| Taking spring corn in Jianghan and Jiangnan west region as research project,based on the daily meteorological data of 57 meteorology stations in the study area from 1961 to 2012,spring corn growth period data and historical disaster data,the difference value between precipitation and water requirement of crop(K-value for short)is calculated on a daily basis.The weight coefficient of current process and earlier stage precipitation as well as K-value on spring corn waterlogging disaster are determined respectively.Accordingly,spring corn waterlogging disaster level indicators based on “equivalent precipitation” and “equivalent K-value” are established,and are verified by independent samples separately.On this basis,spatial and temporal distribution character of spring corn waterlogging disaster risk during different growth stages are revealed.The main results are as follows:(1)In the study area,precipitation of current process,1-10 days and 11-20 days before have significant influence on spring corn waterlogging disaster with weight coefficient being 0.725,0.171 and 0.104 respectively.By contrast,K-value of current process and 1-10 days before have significant influence with weight coefficient being 0.798 and 0.202 separately.(2)The equivalent precipitation indicator thresholds of spring corn waterlogging disaster of light,moderate and severe level are 56 mm,93 mm(without severe level)in seeding-jointing stage;65 mm,104 mm,161 mm in jointing-tasseling stage;and 74 mm,115 mm,182 mm in tasseling-maturing stage respectively.On the contrary,the equivalent K-value indicator thresholds are 43 mm,89 mm(without severe level)in seeding-jointing stage;36 mm,86 mm,136 mm in jointing-tasseling stage;and 50 mm,95 mm,161 mm in tasseling-maturing stage separately.There is high consistency between verification result and history record for both groups of indicators.Therefore,the actual situation of spring corn waterlogging disaster can be well reflected by either group of indicators.(3)An increasing trend is generally showed by the frequency of spring corn waterlogging disaster.The low,moderate and high risk period of spring corn waterlogging disaster are seeding-jointing stage,jointing-tasseling stage,and tasseling-maturing stage respectively.The high-risk areas mainly include Enshi City,southwest of Yichang City,southwest of Jingzhou City,and north of Zhangjiajie City.(4)There is high consistency between the two sets of consequences,including weight coefficient,waterlogging disaster level indicators and waterlogging disaster risk analysis of spring corn,which are get by using the two above-mentioned methods.The difference between the two sets of results are related with the change rule of crop water requirement during spring corn growth period.Both methods have a very good application in the study area. |
