Novel physical and numerical methods for simulating water and heat transfer in land surface models.

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Improved land surface modelling for the terrestrial water cycle is critical for providing better forecasts within a changing climate, for example in flood prediction. Land surface models, such as UKMO's Joint UK Land Environment Simulator (JULES), describe unsaturated flow in soils through a numerical form of the Richards one-dimensional partial differential equation (PDE). Such a solution to a highly non-linear equation inevitably leads to numerical and accuracy issues, which impact on their hydrological performance. Recent attention has focussed on adopting novel approaches to hydrological models.This project concerns the implementation and testing of two recent 1-D unsaturated zone flow solution methods (Ogden et al., 2015; Lee, Baines and Langdon, 2015) into JULES. Both methods use a velocity-based PDE for the depth in terms of the water content, the Ogden approach through a hodograph transformation, the Baines approach through local mass conservation. The (different) PDEs are stepped forward in time using an explicit scheme.The Ogden Soil Moisture Velocity Equation (SMVE) method has already been applied to the transport of three regimes of soil moisture, namely infiltration, wetting fronts disconnected from the surface, and groundwater recharge. The Baines approach (CMF) awaits development.The student will extend both approaches to account for heat flow.The studentship affords the opportunity to apply computational modelling to a real problem of high importance, and will include visits to the UKMO.The intellectual challenge will be to derive a consistent method for coupling water and heat transport within the soil.