关中地区灌溉农业发展对区域蒸发的影响研究

主要从分析参考作物蒸发蒸腾量(ET0)的变化趋势来反映气候变化对蒸发的影响,从灌区实测水面蒸发量的变化趋势来分析灌溉农业发展对区域蒸发的影响。用改进后的Penman公式计算关中地区1961～2001年系列5个气象站的ET0,结果显示:80年代前后气候对关中地区年ET0值的影响有明显区别,80年代以后关中地区年ET0值增长趋势加大,受气候影响明显大于80年代以前。多年平均年内分布表明连续最大3月即6～8月占全年的比例为46%～48%,但80年代以后年内分布6～8月ET0所占比例有降低趋势;从泾惠渠灌区灌溉试验站实测水面蒸发资料分析,显示明显的逐年减少的趋势,年内分布表明6～8月水面蒸发量所占比例有降低趋势。说明灌溉农业发展引起农田小气候的变化,减少了夏季潜在的蒸发和实际蒸发量。

Effect of Irrigational Agriculture Development on Regional Evaporation in Guanzhong Region

This paper studies the effect of weather change on regional evaporation by analyses change trend of reference crop evapotranspiration(ET0), and the effect of irrigational agriculture development on irrigation district actually measured evaporation from water surface. The mean monthly ET0 values for the period 1961～2001 of five weather stations in Guanzhong Region is estimated by modified Penman equation. The annual ET0 values shows a light increasing trend and this trend is enlarge after 1980's. But annual distribution of ET0 values shows that the ET0 proportion of the three months (from June to August) has a decreasing trend. Annual observed evaporation from water surface for the period 1955～1994 of Jinghuiqu irrigation district experiment station shows a decrease trend and annual distribution of it shows that the proportion of the three months (from June to August) has a decreasing trend too. It implies that irrigational agriculture development causes the regional farmland weather change, and decrease ET0 values and actually evaporation in summer season.