About SRH-2D

SRH-2D, Sedimentation and River Hydraulics – Two-Dimension, is a two-dimensional (2D) flow hydraulic and mobile-bed sediment transport model for river systems.  It has been developed at the U.S. Bureau of Reclamation, in collaboration with two other agencies (Federal Highway Administration in the U.S. and Water Resources Agency in Taiwan).  Different versions of SRH-2D were released, as listed below:

  • SRH-2D version 2 - Modeling of flow hydraulics for river systems
  • SRH-2D version 3 - Mobile-bed sediment transport module added to v.2

The latest SRH-2D version 3 solves the 2D dynamic wave equations, i.e., the depth-averaged St. Venant equations.  It also contains the mobile-bed sediment transport module.  Its modeling capability is comparable to some existing 2D models, but SRH-2D claims a few salient features.  First, SRH-2D uses a flexible mesh that may contain arbitrarily shaped cells.  In practice, the hybrid mesh of quadrilateral and triangular cells is highly recommended, though purely quadrilateral or triangular elements may be used.  A hybrid mesh may achieve the best compromise between solution accuracy and computing demand.  Second, SRH-2D adopts very robust and stable numerical schemes with a seamless wetting-drying algorithm.  The outcome is that the model is very stable and few tuning parameters are needed to obtain a final solution.

Major capabilities of the SRH-2D flow solve include:

  • 2D depth-averaged dynamic wave equations (the standard St. Venant equations) are solved with the finite-volume numerical method;
  • Steady state (with constant discharge) or unsteady flows (with flow hydrograph) may be simulated;
  • An implicit scheme is used for time integration to achieve solution robustness and efficiency;
  • An unstructured polyhedron mesh is used, which includes the structured quadrilateral mesh, the purely triangular mesh, or a combination of the two.  Cartesian or raster mesh may also be used.  In most applications, a combination of quadrilateral and triangular meshes is the best in terms of efficiency and accuracy;
  • All flow regimes, i.e., subcritical, transcritical, and supercritical flows, may be simulated simultaneously without the need for special user intervention;
  • Modules to simulate on-stream structures such as weir, gate, culvert, bridge, obstruction, internal boundary, and 2D pressurized zones;
  • Robust and seamless wetting-drying algorithm; and
  • Solved variables include water surface elevation, water depth, and depth averaged velocity.  Output variables include the above, plus Froude number and bed shear stress.

The mobile-bed sediment transport module adopts the most general and accurate mathematical equations in its category and has the following features:

  • Multi-Size Sediment Transport (non-uniform):  All sediments may be divided into an arbitrary number of size classes and each class is tracked and transported separately
  • Total-Load (or Variable-Load) Formulation:  Allows suspended-, bed-, and mixed-load transport simultaneously
  • Non-Equilibrium Transport (vs. Exner Eq):  The sediment dynamic modeling is valid for both slow and fast flows
  • Multiple-Layer Bed Dynamics:  Take the bed stratigraphy into account and allow the simulation of sorting and armoring processes
  • Bedrock Erosion
  • Cohesive or Non-Cohesive Sediments:  They may be present at the same time and as a mixture
  • Sediment Capacity Equations:  Various selections with its own recommendations
  • Secondary Flow and Gravity:  So that the bend scout may be simulated correctly


SRH-2D version 3 (latest version)

  • SRH-2D version 3.2.4 Distribution Package (June 2019) (ZIP 41.1 MB)

SRH-2D version 2

  • SRH-2D version 2.2 Distribution Package (February 2016) (ZIP 66 MB)
  • "What’s New With Version SRH-2D Version 2.2?" (August 2012) (DOC 16 KB)
  • SRH-2D version 2 Theory and User's Manual (November 2008) (PDF 2.4 MB)
  • SRH-2D version 2 Distribution Package (2009 [November 2008]) (ZIP 3.5 MB)
  • Papers/Presentations:
    • Lai, Yong G. 2009. Two-Dimensional Depth-Averaged Flow Modeling with an Unstructured Hybrid Mesh. Paper/Presentation. (PDF 424 KB)
    • Lai, Yong G. 2007. 2D Flow Modeling With SRH-2D. MS PowerPoint Training Presentation (PDF 9.9 MB)
Last Updated: 6/27/19