Modelling the Effects of Climate Change on the Hydrology and Water Quality of Structured Soils

Abstract

The behaviour of cracking clay soils is characterised by the interaction between the development of soil macroporosity and the soil moisture status. If climate change alters the magnitude of the soil moisture deficit, that change may alter the importance of macroporosity in soil hydrological behaviour. This interaction is illustrated by models of three differing degrees of complexity: a simple partition model, a redistribution model, and a relatively complex model. These models can also be used to indicate some of the impacts of possible changes in the climate on the components of the hydrological cycle. One of these models, when used to predict the leaching of nitrate suggested that, despite higher nitrate concentrations in response to greater mineralisation, the nitrate leaching loads may be lowered in a drier climate, because of reduced through-drainage. Lastly, a simple water balance model is used to suggest the impacts of climate change on the hydrology of a managed wetland. Here, the greatest impact was on the recharge volumes needed to maintain wetland status.