干旱区水资源约束下的生态退耕空间优化及权衡分析——以奇台县为例

干旱区耕地大规模扩张导致水资源超载、生态问题频发,亟须退地还水。因此,探索水资源约束下的生态退耕空间优化方案,不仅有助于解决干旱区面临的问题,还可为土地利用规划和决策提供参考。目前对退耕方案多效益矛盾的研究尚量化不足,有鉴于此,本文建立生态退耕空间优化配置及权衡分析模型,以新疆奇台县为研究区进行模型应用,构建了水资源约束下的生态退耕方案群,并设计保有耕地优先和保护生态优先等两种情景,利用蚁群优化算法实现了生态退耕的空间配置模拟与优化。结果表明:耕地面积在保有耕地优先情景将减至9.94万hm2,保护生态优先情景则为6.96万hm2;在此退耕过程中,河道内生态用水占水资源总量的比例从10%增加到30%,防固沙量由713.22万t增加至816.59万t,经济效益则由34.86亿元下降至24.75亿元。通过比较单位经济效益的减少比例可产生的生态效益增加比例,确定耕地面积退至8.35万hm2时是权衡生态和经济效益下的生态退耕最优方案。退耕还草主要发生在奇台县耕地集中区的东北、西北及西南部边缘,将有利于北部的沙漠化防控和南部的水源保护。本研究实现了干旱区水资源约束下生态退耕方案空间模拟和优化,对农...

Spatial optimization of ecological cropland conversion and trade-off analysis under water resources restriction in the arid region:Taking Qitai County as a case study

The large-scale expansion of cultivated land in the arid region has caused water overload and frequent ecological problems,so it is urgent to reduce the area of cultivated land to save irrigation water.Therefore,exploring the spatial optimized scheme of ecological cropland conversion under the constraints of water resources can not only contribute to resolving the current ecological problem of arid areas,but also help implement land use planning and decision-making.Until now,the research on quantitative analyses of the multi-benefit contradiction of the cropland-conversion plan is still insufficient.Therefore,a spatial optimization allocation and trade-off analysis model for ecological cropland conversion is built in this study.Taking Qitai County as a case study,we built a solution group of ecological cropland conversion under the constraint of water resources.Two scenarios,priority for maintaining cultivated land scale and priority for ecological environment,were designed in this research to realize the spatial simulation and optimization of ecological cropland conversion by Ant Colony Optimization Algorithm.Results show that the cultivated land area of Qitai County is 99.39 thousand hectares in priority for maintaining cultivated land scale scenario,and 69.55 thousand hectares in priority for ecological environment scenario.In the cropland-conversion process,the proportion of ecological water consumption in the river channel accounted for 10%of the total water consumption in the cultivated land retain priority scenario and 30%in the ecological protection scenario;and the amount of windbreak and sand fixation increased from 7.13 million tons to 8.17 million tons,while the economic benefit decreased from 3.49 billion yuan to 2.48 billion yuan.Through comparing the reduction of unit economic benefit producing the increasing proportion of unit ecological benefit,the scenario that cultivated land area decreased to 83.49 thousand hectares was chosen as the optimal one considering the trade-off between economic and ecological benefit.The cropland-conversion areas were mainly located in the northeast,northwest and southwest edges of the farmland concentration area in Qitai County,which will benefit the prevention and control of desertification in the north and the protection of water resources in the south.This research realizes the spatial simulation and optimization of the ecological-conversion plan under the constraints of water resources in arid areas,which provide significant reference to agricultural management and ecological protection.