农业旱灾承灾体脆弱性评价--以湖南鼎城区为例

农业旱灾的形成是降水不足、不均与农业生产系统脆弱性共同作用的结果,脆弱性的高低会起到"放大"或"缩小"灾情的作用.本文以湖南鼎城区为例,通过分析该区旱灾致灾因子的特点,确定旱年年型的划分标准及对气象资料进行统计,发现该区干旱的季节性特点是秋旱比夏旱多、比夏旱严重.在此基础上,分析轻旱、中重旱、极重旱不同干旱程度下灾情形成过程及其与承灾体脆弱性的关系,构建了不同的脆弱性评价指标体系,并以不同干旱程度的旱年为实例进行评价.结果表明鼎城区承灾体脆弱性的分布有一定的区域性,其脆弱度高低排序为西北山岗地区、南部低山及丘陵区、中部平原及山岗地区、东北部河湖及平原区,与实际灾情的分布规律基本一致.通过分析不同干旱程度下各区脆弱度的形成和变化原因,提出了具有针对性的降低农业旱灾脆弱性的具体措施.

Vulnerability Assessment of Agricultural Drought Hazard in Dingcheng District of Hunan

Agricultural drought-hazard is the result of a combinationof precipitation shortage or unevenness and the vulnerability of agricultural production system. The degree of vulnerability can magnify or lessen disaster losses. Taking Dingcheng in Hunan as an example, by analyzing the characteristics of hazard-causing factors and using selected meteorological statistical data according to a set of criteria to differentiate drought-year in different drought degrees, it is indicated that drought in fall is more and severer than that in summer. On the basis of this, the relation between hazard losses in different drought degrees and the vulnerability of hazard-bearing body is found and vulnerability assessment indices system is also es- tablished with examples in different situation. The results show that there is a regionality in vulnerability distribution which is in line with the distribution of hazard losses. The sequence of vulnerability degrees is from high to low, in order as mountainous region in southwest, hilly region in south, plain and mountain- ous region in the center and river, lake, plain region in the southeast. Through analyzing reasons of the formation and changes of vulnerability in different drought degrees, the specific countermeasures are put forward to lower the vulnerability.