华北棉区棉花需水量时空变化研究

为分析气候变化背景下华北地区棉花需水量和水分生态适宜性时空变化特点,本研究利用华北棉区47个气象站点逐日气象数据,通过SIMETAW模型分析1986—2015年棉花生育期需水量(ETc)、有效降雨量(Pej)和灌溉需水量(ETaw)及变化趋势。结果表明:近30年来,棉花生育期需水量和灌溉需水量呈减小趋势,生育期有效降雨量呈增加趋势;6—8月棉花需水量最大,不同站点月均需水量在80~160mm;7月和8月是棉花灌溉需水量最小的月份,华北棉区平均灌溉需水量接近零,灌溉需水量最大的月份是6月,多年平均灌溉需水量为56.50mm;华北棉区地下水超采区与非超采区灌溉需水量分别为144.41和70.41mm,降水量的不同是造成这种差异的主要原因;华北棉区棉花生育期多年平均需水量、有效降雨量和灌溉需水量分别为560.19、467.32和98.75mm,棉花一年一熟制的灌溉需水量小于传统的冬小麦-夏玉米模式,而经济收益大于春玉米一年一熟制,在华北地区超采区适当增加棉花的种植面积,有利于缓解华北地区水资源缺乏的现状。

Temporal and spatial variation of water requirement of cotton in cotton-growing area of North China Region

Based on the observed daily meteorological data and agro-meteorological data from 1986 to 2015 from 47 normal meteorological stations and agro-meteorological stations in cotton-growing area of North China Region, the cotton water requirements (ET_c), effective precipitation(P_ej), irrigations demand(ET_aw) were calculated by SIMETAW model. The results showed that the water requirement of cotton declined in recent 30 years, but effective precipitation was risen in the same period. The ET_c in Jun to Aug was maximum during cotton growth period, which was from 80 to 160 mm. However, ET_aw demand of Jul and Aug were minimum, which was almost zero, and the maximum irrigation demand month of cotton growth period is Jun, the mean of North China Region was 56.50 mm. The mean of ET_aw of cotton in funnel area and normal area were respectively 144.41 and 70.41 mm due to the difference of precipitation. The mean ET_c, Pej and ET_aw during cotton growth period were 560.19, 467.32 and 98.75 mm in North China area, respectively. The water requirement of continuous cotton was lower than winter wheat-summer maize, and the continuous cotton had better benefits than continuous spring maize. In conclusion, replacing the traditional crop rotation with continuous cotton was promising for alleviate water shortages in funnel area.