Abstract
Destratification system, or artificial circulation, is one of major countermeasures to control algal bloom in eutrophied dam reservoirs. Effects of destratification largely depend on the depth of the surface mixed layer formed by the circulation. The depth of the mixed layer corresponds to that where the destratification system is installed, so that a formulation is needed to optimize the depth of installation and operation of the system. Our idea is based on the model introduced by Lorenzen (1975), but chlorophyll-a is used in this paper to estimate algal biomass. By using a diagram showing the relation between the depth of mixed layer and the chlorophyll-a concentration that is possible to be produced in the dam reservoir, a required depth of circulation is easily estimated to prevent algal bloom. We applied the formulation to several dam reservoirs and confirmed its effectiveness.
