Modification of the probability-distributed interacting storage capacity model

This paper is concerned with the review and modification of the structure of the conceptual rainfall-runoff model known as the probability-distributed interacting storage capacity (PDISC) model. The significance of the fundamental assumption of the equal-storage redistribution mode used in this model is critically investigated by adopting a more general linear, storage redistribution mode. The investigation is performed using the daily data of six catchments. The results reveal that the original assumption of the equal-storage redistribution mode may not be an optimum in some catchments. Further development of the water-balance module of the PDISC model is also explored. The surface-runoff generation mechanism of the model is modified by incorporating into the model structure a quick-runoff component. The results suggest that this modification can significantly improve the performance of the model. The results of the PDISC model are also compared with that of another established lumped conceptual rainfall-runoff model known as the soil moisture accounting and routing procedure (SMAR). Neither of the two models has worked consistently better than the other under all situations.