基于FLUS模型和SD模型耦合的中巴经济走廊土地利用变化多情景模拟

中巴经济走廊的规划和建设离不开对走廊沿线土地资源、生态环境空间格局及变化过程的科学认识。未来土地利用变化模拟研究,可为区域土地资源管理、生态环境可持续性和潜在风险评估等研究提供可靠的预测数据。本文通过耦合系统动力学模型（SD）和未来用地模拟模型（FLUS）,并结合中巴经济走廊建设和区域的生态环境政策等设置多种情景对中巴经济走廊进行土地利用模拟,充分发挥2个模型在宏观土地需求模拟以及微观土地分配上的优势。首先根据2009—2015年的历史数据构建并验证了区域土地利用SD-FLUS模型,然后模拟了2016—2030年中巴经济走廊区域惯性发展、投资优先以及和谐发展3种不同情景下的土地利用变化。结果表明：① 历年的总量模拟相对误差均小于9.00%,2015年喀什和巴基斯坦模拟的总体精度均达到90.00%以上、Kappa系数达到0.90以上,说明SD和FLUS耦合模型能有效模拟中巴经济走廊土地利用变化格局,适用于其土地利用变化的情景模拟;② 到2030年,不同情景之间的土地利用存在明显的差异。在3种情景下建设用地均扩张,和谐发展情景扩张速度居中,该情景下喀什建设用地增加了235.17 km²,巴基斯坦增加了4942.80 km²,而扩张最快的投资优先情景下,喀什建设用地增加了265.23 km²（惯性发展情景仅增加163.71 km²）,巴基斯坦建设用地增加了5918.91 km²（惯性发展情景仅增加2861.84 km²）;巴基斯坦和谐情景下的耕地增量（4768.60 km²）不到增长最多的惯性发展情景的一半,喀什耕地在和谐发展情景增加了604.44 km²,不到投资优先情景的3/4;3种情景中只有和谐发展情景下的林地得到了有效的恢复。总体而言,和谐发展情景兼顾了社会经济发展和生态环境保护,是3种情景中最理想的情景。模型模拟结果可为中巴经济走廊的可持续性研究和生态环境评估等提供一定的数据和方法支撑。

Multi-scenario Simulation of Land Use Change Along China-Pakistan Economic Corridor through Coupling FLUS Model with SD Model

Planning and construction of China-Pakistan Economic Corridor (CPEC) is inseparable from the scientific cognition of the spatial patterns and changing processes of land resources and eco-environment in this area. Land Use and Land Cover Change (LUCC) simulation can provide reliable prediction data for regional land resources management, eco-environment sustainability, and eco-environment risk assessment. In this paper, based on the coupled System Dynamics Model (SD) and future Land Use Simulation Model (FLUS), combined with the China-Pakistan Economic Corridor construction and regional eco-environment policies, various scenarios were set up to simulate the land use change of the China-Pakistan Economic Corridor, taking full advantages of the two models in macro land demand simulation and micro land allocation. Firstly, the SD-FLUS model was constructed and validated using the historical data of CPEC in 2009-2015. Then the land use changes from 2016 to 2030 under three different scenarios, namely Baseline Development (BD)scenario, Investment Priority Oriented (IPO) scenario, and Harmonious Development (HD) scenario, were simulated. Results show that: (1) The relative error of demand simulation was less than 9%, and the overall accuracy and Kappa coefficient of the simulation were over 90% against the actual land use data in 2015, which indicates the SD-FLUS coupling model effectively reflected the land use change pattern of the China-Pakistan Economic Corridor. The model could be used for further simulation of land use changes in CPEC under different scenarios; (2) There are significant differences in simulated land use under different scenarios until 2030. Construction land expanded under all three scenarios but at different speeds. The expansion speed of HD scenario was in the middle. Under this scenario, the construction land in Kashgar and Pakistan increased by 235.17 km² and 4942.80 km², respectively. The expansion speed under the IPO scenario was the fastest, with the construction land in Kashgar increased by 265.23 km² and construction land in Pakistan increased by 5918.91 km². Under the BD scenario, the construction land in Kashgar and Pakistan increased by 163.71 km² and 2861.84 km², respectively. Under the HD scenario, increment of Pakistan's cultivated land area was less than half of that under BD scenario. Kashgar's cultivated land area increased the most in IPO scenario (about 882.54 km²), which was about three quarters of that in the HD scenario. The forest land was effectively restored only under the HD scenario. Generally, the HD scenario taking both social-economic development and eco-environment protection into account is the most ideal scenario among the three scenarios. Our simulation results can provide useful data support for the construction of China-Pakistan Economic Corridor and the assessment of eco-environment in the future.