Global water and energy cycles occur with various interactions among atmosphere, ocean and land. Approximately 10 percent of the water exchanged between atmosphere and oceans transports through rivers and 40 percent of land precipitation flows into oceans from rivers, which suggest the major role of rivers in the global water cycle. In this study, we assessed the impact of inundation processes on various climatological aspects using different spatial resolutions. We implemented the inundation processes described in CaMa-Flood, a river inundation model, into a climate model MIROC5. By changing the spatial resolution of CaMa-Flood, we assessed the impact of higher resolution river inundation processes on the coupled model. The reproducibility of river discharge showed an overall improvement. Inland floodplains showed an increase due to the representation of complex topographical features, which also improved the model estimates with increased evaporation and decreased 2m air temperature.