河套灌区春小麦适宜秋浇模式的模拟研究

Simulation of Proper Autumn Irrigation Modes for Spring Wheat in Hetao Irrigation District

【目的】在河套灌区尺度探讨相对适宜的秋浇模式有利于保证作物正常生长和节省引黄灌溉水量。【方法】基于已构建并率定验证后的分布式SWAP-WOFOST模型,在灌区尺度上模拟分析2000—2010年春小麦适宜的秋浇模式。【结果】以提高春小麦水分生产力(WP)为目标所得到的推荐秋浇模式,灌区5个旗县区的秋浇定额均较基本情景有所减少,且秋浇的时间均建议提前至每年的9月30日。灌区春小麦的多年平均产量较基本情景增大约6.47%,多年平均WP提高约6.32%。【结论】基于数值模拟所得到的灌区春小麦种植条件下相对适宜的秋浇模式为内蒙古河套灌区维持粮油生产稳定的同时进一步节省灌溉水资源提供了一定参考。

【Background】The Hetao Irrigation District(HID)is located in an arid and semi-arid region of Northwest China.It is one of the three largest irrigation districts in China,and it is an important food production area.Irrigation water accounts for almost 98%of total water consumption in the HID,which is a typical area where there would be no agricultural production without irrigation because of the low precipitation levels.The Yellow River is the main source of irrigation water for the HID,and supplied 97%of irrigation water to the HID before 2000.Long-term excessive water diversion is because of poor management of the field irrigation and water conveyance.However,with rapid economic development and growing demands for water,the amount of water in the Yellow River Basin has sharply decreased,which has led to decreased allocations of water for agriculture.To attempt to match the water demand to the reduced water supply in the Yellow River Basin,the annual amount of irrigation water from the Yellow River will be reduced from 5.581×109 m^3 to 4.369×109 m^3 for the HID in the future,according to the irrigation management proposal from the Chinese Ministry of Water Resource.To maintain sustainable agriculture,it is important to improve crop water productivity(WP)when there is a limited water resource.The WP is an important indicator for evaluating water-saving irrigation practices in arid and semi-arid regions,because it reflects the relationship between water and production.Autumn irrigation is important for sustainable development of agriculture in the HID.The autumn irrigation area accounts for more than 75%of the cultivated land area in the HID,and the amount of autumn irrigation water is about 1.73×109 m^3,accounting for about one third of the annual irrigation water consumption.Its purpose is to leach the soil salt and adjust the soil moisture in order to create a good soil water and salt conditions for the next spring sowing.However,the problems of excessive irrigation and low water utilization efficiency still exist,which not only cause the waste of water resources,but also cause the soil tidal collapse and backwash,and promote the accumulation of salt on the soil surface.【Objective】Therefore,it is significant to ensure crop growth and saved irrigation amount from Yellow River by adjusting autumn irrigation mode to local conditions at the regional scale.【Method】In this study,a distributed SWAP-WOFOST model was used to simulate the proper autumn irrigation modes for spring wheat in the HID during 2000—2010.【Result】The results showed:in order to improve spring wheat water productivity(WP),autumn irrigation modes were recommended.The autumn irrigation amounts were reduced compared with the basic scenario in Hangjinhouqi(HH),Linhe district(LH)and Wulateqianqi(WQQ).Meanwhile,except for LH,the autumn irrigation time in other areas were advanced to September 30th every year.The annual average yield of spring wheat was about 6.47%higher than the basic scenario,and the annual average WP was improved about 6.32%.【Conclusion】The numerical simulation analysis would provide a certain reference for adjusting autumn irrigation modes to local conditions at the regional scale.