THE DEVELOPMENT OF A HYDROLOGICAL CLASSIFICATION OF UK SOILS AND THE INHERENT SCALE CHANGES

Although soil is of major importance in influencing river hydrology, t here is often a lack of soil hydrological data available to quantify t he ameliorating effects of soil on steam flow. The HOST classification (Hydrology of Soil Types) was developed using pedotransfer rules and functions to derive a set of semi-quantified soil attributes from exis ting soil morphological information as surrogates for the missing hydr aulic data. The rules were applied to the soil horizon information and were scaled to the catchment level through the known relationships be tween soil horizons and soil taxonomic units and between soil taxonomi c units and 1:250 000 scale soil map units. The resulting classificati on, however, is not scale-specific and is capable of predicting river flow indices at the catchment scale (r(2) = 0.79) and of predicting th e dominant pathways of water movement through individual soil profiles .