Effectivity analysis of the application of TIA (total impervious area) and EIA (effective impevious area) in a micro scale watershed (case study on Sugutamu sub-watershed)

There are two methods that can be used to calculate the area of impervious cover on a watershed, Total Impervious Area (TIA) and Effective Impervious Area (EIA). Calculation of impervious cover generally uses the TIA method. Recently, based on several researches, EIA is the better indicator for identifying surface runoff discharge. This study aims to analyze the difference of surface runoff discharge using both TIA and EIA methods in different scales of an urban watershed area, specifically the Sugutamu sub-watershed and Sugutamu catchment area. Land cover identification with the TIA method uses the Rupa Bumi Indonesia map of 2017. While for the EIA method, the land cover identification uses the 2017 visual interpretation of high-resolution satellite imagery from the software GIS. FTUI and Cibinong stations have been selected as the daily rainfall data for the surface runoff simulation of the watershed and the catchment area using the software HEC-HMS. The result of the simulation shows that the EIA method in the urban catchment area has a more significant impact. In conclusion, the use of EIA should be considered more in micro-scaled modelling of an urban watershed's surface runoff.