Author(s): Shigeya Maeda
Linked Author(s):
Keywords: Ecological conservation; Drainage canal; Optimization; Genetic Algorithm; Finite element method
Abstract: A decision support model for ecohydraulic design of fish habitat in a canal is developed, aiming at ecological conservation. The model combines (1) the two-dimensional hydrodynamic simulation in a canal, (2) the HSI (Habitat Suitability Index) -based habitat evaluation, and (3) a GA (Genetic Algorithm) -based optimization framework. Designing fish habitat is defined as an optimization problem for arranging blocks on the bed in a section of the canal. The suitability of the canal section is evaluated with two hydraulic factors: water depth and current velocity. Using the computed values of the hydraulic variables and reported SI (Suitability Index) curves (or preference curves) for the two factors regarding spawning of Ayu (plecoglossus altivelis), the elemental HSI values are computed. In order to reduce the inherent effect of the ambiguity in the preference curves to the optimal block configurations, several patterns of preference curves on water velocity are assumed with slight modifications of the originally-reported one. A synthesized average HSI (SAHSI) value computed using the SIs and the associated weights is employed as a single objective function to be maximized in the optimization problem. The problem is then solved using the simulation-optimization procedure. The developed method is applied for optimal configurations of 30 blocks in a hypothetical canal section. The best block configuration is procured with the largest value, which demonstrates the applicability of the developed method for ecohydraulic design.
Year: 2013