MODELING OF RAINFALL INDUCED INFILTRATION INTO SEPARATE SEWERAGE

Flowrate changes in separate wastewater sewerage during wet weather ar e often attributed to inappropriate connections of runoff water. But t hese inputs are not the only cause of such behaviour and infiltration through leaking defects or cracks can supply large flows into collecti on pipes. The characterization of these flows is not an easy task sinc e they involve complex processes, depending not only on rainfall event s but also on hydrological conditions and seasons. Using 16 months of hourly measurements of rainfall and flowrates, we developed a six para meter conceptual model to simulate rainfall induced infiltration into a small sewer system. Sensitivity analysis applied to the proposed mod el showed good achievements under various calibration conditions but d isplayed high parameter interactions which may be a serious drawback f or some specific model uses. Model application to another sewer networ k yielded good agreement between observed and simulated flows. The sui tability of this model must be further checked on other sites.