Indicator Construction and Risk Assessment of Grape Waterlogging in the Bohai Rim

The viticulture area around the Bohai Bay is the largest grape producing area in China. Waterlogging disaster is a major agricultural meteorological disaster in China, which seriously threatens grape production. Waterlogging indexes are utilized on field crops widely, but most of them can only be evaluated after the end of the growing season, which lacks the timeliness of monitoring and evaluating the process of waterlogging disasters. Taking the main grape producing areas in the Bohai Rim of China as the research object, the waterlogging grade index is constructed based on the daily meteorological data, grape growth stage data and grape waterlogging historical disaster data from 303 meteorological stations in the study area from 1980 to 2019. In the process of index construction, the influence of previous water surplus and deficit status on the current waterlogging process is fully considered, and the climate adaptability of crops in a certain place is considered. The daily waterlogging index of grapes is constructed by referring to the relative humidity index method of crops. Taking historical disaster inversion and disaster process analysis as the main line, Lilliefors test of normal distribution and t-distribution interval estimation method are used to construct the grape waterlogging disaster grade index system suitable for the main grape producing areas around the Bohai Bay, starting from the duration and intensity of waterlogging disaster. Based on the classification index of grape waterlogging disasters constructed above, the frequency of waterlogging disasters at each site in the Bohai Rim from 1980 to 2019 is counted, and the probability of disasters at each site is obtained by using information diffusion theory. Considering the probability and intensity of waterlogging disasters of each grade, the risk index of grape waterlogging in each station in the region is calculated. The results show that the occurrence range of waterlogging disaster in the same growth period of grape decreases with the increase of the disaster level, while the occurrence range of severe waterlogging disaster in different growth periods gradually increases with the advancement of development process. The risk of grape waterlogging is relatively low during the period of bud-shoot growth and flowering and fruit-setting, while the high-risk period of grape waterlogging is the period of fruit expansion and coloring and maturity. The high-risk areas of grape waterlogging disaster are mainly located in the southeast of Shandong Province, the southeast of Liaoning Province and the northeast of Hebei Province.