ABSTRACT
The accumulation of a clogging sludge layer in infiltration ponds can be really a nuisance, by hampering the infiltration process and endangering the sustainability of the recharge technique. A model is presented which predicts the mean accumulation rate and mean chemical composition (major components, trace elements and organic micropollutants) of sludge layers in recharge basins or other infiltrating water courses (lakes, canals). This model assumes steady state regarding the hydrology, hydrochemistry and sludge formation (accumulation rate, areal extent, redox conditions, composition). Steady state approximates reality as long as the infiltration rate is not seriously reduced, or when sludge is regularly removed.
The most important processes, factors and calibration parameters are discussed. The model can be used to optimise basin recharge systems, by reducing accumulation rate and getting the best chemical composition of the sludge layer. This is done by calculating the effects of various qualities of the infiltration water, infiltration intensities and water depths.
