Columbia River Treaty 2014/2024: Distributed Computing for HEC-WAT/FRA

Abstract

The United States Army Corps of Engineers (USACE) Institute for Water Resources, Hydrologic Engineering Center's (CEIWR-HEC) Watershed Analysis Tool (HECWAT) with the Flood Risk Analysis (FRA) compute option provides the capability to do a Monte Carlo simulation over a set of integrated numerical models. For the Columbia River Treaty (CRT) 2014/2024 Review analysis, over fifty individual numerical models were linked within a single Monte Carlo simulation. The set of models covered hydrology, reservoir operations, river hydraulics, and flood impact assessment. Reconnaissance level simulations included simulation of 5,000 hydrologic events and key Monte Carlo simulations included 50,000 individual hydrologic events. The time required to compute a single event varied based on the level of flooding, with a range from a few minutes up to one hour. To make the HEC-WAT/FRA Monte Carlo simulation practicable, coarse grain parallelization was implemented as a plug-in based on the GridGain® library for node discovery and communication. In order to maintain consistency of results, the distributed compute plug-in copies the model files to each compute node and triggers the conventional HEC-WAT/FRA compute for a subset of the total number of events on each compute node. When computations are complete, the plug-in performs several post-compute phases to prepare and consolidate the partial results before copying files back to the master compute node. Simulations may be run on a single computer with multiple virtual machines, over several computers on a Local Area Network, or on a cloud service such as the Amazon® Cloud. If events were run sequentially on a single computer, a 50,000 event HEC-WAT/FRA simulation for the CRT could require two 1680 World Environmental and Water Resources Congress 2014: Water without Borders © ASCE 2014