Study on difficulty and time sequence of construction of high standard basic farmland in Chongqing based on remote sensing images

Abstract: The difficulty and timing analysis of high standard basic farmland construction is one of the prerequisites for construction planning. In order to further identify the relationship among the quality of cultivated land, the difficulty and time series of construction, the paper regarded Dianjiang County in Chongqing as the study example. The cultivated land quality, the difficulty and time series of high standard basic farmland construction in Dianjiang County, as well as the differential construction zone and management model were studied and analyzed, by adopting high resolution SPOT5 remote sensing images, agricultural land quality grade data, external survey data, and the project database of land consolidation and high standard basic farmland construction projects statistical data, using the entropy weight TOPSIS model, the construction difficulty index method, etc., and based on the support of ArcGIS and ENVI software. The results showed that: (1) from the aspect of the comprehensive quality, the regional spatial distribution was showing 4 levels obviously. The highest grade "Ⅳ", which occupied 17 499.68 hm2, was mainly in the "H" pattern in the Mingyue Mountain, the medial lower edge of Huanghua Mountain, and the East and west to the central region. The second grade "Ⅲ", which occupied 24 781.16 hm2, was mainly extended to both sides of the north and south central lines, showing a "double core" pattern. In the third grade "II", which occupied 27 133.37 hm2, the "double core" type was transformed into a "mononuclear" type mainly in the Heda platform area of the right lower right side of the Gaotan River. In the lowest grade "Ⅰ", which occupied 11 030.55 hm2, the core distribution was basically the same as that in the lower edge of the Mingyue Mountain area and Heda platform area and the Huanghua Mountain. (2) The difficulty of construction showed good correspondence with the comprehensive quality, the higher the comprehensive quality, i.e. the smaller the difficulty of the construction. In the construction division, there were 4 areas, namely, the priority construction area which occupied 18 590.14 hm2, the key renovation area which occupied 31 084.33 hm2, the condition zone which occupied 22 830.94 hm2 and the poor condition area which occupied 7 939.35 hm2. (3) The timing of construction was presented in 3 periods, namely, the recent term (2016-2020), the medium term (2021-2030), and the long term (2031-2050). Regional differences were existed both in the division and the timing of construction. The recent term construction area was 30 166.79 hm2, accounting for 37.51%; the medium term construction area was 25 983.65 hm2, accounting for 32.37%; and the long term construction area was 23 409.43 hm2, accounting for 29.17%. The timing planning of construction was mainly considering the near future, while building enough space for the medium and long term to facilitate the construction of high standard basic farmland; (4) The area was divided into 3 zones, based on the advantages of regional industrial development, which were the multi-functional agricultural development zone served by the areas along the lower edge of the Yu Wu Road in the lower edge of the Mingyue Mountain, the standardized grain and oil base zone served by the areas of the Mingyue Mountain and Huanghua Mountain trough area, and the stereoscopic and recycling agriculture zone served by the area around the center of grand platform of the right bank of Gaotan River. (5) Based on the current situation of regional agricultural development, three types of development for different regions were put forward, namely, the local government domination, the facility domination, and the location domination. In conclusion, the timing of high standard basic farmland construction is affected by the quality of cultivated land and the difficulty of construction. The construction and management of high standard basic farmland differential construction and management should mainly consider the model of building regional site conditions and industrial development. And the work of this paper will provide reference for the construction zoning of the high standard agricultural fields in Dianjiang County.