Problems of rainfall-runoff modelling in arid and semiarid regions

Abstract The distinctive features of arid and semiarid regions affect rainfall-runoff modelling on both a discrete event basis and a continuous basis. The general characteristics of arid zone hydrological processes and the problems that they present in runoff modelling are discussed. Both sloping lands with integrated stream networks and flatlands with repetitive micro-hydrology are considered. The wide diversity in some characteristics may require different parameter values and possibly different approaches in different regions. Lack of observed data provides the major problem for runoff modelling in arid regions. Some comments are given on appropriate approaches to modelling for sloping regions.