城市快速扩张驱动下的耕地演化模拟与预测——以广东省东莞市为例

在快速城市化进程中,有效地保护耕地数量和质量是一个重要的科学命题。本文以广东省东莞市为例,通过构建Logistic-CA城市扩张模型,试图探明城市快速扩张主导下的耕地演化特征和机制,对耕地演化进行模拟与预测,为城市的可持续发展规划和耕地保护提供科学的参考依据。首先,分析了1998-2013年东莞市各用地类型间的转换关系,对城市扩张与耕地演化的机制进行了探究;其次,综合考虑地理、经济与政策因子,通过对地理因子模拟和地理与经济结合模拟2种结果的比较分析,选取最优因子组合定义了CA转换规则,构建Logistic-CA模型;最后,基于该模型,依据2006-2020年东莞市土地利用总体规划图,对耕地演化进行预测,并进行数量、质量和空间形态上的分析。模拟结果表明,在耕地演化机制上,东莞市在2003-2008年和2008-2013年2个时段中新增城市用地分别有71.96%和80.86%直接或间接来源于耕地,且相应时段内的耕地补给量远小于耕地流失量;在空间形态上,呈现大块耕地边缘破碎化,细碎耕地逐步消亡的空间演化模式。模型的预测结果表明,至2020年耕地将会减少8205.4 hm²,且优等耕地和高等耕地的减少比重分别达到5.16%和5.27%。

Simulation and Forecast of Cultivated Land Evolution under Rapid Urban Expansion: A Case Study of Dongguan City in Guangdong Province

In the process of rapid urbanization, how to effectively protect the quantity and quality of cultivated land is an important scientific proposition. Through constructing Logistic Cellular Automata model (Logistic-CA) for urban expansion and carrying out the simulation and forecast of cultivated land evolution, this paper intend to explore the characteristics and mechanisms of cultivated land evolution under the rapid urban expansion in a case study of Dongguan city in Guangdong province, so as to provide a scientific reference to the sustainable development planning of the city and the protection of cultivated land resources. Firstly, the mechanism of urban expansion and cultivated land evolution is explored through analyzing the conversion relationship between different land use types of Dongguan city in 1998-2013. Based on the result, the optimal factor combination is chosen to define the conversion rule of CA by comparing the simulation results of cultivated land evolution using geographical, economic and policy factors respectively, and the Logistic-CA model is constructed. Finally, in accordance with the general planning of land use in Dongguan city from 2006 to 2020, the evolution of the cultivated land is predicted using Logistic-CA model built based on the optimal factor combination, and the analysis of quantity, quality and spatial patterns is carried out. Simulation results show that 71.96% and 80.86% of the new urban land in Dongguan city directly or indirectly come from the cultivated land in the 2003-2008 and 2008-2013 two periods, and the quantity of the cultivated land supplementation is far less than its loss in the corresponding period. The spatial evolution pattern of the cultivated land has the characteristics that large tracts are turning into fragmentary lands toward the margin, and the fragmentary land parcels gradually disappear. The forecast results show that 8205.41 hectares of the cultivated land will disappear by 2020. At the same time, 5.16% of the top level and 5.27% of the high level cultivated land will disappear.