Although the models SWAP-WOFOST and WOFOST have a long track-record of development and usage in projects in the domains of agrohydrology and production ecology, we will address some issues in both models; this ensures a higher quality status of both models and will also lead to improved model use in future projects.
This project concerns the models SWAP and WOFOST and their integration. Although these models have a long track-record of development and usage in projects in the domains of agrohydrology and production ecology, we have identified the following issues that will be addressed; this co-operation ensures working towards a higher quality status of both models and in our view will also lead to improved model use in future projects.
a) WOFOST version 7.1 has been implemented in the source code of SWAP such that in a dynamic way interaction between crop water demand > soil water availability for crop uptake > and water-limited crop growth can be simulated. There is a need to have test runs available in order to certify that the stand-alone version of WOFOST and the coupled SWAP-WOFOST version provide identical predictions of potential growth, and nearly identical predictions of water-limited crop growth. In the latter case some tolerance will be allowed due to the differences in soil water dynamics. The standalone version of WOFOST does have already a series of tests which thus need to be converted into SWAP-WOFOST test cases.
b) Currently WOFOST is primarily used for arable crops. However, in many farming systems grassland is very important and therefore simulations for growth, water use and nutrient use of grasslands are required. In SWAP, an adapted version of WOFOST is already implemented for grassland simulations. However, this version still requires specific adaptations and proper testing for grassland simulation. Moreover, approaches of existing grassland models (CNGRASS, GRAS2007) will be reviewed in order to take advantage of the algorithms implemented in these models. Therefore, the goal is to finalize a proper simulation of grassland production systems in WOFOST and to harmonize the modelling approach between SWAP/WOFOST and standalone WOFOST. Similar to activity a), a set of tests will be implemented in order to certify the correct implementation.
c) During the project both WOFOST and SWAP will apply for Status A. Both models are already in progress for application of Status A. However, there are still some pending issues that need to be addressed. This will be done within this project. For example, for SWAP several issues that were addressed with the auditing committee will be handled in a technical addendum document.
d) At the end of the project both models will update the self-assessment forms. The current self-assessment forms as well as a description of the meta-information are included as appendices to this proposal.