A SEMIDISTRIBUTED, VARIABLE TIME-INTERVAL MODEL OF CATCHMENT HYDROLOGY - STRUCTURE AND PARAMETER-ESTIMATION PROCEDURES

The conceptual basis and structure of a semi-distributed, deterministic hydrological model is presented. The modelling time interval used is variable and changes automatically according to a series of user defined rainfall thresholds. The model represents a pragmatic compromise between highly detailed physically based and completely empirical approaches. This is achieved using a semi-distributed approach, but incorporating some effects at scales of less than the sub-area level. Model conceptualisations are based on the authors understanding of physical hydrology, but the complexity of the algorithms has been limited to prevent the model's information requirements from being too stringent. The model is designed to be applicable to a range of situations where a simulation of the components of catchment hydrology is required to solve a problem. The paper also briefly discusses the procedures used to estimate parameter values from readily obtainable physical catchment characteristics and presents some example simulations to illustrate the model's operation.