Impact of Hindiya Dam on the Limnological Features of Euphrates River to the North of Babil Governorate, Iraq

Five sites were chosen to the north of Babil Governorate in order to identify the limnological features and the impact of the Hindiya Dam during 2019. Site2 was located near the dam to reflect the ecological features of this site, whereas other sites, S1 was located at the upstream of the dam as a control site. Moreover, the two other sites S3 and S4 were located down the dam. The results of the study showed a close correlation between air and water temperature at all sites. Also there were significant differences in average of thirteen out of eighteen water parameters.Water temperature, total alkalinity, bicarbonate, DO, POS, TH and Mg +2 ions decreased from 22.76 ̊C, 203.33 mg/L, 146.75 mg/L, 8.8 mg/L, 100.023%, 438 mg/L, 35.55mg/L, respectively on S2 to 22.66  ̊C, 200.28 mg/L, 145.58 mg/L, 8.35 mg/L, 95.45%, 422.66 mg/L, 28.81 mg/L, respectively at site below the dam. While, turbidity, TSS, Ca +2 , SO2 +4 , NO3 -2 and PO4 -2 increased from 13.32 NTU, 23.08 mg/L, 116.89 mg/L, 107.5 mg/L, 1.027 mg/L and 0.019 mg/L, respectively on S2 to 26.574 NTU, 26.83 mg/L, 119.23 mg/L, 137.5 mg/L, 1.145 mg/L and 0.032 mg/L, respectively at the site below the dam. However, no apparent dam effect was reported in EC, S, TDS, pH values at Euphrates River. No significant differences of all characteristics were found among sites except, turbidity, TSS, Mg +2 , SO +4 and PO4 -2 . It can be considered that the Euphrates River is very hard, oligohaline, slightly alkaline, well ventilated and clear to turbid. In addition, the turbidity and TSS values exceeded permissible limits of water quality for aquatic life in most samples especially in site below the dam. However, the river was considered by BOD5 to be doubtful in its cleanliness water. Calcium, magnesium, nitrate and phosphate values in this study were within permissible limits.


Introduction:
Water's physical and chemical properties are an important factor in assessing water quality and validity and give an idea of the water content of organic, inorganic compounds and elements 1 . Also, water plays a major role in life of aquatic lives, quality of water affected by change in atmospheric and geological circumstances 2 . For forty decades, the limnology of Iraqi water bodies has received considerable attention and several studies have been recorded in various parts of Iraqi water bodies such as [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . However, the current study dealt with one of the major dams of the Euphrates River to the north of Babil Governorate, for which we can include the major aims in the following points: investigating the ecological characteristics of river, and studying additional basic knowledge on physical-chemical properties under the effect of the dam during the 2019, Therefore, this studycan be considered the first of its kind by dealing with this aspect of the work.

Material and Methods: Study area Description
Hindiya Dam is situated on the Euphrates River to the south of Musayyib City to the north of Babil Governorate, Iraq. The Dam length is 250 m and has 36 dams' spillways, 5m wide of each one. It was designed for treatingsediment matter of the one of two major branches of the Euphrates in this area called Hilla River. Hindiya Dam was constructed from 1911 to 1913.A new canal in addition to the Hillah River was excavated. Willcocks supervised on the work whereas it was done by a British contractor named John Jackson. The dam was developed in 1927 21 . Hindiya Dam contains other canals in addition to the Hindiya and the Hilla branches which are called the Kifil and Beni Hasan 22 .

Description of Study Sites
Five sites were chosen for the collection of study samples onEuphrates River near Hindiya Dam (Fig.1). 1. Site 1: This site is located before the Babylon Cement Factory south of the Musayyib City about 1Km upstream the dam at longitude 44̊ 16̓ 05"and latitude 32̊ 44̕ 18". Euphrates River and is 328m wide. Site 2: It represents the Hindiya Dam site characterized as wider among other sites about 366m width at longitude 4416̓ 07"and latitude 32̊ 43̕ 42". Site 3: It is located about 400m down Hindiya Dam with 235m width at longitude 4416̓ 06"and latitude 32̊ 43̕ 29". Site 4: This site is 293 m wide and located about 5Km down Hindiya Dam at longitude 4415̓ 16"and latitude 3241̕ 24". Site 5: It is 231 m wide and located about 10Km downstream site 4, and about 15Km downstream the Hindiya Dam at longitude 4413̕ 12"and latitude 32̊ 35̕ 50". Water discharges were in range between lower value of 116.92 m 3 /sec. in February 2019 while the greatest value was 409.89 m 3 /sec. in July2019. Water velocity of Euphrates River study sites during study period was in range between the lower value of 0.46 m/sec. in February 2019 while the greatest value was 0.64 m/sec at November 2019 (Ministry of Water Resources, 2019personal communication) (Fig. 2).

Figure2. Water discharges and velocity of Euphrates River during period study.
Samples were collected monthly during year 2019, by using polyethylene containerswithcapacity 2 L and washing well with river water before using it.
Physical and chemical parameters included -Air and water temperature which were measured by using a precise mercury thermometer. Dissolved oxygen and Biological oxygen demand used the modified Winkler method 23 . The percentage of oxygen saturation was calculated as reported in Mackereth et al. 24 , electrical conductivity, salinity, pH, and Total Dissolved Solid in water by HANA (HI9811). The Total Suspended Solids were measured according to the method mentioned in APHA 23 . The turbidity was measured by the turbidity meter Jenwa Company Model-6035. Total hardness, calcium, and magnesium were measured according to Lind 25 . Sulphate used the method described by Brands and Tripke 26 , the nutrients (Nitrate), measured as in APHA 23 , the effective phosphate was measured according to the method APHA 23 . Finally, the Degremont method 27 was used to measure the bicarbonate in the water of the studied sites.

Results and Discussion:
The air temperature having clear variation seasonally ( Fig.3 and 4) and (Table 1) might be due to the air temperature reflection of fluctuations in Iraq weather characterized as long, hot and dry summers. In contrast, it has short and cool winters because of Iraq's location between the Arabian desert areas that give the effect of the subtropical aridity and the Arabian Gulf that give the effect of the subtropical humidity 28 . The current findings proved that the dam affected water temperature apparently on site 3 downstream the dam which caused decreasing water temperature values in this site after opening spillways the dam and releasing colder water from hypolimnetic layer of reservoir to site 3 29 .    Table 1 showed the results of electrical conductivity and salinity .The range of electrical conductivity recorded on site 1upstream the dam was from 690μS/cm(0. 44‰) to 1320μS/cm(0.84‰). The lowest value of electrical conductivity and salinity in was October whereas the highest values were in January, respectively. statistical analysis of EC and salinity had no significant difference among sites P ˃ 0.05 (Table  1). It has been shown that Hindiya Dam has no effect on electrical conductivity and salinity values at Euphrates River and this case could be due to the high water discharges in the river at 2019, which led to disappear of the dam effect on EC and salinity values 30 . Freshwater salinity levels are 0.5 ppt or less. Salinity levels are referred to as oligohaline (0.5-5.0 ppt), mesohaline (5.0-18.0 ppt), polyhaline (18.0-30.0 ppt), or euhaline, where salinity levels of more than 30.0 ppt are the same as those of the ocean 31 .    Table 1 showed thatsite 1 recorded a minimum level of 3.84 NTU in November, while the maximum level in Julywas31.25 NTU. The turbidity values at the Hindiya Dam site were substantially unchanged and ranged from1. 58 NTU to 33.31 NTU reported in August and March 2019, respectively.
The turbidity range at sites downstream the Hindiya Dam site was significantly increased, espe cially at site 3, and then gradually decreased to lowe r values at site 5.The turbidity values ranged from the lowest value of 4.34 NTU at site 5 in April to the highest turbidity value of 45.71 NTU in November 2019 at site 3. The statistical analysis revealed that no significant difference between all turbidity sites (P ˃ 0.05) except site 3 was identified (P≤ 0.05) ( Table 1). Table 1 and Fig. 7 illustrate that site 3 (downstream the dam) had the highest turbidity average compared with other sites which might be related to the frequent fluxes resulting from the opening of dam spillways leading to the release of sediments settled in the lower reservoir layer 32 . Or, it may be because of the higher velocity currents at site3 below the dam resulting from opening the dam spillways 33 . Whereas, the lower turbidity average near Hindiya Dam was because of the lentic state of reservoir water on this site led to the settling of particles and sediment downward bottom 34 . It was believed that both causes are mentioned to increase turbidity values at sit 3 downstream the dam contributed in increase turbidity values at site 3. Site 5 had low turbidity average which could be due to it being far from the city about 10 Km and it was far from sewage and effluents as compared with other sites 35 .Turbidity values exceeded permissible limits of water quality for aquatic life which was 5 NTU 36 in most samples, especially in site 3 (downstream the dam) which might be due to the dam effect on site 3.
The pH values did not show an even notice dam impact on pH values at Euphrates River during 2019, and no significant differences P>0.05 among sites were remarked( Fig. 8 and Table 1). Also, a narrow range of this parameter was recorded which was from 7-8.18. So Euphrates River was considered weak alkaline as it is known in Iraqi freshwater 37 . The pH values remained stable at levels in narrow range owing to the high buffering capacity resulting from high content of calcium bicarbonate 38 . Overall, these local and global studies agreed with this study finding such as (4 ; 5)  According to our findings of TDS, it is proved that no apparent dam effect and no significantdifferences P>0.05 are detected by statistical analysis( Fig. 9 and Table 1).
All the water sources are usually categorized as freshwater (TDS < 1000 ppm), based on the classification system of Pradhan and Pirasteh 39 . Or, it is known as brackish (1000-10.000 ppm) water. Whereas, with extremely high TDS (12.000 ppm), it is known as salty water, almost identical to seawater. So, Euphrates River classified as fresh water because of its TDS values were less than 1000 ppm which ranged from 340 ppm to 690 ppm . Figure 10 and Table 1 show total suspended solid (TSS) values.The results showed that, at site 1 upstream of the dam, the TSS value differed from the lower value of 1 mg / L in May, while 52 mg / L was the highest value recorded in June. While TSS values at the Hindiya Dam site ranged from 3 mg / L to 65 mg / L, the lowest value was recorded in February, whereas in July the highest value was recorded. The values at site 3 downstream of the dam increased and then at sites 4 and 5 decreased. Thevalues of sites Dam downstream ranged from 2 mg / L at site 4 in May to 56 mg / L at site 4 in May. Statistical study of the difference between sites showed that there was no significant difference between sites 2 and 4 P ≥ 0.05, which showed significant differences with other sites (Table 1).  The result of this study indicates that the dam affected on water TSS values especially on site3 (downstream the dam) by causing increasing TSS values after opening the dam spillways, This contributed to the release of sediments found in the lower reservoir layer 32 . Or, owing to the higher velocity currents at site 3 resulted from opening the dam spillways 33 . It can be said that both causes mentioned to higher TSS values at sit 3 downstream the dam contributed in increase TSS values at site 3.USEPA 40 divided water into three classes based on the TSS value: less than 20 mg / L as low turbidity water, between 20 and 80 mg/L as moderate turbid, and more than 150 mg / L as turbid water. So, water quality of Euphrates River ranged from clear to turbid in study area. Figure 11 and Table 1 show the values of total alkalinityvalues at site 1 (upstream of the dam), the total alkalinity values ranged from 152 mg / L in January to 237. 8  from 152.5 mg /L at site 4 in March to 244 mg/L at site 3 (December), site 4 (April and October) and site 5 (March). Figure 12 and Table 1 show the values of bicarbonates at site 1(upstream of the dam), which ranged from 90 mg/L in February to 170 mg/L in May, July and October. Bicarbonates were slightly raised at the Hindiya Dam site, with a maximum bicarbonate concentration of 190 mg/L recorded in May. In comparison, the minimum concentration recorded in February was 115 mg/L. The bicarbonate average values at sites downstream of the dam were especially high in site 4, the lower value was in February, varying from 112 mg/L to 220 mg/L, while the highest value was in May, and both values were on site 3 . No significant differences in total alkalinity and bicarbonate P > 0.05 have been identified. among sites (Table 1).  It can be seen from the Figure above that the dam affected water alkalinity and bicarbonate values especially on Hindiya Dam site which caused increasing the values in this site compared with other sites might be related with lack of macrophytes in reservoir led to increasing CO 2 concentrations that have also been converted to bicarbonates after dissolution in water have contributed to higher bicarbonate concentrations 41 . Exception site 4 had the maximum values of bicarbonate only may owing to its location within the city could be because of sewage and waste water released at this site contributed to a rise in bicarbonate concentrations to higher values compared with other sites 35 . The current study showed that alkalinity values were over the normal limits allowed by Iraqi and international standard water, which were 20-200 mg / L CaCO 3 23 . Also, it was observed that Iraqi waters had alkalinity characteristics because of presence carbonate salts 42 . Figure 13 and Table 1 show the dissolved oxygen concentrations for surface water in study area of Euphrates River. At site 1 (upstream of the dam), the value of dissolved oxygen ranged from 7.2 mg/L in October to 12 mg/L in May, while the value of dissolved oxygen decreased at the site near Hindiya Dam compared with the site1 which its highest value recorded during January was 12.5 mg / L, and the lowest value recorded in July and August was 6 mg / L. However, values of sites downstream of the dam decreased at site 3 relative to the dam site, while these values were steadily increased until they were approximately equal to site1, with values ranging from 5 mg / L at site 3 in July to 12 mg / L at site 5 which reported in February and March.
Whereas, Fig.14 and Table 1 show that the percent oxygen saturated (%) values for the surface water of the study area. The percentage of oxygen saturated (%) on site 1 (upstream of the dam) ranged from 84.56 % in December to 147.7 % in May, While the highest percentage of saturated oxygen (%) on site near Hindiya Dam in June was 142.66 %, and in July the lowest value was 79.26 % . The percent saturated oxygen (%) values at the site near Hindiya Dam were lower compared to site 1. Sites below the dam, however, showed values ranging from 66.05 % at site 3 in July to 163.7% at site 5 in June. For DO and P.O.S., no significant differences were shown by statistical analysis during the study period recorded between sites P > 0.05 (Table 1).  it was proved that the dam affected on water DO and P.O.S. level especially on site 3 (below the dam), which was recorded with depletion DO and P.O.S. could be due to reservoir bottom through release hypolemintic layer with depletion dissolved oxygen and P.O.S. typically by opening dam spillways into site 3 43 . Figure 15 and Table 1 show the results of biological oxygen demand. The total amount of demand for biological oxygen was from 1.5 to 7 mg / L at site 1 (upstream of the dam). The lower number was in November and December, while in July and September it was higher. At site near Hindiya Dam, biological oxygen demand values were declined slightly, The values were in the range of 2 to 8.9 mg/L. The lower value was in May, while the maximum value was in February and March. BOD 5 ranged from 0.5 to 8.8 mg/L at sites downstream from the dam. The statistical analysis showed that there was no significant difference between biological oxygen demand sites of P ˃ 0.05 (Table 1).
Odum 44 divided the water into two types based on BOD 5 as BOD 5 = 2 clean, BOD5 = 5 or more was doubtful in its cleanliness. Therefore, Euphrates River was doubtful in its cleanliness. Our findings showed that no apparent dam effect on BOD 5 levels at Euphrates River during 2019. Figure 16 and Table 1 show the values of total hardness of the water of River Euphrates in the study area. The total hardness of the site (upstream of the dam) was found to range from 280 to 575 mg / L. In June 2019, the lowest value was, while in March 2019, the higher value was. Total hardness values ranged from 336 to 552 mg / L at the site near Hindiya Dam. The lowest value was in October, while during the month of January the higher value was. Hardness levels ranged from 308 mg / L at site 3 in June to 568 mg / L at site 4 in February at sites downstream the dam.
It was shown by statistical analysis that no significant difference among sites P ˃ 0.05 (Table  1).
Our findings proved that dam had a clear effect by raising in total hardness at Euphrates River on Hindiya Dam site, may be owing to the limestone substrate composed of Hindiya storage water 45 . USEPA 46 classified water into four forms based on total hardness as non-hard water with CaCO 3 concentrations less than 50 mg/L, water has range from50-100 mg/L, have been classified as moderate hard water, values between 100-200 mg/L classified as hard water and more than 200mg/L classified as very hard water. So it can consider Euphrates River as very hard water according to total hardness values in the present study.    Table  1. This could be either due to co-precipitation of phosphorous with CaCO 3 which was important in moderating the productivity of deep impoundments with smaller littoral zones. Or owing to very hard water in reservoirs and lakes drive to precipitation process of calcium carbonates and some nutrients which led to decrease calcium ions values in water of reservoirs and lakes 47 .
While, site 4 had the highest average of calcium ionscompared with other site values, which could be associated with increased discharge of city sewage effluents containing large concentrations of calcium salts 35 . In this study, the calcium values were within the acceptable limits in natural waters of 200 mg / L 48 . Figure 18 and Table 1 show magnesium values during the study period. It was reported that the values ranged from 12.02 to 62.81 mg / L at site 1 (upstream of the dam)during September and June 2019, respectively. On the other hand, Hindiya Dam site values ranging from 14.46 to 58.39 mg / L were recorded, the findings suggested that the lower values were in September, while the higher values were in February 2019. The magnesium hardness values were lower at sites downstream of the dam than the dam site ranging from 10.07 to 58.39 mg/L at sites 5 in August and February 2019, respectively. Statistical analysis found that there was no significant difference between all P ˃ 0.05 sites except site 3 (Table 1).
It was proved that the dam affected site 3 downstream the dam which caused decreasing values of magnesium concentrations which may be related to the presence of sulphates in this site, after the discharge of water from the reservoirbottom via the opening of dam spillways 49 , which resulted in the reaction of sulphur compounds with magnesium and magnesium precipitation and reduced their values in the water column in Hindiya Dam reservoir 50 . While, the higher average of magnesium concentrations was on site 1 (upstream the dam) might be related to this site received wastewater from a local wastewater sources 51 . In this study, the magnesium values were within acceptable limits in natural waters of 150 mg/L 48 .    Table 1 show sulphate values during the study period. It is shown that during October and August 2019, the values ranged from 40 to 200 mg/L at site 1 (upstream of the dam), respectively. On the other hand, the recorded values at site near Hindiya Dam were from 50 to 200 mg/L, the lower values were recorded in October, while the higher values were recorded in January. The amount of sulphate at sites downstream of the dam was lower with values varying from 70 to 250 mg/L at sites near Hindiya Dam. The lowest values were in June at sites 3 and 5, while the higher values were in January at sites 3 and 4. No significant variations were demonstrated through statistical analysis. among sites 2 and 3 P ˃ 0.05, while, 1,5 and 3.4 which appeared significant difference with site 2 P ≤ 0.05 (Table 1).
Our finding provides that Hindiya Dam site had a lower sulphate average compared with other sites as showed in Table 1 might be due to change hydrological condition from lotic water to lentic water into reservoir, this led to precipitation of sulphate ions into bottom 52 . Whereas site 4 had a higher average of sulphate compared with other sites as a consequence of discharges of sewage effluents from the city 33 as well as may be due to the chemical nature of the groundwater. This is more abundant in the southern regions of Iraq which led to leaching sulphate ions to river water 53 .   Table 1 show nitrate values during the study period . It showed that, between June and February 2019, the values ranged from 0.17 to 3 mg / L at site 1 upstream of the dam. On the other hand, on site near Hindiya Dam, the values of this parameter were reported ranging from 0.12 to 3 mg / L, the results suggested that the lower values were in August, whereas the higher values were in February and the values were higher compared to site 1. The amount of nitrate at sites downstream of the dam increased slightly, ranging from 0.1 to 3.61 mg / L. The lower values were in August at sites 5, while the higher value was in February at sites 3. Statistical analysis revealed that there was no significant difference between sites P ˃0.05 (Table  1). It was noted that the dam affected by increase the values of this parameter in site 3 (downstream the dam) (Table1) which might be due to the impound of river by the dam caused increment of diversity and soil microbial biomass on this site thus increasing nutrient concentrations especially nitrate ions 54 . Also, Hindiya Dam site had high average could be due to nitrate-rich reservoir bottom, formed by decomposition processes of organic matter in the hypolimnetic layer 49 . However, by reviewing nitrate values, it was found lower values than permissible limit for purpose of aquatic life 48.2 mg/L 36 . Figure  21 and Table  1 show phosphatevalues during the period studied.It has been shown that, during April and March 2019, the values ranged from 0.01 mg/L to 0.046 mg/L at site 1 upstream of the dam. On the other hand, the values ranged from 0.006 to 0.047 mg/L at site 2.
The lowest values were in July, while those in October were higher. The amount of phosphate at sites downstream of the dam was increased slightly at site 3, then decreased from 0.004 to 0.11 mg/L at the last two sites 4 and 5. The lower values were in August at site 3, while the higher value was in November at the same site. It was reported by statistical analysis that there was no significant difference P ˃0.05 among sites 1, 4 and sites 2, 5 that had significant differences P ≤0.05 with other sites (Table 1).
It was found that the lower phosphate average was in reservoir zone on site 2 compared with most sites as showed in Table 1 owing to an increment of precipitation processes which decreased nutrient concentrations 52 . While, the high average was recorded on site 3 compared with other sites might be due to that this site was under dam impact by influxes of hypolimentic layer during opening of spillways of the dam. This layer was rich with phosphate that came from decomposition processes of organics and phytoplankton damage 49 . Our findings agreed with researcher such as Ling et al. 49 when investigated Bakun Dam in Malaysia. Also, Adesakin et al. 55 when they investigated Opa Reservoir in Nigeria. While, it was recorded the lowest average on site 5 compared with other sites could be due to it is far from sources of anthropogenic activities especially sewage effluents 33 .
The permissible range of phosphate concentration in surface water according to Water Watch 56 is from 0.005 to 0.02 mg / L. So according to the recorded values of phosphate that water of Euphrates River was far from permissible range.

Conclusion:
It can be concluded that the Euphrates River is very hard, oligohaline, slightly alkaline, well ventilated and clear to turbid. In addition, the turbidity and TSS values exceeded permissible limits of water quality for aquatic life in most samples especially in site below the dam. However, the river was considered by BOD 5 to be doubtful in its cleanliness water. Calcium, magnesium, nitrate and phosphate values in this study were within permissible limits