Water quality index analysis of lake Rawa Besar, Depok, West Java, and its relationship with land use

The lake's catchment area is one of the objects of land use conversion as a space for community needs. The boundary of the Lake Rawa Besar has been widely used by the surrounding community to carry out activities. Human activity and land use around lake shorelines can affect water quality. This study aims to investigate the pattern of spatial distribution of Lake Rawa Besar water quality and its relationship with land use within the lake shoreline. Water quality was tested based on the insitu sampling method in 30 samples evenly distributed in the water body and laboratory testing based on 6 water quality parameters such as turbidity, BOD, total phosphate, total solid, pH, and nitrate. Water quality is measured based on the water quality index level of WQI (Water Quality Index) and interpolated using the IDW method. Large-scale land use is used from digitizing large resolution images and potential sources of pollutants obtained from field observations. The results showed that the water quality in water bodies was almost evenly distributed with mild polluted criteria. Land use in the form of domestic activities affecting the quality of water in the Lake Rawa Besar is characterized by high turbidity and BOD values, while the total phosphate, total solid, nitrate, and pH value is low. The high correlation between turbidity and BOD which is impacted from land use concluded that the poor quality of the lake's water was caused more by organic waste.