*4.4. The Implications of Water Quality and Eco-Environmental Conditions for Ecological Migration Policy*

The results show that the possibility of a respondent having migration intention will be higher when he/she believes the quality of groundwater is worse, and that the quality of surface water does not have a significant effect on migration intention. These results are consistent with the assertion that groundwater is the major source of irrigation water; the region is limited in surface water resources [46]. In the past five decades, the excessive exploitation of groundwater and the decreasing surface water supplements have caused continuous decline in the groundwater table. Because infiltrated irrigation water is the main source of groundwater recharge, large amounts of saline matter were transferred from topsoil to groundwater in the process of infiltration of the inspissated irrigation water after evaporation. As a result, the quality of groundwater declined gradually and became less suitable for irrigation [21], forcing some people in the victimized areas to out-migrate [33].

Evidently, the eco-environment remains a critical predictor for migration intentions in our case study of marginal communities in the Minqin County. The results show that the perception of change in environmental problems within the past five years impacts migration intentions significantly. This is consistent with the results of increasing studies about the effects of environmental change on population migration [35,47,48]. The main points of these studies could be summarized by stating that positive environmental characteristics decreased out-migration and negative environmental characteristics increased out-migration [49]. Also, some people will be trapped in areas that expose them to serious risk. Even in the context of quite significant environmental change posing serious threats to the sustainability of livelihoods [36], environmental change may further erode household resources in such a way that migration becomes less, rather than more, likely. All of these statements have realistic counterparts in Minqin County, such as the relatively long history of voluntary out-migration and the overwhelming majority of respondents without migration intention in our survey.

Specifically, this study found that changes in the environmental problems of land salinization and vegetation deterioration have significant effects on migration intentions. Land salinization is adversely affecting grain production. Vegetation deterioration is the cardinal symptom of environmental problem in the study area. The antidote to these two problems is increasing surface water supply to Minqin County. This is one of the main policies in the Key Governance Planning for Shiyang River Basin. However, the aim of the policy is to rehabilitate the deteriorated wild environment bordering deserts, rather than to conserve the arable land for rural residents. In fact, the arable land quota has decreased dramatically as ordered by the governance planning.

Another interesting finding in this study is that the assessment of current environmental problems doesn't have significant effects on migration intentions. This is contrary to the effects of the perception of change in environmental problems within the past five years as discussed above. Using the decision framework for environmental induced migration proposed by Renaud, *et al.* [50] as an analogy, the assessment of current environmental problems is slow onset changes. The perception of change in environmental problems within the past five years is rapid onset changes. A slow onset change may lead to voluntary migration because the environmental effects are more difficult to detect and disentangle from other drivers, particularly economic [36]. A rapid onset change is likely to immediately displace people or communities who have to flee in order to save their lives [50]. As stated by Renaud, Dun, Warner and Bogardi [50], rapid onset hazards are not necessarily of natural origin; their trigger can be caused by social or economic factors such as the arable land quota change in the study area.

#### *4.5. The Implications of Demographic Characteristics for Ecological Migration Policy*

The effects of the demographic variables are largely consistent with the previous studies but also reveal some differences. As the surveyed migration intentions in this study are formed within the context of ecological migration policy, migration among respondents would largely take the form of permanent family migration, which is different from the overwhelming pattern of temporary individual migration in other areas lacking rigid resettlement policies, such as the case of Hubei province in China [28]. Therefore, we did not consider migration intention of men and of women as two independent samples as in some influential studies (e.g., [29]). Instead, we used gender of the respondent as a predictor in the analytical models. We found that it has no significant correlation with migration intentions. This result is consistent with Yang [28].

Among the demographic factors, respondent's age as a significant predictor with negative indication is consistent with the previous studies [28,29]. However, the household elderly (>64) dependency ratio as another significant predictors of migration intention with positive indication remains seemingly counterintuitive. From the perspective of the new economics of labor migration (NELM) [51], a household with higher elderly dependency ratio may be more vulnerable to, and more relatively deprived by, a harsh environment with a shortage of labor forces. Therefore, this kind of household can be expected to have a stronger incentive to migrate than one with lower elderly dependency ratio. The results of this study also show that the household child dependency (<15) ratio does not have significant effects on the respondent's migration intention. This could be attributed to no significant difference in the number of children among rural households in China since the implementation of birth control policy from the late 1970s.

#### **5. Conclusions**

By employing Minqin County in the terminus of Shiyang River Basin as a case, the predictors of residents' intentions to out-migrate under ecological migration in arid Northwest China are investigated. As the study area has a relatively long history of eco-environmental degradation and population out-migration, the ecological migration policy faces a population with less ability and intention to migrate. The survey results show that most of the residents in the marginal communities of Minqin County do not intend to migrate; indeed only a small fraction desires to migrate. This is consistent with the larger migration literature. Most people remain in origin areas even in areas of high out-migration. Those who do migrate are usually unwitting migrants: they would prefer to remain in their origin area if they felt they could afford—financially and emotionally—to do so [52,53].

The policy implications for government and the public is that, in addition to demographic and socio-economic factors, the eco-environmental factors of water quantity, groundwater quantity, land quantity and change trends of these problems are also significantly correlated with the possibility of a resident intending to migrate. Additionally, the study provides some evidence that inland river basin governance policies impact rural household livelihood assets and environment quality, both significant predictors of migration intention.

Inland river basin governance policies had mixed and somewhat complex impacts on household livelihoods and environmental integrity, and then on migration intentions. As policies are implemented, water availability and quality, soil quality, and vegetation cover may increase or recover gradually, thereby impeding migration intention. If household annual gross income and the proportion of income derived from non-farm employment are increased by the economic policies, as anticipated by the government, migration intention may increase. However, currently most of the residents' household incomes are derived from household agriculture which impedes the intention to migrate. We argue that ecological migration policy may be ultimately unsuccessful if implemented in a compulsory manner, or even encouraged by the local government out of motivation for financial subsidies from the central government as warned by Wang [54]. The complex interplay among policies, household livelihoods, environmental change, and migration intention deserves further investigation. The Ecological Migration Policy will ultimately be more sustainable when taking into account household interests within complex migration intention contexts, such as household livelihoods dynamics and environmental change.

#### **Acknowledgments**

This work was supported by the National Social Science Foundation of China under Grant number 11BSH059. It is also one part of Yongjin Li's postdoctoral research report that was done in the School of Life Sciences, Lanzhou University. We thank the Human-Environment Dynamics Lab and Department of Geography at UCSB for providing personnel and facilities support and an encouraging environment for the writing of this paper. We thank Fengmin Li in the School of Life Sciences, Lanzhou University, for his kindly help and advices for this study. We are also grateful for the comments and criticisms of an earlier version of this manuscript by the journal's anonymous reviewers.

#### **Author Contributions**

Yongjin Li designed the research, conducted the survey and completed the paper; David López-Carr contributed to the framework of affecting factors and data analysis; Wenjiang Chen contributed to the questionnaire design.

#### **Conflicts of Interest**

The authors declare no conflict of interest.

#### **References**

