宝鸡峡灌区1981—2010年降水及蒸发时空变化特征研究

Spatial and temporal characteristics of precipitation and evaporation during 1981—2010 in Baojixia Irrigation Area

根据宝鸡峡灌区内11个气象站的资料,基于Mann-Kendall检验法、线性趋势法和地理信息系统(GIS),分析灌区1981—2010年降水量和蒸发量的时空变化趋势及特征.结果表明:在a=0.05的水平上,灌区降水量呈不显著下降趋势,变化率约为-29.0 mm/10 a;蒸发量为不显著上升趋势,变化率为32.7 mm/10 a,蒸降比为不显著上升趋势,变化率为0.16/10 a;降水量和蒸发量的空间变化具有互逆特征,从灌区西南向东北降水量递减而蒸发量递增,变幅上东北和西南降水量减幅和蒸发量增幅较大,灌区中部变幅较小,蒸降比变化趋势表明全灌区气候有干旱趋势但统计不显著,灌区西南和东北局部地区干旱化趋势较其他地区更明显.全局和局部站点(乾县、武功和咸阳)的趋势检测出现尺度效应,检测结果及其显著性明显不同.不同县市空间差异较大,部分市县(宝鸡、扶风、高陵、泾阳)的干旱趋势远较其他县市显著,应予以重视.

The changes of spatial and temporal characteristics in precipitation and evaporation in Baojixia Irrigation District were analyzed by linear regression, Mann-Kendall test and geographic information system （GIS）, based on the meteorological data observed at 11 stations during 1981--2010. The results showed that precipitation decreased, while evaporation and the ratio of evaporation to precipitation was increasing, but none of them were significant at a=0.05 level; their rates of changes were -29. 00mm/10a,32.7Omm/10a and 0.16/10a, respectively. There was a reciprocal phenomenon between the spatial characteristics of precipitation and evaporation： from southwest to northeast, precipitation declines and evaporation increases, and the absolute values of their rates are large at southwest and northeast of the district, and small at central area. The scale effects appeared between the whole region and three specific stations （Qianxian, Wugong and Xianyang）. Because of the spatial variability, several counties or cities （Baoji, Fufeng, Gaoling, Jingyang） were more prone to drought.