衡阳市农业旱涝灾害发生规律及大灾预测

衡阳市是湖南省重要的农业生产基地，以雨养农业为主，经常遭遇干旱与洪涝威胁。本文以衡阳市为研究区域，利用近50a的旱涝灾害资料，采用统计分析方法得出衡阳农业旱涝灾害发生的历史规律为：旱灾发生频率高于涝灾发生频率；一年当中夏秋容易出现旱灾，春末夏初容易出现涝灾；北部农业旱灾发生频率大于南部；北部和湘江河谷农业涝灾发生频率大，东部山地和中部丘陵地带发生频率相对较小。利用灰色理论建立大旱、大涝年预测模型，1986—2006年模拟结果与实际基本一致，预测2012年是衡阳大旱风险年、2014年为大涝风险年。结果有利于衡阳积极应对巨灾，有助于促进衡阳农业经济的可持续发展。

Occurrence of Agricultural Floods and Droughts and Forecasting of Serious Disasters in Hengyang City

Hengyang City is an important agricultural production base in Hunan Province. The agriculture was mainly in rain-fed and often suffered from drought and flood risk, especially high risk of drought. The historical disasters were statistically analyzed by using the disaster data in the last 50 years in Hengyang. The results indicated that the agricultural drought hazard occurred more frequently than the agricultural flood hazard in Hengyang. The agriculture drought appeared much in the summer and autumn, while the agricultural flood often occurred in the beginning of the summer and the end of the spring. The frequency of the agricultural drought hazard was bigger in the South than in the North. The Frequency of the agricultural drought hazard was biggest in the middle of Hengyang, while the frequency of agricultural flood hazard was bigger in the North than in the South. The frequency of agricultural flood hazard was bigger in the Xiangjiang River than in the east mountainous region and middle hill regions. The occurrence of serious floods and droughts were forecasted by grey theoretical modeling. The simulated results were consistent with the disasters occurred in 1986-2006. It was forecasted that there would be the risk year of serious drought in 2012 and the risk year of serious flood in 2014. It help to deal with catastrophe in Hengyang City, at the same time help promote the sustainable development of the agricultural economy.