Evaluation of GSMap (Global Satellite Mapping of Precipitation) with the reference to rain gauge observations in Banjarbaru City, Indonesia

Abstract Climate change as one of the essential impacts of global warming in the last few decades, has resulted many disasters in different ways, i.e., floods and landslides, as the effect of extreme rainfall events. At the end of February 2023, a severe flood event occurred in Banjarbaru City, resulted an inundation in many areas. A flood control system is recommended to face this problem. In this research, the flood control presented is a non-structural method by analyzing rainfall data based on field data and GSMaP satellite-based rainfall data. This research aims to determine the type of correlation coefficient relationship between BMKG data and GSMaP satellite-based rainfall data. The data collection includes primary data in the form of field surveys to identify rain events and secondary data obtained from GSMap satellite-based rainfall data and field rainfall data obtained from BMKG online. The Melchior design flood calculation method is used for calculating a flood-designed discharge. The results show that GSMaP data have significant values that correlate to rain gauge observations from BMKG stations in Banjarbaru City. An enough to high correlations values indicate that this GSMaP can be used as an alternative source of rainfall data for hydrological analysis, in particular to ungauged basin.