Evaluation of Water Quality for Lesser-Zab River for Various Applications

Shuokr Qarani Aziz1,*, Evan Ogestin Slewa2, and Wali Ali Abdullah3 1,* Department of Civil Engineering, College of Engineering, Salahaddin University–Erbil, Iraq; Email: shoker71@yahoo.com, shuokr.aziz@su.edu.krd, Tel: +964 750 462 5426 2 Department of Civil Engineering, College of Engineering, Salahaddin University–Erbil, Iraq; Email: evanslewa74@gmail.com 3 Department of Dams and Water Resources Engineering, College of Engineering, Salahaddin University–Erbil, Iraq; Email: waliali9889@yahoo.com

. The river covers an area of 15 600 km 2 with a total perimeter of 1398 km.
The total area of this watershed is 20030 km 2 and its total perimeter is 1537 km [1].
The tributary of Lesser-Zab produces one of the primary tributaries of the Tigris River with a length that extends 400 km over an area of 22,250 km 2 from its origin in Iran [2][3]. The Dukan dam was constructed on Lesser-Zab to control river flow and electrical generation, irrigation, support fish production, and attract tourists [1][2].
Several studies were conducted on the parameters of water quality, monitoring, and impact of [4][5][6][7][8]. Aziz studied the suitability of water in Greater-Zab River for drinking and irrigation [9]. Other research focused on the limnological effects of Lesser-Zab on the characteristics of water in the Tigris and Lesser-Zab The present study examined the parameters of water quality of Lesser-Zab by measuring temperature, pH, total acidity, total alkalinity, total hardness, chloride, turbidity, electrical conductivity (EC), total salts, dissolved oxygen (DO), five-day biochemical oxygen demand (BOD 5 ), total solids, suspended solids (TSS), total dissolved solids (TDS) and sulfate. This study also determined the suitability of water in Lesser-Zab for drinking, irrigation, fish production, swimming, and construction.

Description of the Site
Approximately 76% of the Lesser -Zab watershed area is situated within the border of Iraq and the remainder is positioned within the Iranian border (Figures 1 and 2   Several physical and chemical experiments were conducted to examine the collected samples. The samples were analyzed for temperature, pH, total acidity, total alkalinity, total hardness, chloride, turbidity, EC, total salts, DO, BOD 5 , total solids, TSS, TDS, and sulfate. The tests were conducted at the laboratory of the College of Engineering of Salahaddin University-Erbil, Iraq. All physical and chemical examinations were conducted in accordance with standard procedures [13].

Mathematical Equations
Beside of normal water quality parameters, sodium adsorption ratio (SAR), Na%, and Alkalinity % are essential parameters for irrigation water quality [9,14]. The proportion of sodium ions in the water was generally measured by SAR. Normally SAR represents the sodium hazards of water and is defined as follows [9,14]: Irrigation water with high Na% will produce a soil with a large percentage of replaceable colloidal sodium. Na% can be calculated using the following equation [9,14]: In addition, Alkalinity % is necessary parameters for evaluation of irrigation water quality. Alkalinity % is determined using the following equation [9,14]:

Characteristics of Water in Lesser-Zab
The total acidity values of water in Lesser-Zab ranged from 12 mg/L to 20 mg/L. The quality of water resources in north of Iraq remains within the standard alkaline range because of geological formation, which mainly contains limestone.  Microorganism problems in Lesser-Zab water were not studied in the present work.
But based on literature, authors reported that Greater-Zab contained MPN-Coliform  [5,9]. To overcome microorganisms problems in Lesser-Zab water, disinfection process is necessary.

Irrigation
Normal range of pH for the quality of irrigation water is 6.5 to 8.  Based on SAR, water in Lesser-Zab can be classified as low sodium water (S1) as shown in   Lesser-Zab can be classified as excellent for irrigation (Table 5).
1 Low sodium water (S1), SAR value between 0 and 10 Can be used for irrigation on almost all soils and for almost all crops except those which are highly sensitive to sodium, such as stone-fruit trees and avocadoes, etc.
2 Medium sodium water (S2), SAR value between 10 and 18 Appreciably hazardous in fine textured soils, which may require gypsum, etc. but may be used on coarse-textured or organic soils with good permeability.  Table 2 shows that the alkalinity value of water in Lesser-Zab was 3.82. This result is consistent with the data (2.7% to 6.09%) reported for the Greater-Zab River. A range of 10.81% to 59.031% was recorded for water in the Tigris River [24]. The low concentration of sodium in Lesser-Zab water resulted in alkalinity percentage lower than that in the Tigris River. Abbas [24] cited classified water in Lesser-Zab as safe for irrigation (Table 4).
The EC values of water in Lesser-Zab ranged from 260 µmhos/cm to 400 µmhos/cm.
Abbas [24] classified the water in Lesser-Zab as suitable for irrigation (Table 5). Table 6 shows that water in Lesser-Zab has medium salinity (Class C2). This measurement was based on other classifications of the quality of irrigation water. Table 5 shows that water in Lesser-Zab water is considered excellent for irrigation purposes. This classification was based on the obtained sulfate values.