Reassessment of Todaro's Migration Model to Incorporate Socioeconomic and 
Natural Resource Environment by Using Remote Sensing and GIS: 
A Case of Thailand 
By 
Bhuwneshwar Prasad SAH, Eihan SHIMIZU and Morito TSUTSUMI 
Regional Planning & Surveying Lab./Department of Civil Engineering 
The University of Tokyo 
E-mail: sah@planner.t.u-tokyo.ac.jp, shimizu@planner.t.u-tokyo.ac.jp, tsutsumi@planner.t.u-tokyo.ac.jp 
KEY WORDS: Migration, Natural Resources, Urban and Rural Sector, Regional Development 
ABSTRACT 
Migration is a phenomenon, which include the economic decision, social consequences and spatial relation. To 
address the rural urban migration problem at the policy level in developing countries, Todaro has formulated a 
migration model by including the rural-urban expected wage difference and probability of getting job in urban area. 
This model is well accepted for the economic decision, but lacks the spatial aspects. It is also neutral for the rural 
employment level and the dynamic variation of the rural wage due to productivity condition and population pressure 
on the rural agricultural land. This study will make an attempt to validate and extend the Todaro model. 
The rural sector, origin of the migration, is engaged in agriculture production while the urban sector, destination of 
the migration, is engaged in producing high value added goods. Wage and employment level in urban area is 
determined by the level of industrialization and capital intensity, while those in rural area depends on the 
productivity of agricultural sector. Land use and fertility dynamics of the agricultural land can be analyzed by 
estimating the soil erosion rate with the help of suitable erosion model in GIS environment and remote sensing. Soil 
fertility is directly related with the crop productivity that in turn is the source of rural wage. Furthermore, the 
migration process also reflects relative competitiveness of different region (province) in terms of their potential to 
deliver aggregate welfare to the residents. Such potential (often termed as RDP: Regional Development Potential) is 
dependent on regions economic resources, production structure, natural resource conditions, amenity resources and 
demographic structure. The relevant statistical data will be extracted for time series as well as cross section analysis 
by taking province as unit. Finally, this will pave out the path for extension of the Todaro model. Preliminary data 
pattern has shown the positive results towards this direction. 
1 INTRODUCTION 
Migration remains an integral part of human history. 
There were several reasons for human migration in 
the past, but the economic motivated migration has 
been dominating the world after 1950s. Demographic 
parameters improved, especially after 1950s, which 
leads to over all population growth. The 
industrialization followed by urbanization in the 
Asian countries creates the shortage of labor force, 
which induce the migration from rural areas. The 
economic incentive and government policies fuel this 
migration. Here the Lewis Two-Sector Theory 
(Lewis, 1954) for flow of rural-urban labor migration 
works well. Sooner or later this migration become a 
social problem in many cities in Asian, African and 
Latin American countries. The urban infrastructure, 
utilities and amenities, available job etc., became the 
bottleneck for the many municipalities in those 
countries. 
The migration history in Thailand is also very old. 
During the 19 th century and early 20 th century, the 
main labor supply for the urban industrial sectors was 
from international migration, mainly from China, and 
it was replaced by the internal migration during the 
middle of the 20 th century. It is reported that during 
1960s and 1970s, about half the additions to the 
urban labor force came from natural increase in the 
urban population. The other half was sucked out of 
the countryside (Phongpaichit and Baker, 1997). 
During 1970s, the urban population growth rate was 
5.3 percent where 45 percent was contributed by the 
migration (Todaro, 1995). The agglomeration of the 
population was beneficial in early days, but at present 
Thailand is facing the over urbanization problem. 
The natural population growth along with 
considerable rural-urban migration is concern for the 
policy makers in many municipalities. To address 
this problem, it is desirable to find the reason both at 
the origin and destination of the migration. The rural 
sector, origin of the migration, is engaged in 
agriculture production while the urban sector, the 
destination of the migration, is engaged in consumers 
and luxurious goods production. In general, the rural 
labor is unskilled while the urban labor is skilled. 
There is also wage difference between rural and 
urban sector.