Dadan SumiarsaSunardiDESTY PRATIWI2024-05-162024-05-162023-02-27https://repository.unpad.ac.id/handle/kandaga/250120210008Self-purification is a regulating ecosystem service responsible for river water quality from pollutant inputs. The Citarum River, the longest river in West Java, is a national strategic river that fulfills the water needs of the people of West Java and Jakarta. However, water quality has declined due to pollutant inputs from domestic and non-domestic activities. This study will investigate the water quality, self-purification status, and heavy metal contaminants in the upstream Citarum River in the Cihawuk Segment. Afterward, management strategies for self-purification ecosystem services in the Citarum River will be formulated. Investigation of self-purification using deoxygenation and reaeration values. Determination of deoxygenation coefficient value using laboratory (Slope method) and empirical (Hydroscience) while reaeration coefficient (O`Connor & Dobbins). The results of calculations and analysis show the value of the laboratory deoxygenation coefficient (k1) of 0.042 d-1 and empirical deoxygenation (k1`) of 1.128 d-1 with an ultimate BOD value (Lo) of 182.1 mg/l. Meanwhile, the reaeration coefficient (k2) was 0.193 d-1. The overall water quality has passed the class 2 water quality standard. Measurement of heavy metal contaminants shows heavy metals such as Pb, Zn, Mn, Mg, Ni, and Fe. Based on the deoxygenation and reaeration values, the self-purification status of the Citarum River in the Cihawuk Segment is low. The reason may be that the presence of factors such as heavy metals, pesticides, phenols, and surfactants that interfere with the decomposition process of organic matter can influence the self-purification ability. The management strategy related to self-purification is the improvement of the Citarum Harum Action Plan (Renaksi), such as water quality monitoring with additional measurement sites and parameters, centralized command direction, and improvement of the command center function to be more transparent and detailed regarding Citarum River data, and applied technologies to support quality waterregulating ecosystem servicesself-purificationsungai ciitarum