基于MODIS和SEBAL模型的黄淮海平原冬小麦水分生产力研究

以2011年1月-2012年12月MODIS多时相遥感影像产品、气象数据和作物生育期为基础,借助SEBAL模型估算了黄淮海平原冬小麦实际蒸散量(ETa);通过MODIS NDVI光谱曲线特征与冬小麦单产数据的耦合,将县域尺度作物单产"降尺度"至基于像元的产量栅格图,实现冬小麦产量栅格化。在完成作物实际蒸散量模拟和产量栅格化的基础上,对黄淮海平原冬小麦水分生产力进行估算。结果表明,冬小麦水分生产力区域平均值为1.21kg·m~(-3),高值区主要位于北京、天津、山东北部和河北南部地区。在环渤海山东半岛滨海外向型二熟农渔区(一区)、海河低平原缺水水浇地二熟兼旱地一熟区(三区)和黄淮平原南阳盆地水浇地旱地二熟区(五区)冬小麦产量与水分生产力呈显著正相关,说明随着冬小麦产量的增加,其水分生产力增加;在燕山太行山山前平原水浇地二熟区(二区)冬小麦水分生产力与实际蒸散量呈极显著负相关(P0.01),与产量呈极显著正相关(P0.01),表明水分生产力将随着实际蒸散量的减少和产量的增加而增大,同时产量增加对水分生产力提高的贡献大于实际蒸散量的减少;在江淮平原丘陵麦稻两熟区(六区)冬小麦水分生产力与实际蒸散量呈显著负相关,与产量相关关系不明显,说明在黄淮海平原南部水分生产力的提高主要依靠实际蒸散量的减少。

Investigation on Water Productivity of Winter Wheat Based on MODIS and SEBAL in the Huang-Huai-Hai Plain

Understanding how the crop water productivity can be increased is widely accepted to be a high priority where water resources are currently scarce and/or over-exploited in China.As the primary data source,MODIS remote sensing,statistics,meteorological data,crop growth period data and ground truth-data from Jan.2011 to Dec.2012 were used in actual evapotranspiration estimation,yields rasterizing,and water productivity calculation for winter wheat in the Huang-Huai-Hai Plain(3H Plain).The statistical data for wheat yield was synthesized to calculate district-state-level land productivity,which is then further extrapolated to pixel-level values using a MODIS NDVI image,based on a crop dominance map.Spatial variation of crop water productivity was investigated in order to reveal the key factors of crop water productivity.In addition,the relationship between water productivity and actual evapotranspiration and in subsequence yield for winter wheat was discussed in 3H Plain.The main results indicated that the SEBAL is suitable for estimating evapotranspiration in winter wheat based on the comparison with the evapotranspiration measured by Yucheng (in Shandong province).The regional average value of water productivity for winter wheat was detected to be 1.2 lkg·m-3,with the higher value in Beijing,Tianjin,north part of Shandong province and south part of Hebei province.The pronounced relationship of spatial correlation of the yield and water productivity for winter wheat indicated that the increasing yield governed the increment of water productivity for winter wheat in the coastal land-farming-fishing area (zone1),low plain-hydropenia irrigable land and dry land zone (zone2) and basin-irrigable land and dry land (zone5).Whereas,the increasing water productivity for winter wheat was recognized to be controlled by rather the increment of yield than the reduction of actual evapotranspiration (ETa) for winter wheat in the piedmont plain-irrigable land (zone2).Furthermore,the pronounced relationship of negative correlation of water productivity and ETa for winter wheat described that only the reduction of ETa was responsible for the increment of water productivity for winter wheat in hill-wet hot paddy-paddy field (zone6).The results is expected to provide a basis information for agricultural water management,improvements of crop water productivity and choice of adaptive mechanism under climate change in Huang-Huai-Hai plain.