Application of Water Quality Index in Assessing water Quality: A Case Study of the Shatt Al Arab River.

This investigation pertains to the evaluation of water quality in the Shatt Al-Arab River, located in the Basrah province of southern Iraq, from 2017 to 2022. Its quality should be assessed regularly, and the condition of water resources should be maintained accordingly. The most common analytical method for describing and assessing general water quality is the Water Quality Index (WQI). Various physicochemical parameters like pH, total dissolved solids, total hardness, calcium, magnesium, chloride, and total alkalinity are considered for the present study. The Weighted Arithmetic Water Quality Index Technique is used to evaluate these data. For checking the portability of the parameters within the acceptable limit, WHO is adopted. According to the study mentioned above, the quality has been found to be very low compared to the WQI value. It is also observed that the water was found unsuitable for drinking purposes, and it is considered harmful to human health; therefore, it requires some kind of processing before use. This study will be beneficial to policymakers for identifying and providing details about water quality in the form of a specific value.


Introduction
Water is a crucial natural resource with social and economic significance for humans.Without water, the survival of humans would be in jeopardy.Groundwater and surface water are the world's most significant drinking supplies [1,2].An alteration in the quality of the water source could arise from the accumulation of pollutants in surface water caused by human factors, climate change, and hydrology, due to widespread social and economic growth.In the field of managing water resources, maintaining a suitable level of water quality is a challenge [3,4].Water bodies' physical, chemical, and biological characteristics can be examined for changes associated with either natural or man-made phenomena [5].As a result, by gathering samples and gathering data at particular locations, the physical, chemical, and biological parameters-also known as variables-can be used to test the water quality of any given body of water [6].One tool for assessing water quality is the Water Quality Index (WQI), which is also one of the best ways to summarize the quality of the water since it condenses a lot of information into a single number, making it easier to understand and present the facts in an understandable way [7].To better understand water quality, several researchers have conducted a variety of studies [8,9].The Water Quality Index (WQI) is a useful tool for evaluating or categorizing the quality of different types of water.It can be used to identify physical and regional variations in surface water conditions as well as to educate policymakers and concerned citizens about water quality [10,11].There is currently increased interest in artificial intelligence and its possible applications for controlling and monitoring water quality [12].It is crucial to process, assess, and determine the water resource's quality.Measurements of T C°, electrical conductivity (EC), organic materials, metals, and all other parameters are commonly used to compute WQI [13].because it can ascertain the ultimate water quality condition without the need to interpret individual evaluation methods [14].Then, instead of using temporary weights, these rates are converted.The final weight of each variable is then obtained by dividing each temporary weight by the total of all the temporary weights [15,16].An artificial neural network approach has recently been used to estimate water quality, saving time and effort [17].WQI has an advantage over other evaluation techniques since it can ascertain the ultimate state of the water quality without having to interpret each variable [18].The primary goal of the current study is to use WQI to determine whether the quality of Shatt Al-Arab water is suitable for drinking.

Study Area and Data Collection
The Shatt Al-Arab River is located in the south of Iraq.The Shatt Al-Arab River is roughly 192 kilometers long.It empties into the Arabian Gulf after flowing southeast through Basrah City.The width of the Shatt Al-Arab River varies over its course, reaching 2000 meters at the estuary, 600 meters close to Basrah City Center, and 250-300 meters near the Euphrates-Tigris confluence.It is situated between latitudes (30) and (59) in the north and ( 47) and (26) in the east.The data period is from January 2022 until August 2022.Statistical analyses on the data that had been collected.The sites where the stations are represented as Al-Qurna, Karmat Ali, Al-Ashar, and Sehan.Figure 1 shows the study area map of the Shatt Al Arab River.

2-2 Methods
The test procedure is based on the method described by the American Public Health Association (APHA) in 2012 for the collection and testing of water quality parameters for the assessment of water quality [19].The specified physical and chemical parameters were assessed in accordance with the recommendation provided by the Iraqi Standard Water specification code, and WHO [20].An analytical method known as the Water Quality Index (WQI) was used to measure a number of additional water quality factors and determine their impact on the overall quality of the water.In the following studies, the WQI was evaluated using the Weight Arithmetic Water Quality Index (WAWQI) method [11,12].Ten characteristics of the water quality-pH, turbidity, and total dissolved solids-were analyzed.Complete alkalinity, sulfate, nitrate, calcium, magnesium, chloride, and total hardness.This study employed the WAWQI method, which consists of the following four steps [21]: 1-Choosing parameters to measure the quality of water [16].
2-Every parameter has a scaled quality rating.
3-The weight of the unit (Wi) is determined and is inversely related to the standard value (Si) of the suggested parameters [22].4-The final WQI is obtained by aggregating the sub-index values.The WQI was computed using the following formulas.Equation (1) was used to calculate the unit weight (Wi) for each water quality parameter as follows [13,14].
where Wi represents the ith parameters ′ unit weight.
K is denoted a proportionality constant.Si is the standard value of each parameters .
Technium Vol.21, pp.73-82 (2024) ISSN: 2668-778X www.techniumscience.com Equation ( 3) was used to determine the quality rating scale (Qi) for each parameter [23]: Equation ( 4) determined the quality rating scale for pH, where Vo is the parameter's ideal value and Vi is the concentration value for the ith analyzed parameter.While the ideal value of every other parameter is zero, with the exception of pH, which has an ideal value of 7. The final equation can be presented in Equation (5).
SIi is the sub index of the I th parameter and I represents the number of the parameter taken into consideration.In Table 1, The ideal values and unit weights for the water quality variables and their standard values are shown [17].It was noted that the concentration of various parameters in Table 3 was high and had surpassed the acceptable limit for the area under consideration.In the majority of the cases, the TDS, TH, Ca, Mg, Cl, and total alkalinity concentrations were higher than the allowable limit for the specific year.It has been noted that the TH, TDS, Mg, and total alkalinity influence the water quality and contribute to the WQI with other parameters.Total hardness and TDS, on the other hand, were much higher than the values for TH and TDS given in the acceptable value (WHO) guidelines.The pH values lie within the allowable limits.With rising values for these parameters, the WQI score increases.WQI, which is often used for the recognition and analysis of quality and the state of pollution, can be considered a representation of the combined impact of various water quality variables on the overall water quality.The ecological status of water may be assessed using the WQI value produced using the WAWQI method procedure.The WQI for all samples taken was calculated according to the procedure explained in materials methods, as shown in Tables (4,5, 6, and 7).WQI indicates the quality of water in terms of an index number, which represents the overall quality of water for any intended use.On the basis of the WQI, the water quality index obtained for water samples in different sites in August 2017 and August 2018 (for years in 2018, 2020, 2021, and 2022) is shown in Table 8.According to the range of the WQI, a low number denotes the best water quality, while a higher number denotes the worst quality.Table 8 shows the calculated WQI values for the study area.The WQI for all sites was greater than 100, which indicates an unsuitable quality of water.