Numerical modeling of sub-surface drainage systems in Citraland, West Surabaya

Abstract

Flooding occurs when the existing drainage system is unable to accommodate the water flow, that is due to a decreased drainage system capacity, increased flow of water, or a combination of both. On January 31, 2019, two hours of heavy rain caused Citraland housing to be flooded up to one meter high. This study aims to overcome the existing flooding problems through the assessment of sub-surface drainage systems for hilly areas in the Citraland residential area, Surabaya. Annual rainfall data from the rain stations around the residential area will be processed according to the proportion of the area to get a rain analysis plan that will be used in modeling. Plan rainfall data, area data and types of land cover, and catchment area data are analyzed hydrologically to get the design discharge. The hydraulic data of the dimensions of the existing drainage system will be analyzed for the capacity in flowing of Flow Plan. The Drainage System is then modeled using the Storm Water Management Model (SWMM) application. Through using topographic data and land cover, four alternative solutions have been modeled which include the addition of water reservoirs in various housing locations to overcome existing flooding. The results of this study are the second scenario through the addition of one water reservoirs which can handle flooding most effectively because it reduces 34.61% of the inundation volume that occurs. In addition, the fourth scenario through the addition of three water reservoirs can reduce 57.82% of the inundation volume that occurs.