Scenario of Water Sensitive Urban Design for Cimahi City, Indonesia

Cimahi City as a part of the Upper Citarum Sub-Watershed has problems with flooding, land subsidence, and clean water crisis caused by urban development. Currently, the multidisciplinary approach to urban water management has been expanded to include the hydrological cycle in it; one of the concepts that has been developed is water-sensitive urban design (WSUD). The purpose of this study is to measure changes in surface runoff as a result of changes in infiltration and runoff processes in the water cycle, calculate planned flood volume, determine the potential location and area of five WSUD elements, and formulate and measure the capability of WSUD scenarios in Cimahi City. This study uses the algebraic average, soil conservation service curve figures (SCS-CN), log-Pearson-III distribution, planned flood volume, and geospatial analysis. Based on the results of the SCS-CN method in Cimahi City in 3 time spans (2013, 2016, and 2019), there was an increase in the CN index and a decrease in the value of surface drift (S) that reflected the potential for runoff water produced. However, at the next stage of analysis, the SCS-CN method showed a decrease in surface runoff; this was due to the decreased rainfall from 2013 to 2016, then from 2016 to 2019 in Cimahi City. The geospatial analysis resulted in the potential location and area of five WSUD elements in Cimahi City. Furthermore, after testing the effectiveness of five WSUD elements and formulating a WSUD scenario, three WSUD elements were obtained as a part of the WSUD scenario in this study, namely sediment basin, retarding basin with, and stormwater harvesting. Last, the measurement of the WSUD scenario capability shows that the WSUD scenario reduces the planned flood volume by 84%.