变化环境下农业需水量演变趋势及驱动力

根据宝鸡峡灌区11个气象站近30 a的气象及近20 a种植面积资料,分析了气候及作物种植结构的变化特征,计算了作物需水量和农业需水量,研究了灌区农业需水量的演变趋势,并利用主成分回归分析法揭示了影响农业需水量变化的驱动因素.结果表明:灌区气温呈显著上升趋势,相对湿度和风速呈显著下降趋势,蒸发量和日照时数略有增多,降水量有所减少.灌区农业种植结构变化较大,粮食作物与经济作物种植面积比例显著降低,由1991年的4.08减小为2010年的1.83;粮食作物与农作物总播种面积比例也呈下降趋势,由1991年的0.46减小为2010年的0.40.灌区小麦、玉米、油菜、棉花等4种主要作物需水量呈递增趋势,其中油菜需水量递增速率最快,约为3.558 mm/a;灌区农业需水量呈递减趋势,其递减速率为3.35×107m3/a.影响农业需水量变化的主要驱动因素为种植面积、降水量和蒸发量.降水量的减少和蒸发量的增多使得作物需水量明显增多,而农作物种植面积的减少,引起农业需水量的显著减少.

Evolutionary tendency of agriculture water requirement and its driving force under changing environment

According to the meteorological data of over 30 years at 11 weather stations and cultivated area information of 20 years in Baojixia Irrigation District,the variation characteristics of climate and crop planting structure were analyzed,the crop and agriculture water requirements were calculated;then the evolutionary tendency of agriculture water requirement was investigated and the driving factors that affect the agriculture water requirement were disclosed by using principal component regression method. The results showed that temperature in the irrigation district rises significantly,but relative humidity and wind speed reduce obviously,evaporation and sunshine hour increase somewhat,but precipitation decreases to some extent. Agricultural planting structure of the irrigation district changes greatly,the ratio of food crop planting area over economic crop planting areas decreases markedly,for instance,it is diminished to 1. 83 in 2010 from 4. 08 in 1991. The ratio of food crop planting area over total crop planting area decrease too,for example,it is reduced to 0. 40 in 2010 from 0. 46 in 1991.The water requirement of four kinds of crops,namely wheat,corn,canola and cotton shows an increasing tendency,especially the water requirement of canola exhibits the highest increasing rate,about 3. 558 mm / a; however,the agricultural water requirement has an decreasing tendency and its decline rate is 3. 35 × 10 7 m 3 / a. The major driving factors that affect the agricultural water requirement are planting area,precipitation and evaporation. Declining precipitation and increasing evaporation result in a markedly increased water requirement,however,the decreasing crop planting area causes a significantly reduced agricultural water requirement.