A study of cell models: 1. A manifold cell model for distributed surface runoff systems

As a means of examining the behavior of distributed linear models of catchments (and in particular the cell model) a series of investigations were carried out on the modeling of a long, narrow, rectangular hypothetical catchment. Impulse response functions of three models were studied: the conventional cascade; a modified cascade which can be modeled in series or in parallel; and a new model called the manifold cell model which is characterized by its exclusively parallel nature. The response function of the cascade model converges to a rectangular pulse, and that of the modified cascade model converges to a modified pulse. The impulse response function for the manifold cell model converges to a family of shapes that “look like” hydrographs, i.e., that are intuitively acceptable. The manifold cell model approaches its asymptotic response with a modest number of cell divisions of the same order as the typical discretization along the longest watercourse of a natural watershed.