A spatially distributed. Soil, soil hydrological and agroclimatic model for the prediction of climate change in the European community

To have the ability to predict, by modelling, the effects of a given climate change scenario on the crop suitability of areas of land based on the known soil pattern, the properties of these soils, and the growth requirements of strategic crops (wheat, maize, grass, sunflower, potatoes, sugar beet). An existing agroclimatic soil-crop suitability model is being further developed in terms of improvements in input, and to include a wider range of crops, soil types and climate factors than are considered at present. In the course of this exercise, the following steps are being followed: identification of regional crop requirements (including construction of a phenological database); development of extra modelling routines for the assessment of erosion risk, irrigation requirement, water quality/salinization risk, and baseline soil fertility criteria. An improved water-balance sub- model is also being produced with especial ability to reflect soil and crop behaviour in drier environments, to deal with cracking soils and bypass flow, and to deal with frozen ground and snowmelt. The improved model and associated databases are being integrated into an expert land--evaluation system. An important aspect of the modelling is the way it will deal with spatial aspects of the data. The policy requirements of the model are to make predictions for regions i.e. large areas from several hundred square kilometres to several thousand square kilometres in extent. Experimental sites form the basis for extrapolation to the regions defined above, where fewer data are available. Robust pedo-transfer functions will be developed to enable the model to make use of simple soil survey data, so as to calculate acceptable values for soil hydrological properties which are either difficult or expensive to measure, or are rarely measured. At the regional or national scale (defined as Level I) this part of the model is simple in order to accommodate large amounts of input data describing large areas of land (numerous crop-soil-climate combinations). Conversely, a more complex form of the hydrological model (defined as Level II) has been developed for test sites (small areas of land), where large amounts of very detailed data are available e.g. daily or hourly meteorological data; long term runs of experimental data. The complex modelling is being used as the validation step for the simpler modelling. The system of land evaluation is based on the concept of acceptable regional productivity for specific areas. This allows variation in acceptable yield to take into account local cultivars, cultivation practices, economic returns and so on. Thus each strategic crop can be assessed within its regional climate-soil framework, without the whole model and evaluation exercise being distorted by the yield targets achieved in the highest yielding parts of the Community. The complete system is designed with a user-friendly interface on a PC, and will lend itself to applications through widely-used GIS data formats. Demonstrations of regional applications of the model will be done for areas in southern England, Languedoc-Roussillon (F) and Andalucia (ES), Poland, Hungary and Romania.