降雨量对城镇化的影响机制研究

The Research on the Mechanism from the Precipitation to the Urbanization

在传统两部门经济模型的基础上,探讨降雨量通过影响农业产出与人口迁移,并最终导致城镇化水平发生变化的传导机制具有重要的意义。理论推导表明,降雨量与城镇化水平之间存在着显著的正U型关系,当降雨量从曲线两侧向曲线拐点值靠近时,农业产量增加,农民收入上升,农村人口向城镇转移数量下降,城镇化水平降低;而当降雨量从拐点处向两侧移动时,农业产量降低,最终表现为城镇化水平上升。在实证部分,可先利用全国186个地级及以上城市的数据验证降雨量与城镇化水平的正U型关系;然后以农业全要素生产率为划分标准,深入探讨不同类型城市这一关系的显著性,结果显示在农业全要素生产率低的地区才较为明显。中国新时期进一步推进城镇化发展的正确道路应该是,加快农业现代化步伐,提高农业抵御自然灾害的能力,并通过不断提高农业劳动生产率,释放农业剩余劳动力,推进中国城镇化的健康发展。

Based on a two-department economic model,this article established a transmission mechanism from the precipitation,agricultural yields and demographic migration to the urbanization,attempting to identify the relationship between the precipitation and urbanization with all other confounding factors contro｜led.Theoretical analysis found that a U-shaped relationship exist in between.Namely,as the precipitation approaches to the inflection point from two sides,the agricultural yields increase,so does the famers＇ income,then the population that immigrate from the rural to cities decline,which eventually leads to the higher urbanization;On the contrary,if the precipitation goes away from that point,the agricultural yields reduce,then the urbanization goes down in turn.By using the panel data of China＇s 186 cities from 2003 to 2013,we found the U-shaped relationship between the precipitation and urbanization is robust.Furthermore,we classified those cities into three categories according to the agricultural TFP,results showed that a statistically significant U-shaped relationship is still valid between precipitation and urbanization in the cities with lowest level of agricuhural TFP.Therefore,the policies facilitating the agricultural modernization and labor productivity should be made and conducted,to keep the agricultural yields away from the climate changing,and also to make sure the sustainable development of urbanization in the future.