湖北省旱涝灾害致灾规律的初步研究

Preliminary Study on Disastrous Law of Drought and Flood in Hubei Province

利用1960—2005年湖北省76个地区气象灾害的灾情普查数据和逐日降水量观测资料,对湖北省旱涝灾害的时空分布特征及其致灾规律进行分析。结果表明:干旱灾害的频发区呈东西走向的带状分布,而洪涝灾害的发生频次和频发区面积均明显少于干旱;干旱和洪涝灾害年平均发生站次在1996年以后出现相反的变化趋势,干旱发生站次增加,而洪涝发生站次减少,且两种灾害均主要集中发生在夏季;1996—2001年湖北省部分地区连续出现严重干旱灾害,干旱的累积增强效应导致农业经济损失出现跳跃性增长并在2001年达到最大值;洪涝的致灾强度呈准周期的起伏振荡,农作物受洪涝影响面积最大、损失最多的年份集中在20世纪90年代,农作物受害面积与农业经济损失的决定系数为0.8;受害人口与直接经济损失具有较好的相关特征,且直接经济损失随受害人口增多而增加的速度加快,但近年来人口对洪涝灾害的抵御能力也显著提高;急转干旱和急转洪涝主要发生在鄂西北和鄂东南的夏季,农作物的脆弱度增加,农业经济损失随受害面积增大而增加的速度加快,但所造成的农业经济损失远小于仅发生干旱和洪涝时的数值。

Using the daily precipitation and disaster census 2005, this paper studied the spatio-temporal distribution data of 76 meteorological stations in Hubei from 1960 to and disastrous laws of drought and flood. The results show that the frequent occurrence area of drought presents an east-west zonal distribution, while the annual occur- rence frequency and area of flood are significantly less than those of drought. The annual average drought and flood disasters show opposite variation trends after 1996 in which droughts were more experienced but floods became less. Both of the two disasters concentrate in summer. In addition some areas of Hubei suffered from serious drought disaster eontinously from 1996 to 2001. The cumulative effect of the drought disaster caused the agricul- tural economic loss to be leapfrog growth, reaching the maxima in 2001. The flood disaster-causing intensity is quasi periodic oscillation. The damaged areas of agriculture crops and agricultural economic losses reach maximum values in the 1990s with correlation coefficient being 0.80. So, positive correlation exists between the flood-affect- ed population and direct economic loss. The increasing speed of direct economic losses is accelerated with increasing flood-affected population, while the abilities to prevent flood disaster are also strengthened. The drought-flood ab- rupt alternation mainly occurs in the northwest and southeast of Hubei in summer. During sharp-turn disasterprocesses, as drought strengthens the vulnerability of crops and causes serious economic loss in the early period, the increasing speed of agricultural economic losses is accelerated with the growth of disaster-affected areas, but the agricultural economic loss would be less than the losses separately caused by droughts or floods.