基于Z指数的辽宁省洪涝灾害时空分析

根据辽宁省21个气象站点1958—2008年逐日降水观测数据,通过Z指数计算、区域旱涝等级评定对辽宁省近51年洪涝灾害的时空分布特征进行分析。研究结果表明:从时间变化方面来看,降水变化呈波动式下降趋势,减小趋势为1.963mm/a,且呈周期性变化,主周期约为9年,次周期约为24年和3年;从空间变化方面来看,年平均降水量变化是由辽东南沿海向西北内陆递减;而洪涝灾害频发区与降水集中区的空间分布并不相同,主要集中在辽北、辽中、辽西北部分地区的大、中河流的中下游平原,因受辽东西部高、中部低的地势影响,致使大量降水汇聚于此,因而造成不同程度的洪涝灾害。

Analyzing temporal and spatial distribution of flood calamity in Liaoning province using Z index

According to 21 meteorological stations’ daily precipitation data from 1958 to 2008 in Liaoning province,analysis of temporal and spatial characteristics of flood in Liaoning Province in recent 51 years were conducted by using the Z-index method and the flood rating for a region.The results show that: From the perspective of time variation,there is a fluctuating downward trend in the type of precipitation,which has a decreasing trend of 1.963 mm/a and appearing cyclical variation of which mainly period for 9 years and the secondary period for 24 years and 3 years;From the perspective of spatial variation,the average of annual-precipitation is decreasing warp-wise progressively from the southeast coast of Liaoning to the northwest inland.however,the spatial distribution of Floods disaster Frequently appearing no coincidence with the areas of Rainfall-Concentration,which converging along the plains of the middle and lower reaches of the big or medium-scale rivers’ in the northern,middle,and parts of northwest in Liaoning province.The reasons accounting for it are that the highland in two flanks driving a good deal of rainfall toward the low-lying plains in the midland,and it result in varying degrees of flooding.