Analysis of Rainwater Quality and Runoff Water Quality on Greenroof Based on Various Vegetation

Abstract

Rapid urbanization has led to changes in land use, especially the decline of green open space (GOS) as a result of land replacement by buildings. This phenomenon causes a reduction in vegetation that plays a role in absorbing rainwater, which in turn has an impact on increasing surface water runoff. One solution that can increase the amount of green open space is the application of greenroofs on buildings. As a major component of greenroofs, vegetation can have a significant impact on the quantity and quality of runoff water. This study aims to analyze the quality of rainwater and greenroof runoff water on greenroofs planted with three different types of vegetation especially Chloropytum comosum, Portulaca grandiflora, Arachis pintoi, and soil without vegetation as a control. The greenroof model is filled with growing media in the form of a mixture of soil and manure as high as 10 cm, a 5 cm thick layer of zeolite, a 2 cm thick drainage layer and a geomembrane layer. Greenroof runoff water is accommodated in a tank with a capacity of 120 L. Runoff samples are analyzed to determine the value of water quality parameters used, especially temperature, turbidity, total dissolve solid, potential hydrogen, NO₃^-, NO₂^-, SO₂^-4, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, NH₃. Water quality status assessment can be done by applying the Storet Method or the Pollution Index Method. Greenroof are designed to reduce nutrient values and improve runoff water quality by improving growing media and selecting plants that have high nutrient uptake.