秦岭以南地区降水量变化及其灾害效应研究

近年来气候变化诱发的灾害效应损失严重。利用秦岭以南地区1951-2001年28个站逐月降水资料,计算了降水量的线性趋势值及降水距平变化,分析了降水量的时间和空间演变特征。受地形影响,秦岭南北与东西降水量变化差异较大,西部大于东部,南坡多于北坡,季节性降水过程差异也很明显;年平均最大降水量为1 254.6 mm,出现在镇巴,最少降水量为690.7 mm,出现在丹凤;50年来降水量变化呈减少趋势,平均递减率为56.5 mm/10 a。分析表明,降水突变是触发其它灾害的主要因素。由强降水及连阴雨诱发的干旱、洪涝及地质灾害效应损失严重,在降雨强度达200 mm/d以上的区域成为泥石流、滑坡灾害,水土流失的多发区,主要分布在秦岭以南多暴雨中心的米仓山、大巴山、佛坪、商南及洛南一带。降水诱发的灾害效应与人类活动也密切相关,这些研究为未来防灾减灾和环境治理提供了依据。

Precipitation changes and calamity effects at the southern regions of the Qinling Mountains

In recent years,disaster loss caused by climatic change is still very heavy in the world.Based on the monthly precipitation data at 28 stations during 1951-2001,this paper analyzed the temporal and spatial characteristics of the precipitation by calculating the linear tendency and anomaly change of the rainfall.Owing to the terrain affect of the Qinling Mountains,the variability of the precipitation and the seasonal fall-rain course shows great difference between the southern and northern,western and eastern regions of the Qinling Mountains,and the biggest precipitation is 1 254.6 mm appeared at Zenba,the smallest precipitation is 690.7 mm at Danfeng.The annual precipitation shows a decreasing tendency in the recent 50 years,and the average declining rate is 56.5 mm/10 a.The analysis shows that the abrupt change of rainfall is the main factor to triggering the other disasters.The losses of the drought,flood and geological disasters caused by rainfall changes are extremely heavy in the region.In districts with more than 200 mm/d precipitation,the successive rainstorm and cloudy or rainy weather are consistent with land slip,mud-rock flow and heavy soil and water loss,which are mainly distributed at Micang Mountain,Daba Mountain,Fuoping,Shangnan and Luolan areas.The results of the paper can be references for disaster prevention and environmental control in the region.