Influence of ecohydrologic feedbacks from simulated crop growth on integrated regional hydrologic simulations under climate scenarios

摘要

Hydrologic climate change modelling is hampered by climate-dependent modelparameterizations. To reduce this dependency, we extended the regionalhydrologic modelling framework SIMGRO to host a two-way coupling between thesoil moisture model MetaSWAP and the crop growth simulation model WOFOST,accounting for ecohydrologic feedbacks in terms of radiation fraction thatreaches the soil, crop coefficient, interception fraction of rainfall,interception storage capacity, and root zone depth. Except for the last,these feedbacks are dependent on the leaf area index (LAI). The influence ofregional groundwater on crop growth is included via a coupling to MODFLOW.Two versions of the MetaSWAP-WOFOST coupling were set up: one with exogenousvegetation parameters, the "static" model, and one with endogenous cropgrowth simulation, the "dynamic" model. Parameterization of the static anddynamic models ensured that for the current climate the simulated long-termaverages of actual evapotranspiration are the same for both models.Simulations were made for two climate scenarios and two crops: grass andpotato. In the dynamic model, higher temperatures in a warm year under thecurrent climate resulted in accelerated crop development, and in the caseof potato a shorter growing season, thus partly avoiding the late summerheat. The static model has a higher potential transpiration; depending onthe available soil moisture, this translates to a higher actualtranspiration. This difference between static and dynamic models is enlargedby climate change in combination with higher CO₂ concentrations.Including the dynamic crop simulation gives for potato (and other annualarable land crops) systematically higher effects on the predicted rechargechange due to climate change. Crop yields from soils with poor waterretention capacities strongly depend on capillary rise if moisture supplyfrom other sources is limited. Thus, including a crop simulation model in anintegrated hydrologic simulation provides a valuable addition for hydrologicmodelling as well as for crop modelling.