Human impacts, complexity, variability and non-homogeneity: Four dilemmas for the water resources modeller

Water modellers are commonly faced with a range of dilemmas due to the complex, uncertain and conflicting nature of the problems currently studied. The limitations of present techniques to deal with the variability and non-homogeneity of future data sets in complex water systems are examined. The main limitations are in part due to changing human behaviour and linked anthropogenic land- and water-use impacts, as well as the uncertainty of climatic variability. Suggestions and questions for future practice are raised, as are technical based methods which are more likely to provide successful outcomes for integrated river basin management.