Given the complexity of water quality data sets, water resources pose a significant problem for global public order in terms of water quality protection and management. In this study, surface water quality for drinking and irrigation purposes was evaluated by calculating the Water Quality Index (WQI) and Irrigation Water Quality Index (IWQI) based on nine hydrochemical parameters. The discriminant analysis (DA) method was used to identify the variables that are most responsible for spatial differentiation. The results indicate that the surface water quality for drinking is of poor and very poor quality according to the WQI values, however, the IWQI values indicate that the water is acceptable for irrigation with restrictions for salinity sensitive plants. The discriminate analysis method identified pH, potassium, chloride, sulfate, and bicarbonate as the significant parameters that discriminate between the different stations and contribute to spatial variation of the surface water quality. The findings of this study provide valuable information for decision-makers to address the important problem of water quality management and protection.

In this study, we analyzed the quality and the potential noncarcinogenic health risk of nitrate in groundwater in the El Milia plain, Kebir Rhumel Basin, Algeria. Moran’s I and the ordinary kriging (OK) interpolation technique were used to examine the spatial distribution pattern of the hydrochemical parameters in the groundwater. It was found that the hydrochemical parameters Ca, Cl, and HCO₃ showed strong spatial autocorrelation in the El Milia plain, indicating a spatial dependence and clustering of these parameters in the groundwater. The groundwater quality was evaluated using the entropy water quality index (EWQI). The results showed that approximately 86% of the total groundwater samples in the study area fall within the moderate groundwater quality category. The spatial map of the EWQI values indicated an increasing trend from the south-west to the northeast, following the direction of groundwater flow. The highest EWQI values were observed near El Milia city in the center of the plain. This spatial pattern suggests variations in groundwater quality across the study area, with potentially higher risks near the city center. The potential noncarcinogenic health risks associated with nitrate contamination in groundwater for adults and children through the drinking water pathway were assessed using the hazard quotient (HQ). The results revealed that approximately 5.7% of the total groundwater samples exceeded the HQ limit for adults, indicating potential health risks. Moreover, a higher percentage, 14.28%, of the total groundwater samples exceeded the HQ limit for children, highlighting their increased vulnerability to noncarcinogenic health hazards associated with nitrate contamination in the study area. Taking timely action and ensuring strict compliance with regulations in groundwater management are crucial for protecting public health, preserving the environment, addressing water scarcity, and achieving sustainable development goals.

A numerical investigation was conducted of steady laminar natural convection within a heated square enclosure filled with a mixture of water, carbon nanotubes (CNT), and aluminum oxide (Al₂O₃) (hybrid CNT-Al₂O₃/water nanofluid). Various heat source configurations and different volume fractions for the hybrid nanofluids were examined. The obtained results were analyzed through numerical simulation using ANSYS Fluent software. Thermal and dynamic fields were acquired, along with the Nusselt number (Nu). The influence of parameters such as Rayleigh number (Ra), nanofluid type, and heat source configuration was taken into account. Correlations between the Nusselt number and the various control parameters of our configuration were also established. The acquired findings clearly indicate that the introduction of nanoparticles has notably amplified heat transfer within the cavity (φ = 0.09). Furthermore, the heat source configuration has proven to be a pivotal element that effectively expedites the heat transfer process. Additionally, a direct correlation is observed between the increase in average Nusselt number and the augmentation in volume fraction. Notably, the most favorable outcomes are derived from the implementation of the (CNT-Al₂O₃)/water hybrid nanofluid.

In this study, the validity of the estimation of a single regression equation for the diffuse frac-tion across 22 stations in India using the two parameters: the clearness index and the sunshine ratio is tested. The homogeneity test based on Fisher’s statistics was applied to test the homo-geneity of the estimated parameters across all stations. The results showed that the p-value at the level of 5% for each model is smaller than 0.05, indicating that all stations were heteroge-neous. The Hierarchical Cluster Analysis (HCA) was used to classify the data into homoge-nous clusters. The results of HCA indicated that the longitudinal data were divided into four main clusters. For each cluster, the regression analysis was applied based on the longitudinal data then, the fixed effects model (FEM) and the random-effects model (REM) were used for the evaluation. Further, the Hausman test was applied to choose between the fixed effects model and the random-effects model. Finally, the results showed that the four best regression models were found for the selected stations in the study area.