三峡工程胁迫下重庆库区耕地利用变化及其机制研究

Study on the Change in Farmland Use and Its Mechanism in Chongqing Reservoir Area under the Stress of the Three Gorges Project

本研究选择三峡水库重庆库区为研究区,利用1996-2008年的库区耕地、移民及社会经济统计资料,解析三峡工程建设这个宏观胁迫因子下的库区耕地利用变化特征,并基于PSR模型分析的基础上揭示其对重庆库区耕地利用变化的驱动机制,结果表明:(1)在三峡工程胁迫下,库区耕地数量在三峡水库每次蓄水前后年份表现出明显的减少,尤为突出的是水田,耕地年变化率因各蓄水阶段三峡工程导致的胁迫作用强度不一样而差异较大;(2)在三峡工程胁迫下,随着库区优质耕地被淹没,库区耕地整体质量受到影响,反映耕地质量的地均粮食产量指标在2006年、2008年呈明显下降趋势;(3)在三峡工程胁迫下,为确保搬迁后生产生活水平不降低,库区移民做出响应,通过增加土地投入和改变种植结构来增加土地经济产出;(4)库区耕地利用变化特征的形成机制主要是三峡工程建设导致的工程蓄水、移民搬迁复建、生态退耕、土地开发整理复垦活动的驱动,其中,对耕地数量变化的驱动作用是双重的,正向驱动因子包括土地开发整理复垦活动,负向驱动因子包括三峡工程蓄水直接占用耕地、移民搬迁复建二次占用耕地以及生态退耕.

The study of farmland change and its mechanism in a reservoir area which is under the stress of a large-scale water conservancy and hydropower project is of great significance to the understanding of the mechanism of the effect of the construction activities in farmland change process.In this study,the statistical data of cultivated land,migration and socio-economy in the Chongqing section of the Three Gorges Reservoir between 1996-2008 were used to analyze the characteristics of farmland change under the macroscopic stress of the Three Gorges Project and,on the basis of the PSR model,the driving mechanism of the farmland change in the reservoir area was explored.Under the stress of the Three Gorges Project,the amount of farmland,paddy fields in particular,showed a significant reduction around each impoundment period of the reservoir.The annual change rate of farmland was considerably different due to the different stress strength resulting from each stage of water-storing.Under the stress of the Three Gorges Project,with the loss of high-quality farmland,the overall quality of the farmland in the reservoir area was negatively affected,and food output per hectare the index reflecting farmland quality-dropped significantly in 2006 and 2008.Under the stress of the Three Gorges Project,the reservoir migrants responded to it by increasing investment and changing the cropping pattern to increase the economic output of the land so as to ensure that their living standard would not be reduced after the relocation.The formation mechanism of the farmland change characteristics in the reservoir area was shown to be driven mainly by water-storing,relocation rehabilitation,ecological restoration and land development and consolidation activities.The driving role for farmland change in quantity appeared to be dual,the positive driving factors including land development and consolidation activities and the negative driving factors including the direct occupation of farmland by storing water and the secondary occupation of farmland due to relocation rehabilitation and ecological restoration.