Land use change and its impact on water quality in the Ciliwung Watershed

The Ciliwung Watershed is a strategic water resource supporting the Jakarta metropolitan area, yet rapid urbanization has placed it under intense anthropogenic pressure. This study analyzes the relationship between land use change and river water quality in the Ciliwung Watershed for the observation years 2007, 2011, and 2014. Multi-temporal Landsat imagery (Landsat 5 TM for 2007 and 2011; Landsat 8 OLI for 2014) was classified into seven land use classes, and land use change was quantified through post-classification comparison. Water quality was characterized using five indicators — Total Coliform, BOD, COD, TSS, and DO — and summarized with the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI), supported by Pearson correlation. Over the study period built-up area expanded from 43.07% to 51.54% of the watershed area (an increase of about 3,269 ha), while paddy field, dryland agriculture, and other vegetated classes contracted. Water quality deteriorated accordingly: the CCME WQI fell from 32.85 in 2007 to 15.16 in 2014, remaining in the “poor” category, and Total Coliform rose sharply from 172,375 to 1,777,900 MPN/100 mL. Built-up area was negatively correlated with the CCME WQI (r = −0.80), whereas non-built-up classes such as dryland agriculture and open land were positively correlated, indicating that the loss of vegetated land accompanied declining water quality. These results confirm that land use changes, particularly the expansion of built-up areas, is a significant driver of water quality deterioration in the Ciliwung River.