Investigating the effects of urban landfilling based on satellite data on the water quality of Haraz Dam

Introduction: One of the major health problems in the north of Iran is the production of leachate in landfills and its penetration into water resources, soil, and river sediment. Due to factors such as relatively high rainfall, population density, and elevated groundwater levels in the northern regions of Iran, Mazandaran Province, it is essential to study and scientifically assess landfills and their impact on surface water quality in the rivers. Therefore, in this study, to investigate and prevent water pollution in the Haraz Dam reservoir and preserve water resources and public health, the effect of leachate from landfills at the Emarat site in Amol County is examined on the quality of water resources. The innovation of this study lies in its focus on the use of remote sensing data and the analysis of water quality parameters in the dam reservoir.

Materials and Methods: The study area includes Amol city and the Haraz River basin. Amol city, with a population of 400,000, produces about 280 tons of waste daily. This waste is mainly transported to the Emarat site, which is about 45 years old and is located 25 km from Amol, near the Haraz River and Dam. Using Sentinel-2 satellite images and remote sensing analysis in the Google Earth Engine platform, eight water quality parameters that can be measured and calculated using empirical algorithms, including turbidity, suspended particles, pigments, salinity, pH, NH4+-N, CWQI, and depth of points were investigated in the period '2022-11-01', '2022-12-01' for the wet season (December) and the period '2022-06-01', '2022-07-01' for the dry season (July) at three locations (base point, landfill, and dam water). Pearson regression and multiple linear regression models were used to analyze the data.

Results and Discussion: The results showed that all the quality parameters studied in Haraz Dam and the Emarat landfill have a significant correlation. The highest correlation was related to salinity (81%), turbidity (79%), and pH (78%). In most cases, the concentration of pollutants or water quality parameters increased from the sample location before the landfill to the landfill, and the intensity of this increase increased towards Haraz Dam. The study of pollutants in the wet and dry seasons also showed that the concentration of pollutants was higher in the dry season than in the wet season, which is due to the decrease in rainfall and the warm weather in this season. Also, the quality parameters of the dam water have changed significantly compared to the base point, indicating the direct effect of leachate on the quality of the dam's reservoir water. The correlations obtained from the Pearson regression model between the dam and landfill points for the water turbidity, suspended particles in water, pH, NH4+-N, water pigment, salinity, bathymetry, and CWQI models were 79%, 43%, 45%, 78%, 78%, 81%, 78%, and 71%, respectively. In contrast, the base point water quality and its impact on the dam water had the highest correlation and were significantly related, indicating a direct impact of the leachate from the building's waste on the water quality of the Haraz Dam and increased water pollution.

Conclusion: The results have shown that in most of the quality parameters, there is a significant relationship between Haraz Dam and the Emarat landfill, and in most cases, the concentration of pollutants in the dry season was higher than in the wet season due to the hot weather and other environmental factors. Therefore, the development of waste management systems to reduce pollution and effective management approaches can be a solution to increasing the quality of water resources and public health. The findings of this study will be used by organizations and institutions related to the environment, water resources, and public health.