CRISP (crayfish and rice integrated system of production):: 4.: Modelling water, algae and oxygen dynamics

Algae biomass, hydrology and oxygen dynamics were modelled as part of a project for the management and of crayfish and rice interactions in rice fields. Meteorological data such as temperature, wind speed, cloud cover, evaporation and precipitation, were used as forcing functions. Most of the relevant processes in crayfish/rice fanning are dependent on hydrology and its simulation by the model was successful. Hydrological cycle data simulated by the model are used to control the processes taking place in other submodels of the CRISP series. Filamentous green algae biomass was modelled in a simplified way, i.e. not considering the simultaneous presence of different algae species. The simulation results are in accordance with the field data on algae biomass and the most sensitive parameters were the growth rate and the optimum temperature. Oxygen is simulated in two different layers-dissolved in the water column and in the oxic layer of the sediment. At this stage, the simulation of the oxygen dynamics can only provide a tool for a future prediction of the periods with higher or lower oxygen concentrations. (C) 1999 Elsevier Science B.V. All rights reserved.