یلدا نظری

In this study, effectiveness of the intelligent method of ANFIS-FCM adaptive fuzzy neural inference system to predict the electrical conductivity in groundwater due to physical and chemical parameters in the Rayen plain was evaluated. To achieve this, 29 water samples were taken from wells and springs across the plain and the data were chemically analyzed in the laboratory. Descriptive statistics of data and the correlation matrix of the studied parameters were obtained using SPSS software. By forming a correlation matrix, it was found that the potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl-), sulfate (SO42-), total soluble solids (TDS), total hardness (TH), compared to other available parameters, have the highest correlation with electrical conductivity (EC). Therefore, the model inputs included the mentioned parameters and electrical conductivity was also selected as the output according to the research purpose. After standardization, the data were entered into MATLAB environment and the electrical conductivity of groundwater was predicted using ANFIS-FCM method. In this method, 70% of the data (20 samples) were selected as the training data set and 30% of the data (9 samples) for the test data set. For the training data set of ANFIS-FCM model, R2 and RMSE values were 0.99994, 0.0001569, respectively, and also for test data set of ANFIS-FCM model, 0.9844 and 0.041652 were resulted for R2 and RMSE, respectively. Using the results of this model, it was found that the estimated electrical conductivity in the study area had very good accuracy and high correlation with the measured values. As a result, the ANFIS-FCM intelligent method is an effective, efficient and accurate method to estimate the electrical conductivity of water.

The Rayen plain, which is about 1900km2 in area is considered as a part of the Lut drainage basin and is located in the southwest of Lut and eastern slopes of the Hezar Mountain. This plain lies at the 110km southeast of Kerman city. Geographically, it is at 57˚, 13’ to 57˚, 54’ eastern longitude and 29˚, 23’ to 29˚, 52’ northern latitude. The average height of this plain is about 2600m above msl. Given the location of the plain at the vicinity of the Urmiah- Dokhtar volcanic Belt and considering the role of eruptions as well as volcanic rocks and hydrothermal activities on the concentration of arsenic and the role of this element in environmental problems, this study was performed on the concentration of arsenic in groundwater. In order to determine the variations and source of arsenic, in all,29 samples were collected from the water points (springs, qanats and wells).Subsequently, the concentration of As, major cations and anions(Na+, K+, Ca +, Mg2+,Cl-,SO4 -,HCO3 -), NO3 -,F-, as well as EC,TDS, alkalinity and total hardness were determined. Accordingly, isoconcentration map and correlation diagram were prepared and statistical analysis including Principal Component Analysis (PCA) and Cluster Analysis (CA)were carried out. The arsenic concentration in groundwater of this plain varies from 0.1 ppb up to 248.4 ppb with an average of 21.6 ppb. Based on the statistical analysis, arsenic concentration shows positive correlation with pH. The intrusion of hydrothermal waters into the aquifer and desorption from oxides and hydroxides of iron are considered as the main causes of high-arsenic level in some parts of this plain.