The impacts of land use and cover change on water quality of watershed basin

BACKGROUND AND OBJECTIVES: Land use and cover change are the leading causes of water quality decline in a body of water. However, understanding spatial and temporal variability in land use and land cover change and its relationship with water quality parameters in the eucledian distance area is still limited. To overcome these limitations, this study investigated the impacts between land use and cover change on water quality parameters from the chemical, physical and biological aspects in the Upper Bekasi Watershed, West Java, Indonesia. The aims of the current study is to examine the relationship between land cover types and river water quality in the stuy area.METHODS: Water quality data of Upper Bekasi Watershed comes from six monitoring stations. The river water quality monitoring data period is 4 years, 2018-2022, excluding 2020. The water quality parameters monitored are 15, covering chemical, physical and biological aspects. The water sub-catchment area employs a Euclidean distance-based approach, and land use and land cover classes are obtained based on Landsat image data processed using Geographic Information System. Measurement of Pearson correlation is carried out to determine whether there is a linear relationship between the and use and land cover change variable, considered an independent variable, and the water quality variable as a dependent variable. Principal component analysis is used to determine the main water parameters in the data set's variation. The calculation of the Pearson correlation coefficient and Principal component analysis use statistical package for the social sciences.FINDINGS: The land use and land cover change class in the Upper Bekasi Watershed obtained five classes: built-up areas, agriculture and forests occupying more than 90 percent of the Upper Bekasi Watershed area. During 2018-2022, there was an increase in the built-up area of ​​10.38 percent, while agricultural land decreased by 11.57 percent. The concentration of nitrate, nitrite, phosphate, copper and fecal coliform experienced an increasing trend at all monitoring stations every year. In contrast, only the total dissolved solids and nitrate parameters met the river water quality standards. There is a very strong correlation between forest cover with dissolved oxygen and phospate, agriculture with nitrite and chemical oxygen demand, and built-up areas with fecal coliform. The number of key component obtained three components: the first varifactors had a strong relationship with the total suspended solids, biochemical oxygen demand, and chemical oxygen demand, the second varifactor had a relationship with the total dissolved solids, and the third varifactor had a relationship with the potential of hydrogen and fecal coliform.CONCLUSION: The correlation between land use and land cover changes and water quality in the Upper Bekasi watershed was quantified using the Pearson correlation coefficient and principal component analysis. The results showed an impact of land use land cover changes on water quality in the Upper Bekasi watershed. The results of this study can be used as a basis for water quality management in the Upper Bekasi watershed to help stakeholders select intervention methods to control wastewater pollution.