67
Studies of Al Asfar and Al Uyoun Evaporation Lakes Water Quality and the Potential of Its Reuse in Agriculture
Activities, Al Hassa Area, KSA
A.S. El Mahmoudi, M.A. Massoud, Y.Y. Al-Dakheel and A.H.A. Hussein
Water Studies Center, King Faisal University, Al Hofuf, Saudi Arabia
Abstract. There is a growing concern in the Kingdom of Saudi Arabia to exploit water resources of acceptable quality to meet demands in domestic, industrial, and agricultural sectors. The agricultural water need constitutes approximately 85% of the total demand. Various alternative supplies to meet these demands are considered: Surface water, renewable groundwater resources, treated wastewater, desalinated water, and non- renewable groundwater. Al Hassa Oasis is one of the main and old agricultural centers in Saudi Arabia. An irrigation network of 1, 450 km of concrete canals and drainage network were put into operation in 1971. The project delivers 328 million m3 of spring water for about 22, 000 farms.
The excess drainage water is collected by earthen drainage network and discharged into two evaporation lakes, which are Al Asfar and Al Uyoun.
Such evaporation lakes (wet lands) are important link between water and land ecosystems. They provide habitats and refuges for wildlife, flood protection and contribute to abatement of impact of pollution and promoting groundwater recharge. The aim of this study is to investigate the water quality of these two evaporation lakes of Al Asfar and Al Uyoun and to study the potential of its reuse in agriculture activities at Al Hassa Oasis. Remote sensing, hydrogeological, chemical studies and Geographical Information Systems (GIS) are implemented to achieve the objectives of this study. For Al Asfar Lake, fourteen samples from surface water and the isolated water ponds and twenty samples of soil water from the area characterized by shallow water table (≈20 cm depth) have been collected in May to June, 2007. For Al Uyoun Lake, thirty five samples from surface water and the isolated water ponds and eight samples of soil water have been collected in March to April, 2008. Through chemical analyses, the major and minor ions content of soil pore water, surface water and sabkha soil samples were assessed. ArcGIS software and
satellite image processing software (ERDAS Imagine) were used for the integration of the output parameters of this study and for visualization of their spatial distribution. The results indicate that surface water of Al Asfar and Al Uyoun lakes are characterized by relatively low salinity and then encourage to re-treat this considerable quantity of water and to reuse it in agricultural purposes. This will lead to minimization of the sabkha extension, mitigation of its impact on the nearby farms of Al Hassa oasis and mitigation of aquifer recharge with high saline water and optimization of water use of this surface water body in this arid environment. The results of this study are important in any future development of the Al Asfar and Al Uyoun areas in planning.
1. Introduction
Water resources are essential and play a significant role in the development processes. The Kingdom of Saudi Arabia (KSA) is known by its arid conditions and limited renewable freshwater resources.
Surface water in KSA is very limited and of a little significance in the water budget. To meet the increasing water demands in domestic, industrial, and agricultural sectors, various alternative supplies are considered: Surface water, renewable groundwater resources, treated wastewater, desalinated water, and non-renewable groundwater.
Fresh water supply in arid regions is limited due to scarce precipitation and high evapotranspiration. When the limited supply is coupled with increasing demand for fresh water in these regions due to rapid population growth, it necessitates optimal development and management of water resources.
Al Hassa Oasis is one of the main and old agricultural centers in Saudi Arabia. Al Hassa oasis with an area of 20,000 hectares is located 70 km west of the Arabian Gulf (Fig. 1).
An irrigation network of 1,450 km of concrete canals and drainage network were put into operation in 1971 (Abderrhman and Bader, 1992).
This irrigation project delivers 328 million m3 of groundwater for about 22, 000 farms. Nowadays this amount of water is increased due to the discharge of treated wastewater from Al Hofuf sewage station into the irrigation network.
Fig. 1. Base map of Al Hassa Region and the location of the study area.
Al Hassa drainage water is collected by 1641 earthen lateral open canals having depths of about 1 m. The collected drainage water in the eastern sector of the project flows from the laterals to three sub main drainage canals which are connected to main drainage canal D2 (Fig. 2).
The collected water in this drainage flows towards Al Asfar Evaporation Lake at 13 km to the east of Al Hassa Oasis. The drainage water in the northern sector flows from the laterals to six sub main drainage canals, which are connected to main drainage canal D1.
Drainage water in D1 flows towards Al Uyoun Evaporation Lake outside Al Hassa Oasis, 52 km north of Al Hofuf. The water remains in the evaporation lakes during winter season to be used to supply cattle with drinking water and for aquifer recharge. From December until April each year, the agricultural drainage water overflows from the northern lake through small waterways into the Arabian Gulf, (Abderrhman and Bader, 1992).
Al Asfar
Study area
Fig. 2. Main drainage system of Al Hassa irrigation and drainage project.
The main salient morphologic features of Al Asfar and Al Uyoun Lakes are wet lands (Fig. 3), sabkhas and sand dunes. Salt tolerant vegetation (halophyte) is found in some of the less salt affected sabkha areas. The area is characterized by widespread growth of halophyte shrubs associated with a very thin salt crust on the sabkha surface.
Fig. 3. Parts wet lands of Al Asfar and Al Uyoun lakes.
Al Asfar Lake Al Uyoun Lake
Hydrogeology and hydrochemistry of groundwater of Al Hassa area have been reported in many studies (Etewy, et al., 1983; Al- Mahmoud, 1987; Abderrahman, 1988; Edgell, 1989; Al Dakheel and Al Safarjalani, 2005; Al Safarjalani and Almadini 2007; Al-Zarah, 2007 and 2008; and Al Dakheel,2009).
The aim of this study is to investigate the water quality of these two evaporation lakes of Al Asfar and Al Uyoun, and to study the potential of its reuse in agriculture activities at Al Hassa Oasis, Al Hassa area, KSA.
2. Materials and Methods
Multi-date landsat-5 TM imageries of years 1987, 1993, 1998 and 2000 and SPOT imageries of 2007 of the study area have been processed and analyzed to investigate the dynamics of both water ponds and the associated sabkha with time at Al Asfar and Al Uyoun lakes areas. For Al Asfar Lake, fourteen samples from surface water and the isolated water ponds and twenty samples of soil water from the area characterized by shallow water table (≈20 cm depth) have been collected in May to June, 2007. For Al Uyoun Lake, thirty five samples from surface water and the isolated water ponds and eight samples of soil water have been collected in March to April, 2008, (Fig. 4 (a and b)). The latitude and longitude of the soil and water samples coordinates were measured by using high accuracy differential GPS. The pH and the electrical conductivity (EC) were measured for the collected water samples. Sodium and potassium were determined by flame photometry according to Jackson (1973). Calcium and magnesium were determined by atomic absorption spectrophotometer according to Carter (1993). Soluble carbonates and bicarbonates were determined volumetrically in the soil paste extract by titration against 0.01 N hydrochloric acid using phenolphthalein and methyl orange as indicators according to Jackson (1967).
Soluble chlorides were determined by titration with 0.01 N silver nitrate solution and potassium chromate as indicator according to Richards (1954). Sulphate was determined turbidimetrically with barium chloride as described by Jackson (1973). The concentrations of NO3- were determined in water samples according to Norman, et al. (1985) method. ArcGIS software and satellite image processing software (ERDAS Imagine) were used for the integration of the output parameters of this study and for visualizes their spatial distribution.
Fig. 4(a). Base map of the surface and soil water samples, Al Asfar lake area, Al Hassa, KSA.
Fig. 4(b). Base map of the surface water and soil water samples of Al Uyoun evaporation lake, Al Hassa area, KSA.
3. Results and Discussion 3.1 Remote sensing Investigations
In this study, Landsat -5 TM imageries with seven bands of years 1987, 1993, 1998 and 2000 beside SPOT imageries of 2007 of the study area have been geo-referenced, visually interpreted and analyzed to identify different geomorphic units of Al Asfar and Al Uyoun Lakes
D2
49.76 49.77 49.78 49.79 49.8 49.81 49.82 49.83 49.84 49.85 49.86 49.87 25.51
25.52 25.53 25.54 25.55 25.56 25.57 25.58 25.59 25.6 25.61
AL01AL02
AL03
AL04 AL06AL05
AL07 AL08
AL09 AL010
AL011
AL012 AL013
AL014 ALS1
ALS2
ALS3 ALS4
ALS5
ALS6
ALS7 ALS8 ALS9
ALS10
ALS11 ALS12
ALS13 ALS14
ALS15 ALS17
ALS18
ALS19
ALS20 Als1Soil water sample Location & No.
Wet Land Al01
Surface water sample Location & No.
366000 368000 370000 372000 374000 376000 378000 380000 2840000
2842000 2844000 2846000 2848000 2850000
U01 U02
U03 U04 U05 U06
U07 U08
U09 U010 U011
U012 U013
U014 U015 U016
U017 U018
U019 U020
U021 U022
U024U023 U025
U026
U027 U028 U029 U031 U030
U032 U033
U035U034 US1
US2US3 US4
US5
US6
US7
US8
US1Soil water sample Location & No.
U01Surface water sample Location & No.
Wet Land
D1
Aramco Road
Al Uqair Road
environments. The digital elevation models (DEM) of the study areas were also processed and analyzed. The Elevation Data collected using the GPS system have been used for constructing Digital Elevation Models (DEM) for Al Asfar and Al Uyoun Lakes (Fig. 5 (a and b)). These maps facilitated the interpretation of the chemical analysis as discussed below.
From the map shown in Fig. 5 (a), it is noticed that the elevation of Al Asfar area is decreasing toward east and ranges from 112 m above mean sea level in the southwest to 92m above mean sea level in the northeast.
While, from the map shown in Fig. 5 (b), it is noticed that the elevation of Al Uyoun area is decreasing as well toward east and ranges from 80m above mean sea level in the west to 55m above mean sea level in the east.
The processed landsat-5 TM and SPOT Imageries for Al Asfar Lake area (Fig. 6 a) indicated that there is a general increment in both the sabkha and wet land areas extent with the passage of time (sabkha and wetlands in 1987 vs. sabkha and wetlands in 2000), (Fig. 6 a).
Fig. 5(a). Digital elevation model map of Al Asfar area, Al Hassa, KSA.
49.76 49.77 49.78 49.79 49.8 49.81 49.82 49.83 49.84 49.85 49.86 49.87 25.51
25.52 25.53 25.54 25.55 25.56 25.57 25.58 25.59 25.6 25.61
92 94 96 98 100 102 104 106 108 110 112 114 Elevation (m)
D2 Wet Land
Fig. 5(b). Digital elevation model map of Al Uyoun evaporation lake area, Al Hassa, KSA.
The direction of increment is related to relief where increased sabkha areas have taken place in low relief areas where groundwater rose and pushed salt to the surface. On the other hand, the processed landsat-5 TM and SPOT Imageries of Al Uyoun area (Fig. 6 b) indicated that there is a general decrease in both the sabkha and wet land areas extent with the passage of time (sabkha and wetlands in 1987 vs. sabkha and wetlands in 2000 and in 2007). The reason behind that is due to Hassa Irrigation and Drainage Authority (HIDA) which is recently retreating water of Drain one (D1) and reusing the treated water for irrigation purposes at Al Hassa Oasis.
Fig. 6(a). The processed landsat-5 TM Imageries (in years of 1987 and 2000) and SPOT (in year 2007) for Al Asfar area.
366000 368000 370000 372000 374000 376000 378000 380000
2840000 2842000 2844000 2846000 2848000 2850000
1 2 3 4 5 67
8 9
10 11
12 13
14 15
16
17 18 19
20 21
22
23 24
25 26
27 28
29 30 31
32 33 34
35 36
3738 39
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44
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51
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72
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79 78 80 828183 84
85
8786 88 89 90 91
92
93 94
95
50 55 60 65 70 75 80
1 Sample Location & No.
Elevation (m)
Wet Land
D1
Aramco Road
Al Uqair Road
Fig. 6 (b). The processed landsat-5 TM Imageries (in years of 1987 and 2000) and SPOT (in year 2007) for Al Asfar area.
3.2 Chemical and Hydrochemical Investigations
The water samples were analyzed for their chemical properties;
hydrogen ion concentration (pH), electrical conductivity (EC), and then total dissolved salts (T.D.S.) was calculated and for major constituents (Na+, Ca++, K+, Mg++, Cl-, SO4--, HCO3- and NO3-). Table 1 summarizes
the statistical analysis of chemical properties and for major constituents of the collected surface water and pore water samples for both Al Asfar and Al Uyoun areas. From this table, it could be noticed that, for Al Asfar samples the major cations are in order Na+, Mg++, Ca++ and K+, while for Al Uyoun samples the major cations are in order Na+, K+, Ca++
and Mg++. The major anions for both Al Asfar and Al Uyoun samples are in order: Cl-, SO4--, HCO3- and NO3. The carbonate content is so small that it was undetected as the maximum value of pH is not more than 8.3 which is the threshold at which these ions start to form for both soil and water samples (Stumm and Morgan, 1981). pH was measured for water samples. Figure 7 (a and b) shows the spatial distribution map of pH values for water samples of Al Asfar and Al Uyoun lakes. The pH values of Al Asfar water samples varied between 7 and 8.3. While the water samples of Al Uyoun had pH values ranging between 6.85 and 8.94. It could noticed that pH values of Al Uyoun area (Fig. 7 b) are increasing northward and the samples located to the northeast corner have the maximum pH values. Also, the area around the mouth of Drain One (D1) is characterized by high pH values. Generally, all the water samples of both Al Asfar and Al Uyoun areas indicate a slightly alkaline character with very narrow pH ranges.
Table 1. Statistical analysis for chemical analysis for the major cations and anions for Al Asfar and Al Uyoun surface water and for pore water samples.
Area
Analysis
Values
pH EC (dS/m)
TDS (ppm)
Major Cations (ppm) Major Anions (ppm) Na+
Ca++ MgK+ Cl++ SO- HCO4-- 3- NO3-
Al Asfar Samples
Minimum 9.5 7.0 7624.0 1008.9 235.8 159.7 536.3 1827.2 1349.9 70.0 0.9 Maximum 102.3 8.3 81840.0 10829.6 2531.5 1714.3 5756.7 27335.0 8809.8 1742.4 41.0 Mean 40.5 7.8 32383.5 4285.2 1001.7 678.4 2277.9 10717.7 4321.9 318.7 9.1 SD* 28.7 0.3 22973.4 3040.0 710.6 481.2 1616.0 8079.9 2447.0 287.0 9.4
Al Uyoun Samples
Minimum 6.85 7.49 5992 532.9 275.0 100.3 231.7 1349.7 1313.8 155.6 1.3 Maximum 99.58 8.94 79664 17284.0 2539.3 6023.7 2424.5 20813.1 19595.5 1648.8 99.0 Mean 41.13 7.959 32903.6 5087.2 1241.2 1444.7 1098.5 8446.6 7948.3 391.0 9.3 SD* 28.4740.435 22779.5 5039.8 480.5 1653.8 607.2 5944.7 5633.1 291.1 17.7
*Standard Deviation
a) Al Asfar b) Al Uyoun
Fig. 7. Distribution map of the pH content for the water of Al Asfar and Al Uyoun Lakes, Al Hassa area, KSA.
The total salinity of surface water and pore water samples of Al Asfar area ranged from 7,624 to 81,840 ppm with a mean value of 32,383.5 ppm (Table 1).The relatively low values of total salinity are belonging to the surface water samples from the main lake of Al Asfar (Fig. 8 a and Fig. 9 a), where the irrigation drainage water of low salinity is discharged to the lake through drainage canal D2), while the high values are belonging to surface waters samples collected from isolated ponds around the main lake (where high evaporation and more salt is concentrated).
For Al Uyoun Lake, the total salinity of surface water and pore water samples ranged from 5992 to 79,664 ppm with mean value of 32,903 ppm, (Table 1). The relatively low values of total salinity are belonging to the surface water samples from the main lake of Al Uyoun (Fig. 8 b). This relatively low salinity values of the surface water of Al Asfar and Al Uyoun Lakes encourage to re-treat these water and to reuse it in agricultural purposes, this will lead to minimize the sabkha extension, to mitigate its impact on the nearby farms of Al Hassa oasis and to mitigate aquifer recharge with high saline water and to optimize the water use of this surface water body in this arid environment.
The salt content of soil water for the collected samples depends on the distance from the main water body of Al Asfar lake, i.e. the nearest to the lake, the less of salt content. The soil water salinity at the margins of Al Uyoun Lake ranges from 26,312 ppm to 71,400 (Fig. 8 b). The salt content of soil water for the collected samples as well depends on the distance from the main water body of Al Uyoun lake, i.e. the nearest to the lake, the less of salt content. The soil water salinity at the margins of Al Asfar Lake ranges
366000 368000 370000 372000 374000 376000 378000
2840000 2842000 2844000 2846000 2848000 2850000
U01 U02 U03 U04 U05 U06
U07 U08
U09 U010 U011 U012
U013 U014
U015 U016
U017 U018
U019U020
U021 U022
U024U023 U025
U026 U027 U028 U029 U031 U030 U032 U033
U035U034 US1
US2US3 US4
US5
US6
US7
US8
D1
Al Uqair Road Aramco Road
from less than 10,000 ppm (see for example salinity of samples Nos. Als1, Als5 and Als7) to about 80,000 ppm (see for example salinity of samples Nos. Als 6, Als11 and Als19), (Fig. 8 a &9 b).
a) Al Asfar b) Al Uyoun
Fig. 8. Spatial Distribution map of the total salinity or the water of Al Asfar and Al Uyoun Lakes, Al Hassa area, KSA.
Fig. 9(a). Total Dissolved Salinity of surface water samples of Al Asfar Lake, Al Hassa area, KSA.
Fig. 9(b). Total Dissolved Salinity of soil water samples of Al Asfar Lake, Al Hassa area, KSA.
49.7649.7749.7849.7949.8 49.8149.8249.8349.8449.8549.8649.87 25.51
25.52 25.53 25.54 25.55 25.56 25.57 25.58 25.59 25.6 25.61
AL01AL02
AL03
AL04 AL05 AL06
AL07 AL08
AL09 AL010
AL011
AL012 AL013 AL014 ALS1
ALS2
ALS3 ALS4
ALS5
ALS6
ALS7 ALS8ALS9
ALS10 ALS11 ALS12
ALS13 ALS14
ALS15 ALS17
ALS18
ALS19
ALS20
5000 10000 20000 30000 40000 50000 60000 TDS (ppm)
Als1 Soil water sample Lo
Wet Land Al01
Surface water sample
D2 366000 368000 370000 372000 374000 376000 378000 380000
2840000 2842000 2844000 2846000 2848000 2850000
U01 U02 U03 U04 U05U06
U07 U08
U09 U010 U011 U012
U013 U014
U015 U016
U017 U018
U019U020
U021 U022
U024U023 U025
U026 U027 U028 U029 U031 U030 U032 U033
U035U034 US1
US2US3 US4US5
US6
US7
US8
5000 10000 20000 30000 40000 50000 60000 TDS (ppm)
Us1 Soil water sa U01Surface wate
W D1
Al Uqair Road Aramco Road
0 10000 20000 30000 40000 50000 60000
AL01 AL02 AL03 AL04 AL05 AL06 AL07 AL08 AL09 AL010 AL011 AL012 AL013 AL014
Sample No.
TDS (ppm)
0 10000 20000 30000 40000 50000 60000 70000 80000 90000
ALS1 ALS2 ALS3 ALS4 ALS5 ALS6 ALS7 ALS8 ALS9 ALS10 ALS11 ALS12 ALS13 ALS14 ALS15 ALS16 ALS17 ALS18 ALS19 ALS20 Sample No.
TDS (ppm)
The soil water under this sabkha is more saline than the normal sea water in these so arid environments. It is worthy to mention that the contour pattern of the constructed spatial distribution maps for the major cations of water samples for Al Asfar and Al Uyoun (Fig. 10 (a and b)) are similar to that of TDS shown in Fig. 8 (a and b). However, in case of anions the contour pattern for chloride and sulphate have the similar pattern of TDS while for both Bicarbonate and Nitrate have a different pattern (Fig. 11(a and b)). The bicarbonate in this water is thought to be derived partly from the outcrops of Neogene carbonate ridges originated under marine conditions.
Ca++
Na++
Mg++
K+
Fig. 10(a). Distribution maps of the major cations concentration for the surface water and soil water of Al Asfar area, Al Hassa, KSA.
49.7649.77 49.78 49.79 49.8 49.8149.82 49.83 49.84 49.85 49.8649.87 25.51
25.52 25.53 25.54 25.55 25.56 25.57 25.58 25.59 25.6 25.61
AL01AL02
AL03
AL04 AL06AL05
AL07 AL08
AL09 AL010
AL011
AL012 AL013
AL014 ALS1
ALS2
ALS3 ALS4
ALS5
ALS6
ALS7 ALS8ALS9
ALS10 ALS11 ALS12
ALS13 ALS14
ALS15 ALS17
ALS18
ALS19
ALS20
600 1000 1400 1800 2200 2600 Ca (ppm)
Als1 Soil water sample Location & No.
Wet Land Al01
Surface water sample Location & No D2
49.7649.77 49.78 49.79 49.8 49.81 49.82 49.8349.84 49.85 49.8649.87 25.51
25.52 25.53 25.54 25.55 25.56 25.57 25.58 25.59 25.6 25.61
AL01AL02
AL03
AL04 AL06AL05
AL07 AL08
AL09 AL010
AL011
AL012 AL013
AL014 ALS1
ALS2
ALS3 ALS4
ALS5
ALS6
ALS7 ALS8ALS9
ALS10 ALS11 ALS12
ALS13 ALS14
ALS15 ALS17
ALS18
ALS19
ALS20
500 2000 3500 5000 6500 8000 9500
Als1 Soil water sample Location & No
Wet Land Al01
Surface water sample Location Na (ppm)
D2
Na+ Ca++
K+ Mg++
Fig. 10(b). Distribution maps of the major cations concentration for the surface water and soil water of Al Uyoun area, Al Hassa, KSA.
Cl- SO4--
HCO3- NO3-
Fig. 11 (a). Distribution maps of the major anions concentration for the surface water and soil water of Al Asfar area, Al Hassa, KSA.
Cl- SO4--
HCO3- NO3-
Fig. 11(b). Distribution maps of the major anions concentration for the surface water and soil water of Al Uyoun area, Al Hassa, KSA.
4. Conclusions
Integration of the processed Landsat TM imagery and chemical analysis contributes to a better understanding of the environment of Al Asfar and Al Uyoun Lakes, Al Hassa area. The processed landsat-5 TM and SPOT imageries indicated there is a general increment in both sabkha and wet land areas extent with the passage of time at Al Asfar Lake area. While, for Al Uyoun lake, there is a general decrease in both the sabkha and wet land areas extent with the passage of time and this is attributed to the recycling of Drain one (D1) water by Hassa Irrigation and Drainage Authority (HIDA) and is used for irrigation purposes at Al Hassa Oasis.
The hydrochemical analysis revealed that the surface water of Al Asfar and Al Uyoun are characterized by a relatively low salinity and then re-treating and reusing of this water in agricultural purposes will lead to minimize the sabkha extension, to mitigate its impact on the nearby farms of Al Hassa oasis, to mitigate aquifer recharge with high
saline water and to optimize the water use of this available surface water body in this arid environment.
The evaporation condition prevailing in the present study and the absence of continuous recharge from the main drainage (D1 and D2) led to the concentration of highly saline lagoon water. A monitoring system for water levels and quality at Al Asfar and Al Uyoun Lakes should be established, maintained and updated.
Acknowledgments
The authors would like to express their sincere appreciation to Deanship of Scientific Research, King Faisal University for the financial support of this study under fund grant No. 8095. Special thanks go to Mohamed Al Kulaib and Mohamed Al Farij for their assistance in the field activities and in the laboratory measurements of this study.
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