The purpose of this review is to clarify the issues to cope with from now in order to establish more reliable and practical flood forecasting technology. This paper, as the outline of the recent efforts aimed at advancement of flood monitoring and forecasting technology by MLIT, describes the advancements of topography data, rainfall information, water level measurement, flood forecasting model and data assimilation. The current accuracy of radar rainfall information and trends of its application research for rainfall and flood forecasting are also introduced.

For rainfall forecasting, it is noted that the technology to forecast guerrilla-type heavy rain forecasting has been proposed and its forecasting accuracy with new radar rainfall information (XRAIN) has been improved. For the improvement of flood forecasting, it is important to make the best use of existing and/or new adhoc type of water level gauging data, to improve the accuracy of flood flow observation, and to innovate rainfall-runoff model & its feedback system.