About RRI

The Rainfall Runoff Inundation (RRI) model is developed to analyze the rainfall-runoff process within a watershed, flood flow downstream in rivers, and flood inundation the floodplains. The RRI model is publicly available on the ICHARM website (International Centre for Water Hazard and Risk Management, PWRI) and can be obtained free of charge by anyone.

About RRI on iRIC

RRI on iRIC is a program developed by Mr. Asahi of Riverlink, primarily, who modified the original RRI model to make it compatible with iRIC software. Subsequently, it has been integrated with rainfall-sediment runoff models (RSR model) and other functionalities developed by ICHARM. The display of calculation results using iRIC’s post-processor is particularly useful. Please note that some tools requiring maintenance, such as those for creating topographic and rainfall data, are limited to UC (iRIC User Consortium) members.

About RSR model

The RSR model has been developed to analyze the transport of water, sediment, and driftwood across an entire watershed by using a “unit channel model.” This model defines “unit channels” as the segments between confluences within the river channel cells of the RRI model, and utilizes hydraulic data regarding slopes and river channels obtained from the RRI model’s results. It also allows for the inclusion of sediment supply from landslides, debris flows, and slope erosion. Currently, the RSR model is available only through RRI on iRIC, and it will be updated sequentially.

The solver manual and the examples are as follows;
RRI on iRIC user manual