Data availability and scale in hydrologic applications

This chapter provides background and insight into some of the key questions concerning pedotransfer functions (PTFs), data availability, and scale in hydrology. It discusses the issues associated with the prediction of the soil–water balance at a point in the landscape. This is the conventional basic step in the reductionist approach to test directly in the field the accuracy of the process descriptions and requirements for field parameter estimation. The development of PTFs has catalyzed an important dialogue between soil scientists and hydrologists, which may ultimately enrich the understanding of catchment hydrologic behavior. Runoff and redistribution processes are complex, and detailed spatial information at hydrological scales of interest is often lacking. This has led to reliance on model calibration rather than a more general conceptual understanding of the processes that govern the spatial and temporal distributions of water within catchments. PTFs, together with other auxiliary methods for sensing the response of catchments to rainfall, are not simply land evaluation methodologies but offer the hydrologist important tools for exploring the spatial response of catchments to runoff