| The problem about food and water relates to human existence and social stability, it is a strategic and challenging issue to solve it across the globe. In Northeast China, the three provinces are production base and commercial center for major grain. Being one of the mainfood sources, rice plays a significant role in the agriculture production in China. However, the process of rice growth consumes amounts of irrigation water. At present, water storage across the globe and the usage contradiction among different industries are becoming increasingly intensified. In these contexts, we estimated the rice water productivity (WP) using the method of remote sensing combined with micro-test of field investigation. The relationship between crop yield and water consumption was discussed. The study is expected to provide theoretical guidance for the sustainable utilization of agricultural water resources and the stable production of rice in the Northeast China.This paper specified the rice growth periods (i.e., the periods of this research) and the partition method (in order to improve the accuracy of the results of this research) in the three provinces based on the29agro-meteorological experimental stations, and analyzed the spatial distribution of rice yield as well as its characteristics.Using multi-sensor and multi-temporal remote sensing data derived fromTM, time-series NDVI, MOD12Q1and DEM, the rice planting area in three northeast provinces of China was extracted based on expert Knowledge decision-tree and the division in2009. The evapotranspiration(ET) of rice for different partitions was estimated using the new MOD16algorithm with MODIS products(including MOD12Q1land cover types, MOD15A2vegetation index products, MCD43B3albedo products) combined with GMOA meteorological data from2009to2010in the three provinces. The paper proposed a rice spatialization model of yield which extrapolated the yield to the pixel level. Additionally, the rice distribution maps were showed from2008to2010. According to the production map and ET map, the method of pixels compared one by one was used to get the water productivity map in rice area. At last, the irrigation experiment results in different scale and water condition at the same time periods were compared with the results based on remote sensing for validation.Main achievements and innovations of this paper were as follow:1) a decision tree method using different sources of remote sensing data to extract crop planting area was proposed. This method is verified to have high precision;2) based on the administrative divisions prefecture level analysis, we put forward a space model according to the relationship between rice yield and the maximum NDVI in rice fertility period of the corresponding unit, which expanding statistics yield to pixel level and controlled the error in each unit. The model provides a good solution to the hard traditional problem of the spatialization of the statistical yield data.3) Based on remote sensing inversion MOD16ET model, the paper estimated water consumption and water productivity of rice in a wide range for the north latitude40°-50°in crop growth period for the first time. It concluded that the rice water productivity changed from1.26to2.58with a mean of1.890in the three provinces in2008-2010and the highest value was in the north latitude44°-46°which was reasonable compared with the experiment results. Comparison among the results of the same field showed that the rice water productivity of the three northeastern provinces was significantly higher than the south areas of China, and was higher than that in other rice-growing areas of the world.4) we designed three different scales-the pot (0.07m2), pit (5m2) and community (60m2) under different water conditions for experiment of rice water productivity, the results were similar to these based on remote sensing. This attempt to provide a new paradigm for cooperative research on crop water productivity combined macroscopic satellite remote sensing with microscopic field experiments. |
PDF Full Text Request