Date Published: April 16, 2019
Publisher: Public Library of Science
Author(s): Hua Zhang, Li Zhuang, Bing Xue.
The impact of environmental change on internal migration has received wide attention in recent years. Mass internal migration has been a significant economic and social phenomenon in China, and soil erosion is a major environmental problem that impacts sustainable socioeconomic development. This study aims to identify the impact of soil erosion on internal migration in China at the county level based on gravity model by analyzing related data, such as the sixth national population census data and the soil and water conservation survey data. The results of spatial overlay could not identify an obvious relationship between soil erosion and net outmigration in China. The traditional gravity model of migration is modified to analyze the impact of soil erosion on net outmigration while other variables are controlled. The results indicate that only serious soil erosion increases the possibility of outmigration and that the impact is considerably higher in agricultural counties than in non-agricultural counties. In general, the impact of soil erosion on internal migration is far less than the impact of socioeconomic factors.
As global environmental change has accelerated, its impact on internal migration has attracted great attention from researchers and policy makers . Because it is an interdisciplinary research topic involving both natural and social sciences, great progress has been made from the viewpoints of demography, sociology, anthropology, geography, etc. However, a common understanding of many issues in this field has rarely been reached, and some opinions are even contradictory. For instance, the definitions of terms regarding the migration caused by environmental change have not been settled. Terms such as “environmental refugees,” “environmental migration,” and “eco-migration” frequently have appeared in the literature and sparked controversies [2–7]. Two distinct viewpoints exist with regard to the estimation of the impact of environmental change on internal migration: the maximalists and the minimalists . The maximalists believe that environmental degradation causes mass internal migration, whereas the minimalists hold that the opinions of the maximalists are based on conjecture and lack sufficient empirical evidence. The minimalists view environmental change as a background variable, but it is difficult to reach a clear conclusion owing to the difficulty in analysis and the lack of evidence. There is still no final conclusion on how environmental change impacts internal migration. Taking drought as an example, many cases show that internal migration is a highly possible response to drought, whereas other studies reach the opposite conclusion that drought has scarcely any impact on internal migration [9–12]. In addition, there are disputes over which groups of humans are more vulnerable to environmental change. Chan showed that the rich may migrate, but the poor have lower migration capability owing to their inability to afford the migration costs . However, Morrow-Jones showed that the lower socioeconomic class will most likely migrate after natural disasters, whereas the rich have access to more countermeasures to avoid the impacts of disasters, suffer less from disasters and more easily rebuild their homes . The reason that it is difficult to reach common agreement on this issue is probably due to the complexity of migration decision making. On the one hand, there is a lack of appropriate data and methods to measure environmental change and internal migration; on the other hand, it is very difficult to separate environmental factors from socioeconomic factors that may also impact migration .
This analysis takes Eq (7) as a basic model and DRP as a dependent variable. It also separates the factors influencing outmigration into the push of origins and the pull of destinations. Considering the data availability, the explanatory variables are as follows.
This paper discusses the impact of soil erosion on internal migration in China. In accordance with the data from the soil and water conservation survey in the first national census for water in China and the sixth China population census, DRP and the SESI are used to measure the net outmigration and soil erosion severity of the county-level divisions, respectively. On this basis, spatial overlap is used to analyze the spatial matching relationship between the counties that suffer serious soil erosion and those with net outmigration. The conventional gravity model of internal migration is modified to apply to the study of migration at the county level and is used to analyze the impact of soil erosion on outmigration while other variables are controlled.