| Currently, it is widely recognized that the frequency and intensity of extreme weather events andclimate disasters enhanced obviously with global warming, the influence of climate disasters areaincreased, which caused adverse effect to the social and economic sustainable development. There is adrought tendency both in area and frequency in the Northern China in the context of global change.Huang-Huai-Hai Plain (3H Plain) is ackonwleged as one of the largest plain of winter wheat region.Water deficit is serious in the jointing to heading stage and filling stage which are critical period ofwater requirement of winter wheat due to scarce precipitation during winter wheat growing season, so afrequent occurrence of the drought disasters for winter wheat was found in3H plian. To study effects ofdrought on winter wheat and risk estimation in3H Plain and regional response to climate change hasvery important significance to agricultural production so as to propose reasonable water-savingirrigation measures. Firstly, in this paper relative moist index has been calculated based on themeteorological data of34meteorological stations to investigate the spatial pattern and temporalvariability of the drought characteristics in3H Plain, and probe the temporal variability of droughtcharacteristic in growth stages and its possible climate factors of winter wheat of6typicalmeteorological stations from every agricultural sub-region. Then based on data of6typicalmeteorological stations of3H plain from1981to2010, we determined yield reduction rate of potentialdrought in critical growth stages of winter wheat over the3H plain. Then, the potential risks ofdrought effects on yield was estimated in jointing to heading stage and filling stage of winter wheat in3H plain from2011-2050under RCP4.5and RCP8.5scenario. The results showed that：(1) There were all expressed as varying degree of drought in the spring, winter and winter wheatgrowing season which the drought frequency was more than90%in the past50years in3H Plain, withspring and winter found to be the driest season. High frequency drought area was found in middle andnorth region of3H Plain in the spring, winter and winter wheat growing season. The regionaldistribution of intensity and frequency of the drought were all expressed as a tendency of increasingfrom the south to north. A wet trend was detected in the plain in winter wheat growing season in recent50years, but relative moist index has a mutation in1978, that means the index has a increased trendfrom1961to1980and plain got more wet while the index has a decreased trend from1980to2011andthe plain got drier. Overall, the drought of whole period was alleviated, but a serious drought tendencyemerging in recent20years. In addition, the temporal variability of relative moist index wassignificantly correlated with precipitation, solar radiation and relative humidity, which means that thedrought characteristic of the plain was more sensitive with these three climate variables.(2) The most severe drought occurred in jointing to heading stage but a decreasing drought trend wasdescribed except Tianjin in this stage. A drought trend was detected in heading to maturity. Continuousdrought of Tianjin and Shijiazhuang station was serious while sustained drought was not found inshouxian station in recent30years. With the temperature decreasing, the trend of drought will be alleviated in jointing to heading stage and heading to maturity statge in southern of3H plain. There wasa drought trend detected in Shijiazhuang, Shangqiu and Shouxian stations with the relative humiditydecreasing in growth stages. Besides, with the wind speed decreasing, moisture tendency will be foundin the late growth stage of winter wheat in3H Plain.(3) The yield reduction rate of potential drought showd a clear trend to reduce the disaster losses in1980s in3H plain. It was showed serious regional distribution gradually from south to north of yieldreduction rate in jointing to heading stage. Furthermore, the yield reduction rate in north region in3Hplain was found to be more than﹣40%while the yield reduction rate for region in south plain wasdetected more than﹣40%averagely. The regional distribution of yield reduction rate of everyagricultural region caused by species differences was slightly while it’s mainly caused by the climaticfactors.(4) Due to global warming, the sowing date of winter wheat will be delayed, and maturity stage will beadvanced. In RCP4.5scenario, except Shijiazhuang station, potential droughts reduction rates fromjointing to heading stage of winter wheat will decrease in the late2010s to the2030s while it willincrease in the late2030s to2050s in whole area. In the filling stage, the drought reduction rate willdecrease over the next40years in southern region. In RCP8.5scenario, there is an increasing trend ofpotential drought-reduction rate in jointing-heading stage in2020s-2030s while a decreasing trend in the2040s in central and southern areas of3H region. The probability of the same level of yield reductionrate in northern region was much larger than partial southern area except Shijiazhuang station. Theprobability of the same level of yield reduction rate in jointing to heading stage was much larger than infilling stage. The probability caused by different degrees of reduction in the two periods in RCP8.5scenarios are generally lower than the probability in RCP4.5scenarios, and the probability difference ofthe same degree of reduction caused by jointing to heading stage and filling stage under RCP8.5scenarios is less than the difference RCP4.5scenario.(5) The potential reduction degree by the drought from jointing to heading stage will be serious over thenext40years in3H plain. In RCP4.5scenarios, it can be concluded that regionⅠwill be the severedrought reduction area, region Ⅱ, Ⅲ, Ⅳ will be the serious drought reduction area, region Ⅴ willbe the medium drought reduction area, and that region Ⅵ will be the slight drought reduction area.Additionally, in RCP8.5scenarios, it can be concluded that regionⅠ, Ⅱ and Ⅲ will be the seriousdrought reduction area, region Ⅳ, Ⅴ will be the medium drought reduction area, and that region Ⅵwill be the slight drought reduction area. Furthermore, the potential reduction degree by the droughtfrom filling stage will be slight. The3H region will be the slight drought reduction area except regionⅠwas medium in RCP4.5and RCP8.5scenarios. Compared with baseline, in jointing to heading stage,the drought risk of regionⅠ, Ⅱ, Ⅲ, Ⅳ will be more serious while for region Ⅴ, Ⅵ the droughtrisk will be reduced in RCP4.5scenarios. But in RCP8.5scenarios, the increasing trend of drought riskis found only in region Ⅲ except the other regions. In filling stage, the drought risk of regionⅠ, Ⅲwill increase while the others’ will decrese in both RCP4.5and RCP8.5scenarios.Much attention has been given to addressing climate change in recent years in Northern China. It is acknowledged that the early warning system of extreme weather events and natural disaster should becreated by governments to improve the regional agricultural scientific management and decision supportsystem in agricultural production in the future. Furthermore, measures should be taken to adapt climatechange by selecting the strong drought resistance varieties and adjusting the way of cultivation andmanagement measures especially adjusting the irrigation measures in the3H Plain. |
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