关键词: 作物生长模型, 遥感植被指数, 尺度扩展, 区域模拟

Abstract:

With the support of GIS information, a process-based crop growth model is designed to estimate the spatial pattern of dry matter accumulation, seed yield and evapotranspiration of winter wheat in the Hebei Plain, from October, 1989 to June, 1990. The crop leaf area index in the model is retrieved from NOAA-AVHRR monthly maximum composite NDVI and the daily meteorological variables are scaled up with gradient inverse distance square method. The simulated domain ranges from 113°E to 118°E and 36°N to 41°N with an area of about 60,000 km 2. The grid resolution is 1 km 2 and time step is daily in this paper. The model was tested with field sampled dry matter data of five varieties and the district statistical economic yields. The absolute bias between the simulated and the statistical yields is about 12% in the domain. The simulated results show that the high yields are located in Baoding, Shijiazhuang, the central part of Xingtai and the eastern part of Handan districts from North to South with values of 6000 to 8400 kg hm -2. The low yields are shown at the eastern part of Langfang, Cangzhou, Hengshui and the eastern part of Xingtai with values lower than 3000 kg hm -2. Compared with the simulated potential yield, it is found that the differences between actual yields and potential yields are significant in this region, of which 72% shows a yield gap as large as 5000 kg hm -2. The simulated amounts of evapotranspiration over the growing season are from 310 to 500 mm, and the water use efficiency (WUE) in the irrigated fields is about 10 to 17 kg ha -2 mm -1. Low WUE area (<8 kg hm -2mm -1) occupies 42% of the whole area. The spatial pattern of WUE is similar to that of yield. As suggestion, some water conservancy techniques should be taken to increase the water use efficiency in this area, such as stalk cover, new irrigation projects,etc.

Key words: crop growth model, remote sensing, vegetation index, scaling up, regional modeling