Liquids HCA Tool introduction
The Liquids HCA Tool is a part of G2-IS’s comprehensive pipeline integrity management software suite that helps operators manage risk, ensure compliance, and optimize performance. The Liquids HCA Tool is designed to meet all the requirements for ‘could affect’ segment determination for hazardous liquids pipelines, as specified in 49 CFR §195.452, Pipeline integrity management in high consequence areas. The Liquids HCA Tool performs hydrocarbon plume transport simulations that support the following product transport mechanisms:
- Overland flow – simulation of the hydrocarbon release plume over the surface of the Earth, taking topography into account.
- Hydrographic transport – simulation of the downstream transport of a hydrocarbon release plume that has entered into a stream/river network.
To facilitate overland flow release plume simulations, The Liquids HCA Tool uses a customized version of an open source Computational Fluid Dynamics (CFD) modeling package, called GeoClaw, to perform overland flow plume simulations (Berger, M.J., George, D.L., LeVeque, R.J. and Mandli, K.M. (2011) The GeoClaw software for depth-averaged flows with adaptive refinement.Advances in Water Resources, 34, pp. 1195 – 1206). GeoClaw uses high-resolution, Godunov-type, shock-capturing finite volume methods and Riemann solvers to solve the shallow water equations, a simplified, depth-integrated version of the general Navier-Stokes equations for incompressible, viscous fluid flow. Of particular importance to modeling pipeline releases and storage tank ruptures, dry states in the model space are handled automatically by GeoClaw. Unlike many CFD tools, the use of shock-capturing methods allows dry portions of the model space to be handled implicitly and accurately. GeoClaw also incorporates Adaptive Mesh Refinement (AMR) to facilitate efficient and stable simulation of the highly transient flows typical of pipeline releases and storage tank ruptures.
G2-IS has modified the GeoClaw kernel, replacing the Manning equation in GeoClaw for friction factor calculation with the more generic Darcy-Weisbach equation, which allows for the incorporation of fluid density and viscosity terms. Unlike many other offerings, this enhancement enables GeoClaw to be legitimately used in modeling fluids other than water (i.e., hydrocarbons). This refined simulation capability is extremely important when the working fluid is a hydrocarbon product whose density differs from water, and whose viscosity may differ from water by multiple orders of magnitude.
The use of GeoClaw in the overland transport modeling portion of the Liquids HCA Tool enables the effective use of the high-resolution digital elevation data now available via the USGS 3D Elevation Program (3DEP). In many parts of the United States, 3DEP Digital Elevation Model (DEM) data is now available at 1-meter horizontal resolution.
The hydrographic transport engine of the Liquids HCA Tool makes use of Esri’s Network Analyst extension technology in performing downstream trace calculations. Although the NHDPlus HR dataset is primarily designed for use with Esri’s Trace Network (or Esri’s older Geometric Network) technology to perform downstream traces, in areas of highly anastomosing stream drainage networks this technology is computationally inefficient, with downstream trace performance degrading asymptotically with increasing drainage network complexity. Esri’s Network Analyst technology is not subject to these limitations, which makes the hydrographic transport module of the Liquids HCA Tool far more performant in areas of complex drainage topology.
The combination of Liquids HCA Tool simulations algorithms together with the extreme resolution of the USGS 3DEP and NHDPlusHR datasets facilitates more accurate and detailed release plume modeling than ever before possible. The output of both the overland flow and hydrographic transport modules of the Liquids HCA Tool is fully time aware. This facilitates your ability to visualize the evolution of both overland and hydrographic transport plumes through time, using the ArcGIS Pro time slider. This capability enables you to use Liquids HCA Tool output as an aid in emergency response plans and exercises.
The Liquids HCA Tool is implemented in Esri’s ArcGIS Geoprocessing framework as a Python module, together with an accompanying collection of Python toolbox tools. This allows you to use the Liquids HCA Tool on the desktop and/or expose Liquids HCA Tool geoprocessing services in ArcGIS Enterprise or in web apps.
By design, the analytical workflows of the Liquids HCA Tool are highly configurable. The Liquids HCA Tool provides you with a suite of high-level analytical workflows that can be used as-is, or as a base for customization. The high-level workflows are implemented as ModelBuilder model tools; each of which, in turn, is composed of multiple Python toolbox tools called in sequence to effect the workflow. Each tool has its own set of parameters for configuration. You are free to make copies of ModelBuilder model tools and modify them to best suit your needs.
Licensing for the Liquids HCA Tool is flexible and provides you with several licensing options, including traditional perpetual licenses, as well as software subscriptions. The Liquids HCA Tool License toolset provides licensing utility tools that allow you to request and register a license for the software.
For more information about the Liquids HCA Tool, please visit the Liquids HCA Tool Reference Overview Sections page.