In FAO-MOSAICC two models are available to produce crop yield projections, both chosen for there simplicity and robustness though their level of sophistication is different. The first one is a crop specific water balance model called WABAL. The model is designed to simulate the soil water balance at the level of the crop using minimal input data: bioclimatic data (precipitation and reference evapotranspiration plus the starting date and the length of the growing season), soil data (soil water holding capacity) and crop parameters (crop factors and length of the crop growth stages). The results consist in the values of a number of crop water balance variables (such as actual evapotranspiration water excess and deficit, water satifaction index etc.) for the growing season and the different growth stages. This model has been extracted from AgroMetShell, the FAO crop yield forecasting software. It can be used for any type of crops.
The second model is called AQUACROP and was also developed at the FAO. This crop model simulates the crop response to water in a more sophisticated way than WABAL. Indeed, AQUACROP distinguishes the soil evaporation and the crop transpiration, simulates the root develpment, the expansion of the canopy as well as the water stresses, and provides biomass production and yield estimates. The effect of the CO2 concentration in the atmosphere is taken into account as well. The following crops are already available: cotton, maize, potato, qinoa, rice, soybean, sugar beet, sunflower, tomato and wheat.
These models have been adapted to work with spatial data.