Composite Index and Regulatory Assessment of Water-Quality Impairment in the Sedapat River and Shallow Dug Wells near Sukawinatan Landfill, Indonesia

Abstract

Leachate from landfill sites (TPA) is a source of pollution for nearby water sources. This study assesses the impact of leachate on river and groundwater quality in Palembang, Indonesia, by combining a composite pollution index and Partial Least Squares Structural Equation Modeling (PLS-SEM). Leachate Pollution Index (LPI), Nemerow Pollution Index (NPI), Organic Pollution Index (OPI), Heavy Metal Pollution Index (HPI), Leachate Water Pollution Index (LWPI), as well as changes in LWPI (ΔLWPI) were used to analyze the intensity of pollution. The PLS-SEM results show that leachate significantly reduces river water quality (path coefficient = 0.38, p = 0.021), with high nitrogen and iron pollution. Conversely, the structural influence of leachate on groundwater quality is not statistically significant (path coefficient = 0.117, p = 0.511), although local pollution is detected at distances of <100 m from the landfill, as indicated by very high LWPI values. The strong negative correlation between the distance from well to landfill and ΔLWPI (Pearson r = −0.79; Spearman r = −0.84; p < 0.001) highlights the role of spatial heterogeneity and the soil’s attenuation capacity in contaminant migration. These findings support the need for improved leachate treatment and enhanced protection of local community water sources.