Variation of drought and regional response to climate change in Huang-Huai鄄-Hai Plain

It is widely recognized that the frequency and intensity of extreme weather events and climate disasters have strongly increased with global warming. The area of influence of climate disasters has also increased, which has had adverse effects on sustainable social and economic development. Drought is a recurring natural phenomenon, and is associated with a deficit of water resources over a large geographic area and long duration. Drought is attracting increased attention from scholars, with a focus on its intensity, duration and areal extent in northern China within the context of global change. Investigation of the variation of drought and regional response to climate change is very important to agricultural production, and can provide a reference fordeveloping appropriate measures to reduce droughts on the Huang-Huai-Hai(3H) Plain. At present, relevant research is more inclined to study meteorological drought itself, without consideration of droughtcharacteristics in different phases in crop-growing seasons and the climate background of global change. In this paper, we determine drought characteristics in all four seasons and the winter wheat growing season on the 3H Plain, together with the effects of climate change. Based on data of 34 meteorological stations from 1961 to 2011, a relative moisture index was calculated to investigate the spatial pattern and temporal variability of drought characteristics on the 3H Plain. The results show varying degrees of drought in spring, winter and the winter wheat growing season. Drought frequency exceeded 90% over the past 50 years on the plain, with spring and winter the driest seasons. There were high-frequency drought areas in central and northern parts of the plain during spring, winter and the winter wheat growing season. The regional distributionof drought intensity and frequency showed an increasing tendency from south to north. A wet trend was detected on the plain in the winter wheat growing season over the last 50 years. However, the relative moisture index changed since 1978. That is to say, the index had an increasing trend from 1961 to 1980 when the plain was wetter; the index decreased from 1980 to2011 when it was drier. Overall, although drought eased over the entire analysis period, a serious drought tendency has emerged over the last 20 years. In addition, temporal variability of the relative moisture index was significantly correlated with precipitation, solar radiation and relative humidity. This indicates that drought characteristics of the plain were more sensitive to these three climate variables. This has received increased attention in recent years with respect to addressingclimate change. The results of our study indicate an arid trend, with increase of temperature in spring and summer on the 3H Plain. Therefore, relevant agencies should create an early warning system of extreme weather events and natural disasters, toward improvement of future regional agricultural scientific management and decision support systems in agricultural production. These agencies should also adapt to climate change by selecting strongly drought-resistant cropvarieties and by adjusting cultivation methods and management measures, especially irrigation measures aimed at spring drought on the 3H Plain.