R-groundwater : model user's manual for NERC Virtual Observatory implementation

This report describes the structure and usage of the R-Groundwater model for implementation within the NERC Virtual Observatory project. R-Groundwater is a simple lumped catchment groundwater model written in the R programming language and run within the R environment. It has been developed to model groundwater level time series at observation boreholes by linking simple algorithms to simulate soil drainage, the transfer of water through the unsaturated zone and groundwater flow. Time-series of flow through the outlets of the groundwater store are also generated, which can be related to river flow measurements. The model is calibrated through a Monte Carlo process by randomly selecting input parameter values from ranges specified by the user. Simple text files are used to define the input to the model and to write the output.