辽宁省玉米地水分盈亏时空分布特征及灌溉模式分区研究

Temporal and spatial distribution characteristics of maize water surplus deficit and irrigation mode partition in Liaoning province

根据不同区域农作物需水规律和水资源供需状况,对区域内干旱区域类型、水分盈亏特性与干旱发生频率等进行综合分析和科学区划,对于提高整个地区(流域)农作物水分利用效率和水资源高效利用具有重要意义。该文基于辽宁省27个气象站1955—2014年逐日气象数据和玉米生长发育资料,对辽宁省不同玉米种植区域玉米生育期的需水过程、需水量、灌溉需水量、水分盈亏指数(crop water surplus deficit index,CWSDI)、干旱发生频率等的时空分布特征进行深入研究,得到以下结论:辽宁省不同区域玉米逐月需水量均呈现单峰变化趋势,7月需水量最大,全省生育期总需水量在335~391 mm之间;不同水文年玉米需水亏缺量在0~220 mm之间;CWSDI和干旱发生频率在全省的空间分布规律类似,综合两指标的数值分布特征,将辽宁省玉米灌区划分为干旱区和易旱区2种类型,并结合不同水文年型玉米灌溉制度,将辽宁省玉米种植区划分为7种灌溉模式。该研究成果可以为辽宁省区域农业用水区划与管理提供理论依据。

It is necessary to formulate a partition irrigation management mode based on the feature of water resource and meteorology of different sub areas in a large area.Maize is the main crop and major agricultural water consumer in Liaoning province.The objective of this study was to analyze the temporal and spatial distribution characteristics of maize water surplus deficit and lay out an irrigation mode partition scheme in Liaoning province.We collected the data of maize growth index,irrigation,and daily meteorological data from 1955 to 2014 in 27 agricultural meteorological stations in Liaoning province.The calculated index included evapotranspiration(ET),irrigation requirement,crop water surplus and deficit index(CWSDI)?the drought probability during the maize growth stage in Liaoning.The results showed that:the ET during the growth stage of maize varied in a single peak style in all the regions of Liaoning.The ET in western Liaoning was the highest in Liaoning,and the monthly ET of the western Liaoning was more than 140 mm in July.The high value of ET mainly appeared in the western region(ET≥380 mm).The ET was lower in the central and southern regions in Liaoning.The minimum value of ET was in the southern Liaoning,which was less than 345 mm.The standard deviation of ET were higher in the central and southern Liaoning around the Bohai sea(SD>15 mm),but it were stable in eastern and western Liaoning(SD<8 mm).A total of 4 typically deficient irrigation schedule were recommended and the irrigation norm in different hydrological years were 40,80,120 and 135 mm,respectively for the wet year,the normal year,the dry year and the drought year.In most years,CWSDI of maize were above 0 in the eastern Liaoning,and the peak was above 2.5(in the year of 1985).It indicates that the crop water supply exceeded demand in most of years.It was significantly different between the western and eastern Liaoning.In the western Liaoning,the most of the CWSDI was below 0,and sometimes even below?0.14.There was a widespread mild dry in most of the years,sometimes was dry even drought in this region.The spatial distribution of the dry frequency indicated that,in addition to the southeast Liaoning,the most regions may become mild dry,dry or drought,most especially in the western Liaoning.In the northwest Liaoning,the frequency of mild drought occurrence was high.The dry mainly appeared in the western Liaoning.The CWSDI and the dry frequency had the similar spatial distribution pattern.The area with mild dry frequency not less than 0.45,dry frequency not less than 0.28,the drought frequency not less than 0.12 and CWSDI higher than 0 was same.Thus,we defined the area meeting one of the conditions above as the arid area.Those areas were in the western and northern Liaoning where the water resource supply was less than demand and the dry condition appeared very often.We defined the area with mild dry frequency not less than 0.1 or CWSDI higher than 0.45 as the drouht-prone area.These areas were in the northern Liaoning,middle Liaoning and the west of eastern Liaoning.Based on the CWSDI and dry frequency,a total of 7 irrigation modes were set up.A total of 6,4,3 and 1 irrigation mode were for the drought,dry,normal and wet year,respectively.The study would improve not only the areas water resource utilization but also food security.