Water Quality Variation Along the Tigris River

Abstract

The Tigris and Euphrates Rivers are the main water resources for Iraq. Recently, Iraq has experienced water shortage problems due to the climate change and the construction of dams within the upper parts of the catchment. In this work, the total dissolved salts (TDSs) along the Tigris River were measured in eleven stations during wet and dry seasons. The interpolation method (IDW) in ArcGIS was used to generate the interpolation for TDS in the wet and dry seasons in the Tigris River. The regression prediction was used between the three measured and the observed values in the other three stations. The results showed that the quality of TDS becomes more unsuitable for human use beyond Baghdad toward the south.

Full text

Water Quality Variation Along the Tigris
River
Ali Chabuk, Nadhir Al-Ansari, Ali Almaliki, Jan Laue,
and Hussain M. Hussain
Abstract
The Tigris and Euphrates Rivers are the main water
resources for Iraq. Recently, Iraq has experienced water
shortage problems due to the climate change and the
construction of dams within the upper parts of the
catchment. In this work, the total dissolved salts (TDSs)
along the Tigris River were measured in eleven stations
during wet and dry seasons. The interpolation method
(IDW) in ArcGIS was used to generate the interpolation
for TDS in the wet and dry seasons in the Tigris River.
The regression prediction was used between the three
measured and the observed values in the other three
stations. The results showed that the quality of TDS
becomes more unsuitable for human use beyond Baghdad
toward the south.
Keywords
Total dissolved salts Water quality IDW 
Interpolation method Tigris River Iraq
1 Introduction
The water resources in the Middle East are scarce. Iraq was
considered as an exception due to the presence of the Tigris
and Euphrates Rivers. The area of Iraq covers 438,103 km
2
,
and its population exceeds 32 million. The total water
consumption in Iraq reaches 42.3 billion m
3
/year. This is
used for agriculture (90%), industry (6%), and human use
(4%). Recently, the flow of the Tigris and Euphrates Rivers
started to decrease, and Iraq is now facing water shortage
problems (Al-Ansari and Adamo 2018; Al-Ansari et al.
2018a,2018b). This is due mainly to climate change and to
the construction of dams in the upper parts of the catchment
in neighboring countries.
The Tigris River rises from the southeastern part of
Turkey. It is 1718 km long. It drains an area of 472,606 km
2
(17%, 2%, 29%, and 52% in Turkey, Syria, Iran, and Iraq,
respectively). The average flow of the Tigris River was
about 21 billion m
3
until 1973, when dams started to be
built. At that period, the discharge of the river at Baghdad
was 1207 m
3
/s. Now, the discharge is 522 m
3
/s (ESCWA
(Economic and Social Commission for Western Asia) 2013;
Al-Ansari 2016).
It has been noticed that, with the decrease of the flow in
the Tigris River, the quality of its water is deteriorating
(ESCWA (Economic and Social Commission for Western
Asia) 2013; Al-Ansari et al. 2018c). In this research, the total
soluble salt (TDS) along the Tigris River was studied in 11
locations during the year 2016 to observe the variations in
wet and dry seasons.
2 Predicting the TDS Concentration Along
the Tigris River Using the Interpolation
Method (IDW)
Eleven locations were selected on the Tigris River from the
northern part near the Turkish–Iraqi border to the southern
part near the confluence of the Tigris and Euphrates Rivers
(Fig. 1). The total dissolved salts (TDSs) from all these
stations were measured in the year 2016 during the wet
season (October to March) and the dry season (April to
September). Three stations (Al-Shraqat, Al-Tarmiyah, and
Ali Al-Garbi) were used for prediction after implementing
A. Chabuk
University of Babylon, Al Hilla, 51001, Iraq
N. Al-Ansari (&)J. Laue
Lulea University of Technology, 971 87 Lulea, Sweden
e-mail: nadhir.alansari@ltu.se
A. Almaliki
Ministry of Science and Technology, Baghdad, 10001, Iraq
H. M. Hussain
University of Kufa, Kufa, 54003, Iraq
©The Author(s), under exclusive license to Springer Nature Switzerland AG 2022
H. Chenchouni et al. (eds.), New Prospects in Environmental Geosciences and Hydrogeosciences,
Advances in Science, Technology & Innovation, https://doi.org/10.1007/978-3-030-72543-3_101
447

the interpolation between the eleven points using the inverse
distance weighted (IDW) method in ArcGIS (10.5). This
method was used to generate the interpolation for each map
of a parameter in the wet and dry seasons in the Tigris River.
The IDW technique is principally reflected in the first law of
Waldo Tobler in geography (Tomislav 2009). The IDW
method depends on a technique of accurate local determin-
istic interpolation (Watson and Philip 1985). According to
Panhalkar and Jarag (2015), the IDW method is considered
more suitable than other methods (e.g. kriging and Topo to
Raster), because these methods generate an interpolation for
the selected points with more deviation.
3 Results and Discussion
Figure 2shows the predicted maps for the TDS concentra-
tions along the Tigris River for wet and dry seasons through
measuring the TDSs at eleven locations from the north
toward the south. The results evidently showed that the TDS
values were increasing toward the south (Fig. 3). This
increase is related to several reasons. These are:
(a) Construction of dams and related irrigation projects:
This is where evaporation increases to reach about
8 billion m
3
(Al-Ansari and Adamo 2018; Hillel 1994;
Abbas et al. 2018). In addition, the backwater to the
river from irrigation projects is another factor which
contributes to increasing the salinity of the water.
(b) Wastewater and waste of war: About 83% of wastew-
ater is directly discharged into the rivers (Geopolicity
2010). Waste from the two Gulf wars is another source
of contamination.
(c) Population growth rates: This rate is considered very
high, particularly in Iraq. Besides, most of the popula-
tion in riparian countries resides on the banks of the
rivers (Worldmeters 2018).
For the wet and dry seasons, the regression prediction
between three observed values and predicted values (re-
sulted from predicting maps) was used (Fig. 4). These three
stations are: Al-Shraqat, Al-Tarmiyah, and Ali Al-Garbi.
The results showed that the coefficient of determination
(R
2
) between the observed and the predicted values was
high.
Fig. 1 Tigris River map and the
stations that were used for
measuring the different
parameters
448 A. Chabuk et al.

Fig. 2 TDS variation along the Tigris River in wet and dry seasons
Fig. 3 TDS variation at the selected stations with their respective distance along the Tigris River
Fig. 4 Relationship between observed and predicted values for TDS in the Tigris River for the wet and dry season
Water Quality Variation Along the Tigris River 449

4 Conclusions
The current study was conducted to measure the TDS con-
centrations in the Tigris River in 2016. The IDW interpo-
lation method in ArcGIS was used to generate the TDS
values along the Tigris River, where eleven stations were
selected on the River for predilection purposes. Three sta-
tions were then used to confirm the values that resulted from
the predicting maps using the IDW method within GIS.
Generally, the flow of the Tigris River is decreasing with
time while the salinity of water and soil is increasing. The
water becomes improper for human consumption in the
south of Baghdad. This is due to several factors such as the
extensive backwater flow from irrigation projects as well as
industrial activities.
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