Water Quality Index Response of UI Cascade-Pond System on Catchment Imperviousness Temporal Variation

This study focuses on the water quality in a catchment area that is affected by the imperviousness cover. The purpose of this study is to prove the correlation analysis between impervious cover as the independent variable and the water quality index as the dependent variable by analysing the correlation and regression relationship. The study area is located in the catchment area at the campus of Universitas Indonesia, Depok, West Java. The data of the imperviousness is collected from the digital globe imagery and digitized based on identified rooftops. The water quality data is determined based on previous reports and collected manually in the pond by the author. The water collected from the pond will be put for laboratory test to be able to get the quality of the sample according to the determined parameters and then knowing the quality of the pond using the National Sanitation's Foundation Water Quality Index (NSF-WQI) method. The targeted water quality index is determined based on water usage suitability referring to the Indonesian government regulation number 82/2001. As time goes by, the impervious cover grows and gives an effect to the water quality of the UI cascade-pond. As a tool to set a plan for future development on the catchment area of the pond system in Universitas Indonesia, it is possible to use the linear relationship between catchment area imperviousness and water quality index. After doing a linear regression analysis between imperviousness and water quality, a relationship was found that the change of impervious cover has an effect towards the water quality and is getting worse over time.