基于标准化降水指数的近40a陇东地区旱涝时空特征

论文基于陇东地区15个气象站点1971-2010年的月降水资料,采用不同尺度的标准化降水指数(SPI)反映不同时间尺度的旱涝状况,并结合GIS空间分析技术和数理统计理论,对其旱涝特征进行定量化分析,阐述其时空演变规律。结果表明:近40 a陇东地区呈干旱化演变趋势;1971-2000年旱涝频繁,30 a间共出现7次干旱事件和5次雨涝事件,而2001-2010年旱涝频率较小。春、 夏、 冬季干旱呈弱增加趋势,秋季旱涝基本持平。该区降水存在三种空间分布型,并依此划分为三个旱涝区域,即东南部(雨涝区)、 北部(干旱区)和中西部(降水适宜区)。季节旱涝存在较大的空间分布差异,其中北部的环县、 华池在夏秋冬三季普遍干旱,西部的静宁在冬春夏三季易旱;而中部的西峰、 镇原和南部的泾川、 崇信、 华亭等地四季降水偏多,易形成雨涝。

Analysis of Drought-flood Spatial-temporal Characteristics Based on Standard Precipitation Index in East Region of Gansu in Recent 40 Years

The characteristics of drought and flood in east region of Gansu are shown based on monthly precipitation data of 15 meteorological stations from 1971 to 2010 by means of different scales of standard precipitation index, combined with GIS spatial analysis techniques and mathematical statistical theory. The characteristics of drought and flood were quantitatively analyzed and the evolution of the spatial and temporal change of precipitation was illuminated. The results showed that: over the past 40 years, there was a slow decreasing trend of average monthly standard precipitation index (SPI) and an evolution trend of drought was showed in east region of Gansu. Droughts and floods are frequent in the study area from 1971 to 2000, there were seven drought events and five flood events during the 30 years, but frequency of drought and flood was smaller from 2001 to 2010. The weakly increasing trends of spring, summer and winter drought were shown but drought and flood in fall was in a balanced state. There are three types of spatial distribution of precipitation in the area, and were divided into three regions accordingly, i.e., Southeastern (waterlogging area), Northern (arid area) and Midwest (precipitation comfort zone). Meanwhile, seasonal drought and flood differ greatly in spatial distribution, of which Huanxian and Huachi counties in the north are dry generally in summer, autumn and winter, and Jingning in the west tends to be dry in winter, spring and summer; but there are more rainfall in all seasons and easy to form waterlogging in central Xifeng, Zhenyuan and the southern Jingchuan, Chongxin and Huating.