武陵山地区干旱时空特征分析

SPATIO-TEMPORAL ANALYSIS OF DROUGHT IN WULING MOUNTAIN AREA

利用1960~2012年降水气象资料,计算了武陵山区各个季节的降水距平指数,在此基础上,分季节分析了该区域干旱发生时空分布特点,其中,在春季和夏季,轻旱和中旱发生频率略高,中北部地区较重;在秋季和冬季,各个等级干旱均有较高频率分布,且不同等级分布格局有所不同。通过构建旱灾危害度指数,分析了各个季节及年度旱灾危险性空间分布特点,认为春旱和夏旱北部风险度较高,秋旱中东部风险度较高,冬旱在东北部及中部局部风险较高,年尺度旱灾风险区域整体较低。在此基础上,通过将各季节旱灾危害度与地形要素进行关系分析,认为春旱和夏旱与海拔相关度较高,各季节干旱与坡度及地形起伏度相关性不显著。本研究结论对武陵山区合理规划建设,发展农业生产具有一定参考意义。

Precipitation anomaly indexes of four seasons were calculated using precipitation data of Wuling Mountain area from 1960 to 2012,then the occurrence of drought events were rebuilt according to drought criterion.Based on this,the temporal and spatial distributions of drought at seasonal scale were analyzed.In spring,higher occurrence frequency of wild drought was appeared in most part of this area than in south-east area,and north-west area,north area and part of south area had the highest occurrence frequency,reaching 50.82%.During summer,mild drought and moderate drought covered large range of high-frequency distribution.Mild drought appeared in most parts,western and north-central regions had higher frequencies,up 57.38%.Almost all part of this area had higher occurrence frequency of moderate drought than south-west area,especially in west,north and middle area,where peaked at 37.71%.In autumn,the distribution of different levels of drought appeared significantly different characteristics.Higher occurrence frequency of mild drought appeared in west-central area and south area,where peaked at 54.10%;moderate drought largely concentrated in east and south area and south area had larger distribution of higher occurrence frequency,where peaked at 40.98%;severe drought mostly happened in middle and south part of Wuling Mountain area and the occurrence frequency was up to 27.87%;very severe drought mostly happened in middle and east part of this area.In winter,mild drought mostly happened in north-central area where peaked at 57.38%,and low occurrence frequency appeared in south area;moderate drought happened in most part of this area,together with higher occurrence frequency,which was up to 39.34%;severe drought mostly happened in north-east area and part of south area,where peaked at 31.15%;very severe drought had lower occurrence frequency,which mainly distributed in north and middle area.In addition,drought hazard degree index was constructed which was used to analyze the distribution of drought hazard at seasonal or annual scale.Conclusions at seasonal scale were drawn that spring and summer drought hazard degree were higher in north area than in other area,autumn drought hazard degree was higher in east-central area and winter drought hazard degree was higher in north-east and part of middle area.There was low drought hazard degree in the whole Wuling Mountain area at annual scale.On the basis of the above,correlation analysis between drought hazard degree of different seasons and topographic factors were conducted.The results showed that spring drought and summer drought were significantly correlated with elevation and there were no significant correlation between seasonal drought and slope or surface rolling.This study can provide a reference for the development of rational planning and the guidance of agricultural production in Wuling Mountain area.