Modelling for environmental assessment of municipal solid waste landfills (part 1: hydrology).

A three-dimensional dynamic simulation program for the prediction of leachate flows, their organic contamination and the gas generated in municipal waste landfills, (MODUELO) has been developed. It permits the simulation of canyon landfills in which the surface area changes throughout the landfill's history and of complex drainage systems. The "hydrologic module" calculates, based on the saturated flow equations, the water flow between cells and the overall moisture balance. Its results allow the "contamination module" to carry out the balance of organic material. This paper presents the development of the "hydrologic module". The contamination models are included in another paper. A preliminary application to the Meruelo Landfill (Spain) is also shown here. The fitting of a data series of leachate flows in Meruelo indicated the existence, in this particular landfill, of unconsidered phenomena. The final adjustment of the results makes it possible to obtain a reliable simulation of the degradation processes.