The system “WAQUA in SIMONA” (WAter movement and water QUAlity modelling) is used for 2D and 3D hydrodynamic and water quality simulation of well-mixed estuaries, coastal seas and rivers. WAQUA in SIMONA contains the shallow water flow models WAQUA and TRIWAQ, which are intended to solve the shallow water equations in 2D (WAQUA) and 3D (TRIWAQ) in an accurate and fast way.

The hydrodynamical models WAQUA and TRIWAQ compute water levels, currents and particle transport in open water. Several modules are available for temperature modelling, transport of salinity and conservative constituents.

TRIWAQ is mostly used in modelling water systems with high vertical density gradients (3D circulations where fresh water meets the sea). TRIWAQ will generally approach the physical behaviour of a water system more accurately than WAQUA, but the model computations require more time. WAQUA and TRIWAQ apply rectangular or curvilinear grids.

Commissioned by Rijkswaterstaat, Svašek Hydraulics has developed several WAQUA and TRIWAQ models for the Dutch coast, estuaries and rivers. For the port of Rotterdam a fully operational system is built, predicting currents and water level for the coming 24 hours. Besides developing, Svašek Hydraulics has a large expertise on using WAQUA and TRIWAQ models in a decision-making process. With the use of specific in-house developed presentation techniques the WAQUA and TRIWAQ results can be presented in a visually clear manner. WAQUA and TRIWAQ have been applied by Svašek Hydraulics for environmental impact assessment of cool water discharges, river improvement projects and the impact of changes in shoreline and bridge piers on currents and water levels.


  • Dutch Ministry of Infrastructure &
    Environment, Rijkswaterstaat


  • 2D and 3D currents
  • water levels
  • vertical density gradients (due to fresh-salt or warm-cold)
  • particle transport