The population in the delta

These data are drawn from " Identification of agricultural and irrigation patterns in the Central Plain of Thailand : prospects for agricultural research and development"

For quotation : Kasetsart University, ORSTOM, 1996. Agricultural and irrigation patterns in the Central Plain of Thailand : prospects for agricultural research and development, DORAS Project, Kasetsart University, Bangkok, pp. 220.

1. Absolute population and human density in 1990

The population of the Central Plain totals almost 14 million habitants (in 1990), that is to say approximately 20 % of the total population of Thailand is concentrated in less than 6 % of the territory. Most of this population (5.9 million) live in the Bangkok Metropolitan Area and, among the remaining 8 million people, two live in the vicinity of Bangkok, defined as the neighbouring provinces of Pathum Thani, Nonthaburi, Samut Prakan, Samut Sakhorn (Tab. 1).

This population is therefore distributed very unevenly over the Central Plain : human density culminates in Bangkok and its vicinity (1374 habitants/km2) but has an average of 276 habitants/km2 in the remaining rural area, which is slightly higher than in other regions (for example 200 habitants/km2 for the Northeast). This value of 276 is an average of densities by changwat which are generally comprised between 120 and 300 habitants/km2 The less populated ones are Lop Buri (119), Chai Nat (137), Saraburi (153), whereas Sing Buri (269), Ayutthaya (271), Angthong (293), Nakhon Pathom (310) show higher densities. Details at amphoe level (map 2.12, data from 1990), show that all the area south of Ayutthaya and the flood plain have densities greater than 200, with growing urban concentration around Nakhon Pathom, Chonburi and Ayutthaya.

Table 1 : Population in the Central Plain (1990)

Source : Population census 1990 NSO.

2. Evolution in the 1960-1990 period

Population in the Central Plain increased more than twofold in the 1960-1990 period. In the same period, population in Bangkok has been multiplied by 2.75 but the growth rate over each of the three decades has shown a significant decline from 44 % to 35 % (Tab. 2 and Fig. 1). This means than saturation is taking place and the rate for the present decade is expected to decrease even more dramatically. On the contrary, no saturation can be evidenced concerning Bangkok's vicinity area, where the current growth is similar to the one observed in Bangkok for the 1960-1980 period.

If we now consider the whole of the Central Plain, growth rates by decade seem to have leveled off around a value of 30 %. These growth rates are of course the combined result of natural growth and immigration flows. The annual growth rate has been declining a lot in Thailand and the yearly average rate of growth - for the whole country - is now as low as 1.5 %. If we consider the Central Plain during the1985-1990 period, with an average growth of 14.2 %, the observed overall population increase of 1.68 million habitants can approximately be divided between a share of 673,000, due to net migration flows from outer provinces (see next section), and a share of almost 1 million persons due to natural growth.

Table 2 : Population evolution in the Central Plain (1960-1990)

Source : NSO population census

Fig. 1

Source : NSO population census

Change in population can be specified at amphoe level. Map 1 shows the evolution of the population density during the 1960-1990 period. It can be observed that, 45 years ago, three areas presented a human density above 500 habitants/ km2 : Bangkok, the capital of the Kingdom, Ayutthaya, the first large settlement in the Central Plain and one area near the canal of Damnoen Saduak, in the Province of Ratchaburi.

From this point, three axis successively developed in the Central Plain. The first axis is located in the western part of the Central Plain, from Bangkok to Ratchaburi and Nakhon Pathom Provinces, where urbanization has become important since 1970. The second axis heads towards the eastern part, from Bangkok to Chachaengsao and Prachinburi. At last, a new trend seems to surface, with the development of the hinterland of Sing Buri, Ang Thong and Ayuthaya.

Three areas remain more rural in the Central Plain. The Nakhon Nayok area, where the density of the population is near 100 ha/km2, the south of Suphan Buri and the south-west of Chai Nat. Not surprisingly, they also correspond to areas with higher ratio of full owner farmers.

maps 1

3. Population and migrations

The migration balance in the Central Plain can be approached considering either the flows between the changwats of the Central Plain (and only these changwats), or the total migration flows between the Central Plain and the rest of the country. We distinguished four successive units for this analysis, namely Bangkok Metropolitan Area (Bangkok), Bangkok vicinity (Samut Sakhon, Samut Prakan, Nonthaburi, Pathum Thani), the "rural" Central Plain (the remaining amphoes of our study area) and the rest of Thailand (all changwats not belonging to the study area).

Table 3 displays some of the main features of the migration process in Thailand. Over 1.6 million people moved within the country between 1985 and 1990, that is to say approximately 2.8 % of the total population of Thailand in 1990. At the level of the (whole) Central Plain, 503,960 persons decided to move within this region during the same period, that is to say 3.1 % of the population of this area in 1990. Within these five years, the Central Plain recorded a net gain of 672,918 persons (4.1 % of the total population in 1990). The region stands out as the main pole of attraction in the country. Within the Central Plain, Bangkok and Vicinity received 677,441 more habitants between 1985 and 1990, that is to say 8.5 % of its population in 1990.

Table 3 : Some characteristics of the migration process

Source : POPULATION AND HOUSING CENSUS 1990, National Statistical Office

3.1 Infra-regional migration flows

Map 2 shows the migration balance of each changwat when only internal flows within the Central Plain are considered. People in the Central Plain clearly tend to migrate to Bangkok Vicinity, but not to Bangkok Metropolitan Area which - on the contrary - shows a slight trend toward return flow.

Map 2

All changwats have a negative balance, mostly as a result of migration toward Bangkok vicinity, with the exception of Nakhon Pathom and Prachin Buri, which have enough developing activities to retain their population.

3.2 Inter-regional migration flows

• Total migration flows in the changwats of the Central Plain

Map 3 displays the net migration balance of each changwat when all flows within the country are considered. A sharp contrast appears between the old delta in the north and the young delta. The southern part of the Central Plain experienced a net gain of population through migration, during the five year period, resulting in a growth of between 10 and 15 % in four changwats (Nonthaburi, Samut Sakhon, Samut Prakan, Pathum Thani). In the north of the delta most of the changwats, and especially those which have a high agricultural ratio, have undergone a net loss of population, as high as -3.1 % and - 2.6 % in the case of Chai Nat and Sing Buri respectively. Bangkok and Vicinity continued to swell, with a rate of 7.3 and over 10 % respectively. This phenomena is likely to continue in the future. The map also shows that the migration balances of Chon Buri, Saraburi and Kanchanaburi are positive, which is related to the industrialization of these provinces.

Map 3

• Migration flows between the zones of the Central Plain and other regions

If we consider the four zones described above and represented in figure 2, we can now summarize their interaction (Tab. 4): 285,049 persons have left Bangkok in the 85-90 period but this outflow have been widely offset by an inflow of over 700,000 mainly coming from the outer regions (77 %) and, secondarily, from the (rural) Central Plain (33 %). With an inflow of over 300,000 persons, Bangkok Vicinity received 5 times more than its loss and sticks out as the main target of a migration flow originating in both the outer changwats and - more surprisingly - Bangkok City itself.

Fig. 2 : Schematic view of migration flows in the Central Plain

The (rural) Central Plain appears to be almost balanced, with an inflow mostly coming from outer changwats (76 %) and an outflow directed to Bangkok (47 %), Vicinity (18 %) and outer changwats (35 %). Almost 900,000 persons have left the outer changwats, trend counterbalanced by only 223,882 returns.

Table 4 : migration flows between the regions considered

In brief, the (rural) Central Plain has an almost zero net flow, whereas the other surrounding regions have been depleted by almost 673,000 net departures, benefiting both Bangkok (two thirds) and vicinity (one third) (Tab.5).

Table 5 : Net migration flows between the regions considered

4. Age and gender distribution

The comparison between the pyramid of age of all the population in the Central Plain and the pyramid of age of the agricultural population shows clear discrepancy in the weight of people over 50 years old.

Young people prefer to leave rural areas, but with different intensities according to each region. Map 4 describes the population distribution under the criteria of age repartition, considering the percentage of people over 50 years old. The agricultural population is especially "old" between Ayutthaya and Chai Nat and between Ratchaburi and Samut Songkhram. In the same time, the sex ratio (male/female) in these areas is correspondingly really low : map 5 displays the percentage of the male population within the total population. It shows that the region with older population also have less men, which suggests that women are less concerned by migration. The percentage of males is lower than 48 % in Ayutthaya and near Samut Sakhon.

Nowadays, the main changes in the structure of the agricultural population occur in the old delta, specially along the Chao Phraya, between Ayutthaya and Chai Nat.

Map 4

Map 5

5. The agricultural population and its dynamics

The rural Central Plain differs from the rest of the country not only because of its higher density but also because of its lower agricultural ratio. Whereas over 60 % of the total population of Thailand is engaged in agriculture, this ratio must be almost halved when considering the Central Plain without Bangkok (37 %) and without its Vicinity (32 %). This means that industry and services also developed out of Bangkok, mainly in its vicinity and around the changwat capitals.

Map 6 displays the contrasting distribution of the agricultural population ratio, (i.e the percentage of agricultural population in the total population). Areas where the agricultural population is still in majority roughly match the less populated areas (see earlier sections) and follow the axis Chai Nat - Suphan Buri - Nakhon Pathom, with more than half of the population engaged in agriculture. The Nakhon Nayok area bears similar feature.

Map 6

We can also distinguish the area where the industrial and service sectors are particularly developed, roughly the triangle Samut Sakhon - Pathum Thani - Chon Buri, with less than 20 % of the population working in agriculture.

This situation is the result of a rapid evolution since 1960. The agricultural population, during these thirty years, has slowly but significantly undergone a decrease of 16 %. If we consider that the average farm size in the Central Plain has also been found to decrease slightly between 1975 and 1991 (OAE), from 26.85 to 24.58 rai (8 %), this evolution also mirrors a decrease in farm land.

As for the agricultural ratio, on the other hand, the decline has been spectacular. In rough terms, the percentage of the population engaged in agriculture has dwindled down from two thirds to only one third between 1960 and 1990. This means that the net gain of population (natural growth + migrations) has been completely transferred to the non-agricultural sectors which now account for two thirds of the activity outside Bangkok. This phenomena is only partly due to the industrialization of Bangkok vicinity. If we consider the evolution of the ratio outside Bangkok and Vicinity, we find a similar trend from 70 % to 37 %, in the same period. This shows the growth and the importance of non-agricultural activities in the countryside .

Map 7 shows how this general decrease of the agricultural population ratio in the Central Plain (expressed as the ratio of agricultural population ratios in 1990 and 1960), has affected the different sub-regions. Although the decrease is general (the indice is always lower than one), two zones are specially affected :

• The southern part of the delta, under the influence of Bangkok, with the exception of the fruit and vegetable area around and above the Damnoen Saduak canal;

• The vicinity of the changwat capitals located along the Chao Phraya river (Sing Buri, Ang Thong and Ayutthaya), together with Lop Buri.

In these areas, where the density of the population has increased considerably since 1960, the agricultural population rate has been divided by a factor ranging between 2 and 5, and even between 5 and 10 in Bangkok Metropolitan Area. The regions less affected by the (relative) decline of the agricultural sector is, again, the western part of the northern delta.

Map 7

All these demographic data enable us to draw some general conclusions about their impact on the agriculture of the delta. The first one is that the evolution of the agricultural sector cannot be separated from urbanization and industrialization. Three factors bring pressure upon the agricultural population :

The urban growth, which implies a transformation of agricultural land to other purposes, therefore reducing the number of farmers; a significant proportion of idle land can be found around Bangkok (and even in some more remote areas such as the east of Kamphaengsaen Project, Nakhon Pathom Province, or along the Asian Highway), because it has already been acquired for speculation or construction.

• The industrial and service sectors, which draw the labour force from the fields to factories and offices. Migrations have a clear direct impact on the agricultural ratio, the aging of the population and the sex ratio. This has brought about drastic change in the structure of the labour force and on labour availability.
  This impact is more acute in areas where agricultural intensification is impossible or uneasy, principally the flood plain. Pluriactivity also often constitutes a prerequisite of the viability of agriculture in these areas. Multiple occupations, migration to urban centers also have a dramatic impact upon farm economics : on one hand, because of additional revenues sent by relatives to the rural households; on the other hand, because of the differential in wages which influences both rural and urban labour costs.

• The urban demand for new products, with possible new foodstuff production chains, diversification and labour intensive farming, which partly counterbalances the first two trends.

Lastly, we can consider the current agricultural population density . Areas devoted to horticulture and the triangle Suphan Buri / SIng Buri / Ang Thong sharply stick out with densities higher than 150 persons/km2. The East Bank, together with some of the areas with extensive rice-farming, show densities lower than 100 persons/km2, which must be linked with larger average farm areas .

6. Aspects of the family structure

To complement this overview of the population in the delta, we may add here some aspects about the family structure. Many studies, and not only in the anthropological field, have emphasized the role of the family structure on historical evolution in different parts of the world and on agricultural innovation.

The population census of Thailand distinguishes nuclear and enlarged families, among which we find vertical ones (several generations leave together), horizontal ones (joint siblings’ households) and vertical-and-horizontal ones. In each of them, social life, conventions and patterns of authority are different. In a joint family for example, the head of the family concentrates decision, power and capital and the siblings work together. One or various successors to the farmer can be chosen early. In addition, relationship within the village or the social relations of production depend a lot on this basic structure.

Although the delta has also been populated by Cambodian, Lao or Mon, the main contrast nowadays rests on the ethnic difference between the Thai groups and the Chinese, or their Sino-Thai descendants. For the first ones, the family is nuclear and villages have been defined as loosely-structured. For the latter, the family is enlarged and a high level of internal trust prevails. This enables them to gather money and to lend within the community, as well as to decide the fate of the children. It especially proved efficient to ensure the continuity of a farm. This kind of relationship also favours trading, from retailers to wholesalers, and export companies.

The size of rural families  is a meaningful criterion in agriculture because it can be linked to the available manpower. There is no doubt that many factors account for differences in the size of families. However, small families are found in the old delta, the flood plain and in the Nakhon Nayok area. This pattern suggests that a poor and extensive agriculture (with high tenancy for Nakhon Nayok), give way to smaller families. In the old delta, the recent frontier before World War 2 explains small families.

Horizontal and vertical-and-horizontal families are found in Bangkok and vicinity, but also on the coast, as well as northward along the Chao Phraya. By contrast, vertical families (not displayed) are on the edges of the delta. To localize concentrations of Sino-Thai population, Chinese-speaking ability is a possible indicator, although most persons under 40 years-old do not speak Chinese anymore. Many Sino-Thais live in the southern part of the delta, mainly in Greater Bangkok and in a strip along the coast where coolies settled at the turn of the century. Their location matches the areas with more horizontal families, as seen in the previous map.

Old narratives such as traditional nirat show that ethnic Chinese lived in the more remote areas of the country as traders, miners, collectors, etc. However, the mass immigration of coolies and the settlement of traders, first in Ayutthaya, then in Bangkok, probably explains the present distribution.