Changes in hydrological processes due to climate change will have various potential impacts on water resources and related human activities. To prevent crop failure caused by high temperatures, farmers are likely to adopt adaptation measures that could alter regional water use patterns. However, the implementation of these measures may be hindered by other factors, even when their benefits are recognized: “soft adaptation limits.” We introduce a novel framework for predicting the occurrence of soft adaptation limits in typical Japanese watersheds, where irrigation water use is predominant. The framework integrates two process-based models—a crop model and a watershed hydrology model—designed to evaluate water resources and rice production. This framework successfully predicted potential soft adaptation limits that may arise when implementing adaptation measures. We applied this framework to other regions, which enhanced our understanding of soft adaptation limits, yielding more robust insights based on varying climate and regional characteristics.