1950—2009年洞庭湖流域农业水灾演变特征及分异规律

Evolutive Characteristics and Differentiation Rules of Agricultural Flood in Dongting Lake Basin from 1950 to 2009

洞庭湖流域为我国重要农业生产区,而农业水灾却一直是制约农业可持续发展的最大障碍因素。以1950—2009年水灾统计资料为依据,用定性与定量相结合的方法,系统分析了该流域农业水灾演变特征及区域分异。结果表明:①年年发生流域性或区域性的农业水灾,其中重灾、特大水灾频率呈增大趋势;②在长时间尺度演变过程中,受灾率异常指数岀现2个波峰期和4个波谷期,成灾率异常指数岀现3个波峰期和3个波谷期,且水灾受灾率与成灾率大体上呈同步变化,但短时间內受灾率与成灾率却呈反向波动;③农业水灾具有突变性,但总体演变呈增加趋势;④受孕灾环境、洪涝致灾因子及经济发展水平组合差异的制约,农业相对灾情与绝对灾情在空间上的分布均呈明显的南北分异与东西分异。

Dongting Lake Basin is an important agricultural production area in China,however agricultural flood remains obstruction factors in restricting agricultural sustainable development.Based on the flood data from 1950 to 2009,by using the measurable and qualitative methods,the paper analyzes the evolutive characteristics and regional differentiation of agricultural flood in Dongting Lake Basin.The results show that： 1） Annual frequent basin-wide or regional agricultural floods present mountain torrent disasters,among them,disastrous floods and extraordinary floods present increasing trend.2） Long-term span evolutive process abnormal indices of flood disasters present two wave crest periods and four trough periods,abnormal indices of flood suffering present three wave crest periods and three trough periods.Rates of flood disaster and flood suffering present isochronous changes,but the short-term span has varied in different stages of the inverse relationship between rates of flood disaster and flood suffering.3） Agricultural flood has mutations,but the characteristics of total evolutive trends present rise.4） According to disaster environment,flood causing factors,and the level of economic development,the relative and absolute disaster condition of agriculture differs regionally from east to west,and north to south,on aspects of time and space.