Coupling of Engineering and Biological Models for Ecosystem Analysis

Robust ecosystem analysis of water resource systems remains elusive. A principle reason is the difficulty in linking engineering models used to simulate physicochemical processes associated with project design or operation with biological models used to simulate biological population attributes. A retrospective shows that each modeling tradition can be generally assigned (with exceptions) into either an Eulerian or Lagrangian reference framework. Eulerian and Lagrangian reference frameworks can be coupled to create a new synthesis, the Coupled Eulerian-Lagrangian Hybrid Ecological Modeling Concept (CEL Hybrid Concept), capable of simulating different ecosystem processes that range widely in spatial and temporal scale. The foundation of the CEL Hybrid Concept is the coupler, a collection of algorithms based on conservation principles that transform and conserve data in a way that allows the two frameworks to share a common information base. The coupling algorithm allows the simulation to aggregate, disaggregate, and translate information, as required by each framework, so that processes that differ substantially in scale can each be adequately simulated. The coupled system is illustrated by linking a fish swim path selection model with a hydrodynamic and water quality model.