علوم محیطی (Jun 2024)
Assessment of Relationship between Land Use Pattern and Spatial Distribution of Water Quality at the Watershed Scale: A Case Study of Maroon River Sub-basin
Abstract
Introduction: The health of the river basin is determined by the health of its ecosystem to provide important and valuable resources and services for human use and the basin itself. However, the changes in the land use pattern, which is an effective reflection of anthropic activities, have greatly disturbed the health of the river and are the main driver of water quality reduction. Examining the relationship between land use patterns and river water quality provides an important basis for water quality safety and effective land use management. Therefore, the aim of this study is to investigate the influence of land use patterns on surface water quality based on the water quality monitoring data and land use data from 38 sampling points in the sub-basin of the Maroon River. Material and Methods: In order to sample from the study area, first, the boundary of the sub-basin of the maroon river was determined, and then the sub-basin was divided into different smaller sub-basins using the hydrological analysis tool in ArcGIS software, and the map of waterways in the region was also prepared. Then, sampling stations were selected from the exit point of each of these sub-basins in the main sub-basin area. In order to measure the water quality parameters of the studied area, sampling was done from 38 monitoring stations in the sub-basins in triplicates in the spring of 2023. The land use map was prepared using Landsat satellite images to evaluate the changes and the impact of land use patterns on the water quality status of the Maroon River sub-basin. Then, using geographic information system and multivariate statistical techniques, the effects of land use on river water quality in the Maroon sub-basin were estimated. In addition, in order to evaluate the quality of river water in different sub-basins, water quality data was analyzed using the water quality index (WQI). Results and Discussion: The results of the evaluation of the distribution of land use patterns showed that the use of pasture is the dominant use in the sub-basin of the Maroon River and the water quality parameters exhibited significant changes in the stations covered by agricultural and forest use. The results of correlation analysis and linear regression of water quality parameters and land use patterns in the Maroon River sub-basin showed that agricultural land has a negative relationship with pH and DO parameters and a positive relationship with parameters , and Ca2+, forest land has a positive correlation with DO and a negative correlation with , and urban land also showed a negative correlation with DO. WQI values in different monitoring stations were estimated between 73.80 and 288.73 which showed that the health level of the river upstream of the sub-basin was better than downstream. In general, based on the WQI classification, 62.5% of the water quality of the Maroon River sub-basin was in the "poor" class, 25% in the "very poor" class, and 12.5% in the "good" class. Conclusion: The findings of the research showed that agricultural land was the key factor affecting the water quality parameters and as a result the decrease in water quality in the sub-basin of the Maroon River, so limiting the discharge of runoff from agricultural activities is critical for improving water quality in the study area. This study highlights the importance of LULC changes in water quality for making informed decisions on proper watershed planning and management.
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