ویلکاکس

Accurate quantification of environmental trends must consider variation at different temporal scales when ignoring variation at one scale could lead to incorrect conclusions about variation at another scale. Many environmental monitoring programs collect temporally resolved but irregular time series data to quantify trends for regulatory, management, or research purposes. Conducting a study to understand the trends and predict future conditions in hydrological aspects such as river water quality is essential. During the last decades, river water quality monitoring has increased by measuring several water quality parameters. Therefore, the analysis of water quality trends is important in providing information about changes or variations in water quality through time series data .Furthermore, determining the quality status of water resources is necessary to adopt proper policies to prevent and enhance the reduction of water quality. Additionally, based on this information, it is possible to identify the quality of river water and implement protective measures to improve and manage rivers and drainage basins in a more integrated way. In recent years, the water quality of the Karun River has been affected by various pollutants, including agricultural runoff and industrial wastewater; Therefore, it seems necessary to monitor the quality of the river and the process of its changes over time and place to know the current situation and provide the necessary measures in the future. Therefore, this research analyzed the Karun River's water quality trend over 20 years at four water quality monitoring stations.

To check the quality of river water in hydrometric stations, the obtained data were assessed from physical and chemical parameters, including Total Dissolved Solids (TDS), Electrical Conductivity (EC), Sodium adsorption ratio (SAR), Na, and Cl in 20 years from 1998 to 2017 in four hydrometric stations including Gotvand, Shushtar, Mollasani, and Ahvaz of Karun river in the wet season (first six months of the water year) and dry season (the second half of the water year). The process of river water quality and inspecting the changes were conducted using the Mann-Kendall test and a geographic information system, respectively. Wilcox's classification was used to check the water quality from an agricultural point of view, as there are relevant standards. By putting the sodium absorption ratio against salinity, Wilcox presents a chart for the water quality assessment for agricultural purposes and can classify water into different classes based on EC and SAR values.

According to the results, the river water salinity in the wet season in three hydrometric stations significantly increased. The increment was at the level of 10% at the Shushtar and Mollasani stations. However, at the Ahvaz station, it rose to the level of five percent. Due to the different annual rainfall amounts during the study period, the river water’s electrical conductivity had relatively large fluctuations in all the investigated stations. The range of electrical conductivity (EC) alterations in the wet season was between 490 and 2800 µS/cm and in the dry season between 397 and 2806 µS/cm. TDS increased in the wet and dry seasons. Moreover, the p-value showed that the value of this statistic was significant at the level of 10% in the Shushtar and Mollasani stations and at the level of five percent in the Ahvaz station. The range of changes in the wet period was between 250 and 1750 mg/liter and in the dry period between 220 and 1700 mg/liter. The alterations in total dissolved solids were more in the wet than in the dry season and did not have a uniform trend. In fact, the decrease or increase in the amount of precipitation affected the intensity and weakness of the TDS amount during the year.

The results of the Mann-Kendall test showed that the parameters of TDS, SAR, Na, Cl, and EC increased during the last twenty years, indicating the expansion of the entry of sewage and industrial and agricultural effluents. According to the Wilcox index, water quality for agricultural purposes was in the average category in all the studied stations. Meanwhile, Na, Cl, and TDS parameters were in the average and inappropriate range in some years, being an alarm regarding the low water quality. Additionally, there is a risk of water quality decline in the investigated stations. In general, the watershed of the Karun River is noteworthy due to the presence of a large population, cities, and centers. Specifically, the city of Ahvaz and the heavy steel industries located in this watershed are important fundamental in terms of water consumption and producing pollutants affecting the quality of water resources, which faces many quantitative and qualitative challenges in water. The study of the changes in the water quality parameters of the stations located in the Karun River during the study period demonstrated that the amount of dissolved salts in these rivers increased and caused the reduction of water quality due to incorrect utilization and failure to comply with the principles of river exploitation.

The study of surface water quality control in water resources and environment management programs is very important. Surface water is one of the most important water sources that have crucial impact on agricultural, industrial, drinking and electricity production activities. Due to insufficient water sources with good quality and the increase in population growth rate and as a result of the increase in demand, the study of water quality parameters is very important. The Water Quality Index (WQI) serves as a prominent indicator in classifying surface water quality. Moreover, in recent years, the TOPSIS method has gained traction for evaluating water quality. This approach, known for its simplicity, is increasingly utilized in prioritizing river water and assessing its quality. Through this index, various components of water quality are condensed into a single numerical value, effectively expressing overall water quality. To ascertain the weight index, Shannon's entropy method was employed. Furthermore, to assess water suitability for drinking, agriculture, and industrial purposes, Schuler, Wilcox, and Piper diagrams were utilized. These diagrams provide valuable insights into the quality of water, aiding in decision-making processes regarding its utilization across different sectors. Therefore, the results of this study also confirmed the effectiveness of the TOPSIS method in identifying contaminated stations.

This research focuses on evaluating the water quality of three stations within the Aji Chai river watershed on an annual basis. These stations are identified as Arzanag, Akhola, and Markid. The assessment spans the years 2003 to 2021 and aims to classify water quality for both drinking and agricultural purposes. Utilizing the standards set forth by the World Health Organization, the surface water quality index of the Aji Chai basin is investigated to ascertain its suitability for drinking purposes. Shannon's entropy theory was used to prevent expert judgments in determining the weight of each parameter. TOPSIS method was used to classify eleven qualities including TDS, EC, pH, HCO3-, Cl-, , Ca2+, Mg2+, Na+ , K+ and TH. In all the three stations water quality were ranked, based on TOPSIS numerical values. Also, in order to check the quality of drinking, agricultural and industrial water, Schuler, Wilcox and Piper diagrams were used. 

The initial findings from the %RE error analysis revealed that throughout the entire statistical period (2003-2021), the %RE values were consistently close to zero, with the majority being positive. This suggests that the total number of cations surpasses the total number. In terms of the Shannon water quality index, the results indicate that Markid station exhibited the highest index value at 945.92, while Arzanag station displayed the lowest value at 127.365 among the surveyed stations. The results of the water quality index showed that Arzanag and Akhola stations are in an average condition (100 < EWQI < 150) and Markid station is in a very poor condition (EWQI > 200). According to Schuler's diagram, it was found that the water of Arzanag station is in the average level in terms of water quality, which is in a good position in terms of quality compared to the other two stations, while the water of Akhola station is in a good position. In the range of poor quality, Markid water was undrinkable, which ranked worst among the three stations. According to the Wilcox diagram, it was found that the water quality of Markid is very poor, which is even outside the boundary of the Wilcox diagram, while the water of Arzanag station was ranked 1st in terms of quality. Arzanag water is in C4S2 class in terms of quality. Finally, the water class of Akhola station was placed in the C4S4 class (in the Wilcox chart), which shows very low water quality. According to the TOPSIS method, the first priority in terms of water quality pollution belonged to Markid station. Two other stations, including Akhola and Arzanag, were ranked second and third in this respect. Therefore, the most important station in this basin is Markid station. 

The results of Shannon water quality index showed that among the stations, the highest index value is related to Markid station with a value of 945.92 and the lowest one is related to Arzanag station with a value of 127.365. According to Schoeller diagram, it was found that the water quality of Arzanag station is average, compared to the other two stations, it was in the right place and the water of Akhola station was in the range of poor quality. The quality of Markid water was found to be undrinkable, which was the worst one among all the three stations. The range of TOPSIS values in different stations is between 0.054 and 0.894, which belonged to the Arzanag and Markid stations, respective ly. According to the results of the Arzanag station, the best water quality condition and the Markid station were assigned the worst water quality condition among all the three stations.

The limitation of the country's water resources and the aggravation of this limitation, which is caused by the continuous increase in the demand, has caused the maximum use of the available water resources and the increase in productivity and, as a result, the increase in production per unit area. The present research was conducted with the aim of evaluating the water quality of Dez River in terms of efficiency in pressurized irrigation systems.

For quality assessment of Dez River water in terms of efficiency in pressurized irrigation systems, 7 hydrometric stations were selected including Sepid dashte Sezar, Sepid dashte zaz, Tange pange sezar, Tange pange bakhtiari, Dezful, Harmaleh, and Bamdezh. Qualitative data of Dez River water along a decade (2005-2014) were taken from Khuzestan water and power authority.

The Qualitative analysis using piper diagram showed that water quality in Sepid dashte Sezar, Sepid dashte zaz and Tange pange sezar stations was calcium bicarbonate. Although, in Harmaleh and Bamdezh stations the most of samples were neutral. The results showed that salinity amount was increased from the upstream to the downstream of the river. Whereas, Bamdezh station had low to medium limitation at 95 percent of times for drip irrigation usage. Dez River had no limitation for infiltration due to suitable averages of SAR and EC. Besides, cations and anions coefficient of correlation was variable between 0.67 to 0.78 and -0.249 to 0.6 respectively. Chlorine in the river water from Harmaleh station toward the downstream of the river, had low to medium limitation for sprinkler irrigation usage. The most limitation of bicarbonate was observed at 97.5 percent of times in Sepid dashte Sezar station for using sprinkler irrigation. In addition, sodium amount in Harmaleh and Bamdezh stations compared to Dezful station increased 134 and 233 percent respectively. Langelier Saturation Index (LSI) was negative in the entire stations and calcium carbonate sediment won’t be created.

Groundwater is an important source of exploitation in arid and semiarid regions. In the Azarshahr plain, due to the reduction in annual precipitation and lack of surface runoff, groundwater resources play an important role in supplying agricultural, drinking, industrial and domestic water requirements. The aim of this study was to evaluate the quality of groundwater resources in Azarshahr plain for agricultural irrigation and to analyze the EC and SAR variations by using geostatistical methods. So, for spatial mapping of SO4, Cl, TDS, EC and SAR, the observational data from 47 wells in this region, which were measured during the years 2003-2017, were utilized. In order to select the best interpolation method, Kriging approach with Gaussian variogram and IDW methods were used. The obtained results revealed that the Kriging with Gaussian variogram showed the lowest RMSE and the highest NS values. The results of the groundwater quality classification (using Wilcox diagram) and EC/ SAR zoning showed that the groundwater quality in the Azarshahr plain is very saline (C4S1) in most of the cases, which might be linked to the higher amounts of withdrawals from the aquifer.

Evaluation of groundwater hydro chemical characteristics is necessary for planning and water resources management in terms of quality. In the present study, a self-organizing map (SOM) clustering technique was used to recognize the homogeneous clusters of hydro chemical parameters in water resources (including well, spring and qanat) of Kerman province; then, the quality classification of groundwater samples was investigated for drinking and irrigation uses by employing SOM clusters. Patterns of water quality parameters were visualized by SOM planes, and similar patterns were observed for those parameters that were correlated with each other, indicating a same source. Based on the SOM results, the 729-groundwater samples in the study area were grouped into 4 clusters, such that the clusters 1, 2, 3, and 4 contained 73%, 6.2%, 6.7%, and 14.1% of groundwater samples, respectively. The increase order of electrical conductivity parameter in the clusters was as 1, 4, 3 and 2. The results of water quality index based on the entropy weighting (EWQI) showed that all of the samples with excellent and good quality (36.3% of samples) for drinking belonged to the cluster 1. According to the Wilcox diagram, 435-groundwater samples (81.7%) in the cluster 1 had the permitted quality for irrigation activities, and the other 285-groundwater samples were placed in all four clusters, indicating the unsuitable quality for irrigation. The Piper diagram also revealed that the dominant hydro chemical faces of cluster 1 were Na-Cl, Mixed Ca-Mg-Cl and Ca-HCO3, whereas the clusters 2, 3, and 4 had the Na-Cl face. This study, therefore, shows that the SOM approach can be successfully used to classify and characterize the groundwater in terms of hydrochemistry and water quality for drinking and irrigation purposes on a provincial scale.

Groundwater is one of the most important water resources in arid and semi-arid regions. The main aim of this study was to evaluate the accuracy of interpolation methods for predicting the spatial distribution of some groundwater quality indices for Shahr-Babak Plain in Kerman Province. First of all, the water quality data of about 56 wells in the period 2011-2012 were selected; based on their accuracy and scattering in 2011-2012; then the missing data were reconstructed and controlled. According to the Kolmogorov-Smirnov test, data were not normally distributed, so the logarithms of them were used. The results showed that for these water quality parameters, the best variogram models were the Spherical, Linear and Exponential ones. The variability of the data was investigated using different interpolation methods such as Kriging, Cokriging and IDW with powers 1 to 3. The results showed that the geostatistical methods had remarkable superiorities to the deterministic methods so that the Kriging method was the best one. For the parameters TDS, EC and Cl the lowest values of RMSE were calculated using Ordinary Kriging with the Spherical model, which were 844.6, 1214 and 10.61, respectively. Then the zoning maps of these three elements were drawn with the most appropriate method of ArcGIS software. The spatial and temporal variations of the most parameters were investigated and their correlations with the decreasing trends were shown during the period of the study. Also,the suitability of the plain aquifer water for agricultural and drinking uses was investigated with the Wilcox and Schoeller Standards. Wilcox standard results indicated that the water qualities of 30 wells were in unsuitable conditions, and the results of Schoeller diagram confirmed that in 49.3 percent of the plain area the groundwater was undirinkable.