. Mashat and H. Abdel Basset
occurs during September, October, November and December at these
stations.
30
Arar
Turaif
Guriat
Aljouf
Tabouk
Hail
precipitation (mm)
25
20
15
10
5
0
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Fig. 1(a). The average monthly rainfall amounts for each month of the year at the Arar,
Turaif, Guriat, Aljouf, Tabouk and Hail stations.
35
Alwajh
Rafha
Alqaisoma
Hafr Albaten
Dhahran
Alahsa
30
precipitation (mm)
25
20
15
10
5
0
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Fig. 1(b). The average monthly rainfall amounts for each month of the year at the Alwajh,
Rafha, Alqaisoma, Hafrelbaten, Dhahran and Alahsa stations.
65
Analysis of Rainfall over Saudi Arabia
40
Qassim
Riyadh new
Riyadh Old
Wadi Aldwaser
Sulayel
Madinah
35
precipitation (mm)
30
25
20
15
10
5
0
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Fig. 1(c). The average monthly rainfall amounts for each month of the year at the Qassim,
New Riyadh, Old Riyadh, Wadi Aldwaser, Sulayel, and Madinah stations.
40
Yanbo
Jeddah
Makkah
Taif
Albaha
Bisha
35
precipitation (mm)
30
25
20
15
10
5
0
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Fig. 1(d). The average monthly rainfall amounts for each month of the year at the Yanbo,
Jeddah, Makkah, Taif, Albaha and Bisha stations.
66
A. Mashat and H. Abdel Basset
70
Abha
Khamis Moshet
Najran
Sharorah
Gizan
60
precipitation (mm)
50
40
30
20
10
0
jan
feb
mar
apr
may
jun
jul
aug
sep
oct
nov
dec
Fig. 1(e). The average monthly rainfall amounts for each month of the year at the Abha,
Khamis Moshet, Najran, Sharorah and Gizan stations.
The stations that lie north of 24.5oN do not receive a considerable
amount of rain during the summer months in additions to September. In
the winter, the highest amounts of rainfall occur at the stations in the east
of the middle of KSA (the Hail, Gassim, new Riyad, old Riyad, Hafr
Elbaten and Qaisoma stations). In spring, the southwestern stations and
stations to the east of the middle of KSA received higher amounts of rain
with the maximum at Abha in March (60 mm). In the autumn, the seven
stations of Hafr Elbaten, Qaisoma, Jeddah, Makkah, Taif, Hail and Gizan
receive considerable amounts of rain (more than 20 mm). From the
seasonal analysis of rainfall, the periods of rainfall over KSA can be
divided into two main periods. The first period includes November,
December, January, February, March, April and May. About 80% of the
total rainfall over KSA occurs during these months. The second period
includes the other five months (June through October).
3.2 Annual Rainfall
In this section, the annual amounts of rainfall at 29 meteorological
stations in KSA are discussed. The slopes of the time series trends at
each station were calculated by least squares linear fitting. Figure 2(a)
presents the annual rainfall amounts at the Turaif, Guriat, Arar, Aljouf,
Rafha, Tabouk, Alqaisoma and Hafr Albaten stations for the available
Analysis of Rainfall over Saudi Arabia
67
periods. It is interesting to note that there are two peaks in the rainfall
time series for Turaif. The first one occurs during 1979 and the second
one occurs in 1982. The maximum of the annual mean values at Guriat
occurs in 1988 while the minimum values occur in 1993 and 2000. The
maximum annual rainfall received at Arar is in 1988 while the minimum
amount is in 1996. Negative trends can be observed for these three
stations. Although the annual amount of rainfall received at Aljouf is
small, there is a positive rainfall trend. The highest amount recorded at
Rafha is in 1974. Figure 2(a) also shows that the trend of the annual
rainfall amounts at Tabouk and Alqaisoma is negative and the amount of
rainfall received at Alqaisoma is greater than at Tabouk throughout the
period of this study.
Figure 2(b) shows the annual rainfall amounts at Hail, Qassim,
Dhahran, Alwajh, Alahsa, New Riyadh, Old Riyadh and Madinah
stations during the available period for each station. It is interesting to
note that there are four peaks in the rainfall time series for Hail (greater
than 20 mm). The first peak occurred in 1976; the second and third were
in 1982 and 1984; while the last in 1993. Large variability in the time
series at Hail can be observed with a positive trend. The maximum
rainfall amount received at Qassim is in 1982 (40 mm), while the
minimum values are recorded in 1990. Considerable variability in the
time series for Dhahran can be observed with a positive trend. Three
maximum values occurred (greater than 20 mm). The first one was in
1972, the second in 1976, while the last in 1982. Although the trend of
the time series for Alwajh is positive, it receives small amounts of rain
throughout the period. As at most stations, it is clear that a wave length 4
years is the dominant wave of the time series for the Old Riyadh station.
Three peaks (greater than 20 mm) in the annual rainfall appeared for this
station, one in 1972, the second in 1976 and the last in 1995. A
considerable variability in the annual rainfall time series for Madinah is
evident, although the amount of rainfall is small throughout the period for
this station. The trend for the time series for Madinah is positive.
Figure 2(c) shows the annual rainfall amounts for the Yanbo,
Jeddah, Taif, Makkah, Wadi Aldwaser, Albaha, Bisha and Khmis Moshet
stations during the available period for each station. It indicates that
higher annual rainfall amounts at Yanbo occur in 1992 and 1993, while a
lower amount occurs in 1995. The annual amount of rainfall at Jeddah
reached 24 mm in 1996, while this amount in other years does not
exceeded 10 mm. The lowest value is recorded in 1982. The time series
68
A. Mashat and H. Abdel Basset
for Taif follows a wave pattern with 5-year wave length. The maximum
values occured in 1992 and 1996. Like in Taif, the maximum annual
values at Makkah occur in 1992 and 1996. The trend for these four
stations is positive. The trends for the time series for Wadi Aldwaser,
Albaha, Bisha and Khamis Moshet are negative. The average values of
the annual time series for Nisha and Khamis Moshet are 8.5 and 17 mm,
respectively. Figure 2(d) shows the annual rainfall amounts for the Abha,
Najran, Sharorah and Gizan stations during the available period for each
station. It indicates that time series for Abha is very similar to those for
Bisha and Khamis Moshet due to the proximity of these stations. The trend
of the last three stations that fall in the same area is positive. The mean
annual rainfall for the most stations in KSA was highest in 1982. The
trend analysis of the mean annual rainfall at KSA stations indicates a
positive trend (wet) at 14 stations (Aljouf, Hafr Albaten, Rafha, Dahran,
Alwajh, New Riadh, Madinah, Yanbo, Jeddah, Mekkah, Najran, Sharora,
and Gizan). There is a negative trend (dry) at 15 stations (Turaif, Guriat,
Rafha, Alqaisoma, Tabouk, Hail, Qassim, Albaha, Old Riyadh, Wadi
Aldwaser, Albaha, Bisha, Kamis Moshet and Abha).
3.3 The Horizontal Distribution of Rainfall over KSA
Figure 3(a) gives the names and positions of the KSA
meterological stations, while Fig. 3(b) shows the average annual amounts
of rainfall at KSA meterological stations. It is clear that the maximum
annual rainfall occurs in two regions: The first is east of the middle
region (Hail, Gassim, Hafr Albaten, Qaisoma, Riyad and Dharan) and the
second is the southwest region (Taif, Baha, Khamis Meshet, Abha, and
Gizan). The lowest rainfall values occur in the north and northwest areas.
The southeast area does not house a meteorological station but it is
considered a dry area.
Figure 4(a) shows the average mean amounts of rainfall during the
winter in KSA, while Fig. 4(b) shows the average mean amounts of
rainfall during the spring in KSA. It is clear that the maximum rainfall
during the winter occurs in the north and the middle of the eastern area
and over the mountainous area in the southwest region. The highest
rainfall amounts in KSA occur during the spring. Similar to the annual
values (Fig. 3b), there are two regions with maximum rainfall, the first
in the northeast and the second is in southwest of KSA. The maximum
amount (21.9 mm) occured at Hafr Elbaten, while the maximum
amounts during the spring (44.4, 34.1 mm) occured at Abha and
69
Analysis of Rainfall over Saudi Arabia
Khamis Meshet, respectively. Figure 5(a) shows the average amounts
of rainfall during the summer in KSA.
30
9
Turaif
Guriat
8
25
Precipitation (mm)
7
6
Precipitation (mm)
20
5
15
4
3
10
2
5
1
0
0
1978
12
1982
1986
1990
1994
1998
1985
2002
9
Arar
1991
1994
1997
2000
2003
Aljouf
8
10
1988
Precipitation (mm)
Precipitation (mm)
7
6
8
5
6
4
3
4
2
2
1
0
0
1979
16
1982
1985
1988
1991
1994
1997
2000
1978
2003
8
Rafha
12
6
10
1987
1990
1993
1996
1999
2002
1984
1987
1990
1993
1996
1999
2002
Tabouk
5
8
4
6
3
4
2
2
1
0
0
1970
25
1984
Precipitation (mm)
7
Precipitation (mm)
14
1981
1973
1976
1979
1982
1985
1988
1991
1994
1978
30
Alqaisoma
1981
Hafr Albaten
25
Precipitation (mm)
Precipitation (mm)
20
20
15
15
10
10
5
5
0
0
1978
1981
1984
1987
1990
1993
1996
1999
2002
1990
1992
1994
1996
1998
2000
Fig. 2(a). Annual rainfall amounts at the Turaif, Guriat, Arar, Aljouf, Rafha, Tabouk,
Alqaisoma and Hafr Albaten stations during the available period for each station.
70
A. Mashat and H. Abdel Basset
30
45
Hail
40
25
Precipitation (mm)
Precipitation (mm)
35
30
20
25
15
20
10
15
10
5
5
0
0
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
1978
1981
1984
1987
1990
1993
1996
1999
2002
1984
1987
1990
1993
1996
1999
2002
14
30
Dhahran
Alwajh
12
25
Precipitation (mm)
Precipitation (mm)
10
20
15
10
5
8
6
4
2
0
0
1970
25
Qassim
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
1978
2003
30
Alahsa
1981
Riyadh New
25
Precipitation (mm)
Precipitation (mm)
20
20
15
15
10
10
5
5
0
1985
25
1988
1991
1994
1997
2000
0
2003
1985
16
Riyadh Old
1988
1991
1994
1997
2000
2003
Madinah
14
20
Precipitation (mm)
Precipitation (mm)
12
10
15
10
8
6
4
5
2
0
0
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
Fig. 2(b). Annual rainfall amounts at the Hail, Qassim, Dhahran, Alwajh, Alahsa, New
Riyadh, Old Riyadh and Madinah stations.
71
Analysis of Rainfall over Saudi Arabia
8
25
Yanbo
Jeddah
7
20
Precipitation (mm)
Precipitation (mm)
6
5
15
4
10
3
2
5
1
0
0
1978
35
1981
1984
1987
1990
1993
1996
1999
2002
1970
25
Taif
30
1982
1985
1988
1991
1994
1997
2000
2003
Makkah
Precipitation (mm)
Precipitation (mm)
15
10
10
5
5
0
0
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
1985
30
Wadi Aldwaser
1988
1991
1994
1997
2000
2003
1991
1994
1997
2000
2003
Albaha
25
4
Precipitation (mm)
3.5
Precipitation (mm)
1979
15
20
5
1976
20
25
4.5
1973
20
3
2.5
15
2
10
1.5
1
5
0.5
0
0
1991
1993
1995
1997
1999
2001
2003
35
1985
40
Bisha
1988
Khamis Moshet
35
30
30
Precipitation (mm)
Precipitation (mm)
25
25
20
20
15
15
10
10
5
5
0
0
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003
Fig. 2(c). Annual rainfall amounts at the Yanbo, Jeddah, Taif, Makkah, Wadi Aldwaser,
Albaha, Bisha and Khamis Moshet stations.
72
A. Mashat and H. Abdel Basset
50
45
25
Abha
40
Najran
20
Precipitation (mm)
Precipitation (mm)
35
30
15
25
20
10
15
10
5
5
0
0
1978
20
18
1981
1984
1987
1990
1993
1996
1999
2002
30
Sharora
1981
1984
1987
1990
1993
1996
1999
2002
Gizan
25
16
Precipitation (mm)
14
Precipitation (mm)
1978
20
12
10
15
8
10
6
4
5
2
0
0
1985
1988
1991
1994
1997
2000
2003
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
Fig. 2(d). Annual rainfall amounts at the Abha, Najran, Sharorah and Gizan stations.
It indicates that the lowest amount of rainfall in KSA falls is during
the summer. Except the southwest area, the amount of rainfall in the
summer in the other areas is very low. The maximum amount of rainfall
in the summer occurs at Abha (16.3 mm) and Khamis Meshet (23.4 mm).
Figure 5(b) presents the average amounts of rainfall during the autumn in
KSA. It indicates that six stations have an average amount greater than
10 mm (Hail, Hafr Elbaten, Qaisoma, Makkah, Taif and Gizan). The
northwest and the southwest areas may be considered to be drier areas
during autumn.
4. Conclusion
In this paper, the climatology of monthly and annual rainfall in the
Kingdom of Saudi Arabia has been analyzed using the available data
from 29 meteorological stations. The mean amount of annual rainfall
seems to be homogeneous except at the Tabouk and Sharorah stations,
according to the Bartlet test with a 95% significance level. Analysis of
these data shows that the highest amounts of rainfall occur during the
Analysis of Rainfall over Saudi Arabia
73
Fig. 3: A) The names and positions of KSA meterological stations, B) The average amounts
of rainfall at KSA stations.
74
A. Mashat and H. Abdel Basset
Fig. 4: A) The average amounts of rainfall during the winter in KSA, B) The average
amounts of rainfall during the spring in KSA.
Analysis of Rainfall over Saudi Arabia
75
Fig. 5: A) The average amounts of rainfall during the summer in KSA, B) The average
amounts of rainfall during the autumn in KSA.
76
A. Mashat and H. Abdel Basset
spring in the southwest, middle and east regions of KSA. The second
highest amounts of rainfall occur during the winter in the east and
northeast of KSA. Summer is the season of lowest rainfall in KSA,
where, except in the mountainous area in the southwest region, the
amount of rainfall is very low. While the horizontal distribution pattern
of rainfall in the autumn is somewhat similar to that of in the spring, the
amount of rainfall in the autumn is less than in spring.
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