عنوان مقاله [English]
Water quality is the process to determine the chemical, physical and biological characteristics of water bodies and identifying the source of any possible pollution or contamination which might cause degradation of the water quality. Due to the rapid growth of industries, the disposal of liquid and solid wastes is increasing, thereby polluting soil and water. If the waste is not disposed of properly, then it percolates into the ground and causes problems like groundwater contamination, degradation of vegetation, soil contamination and modification of soil properties, etc. Nevertheless, traditional methods of water quality monitoring are often expensive and time-consuming. This is especially important for large water bodies such as lakes, dams, and rivers where sampling does not cover the entire body of water. Publicly available RS data are collected at regional scales and temporal resolutions (i.e., repeat collection time) that are much more frequent than field sampling campaigns. The physics and chemical characteristics of water can be determined from spectral signatures. Also, extracting water quality measurements directly from satellite imagery can allow rapid identification of impaired waters, potentially leading to faster responses by water agencies. Remote sensing data is an appropriate alternative to monitoring water resources due to its time and cost-effectiveness in a wide range of temporal and spatial scales. Currently, there are various types of remote sensing data such as hyperspectral and multispectral data that can be used to monitor and evaluate water quality. Geographical information systems (GIS) and remote sensing (RS) have been used extensively to assess the water quality all over the world. The Euphrates River is one of the most important rivers in Iraq, which has hosted various civilizations in the ancient Mesopotamia region since ancient times and is still of great importance to the urban and rural communities of Iraq. The Hillah River is one of the two main branches of the Euphrates River, which flows eastward by branching off from it. This river is the most important river in the Babylon governorate in Iraq, which passes through a wide area and several small streams flow from it to supply water to agricultural lands in other governorates. The Hillah River passes through several cities and is affected by industrial, agricultural, and domestic wastewater, which has received less attention than other areas of the Euphrates River. For this purpose, in this research, a detailed assessment of the quality and pollution of the Hillah River in the Babylon governorate is carried out using different methods of remote sensing, GIS, and field and laboratory operations to determine the quality of this river.
the purpose of its performance is to assessment the quality of water and soil for the area of Hillah river in Babylon governorate in Iraq. The method of collecting data and information needed to perform quantitative and qualitative analyzes in research was based on field, laboratory and library operations, and various software tools were used in data processing. In order to determine and collect water and soil quality samples, field operations have been used. For this purpose, the area of Hillah city is considered as the base point and samples have been collected parallel to the river Hillah in the north and south of the city. Accordingly, in terms of number, distribution and accuracy in field sampling, 10 points were collected from the area by using Garmin handheld GPS device, 7 points were taken from water and 3 points were taken from the soil of the area. The field work to determine the sampling locations was based on several reconnaissance trips and as a result, the locations of the main water sampling stations were identified. Then, they visited the desired places twice a month, and each time they visited, relevant samples were taken. The samples were collected in standard plastic bottles with a capacity of 1.5 liters and their lids were tightly closed. Paying attention to the change in composition, soil samples were taken with a wider spatial distribution and from places with far distances from each other in the Hillah river basin, and the volume of each soil sample varied between 1 and 1.5 kg. Two different laboratories in Babylon governorate have been referred to perform quality tests on the collected samples. The laboratory measures have been carried out in two separate stages. In the first step, the measures of preparing the samples and separating them from each other have been carried out, which includes labeling, determining the date of water and soil samples, and classifying the samples for laboratory analysis. In the second stage, laboratory equipment and operations have been used for the qualitative analysis of the samples, and various devices such as CRISON have been used to test the physical and chemical parameters on the samples. Using laboratory tools and facilities, various physical and chemical variables of water quality have been measured based on the collected samples. For this purpose, 13 parameters have been tested on the samples. Electrical conductivity and total dissolved solids were measured using an EC meter and pH using a pH meter according to the relevant methods. The capacity of calcium and magnesium ions in water samples has been measured using the weighing method. Soluble sulfate, phosphate and nitrate were measured by a spectrophotometer. Sodium concentration in water was measured by flame photometer. Chloride in water was estimated from the scaling method using silver nitrate standard solution and using potassium chromate solution as the relevant guide and the results were expressed in ppm. Total hardness was measured as calcium and magnesium in water as milligrams per liter or ppm. Turbidimeteror is used to measure water turbidity. Finally, the iodometric method has been used to measure dissolved oxygen in water. In soil quality measurement, in addition to the parameters of electrical conductivity, pH, calcium, magnesium and sodium, which are also evaluated in the measurement of water samples, other parameters were also measured. including sodium absorption ratio (SAR) and calcium carbonate (CaCo). For the measurement of the mentioned two elements, special laboratory tools have been used like other elements. WQI index has been used to evaluate the water quality at the region of the Hillah river. For this purpose, the data related to the stations sampled from the water level were entered into the calculations of the WQI index, and based on this index, the water quality was evaluated on a monthly basis, and water quality maps were prepared for the region. The WQI index equation creates a range between 1 and 100, where 1 means the poorest and 100 the best water quality, and within this range, five classes are set to classify the water quality as very poor or inadequate, poor, moderately good, good and excellent. For satellite images processing, Landsat satellite imagery data provided by the United States Geological Survey (USGS) database archive has been used. In this regard, the image of Landsat 8 satellite OLI sensor for the date 2021/06/27 of the area has been selected as the main satellite data for processing.
The research results can be presented in several sections. In the analysis of water quality in terms of quality parameters, it has been determined that, except for several cases in different months, in most cases, the concentration of chemical parameters of water did not exceed the permissible limit, and the physical parameters were appropriate. However, the results of the drinking water quality index have shown that the water of the Hillah River is at a poor and very poor level in terms of quality according to the location of the samples, and the spatial quality map of the Hillah river has also shown that the central to northern areas are of a more suitable quality than The southern regions have it, the main reason of which is the concentration of agricultural lands and the entry of waste and various effluents into the water in those areas. The results of evaluating the physical and chemical quality of soil in the studied area have also shown that soils with sandy texture are richer than mixed clay soils in terms of parameters such as electrical conductivity, sodium, calcium, magnesium, and SAR, and on the other hand, pH and calcium carbonate of Clay soils were more than sandy soils. The evaluation of the correlation of the parameters between the values of the water and soil samples has been done and the coefficient of the orrelation between them has been obtained, and in some cases, there has been a high correlation between the parameters. Finally, by evaluating the correlation between the quality parameters and the Landsat image bands in terms of combinations and band ratios, it has been determined that there was a direct correlation in a few cases, and on the other hand, the linear relationship also indicated the absence of a relationship between the WQI index and the spectral bands.