气候变化条件下石羊河流域农业灌溉需水量的模拟与预测
Simulation and estimation of impact from climatic changes on irrigation water requirement in Shiyang River Basin

根据石羊河流域及周边共11个气象站点1959—2012年的逐日气象资料，利用大气环流模型HadCM3的输出和SDSM统计降尺度模型，生成A2、B2两种排放情景下未来石羊河流域各站点2020 s，2050 s和2080 s的ET0和降水日值；使用作物系数法，扣除有效降雨量，计算现状和未来不同作物净灌溉定额、流域净灌溉需水量和耗水量；应用反距离加权插值法（IDW）研究作物净灌溉定额的空间分布特征。结果表明，石羊河流域小麦、玉米、甜椒、棉花、胡麻和苹果的多年平均作物净灌溉定额都呈现从西南到东北递增的趋势，预测未来气候变化情景下，6种典型作物净灌溉定额呈增加趋势；多年平均流域净灌溉需水量为12.65×108 m3，多年平均耗水量为15.42×108 m3；在种植结构维持现状条件下，预计2020 s，2050 s和2080 s，在HadCM3模式的A2情景下净灌溉需水量分别为13.45×108 m3、15.02×108 m3、16.94×108 m3，耗水量分别为15.53×108 m3、16.65×108 m3、18.18×108 m3，B2情景下净灌溉需水量分别为13.55×108 m3、14.63×108 m3、15.51×108 m3，耗水量分别为15.56×108 m3、16.34×108 m3、17.00×108 m3，未来流域净灌溉需水量和耗水量都呈明显上升趋势，且A2情景下的上升幅度大于B2情景。石羊河流域的农业灌溉需水在未来将持续增加，2050 s之后增加趋势更为显著。
Upon the simulation and estimation of the impact from climatic changes on net irrigation requirement quota of crop, irrigation water requirement (IN) and total crop water demand (Wt) in Shiyang River Basin could provide support for efficient use of water resources and sustainable development of agriculture. While daily ET0 and precipitation in 2020 s, 2050 s and 2080 s were downscaled from HadCM3 (Hadley centre Coupled Model, version 3) outputs under A2 and B2 emission scenarios by SDSM (Statistical Downscaling Model), based on meteorological data from 11 meteorological stations located in and around the Shiyang River Basin during 1951—2012. Net irrigation requirement quota, IN and Wt were calculated by using crop coefficient method, and removing the effective rainfall. The spatial distribution of net irrigation requirement quota was investigated by Inverse Distance Weighted Interpolation. The results showed that net irrigation requirement quota performed an increasing tendency from southwest to northeast gradient for wheat, maize, sweet pepper, cotton, sesame and apple. HadCM3 projected an increasing trend for these six typical crops. The present IN and Wt were 12.65×108 m3 and 15.42×108 m3, respectively in the whole basin. When the present planting structure was maintained, under A2 emission scenario, the IN were 13.45×108 m3, 15.02×108 m3, and 16.94×108 m3, and the Wt were 15.53×108 m3, 16.65×108 m3, and 18.18×108 m3, respectively in 2020 s, 2050 s and 2080 s. Under B2 emission scenario, the IN were 13.55×108 m3, 14.63×108 m3, and 15.51×108 m3, and the Wt were 15.56×108 m3, 16.34×108 m3, and 17.00×108 m3 respectively in 2020 s, 2050 s and 2080 s. A remarkable increasing temporal trend was observed in net irrigation water requirement, IN and Wt. The increase under B2 scenario was lower than that under A2 scenario. There would be a significant increasing trend about requirement of irrigation water in the