Water Quality Analysis Using QUAL2Kw Model During The Rainy Season and Dry Season in Upper Citarum Watershed, West Java, Indonesia

Abstract

The Increasing population in the upstream Citarum watershed area can trigger increased water pollution caused by anthropogenic pollution such as from domestic waste, agriculture, landfills, and settlements. The equilibrium of ecosystems is disrupted when there is an increase in excess pollutants such as suspended materials and nutrients that will cause eutrophication. The purpose of this study was to analyze river water quality from temperature, pH, DO, BOD, Total phosphate (PO4), and Nitrate (NO3) parameters from upstream Citarum watershed waters using a water quality model, namely Qual2Kw. This model is based on the Streeter-Phelps theory, which includes the natural purification process of river water. The Qual2Kw model can be used for decision-making to limit river water pollution. The locations reviewed in the upstream Citarum watershed area were five sampling points (SP), namely at Cisanti Outlets (1), Wangisagara (2), Koyod (3), after the Cisirung WWTP (4), and Nanjung (5). Site selection is based on sources of pollutants from anthropogenic activities that can pollute river water. The QUAL2kw model is used to simulate water quality and is used as a basis for calculating the carrying capacity of pollutant loads against the desired target water quality. The simulation results of a valid water quality model with the observation results are BOD, TSS, and NO3. and parameters such as temperature, pH, DO, and PO4 are invalid because they have errors below 25%. These three parameters (BOD, TSS, and NO)3 have exceeded the Indonesian government’s water quality standard values both in the dry and rainy season. These three parameters indicate that the high pollution in the upper reaches of the Citarum River is caused by pollutant sources from settlements, agriculture, and animal husbandry.