A MODEL FOR CALCULATION OF DIFFUSE LIGHT ATTENUATION (PAR) AND SECCHI DEPT

To evaluate measures and to analyze the possibilities of achieving lake restoration goals a model was developed to calculate Secchi depth and diffuse attenuation for PAR (Kpar). Inputs in the model are water the quality parameters chlorophyll-a, inorganic suspended matter, detritus and yellow substance. The model uses a spectral description of the radiative transfer of light. The coefficients relating the optical properties with the water quality parameters were found using an optimization procedure. The model was calibrated for four lakes in The Netherlands. Calculation of Secchi depth based on summer averaged input concentrations gave good results. Model results can be used to estimate the relative contribution of water quality parameters to the Secchi depth.