A soil water-balance ‘bucket’ model for paleoclimatic purposes 1. Model structure and validation

Models currently used to describe soil water content in paleoclimatic settings develop evapotranspiration equations which do not vary with soil type and vegetation cover and which do not separate percolation from runoff. The paper describes the selection of one model (SWBBM/B) predicting soil moisture at daily scale, using a limited number of input parameters (precipitation, insolation and temperature). The models implement equations describing potential evapotranspiration which vary with vegetational cover and soil type and which separate runoff and percolation. Values of potential evapotranspiration are compared with more complex equations such as Penmanʹs equation. The SWBBM/B model is validated with evapotranspiration patterns for major vegetation types, with percolation data from field lysimetric trials and tested for sensitivity to input parameters. The SWBBM/B model is considered suitable for reconstructing soil water content and runoff in paleoclimatology.