Les migrations intérieures en Chine sont régulées par le système du Hukou. Celui-ci distingue la population rurale de la population urbaine et matérialise le droit d’accès aux biens publics du lieu d’enregistrement. Deux types de migration sont à distinguer selon que l’individu a pu convertir/ transférer ou non son Hukou en déplacement : migration permanente et migration temporaire. Notre recherche adopte donc une approche dichotomique et comparatiste en vue d’avoir une vue plus intégrale de la migration intérieure en Chine.D’abord, nous nous interrogeons sur les déterminants du choix de la localisation. Le résultat économétrique montre que la migration temporaire est plus déterminée que la migration permanente par les caractéristiques du marché du travail (salaire et chômage). Par ailleurs, les afflux de l’IDE et le développement de l’entreprise rurale représentent un attrait significatif pour les migrants temporaires, contrairement aux migrants permanents. L’autre remarque consiste dans l’attraction des régions autonomes de minorité à l’égard des migrants permanents.Ensuite, nous nous demandons si les deux types de migration créent des différences en termes de profils individuels et d’insertions professionnelles des migrants. Les permanents sont plus qualifiés que les natifs urbains alors que les temporaires sont loin derrière. Quant aux insertions professionnelles, deux indicateurs sont choisis : accès à l’emploi et rémunération. Les temporaires gagnent de 14 à 20% de moins, même si les attributs du capital humain sont contrôlés. Sans discrimination institutionnelle, ils verraient leur proportion dans l’auto-recrutement baisser de 34 %, alors qu’elle augmenterait de 11% pour l’employé et de 50% pour l’ouvrier, toutes choses égales par ailleurs. Or, les permanents sont beaucoup mieux insérés. Ils connaissent seulement une légère discrimination salariale, mais une « discrimination positive » pour l’accès à l’emploi par rapport aux natifs.A la fin de la thèse, nous nous intéressons aux rationalités du système du Hukou. D’une part, la ville d’accueil se sert du Hukou, grâce à la migration permanente, pour attirer les facteurs de production dont elle a besoin : capital et travail qualifié. D’autre part, elle peut bénéficier de la main-d’oeuvre de moindre coût, sans assumer les coûts sociaux à travers la migration temporaire. La Chine en a retiré des gains considérables, tels que la sécurité alimentaire, l’industrialisation à faible coût et la diminution du chômage urbain. Mais les coûts du maintien de ce système sont devenus plus préoccupants à l’heure actuelle, dans la mesure où il renforce la disparité économique, restreint la demande intérieure et forme une attention insuffisante sur les droits et l’égalité. C’est pourquoi nous proposons des mesures de réforme en insistant sur le rôle du gouvernement central. / In China, internal migrations are governed by the Hukou system. This system distinguishes between rural and urban residents and gives citizens' right to public service of the place of registration. We distinguish two types of migration depending on whether the individual was able to convert/transfer his/her Hukou during his/her moves: permanent and temporary migrations. This study will adopt a dichotomous and comparatist approach so as to have a more comprehensive view of internal migrations in China.First of all, we will analyze the determining factors of location purposes. The econometric result suggests that, compared to permanent migration, temporary moves are caused by variations in the labour market (wages, unemployment). Furthermore, the FDI inflows, and EVB (village enterprise) development are great incentives for temporary migration unlike permanent migration. Another observation is related to the attractiveness of autonomous minority regions for permanent migrants.Secondly, we wonder if both types of migration generate some differences in the individual profiles and the integration of workers. Permanent migrants are more qualified than urban residents, while temporary migrants are far behind them. As far as vocational integration is concerned, two indicators have been selected: access to employment and wages. The temporary workers earn 14 to 20% less than the others; their ratio in self-recruitment would otherwise be 34% lower but it would be 11% higher for the employee and 50% for the worker, all things being equal. On the other hand, the permanent migrants are only faced with low wage discrimination, and to a “positive discrimination” as far as access to employment is considered.At the end of the thesis, we will focus on the rationale of the Hukou system. The host towns resort to the Hukou system to attract permanent migrants in order to obtain the production factors they need: investment and skilled labour. Through temporary migration, they can take benefit from low-cost manpower without accepting the social costs. It is obvious that China has substantially gained by the contemporary Hukou system: food security, low-cost industrialization, and control over urban unemployment. However, the cost of maintaining it is increasingly worrying since it reinforces economic disparity, reduces domestic demand, and causes the policy to depart from aim of right and equality. In this case, it will be an opportunity to propose reforms while emphasising the role of the central government.

Background: The study is based in post-apartheid South Africa and looks at the health and well being of households in the rural northeast. Temporary migration remains important in South Africa because it functions as a mainstay for income and even survival of rural communities. The economic base of rural South Africans is surprisingly low because there is high inequity at a national level, within and between racial groups. There has now been a democratic system in place for 15 years and there is no longer restriction of mobility, but there remain high levels of poverty in rural areas and rising mortality rates. Migration patterns did not change after apartheid in the manner expected. We need to examine consequences of migration and learn how to offset negative impacts with targeted policies. Aims: To determine a relevant typology of migration in a typical rural sending community, namely the Agincourt sub-district of Mpumalanga, South Africa, and relate it to the urban transition at a national level – Paper (I) . To evaluate the dynamics of socio-economic status in this rural community and examine the relationship with migration – Paper (II). To explore, using longitudinal methods, the impact of migration on key dimensions of health, including adult and child mortality, and sexual partnerships, over a period of an emerging HIV/AIDS epidemic – Papers (III), (IV) and (V). Methods: The health and socio-demographic surveillance system (HDSS) is a large open cohort where the migration dynamics are monitored as they unfold. They are recorded as temporary or permanent migration. Settled refugees are captured using nationality on entry into the HDSS. Longitudinal methods, namely a household panel and two discrete time event history analyses, are used to examine consequences of migration. Results: Migration features prominently and different types have different age and sex profiles. Temporary migration impacts the most on socio-economic status (SES) and health, but permanent migration and the settlement of former refugees are also important. Remittances from migrants make a significant difference to SES. For the poorest households the key factors improving SES are government grants and female temporary migration, while for less poor it is male temporary migration and local employment. Migration has been associated with HIV. Migrants that return more frequently may be less exposed to outside partners and therefore less implicated in the HIV epidemic. There are links between migration and mortality including a higher risk of dying for returnee migrants compared to permanent residents. A mother’s migration can impact on child survival after accounting for other factors. There remains a higher mortality risk for children of Mozambican former refugee parents. Interpretation: Migration changes the risks and resources for health with positive and negative implications. Measures such as improved transportation and roads should be seen as a positive, not a negative intervention, even though it will create more migration. Health services need to adapt to a reality of high levels of circular migration ranging from budget allocation to referral systems. Data should be enhanced at a national level by accounting for temporary migration in national censuses and surveys. At individual level we can offset negative consequences by treating migrants as persons striving against adversity, instead of unwelcome visitors in our better-off communities.