River and Coastal Model (RiCom)


River and Coastal Ocean Model (RiCOM) is a hydrodynamic model that is used to understand threats from coastal inundation events


The River and Coastal Ocean Model (RiCOM) is a numerical hydrodynamic model used to demonstrate near shore hydrologic conditions primarily surrounding water velocity and height.

The interactions of incoming waves/tsunamis with bathymetry, topography and the possible resulting inundation are the primary use of this model. This model has been used in the modelling of many locally sourced tsunami scenarios as well as far field scenarios.

RiCOM was developed by NIWA in an effort to build a framework that could effectively model the behaviour, effects and levels of inundation that coastal New Zealand could expect under different tsunami scenarios.                                    

RiCOM operates as a coastal and inundation model within defined boundary conditions for the users chosen study area. RiCOM uses an unstructured, irregular triangular grid to define the study area with varying resolution; often lower resolution in Open Ocean and deeper water with increasing resolution the closer to shore where bathymetry and topography become more of an influence.

The model is based on a standard set of equations - the Reynolds-averaged NavierStokes equation (RANS) and the incompressibility condition.

Due to the models finite area of processing (output results are for a limited study area), RiCOM is generally used with a Far-field modelling counterpart such as Gerris which will model open ocean behaviour (Water Velocities and Height) up to RiCOM grid boundary points where this data will be used as inputs for RiCOM.                                                             

State of Development Unknown

Development Contact



Outcome Areas Environmental
Management Domains Coastal, Freshwater
Intended End Users
  • Researcher
Steady State or Dynamic Unknown
Level of Integration Environmental

Input & Output Data


Open/Closed Source Closed Source
Licence Type Unknown

User Information

Operating Systems MS Windows
User Interface Unknown
Ease of Use Unknown

Technical Considerations

Analytical Techniques Input/output
Key References

Lane, E.M.; Gillibrand, P.A.; Wang, X.; Power, W. (2012). A Probabilistic Tsunami Hazard Study of the Auckland Region, Part II: Inundation Modelling and Hazard Assessment. Pure and Applied Geophysics,

Walters, R.A. (2005). Coastal ocean models: Two useful finite element methods. Continental Shelf Research, 25:775‐793.

Walters, R.A. (2005). A semi‐implicit finite element model for non‐hydrostatic (dispersive) surface waves. International Journal for Numerical Methods in Fluid. 49: 721–737.

Associated Case Studies

RiCOM - Coastal Canterbury Inundation

This case utilises the RiCOM model in conjunction with others to model near shore wave behaviour including inundation as a result of distal source tsunamis.


Other Key Case Studies

Probabilistic Hazard Analysis and Modelling of Tsunami Inundation for the Auckland Region from Regional Source Tsunami: Gillibrand, P., et. l. (2010). NIWA Client Report: CHC2010-102, GNS Consultancy Report 2010/200, Prepared for Auckland Council.

Wairakei/Te Tumu Tsunami Inundation Study: Walters, R., et. al. (2006). NIWA Client Report: CHC2006-020, Prepared for Bay of Plenty Regional Council