Statistical-dynamical modelling of catchment water balance: climatic and vegetation controls on hydrological fluxes

© 2005 Dr. Nicholas Jan PotterPublication included in thesis:Potter, N. J. (2005). Effects of rainfall seasonality and soil moisture capacity on mean annual water balance for Australian catchments. Water Resources Research, 41(6), W06007. DOI: 10.1029/2004WR003697The prediction or modelling of catchment water balance is a fundamental hydrological question. So many natural resource management problems rely on accurate modelling of catchment water yield. Both Australian and global water resources are likely to face new and increased pressures in the future as a result of land-use changes, climate change and increased demand for water from both urban and agricultural users. However, the variability of catchment water balance, as well as the sources and timescales of this variability, still remains insufficiently understood. The principal aim of this thesis is an analysis of the water balance of Australian catchments. Using a variety of models, particularly recently developed probabilistic soil-moisture accounting models, catchment water balance and soil moisture variability are examined at different timescales, with particular emphasis on the mean annual timescale of catchment water balance. Recently published stochastic soil-moisture accounting models are presented in detail. This survey highlights the assumptions of the models, the theoretical and observational background to these assumptions, as well as the solutions, limitations and possibilities for improvement of the models. These models are then compared with observational data, and further extensions and solutions to some of the models are presented and discussed. Water balance variability at other timescales is also considered, by testing and extending theoretical hydrological models, resulting in a clearer understanding of the relative roles of climate, soil and vegetation to the variability of catchment water balance