Abstract. Large-scale deployment of bioenergy plantations would have adverse
effects on water resources. There is an increasing need to ensure the
appropriate inclusion of the bioenergy crops in global hydrological models.
Here, through parameter calibration and algorithm improvement, we enhanced
the global hydrological model H08 to simulate the bioenergy yield from two
dedicated herbaceous bioenergy crops: Miscanthus and switchgrass. Site-specific
evaluations showed that the enhanced model had the ability to simulate yield
for both Miscanthus and switchgrass, with the calibrated yields being well within the
ranges of the observed yield. Independent country-specific evaluations
further confirmed the performance of the H08 (v.bio1). Using this improved
model, we found that unconstrained irrigation more than doubled the yield
under rainfed condition, but reduced the water use efficiency (WUE) by
32 % globally. With irrigation, the yield in dry climate zones can exceed
the rainfed yields in tropical climate zones. Nevertheless, due to the low
water consumption in tropical areas, the highest WUE was found in tropical
climate zones, regardless of whether the crop was irrigated. Our enhanced
model provides a new tool for the future assessment of bioenergy–water
tradeoffs.