Effects of surface wind speed decline on modeled hydrological conditions in China

摘要

Surface wind speed decline in China has been widely reported, butits effects on hydrology have not been fully evaluated to date. In thisstudy, the effects of wind speed change on modeled hydrological conditionsare investigated using the Variable Infiltration Capacity (VIC) hydrologicalmodel for China during the 1966–2011 period. Two model experiments, i.e., VICsimulations with the observed (EXP1) and detrended wind speed (EXP2), areperformed over the major river basins in China. The differences between thetwo experiments are analyzed to assess the effects of wind speed decline.Results show that wind speed has decreased by 29% in China. The windspeed decline would have resulted in a decrease in evapotranspiration of1–3% of mean annual evapotranspiration and an increase in runoff of1–6% of mean annual runoff at most basins in China. The sensitivities ofevapotranspiration and runoff changes to wind speed change are larger inhumid areas than dry areas, while the sensitivity of soil moisture change towind speed change is situation dependent. The wind speed decline would haveoffset the expansion of the drought area in China. It has contributed toreducing drought areas by 8.8% of the mean drought area (i.e.,approximate 106 × 103 km2 out of 1.2 × 106km2) over China. The reductions of soil moisture drought induced bywind speed decline are large (more than 5% of the mean drought area) inmost basins, except in the Southwest and Pearl River basins.