The water environment is composed of lakes and swamps, tributaries, main stem rivers, estuaries, coasts, and offshore waters, and it changes in response to various external forces such as weather, rainfall, topography, and flow. To understand and predict these changes in aquatic environments, we use tools called numerical models. A numerical model is a program that can be computed by expressing complex interactions between environmental elements as physical and mechanical numerical equations to analyze the dynamics of the water environment. Depending on the scope of application, numerical models can be classified into meteorological, watershed, river, marine, ecological, and ecological models, and an integrated approach is required for accurate analysis and prediction of the water environment. In other words, integrated modeling of the water environment requires integration of models (linking individual models that can be operated independently) and integrated modeling system (computer software that supports a series of modeling processes). Geosystem Research has modeling technology to predict changes in rivers, estuaries, and coastal environments caused by human activities and climate change using integrated aquatic environment modeling, and provides services to agencies and institutions