# Mapping Paddy Rice in China in 2002, 2005, 2010 and 2014 with MODIS Time Series
## 4 Results
### Rice Area Change
The northernmost province, Heilongjiang, saw a rice area increase of 183% from 2002-2014. It is now the province with the largest paddy rice area and number three in terms of rice production after Hunan, whose rice area decreased every year, and Jiangxi, which saw an increase from 2002-2010, followed by a slight decrease to 2014. This increase of paddy rice area in the north came at the expense of rice area decrease in the southern provinces. Zhejiang and Fujian saw a reduction in rice area by 28% and 58%, respectively, from 2002-2014. Jiangxi, Anhui and Henan, on the other hand, had net rice area increases of 20%, 14% and 81%, albeit with some area losses for the first two, from 2010-2014. Chongqing, Guangdong, Guizhou, Shandong and Yunnan experienced constant losses in rice area for every year we classified. Guangxi showed large losses in rice area from 2002-2010 with a notable increase from 2010-2014. Our results show that most provinces in China's south experienced a net loss in paddy rice area, with the coastal provinces showing the clearest trend, whereas the southeastern provinces that are further inland exhibited a more diverse behavior in regard to changes in their paddy rice areas. Figure 7: Provincial rice area changes from 2002–2014. Within the provinces, changes in paddy rice area are far from being uniformly distributed. Our classifications show where paddy area was gained and lost. Three example regions that saw substantial shifts are shown in Figure 8.  
Figure 8: Rice area changes in **(a)** Heilong Jiang Plain, Heilongjiang province, **(b)** Dongshan Bay, Fujian province, and **(c)** Beimin Lake, Hunan province. Landsat 8 RGB overview images are presented in the first row; the next four rows are based on the OCSVM classification, with slope relief derived from the Shuttle Radar Topography Mission (SRTM, 1 arc-second) Digital Elevation Modelas the background. Red stars show bifurcations of the Heilong Jiang (1) and Songhua Jiang (2) rivers, the plain at Beimin Lake (3), the southern part of Guanting Reservoir (4) and Wangjiachang Reservoir (5). Figure 8a shows the increase of paddy rice area at the river bifurcation of the Heilong Jiang and Songhua Jiang rivers in Heilongjiang province. The rice areas from 2002-2005 show no significant change. From 2005-2010, we can observe an increase in paddy rice area and even further from 2010-2014. By 2014, the largest part of the agricultural area between the two rivers is dedicated to rice. Overall, Heilongjiang province saw a massive increase in grain production and is now China's largest grain producer, contributing upwards of 10% to the countries rice production [2]. Figure 8b shows the decreasing rice areas in the coastal provinces with the example of Dongshan Bay, Fujian province. From 2002-2005, our classifications indicate a loss in rice area followed by almost complete depletion towards 2010. By 2014, only small patches along the river plains further from the coast are still classified as rice. We suspect that this might be due to rice paddies being converted to other crops and possibly conversion to aquaculture ponds, since the southeast coast of China is the World's leading aquaculture region [72]. Figure 8c shows the plain at Beimin Lake in Hunan province, which was dominated by rice agriculture in 2002 and saw a constant decrease on overall paddy rice area throughout the years we studied. The most visible decrease can be seen in the southwest, south of Guanting Reservoir, where in 2010, almost none of the rice area from 2002 is cultivated anymore. The same holds true for the western and northwestern part, between Wangjiachang and Weishui Reservoir, where the rice area diminished prominently after 2005.