Application on remote sensing survey of abandoned farmlands in winter along the Huaihe River based on GF-1 image

Abstract: The total supply of arable land resources and reserved land resources is very limited in China, and the contradiction between people and land is prominent. The rural land, as the property of farmers, is considered as a scarce resource . However, with the development of the market economy and rural economy, the phenomenon of abandoning rural lands will inevitably lead to the waste of land resources, affecting our food security and rural incomes. In addition, the phenomenon will further increase the cost of land law enforcement, which is not conducive to the stable development of rural economy and society. In order to obtain the situation of abandoned farmlands in winter in the region along the Huaihe River, a method for surveying the abandoned farmlands by using remote sensing technology was researched and used in this study. Huoqiu County, the main grain-producing area along the Huaihe River in Northern Anhui Province, was selected as the study area. GF-1 image with 16 m resolution in April from 2015 to 2017, while the winter wheat growing, were used as the data source to survey the situation of farmland abandonment. 1) The distribution of crops growing in winter was extracted, mainly winter wheat, from remote sensing; 2) Then the accurate planting area of crops was got by subtracting small features area using a deduction coefficient of small ground objects which from the 10 km × 10 km sampling frames. Finally, the winter wheat planting areas in 2015, 2016 and 2017 were compared. Because winter rape planting area only accounted for about 6.2% of winter wheat planting area in local, so crop of winter rape was not considered as in this study when interpreting images, and would produce some errors within the acceptable range. Two important conclusions were drawn: 1) In the whole county, the winter wheat planting areas from 2015 to 2017 were respectively 937.72, 821.79 and 608.91 km2. 2) Based on the winter wheat planting area in 2015, the areas of abandoned farmlands in winter in the year of 2016, 2017 were 115.93 and 328.81 km2 with ratio of 12.36% and 35.06%. Based on the investigation and interview of local farmers, it was considered that the continuous rainy season weather during the sowing period of winter wheat was the direct reason for the obvious increase of abandoned farmland area in 2017. Because of the continuous rainfall, serious water accumulation in low-lying areas prevented the winter wheat from being sowed and farmland were abandoned passively. Further analysis showed that the main reasons for the increase of abandoned framland in Huoqiu County and in the region along the Huaihe River in winter in recent years were insufficient irrigation and drainage facilities, low benefit of wheat which following rice, and farmers' empolyment behavior in cities, and so on. Therefore, the government should focus on improving the local farmland infrastructure conditions, enhancing the ability of disaster prevention and resilience, and take various measures to improve the profits on winter wheat planting, innovate the way of utilization of winter fallow field, and so on, in order to alleviate the farmland abandonment problem in region in winter. Remote sensing technology has great advantages in obtaining large range of farmland abandonment information, and the research in this paper could provide a reference for remote sensing investigation of winter farmland abandonment in the region along the Huaihe River.