Comparison of the root water uptake term of four simulation models

Water uptake by plant roots is an important component of the soil water balance. In this report we studied four water uptake models, of different complexity, that were all embedded in a greater model dealing with transport of water in (an unsaturated) soil. Though also some attention was paid to performance of the routines by themselves, the focus was directed to their functioning as a part of the greater models. We examined the results of two scenarios of potential transpiration and precipitation, comprising a period of 16 days. As could be expected the models yielded different results, but the differences in actual transpiration are modest due to feedback mechanisms.