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2. The Himalayan region: a geographical overview

Introduction
The physical basis
People and population
Breakdown into regions

Introduction

The purpose of this chapter is to provide a very brief overview of the general geography of the Himalayan region. This is a necessary but rather unsatisfactory task, in part because of the constant outpouring of publications on practically every conceivable aspect, with a heavy emphasis on applied topics - resource development, environmental degradation, foreign aid - and in part because of the very complexity of the topic. Regrettably, there is no recent systematic treatment. It is even difficult to produce a justified regional break-down. We have added a short section at the end of the chapter which is a synthesis of the most recent attempt to tackle this difficult problem of regionalization. This is the result of a graduate diploma study of Markus Wyss, Geographical Institute, University of Berne (1988). We will largely limit ourselves, nevertheless, to a brief indication of the region's complexity in the process of sketching some of the major components of the topography, climate, vegetation, and human geography. We are not attempting a geography per se; rather we are providing selected background material and additional literature citations to support the discussion that forms the core of the book. First we will define the area under review.

The traditional definition of the Himalaya, sensu stricto, is that great range of mountains that separates India, along its north-central and northeastern frontier, from China (Tibet), and extends between latitudes 26° 20' and 35°40' North, and between longitudes 74°50' and 95°40' East. In this sense the Himalaya extend from the Indus Trench below Nanga Parbat (8,125 m) in the west to the Yarlungtsangpo-Brahmaputra gorge below Namche Barwa (7,756 m) in the east, a west-northwest to east-southeast distance of about 2,500 km. This definition includes, politically, the independent kingdoms of Nepal and Bhutan, a small part of Pakistan, parts of China (Xizang Autonomous Region), as well as the western, central, and eastern sections of the Indian Himalaya (see Figure 2.1): sections 6 (Kashmir Himalaya), 7 (Central Himalaya), and 9 (Assam Himalaya), together with portions of the Plateau (8) and the Plains, as shown on Figure 2.2.

Also, traditionally, a north south topographical transect across the Himalaya would include the whole, or parts, of several aligned physiographic provinces: a small slice of the Qinghai-Xizang (Tibet) Plateau; the transHimalayan ranges and intervening valleys; the Greater Himalaya; the foothills (locally referred to as the Siwaliks or Churia Hills); the Middle Mountains, the Lesser Himalaya (including the Mahabharat Lekh); and the Terai. The Terai can best be described as the upper section of the Ganges Plain; it is also convenient to subdivide it into the barbar (porous place), which immediately abuts the Siwalik front and is composed of a series of giant coalescing fans that have been laid down by numerous torrents and major tributaries of the Ganges, and the Ganges flood plain proper, into which the barbar grades imperceptibly.

Figure 2.3 is a schematic north-south transect characterizing the Central, or Nepal, Himalaya. Similar transects, drawn to represent sections further east or west, would show the same major physiographic divisions, but with many local variations. The terminology that we have adopted for the main physiographic divisions is not universally accepted, as will be illustrated in the next section (pp. 22-24).

The Ganges includes the catchment of the enormous Ganga (Hindu spelling) river system; this embraces much of the Himalaya as defined above, as far east as Sikkim, a large part of densely populated northern peninsula India, and part of Bangladesh. The western-most section of the Himalaya is drained by the Jhelum, Chenab, and Sutlej, major tributaries of the Indus, as well as by the upper Indus itself. The Brahmaputra is the Hindu name for that section of the other main trans-Himalayan river (Yarlungtsangpo-Brahmaputra) from the point where it enters Indian territory. It rises high on the Tibetan Plateau in longitude 82° East, remarkably close to the main headstream of the Indus, and flows eastward for more than 1,200 km north of the Himalayan crest-line before making its spectacular turn to cut through the mountains in one of the world's most impressive gorges. It enters India through Arunachal Pradesh and flows roughly westward across Assam and Bangladesh before turning south again to produce a maze of distributaries that merge with those of the Ganges, and eventually enters the Bay of Bengal through the great delta.

The term Himalayan region is being used in a very broad sense, and we will draw no precise boundaries. It will include the Hindu Kush, Karakorum, and the Hengduan mountain ranges, and a large slice of the Qinghai-Xizang (Tibet) plateau (see Figures 2.1 and 2.2). We will also include the Ganges and Indus Plains. In other words, our discussion will draw freely on available information from that vast tract of mountain, plateau, river gorge, and plains that can perhaps best be described as the south-central Asian mountain, plateau, and plains region. Thus, Bangladesh is included, as well as part of Afghanistan, northern Pakistan, Xizang Autonomous Region of China, western Sichuan, and northwestern Yunnan, and the border regions of northern Burma and Thailand. Nevertheless, we will concentrate heavily upon the Himalaya, sensu stricto, and especially on Nepal, and the immediately subjacent sections of the Ganges, Teesta, and Brahmaputra plains.

The region, broadly defined, provides the life-support base for about 50 million mountain people and probably in excess of 450 million people of the plains - the very densely populated areas of the Indus, Ganges, Brahmaputra, and upper and middle Jinsha Jiang (Sichuan Basin) - a significant proportion of humankind. While this book is principally a Himalayan story, the mountains and plateaus are the source of Central and South Asia's great rivers. As we seek to show, erosion of the mountains, over geological time, is the prime reason for the existence of the plains; and the lowlanders tend to perceive many of the 'natural' catastrophes with which they must contend as the result of landscape changes in the mountains brought about by the mountain people. The reverse of this antagonism, albeit over-simplified, is that many of the political and economic forces that are disrupting life in the mountains have a lowland base. Thus, the Himalaya-Ganges system, in the narrow sense, or the south-central Asian mountains-plateaus-plains system, in the broad sense, can be considered as one of the world's largest 'highland-lowland interactive systems.' It also embraces one of the world's greatest accumulations of poverty, malnutrition, and accelerating population growth. It is recommended that the reader consult a good world atlas.'

Figure 2.3 Schematic cross-section of the Nepal Himalaya: geology, Daniel Vuichard, Institute of Mineralogy, University of Berne; topography, modified after W. J. H. Ramsay.

The physical basis

Figure 2.3 has been introduced as a general model for describing the basic landscape elements of the Nepal Himalaya. For the purpose of our discussion it is necessary to emphasize that the 2,500 km west-northwest to east-southeast alignment of the Himalayan crest-line, reaching altitudes in excess of 8,000 m in a series of distinct mountain massifs separated by areas of lower altitude, often the locus of major river gorges, is paralleled by lower and less spectacular physiographic divisions to the south. This large-scale pattern is essentially the result of the Indian tectonic plate thrusting beneath the Central Asian plate. Despite the rapid uplift that this plate convergence has caused throughout the past several million years, some of the main rivers have been able to maintain their courses - as antecedent streams. The entire river network, however, displays a rectilinear pattern, with long sections of the mainstreams having developed courses along the structures at right angles to the gorge sections that cut across the structure. These patterns, the extreme altitudes, and also the very limited north-south extent (less than 150 km in places) reflects the enormous crustal shortening, over-thrusting, faulting, and folding that has occurred, and is occurring. The reader is referred to Hagen (1960, 1969) for a general account of the geology and structure of the Nepal sector. Of special importance, however, in terms of tectonics, are the absolute heights, with a roughly east-west crest-line, the continued rapid uplift (in many areas in excess of the estimated rates of down-wasting - see Chapter 5), and the great accumulations of sediments in the foredeep, which underlie the Ganges Plain and neighbouring plains. The close proximity of maximum altitudes in excess of 8,000 m, and maximum depths (of sediment) to more than 5,000 m below sea level, is dramatized by three major tectonic discontinuities. These are: the Main Central Thrust Zone (MCT); the Main Boundary Fault (MBF); and the Main Frontal Thrust (MFT), which, in essence, parallel the entire Himalayan system. As indicated in Figure 2.3 (and discussed in more detail, from the perspective of susceptibility to erosion, in Chapter 5) this 'standard' north-south transect includes nine distinct physiographic divisions. Gurung and Khanal (1987) discuss the names of these units from a Nepalese point of view and, while we have not adhered closely to them, their discussion is introduced here for basic reference.

Gurung and Khanal (1987) proceed from Hagen's (1960) division into seven zones, from north to south:

Tibetan marginal Mountains
Inner Himalaya
Himalaya
Nepal Midlands
Mahabharat Lekh
Siwalik Hills
Terai

Hagen (1969) later added three more: the Dun Valleys ('Mid-terse); the Fore Himalaya (Lesser Himalaya); and the Tibetan Plateau. Gurung and Khanal (1987) explain that for Nepal there exists a long-standing traditional terminology: thus, terse, or madhes for the plain; pahar for the hills; and himal for the mountains. They differentiate the plains into the terse and the inner terse (dun), the latter being tectonic depressions in the Chure range (or Churia = Siwaliks), or between the Siwaliks and the Mahabharat Lekh. Similarly, the limit of the sub-tropical middle hills (Hager, Nepal Midlands; Ives and Messerli, Middle Mountains) is the higher and temperate highlands - the Mahabharat Lekh - on the south. Finally, the trans-Himalayan valleys (bhot: hence Bhotia people = of Tibetan or Mongol origin) are enclosed by the himal (Great Himalaya) and the Tibetan border ranges. Gurung and Khanal maintain that the distinction between 'Himalaya' end 'Mountain' is spurious as they are synonymous terms, and that the epithet 'high' in this context is superfluous. The 'Middle Mountains,' a term we retain, actually relates to the conventionally recognized 'hill'region. Also, the native terms differentiate between the hills (pahar) which have no snow, the highland (we prefer 'higher mountains') or lekh, which only experiences snow in winter, and the mountain or himal, with permanent snow. Siwalik, according to these authors, is a geological term and is a composite of the Chure range (Churia) and the intermontane valleys and depressions, known as dun in the west (for example, Dehra Dun; also Doon Valley), marhi in the centre, and khonch in the eastern inner terse. Terai is often spelled 'Tarai,'as it is in Gurung and Khanal (1987).

Undoubtedly, there will prove to be many more local names; an examination of this topic is both beyond our competence and the limits of this study. Such a review would be of great future value and interest. For our purpose, however, we have adopted an amalgam that will not likely meet with universal approval. For much of this discussion we are indebted to Dr. Harka Gurung whose documents reached us after the main body of this book had been completed (Dr. H. Gurung, personal communication, December 1987). Table 2.1 indicates some of the variety of terminological usages.

Table 2.1 Nepal: Physical divisions - a comparison between several sets of terminology from different sources (after Gurung and Khanal, 1987).

¹LRMP Land Resources Mapping Project (Canada/ HMG) (from Gurung and Khanal, 1987)

Given the enormous range of altitude in such a short north-south horizontal distance, it follows that the 'normal' climate for the latitude, a sub-tropical monsoon type, is strongly modified by the presence of the extremely high eastwest trending Himalaya which, by reducing outbursts of cold air from Central Asia, ensures for northern peninsula India warmer winters than would otherwise be the case; in addition, the regional climates are modified with increasing elevation. This is best portrayed by a reconstruction of the natural vegetation belts that range from tropical monsoon rain forest (Shorea robusta = sal forests) in the south, through a series of forest belts, to the upper timberline at approximately 4,000 4,500 m. Above this a rhododendron-shrub belt gives out onto alpine meadows, a sub-rival belt of extensive bare ground and scattered dwarf plants, mosses, and lichens, and finally, at 5,000-5,000 m, permanent ice and snow with steep rock outcrops. Joshi (1986b), following Numata (1981) gives the following generalized pattern of vegetation belts for the central part of Nepal, chosen to relate to our schematic transect shown in Figure 2.3:

Dobremez (1976), in a major study of the plant ecology of Nepal, provides a wealth of detailed information, and Figures 2.4 and 2.5 have been taken from his work. Figure 2.4 shows the extreme complexity of vegetation types in Nepal, using a strictly schematic approach based upon his own fieldwork (Dobremez, 1976: 244). This provides a combined altitudinal (latitudinal) transect and a moisture gradient (decreasing moisture with decreasing longitude). Figure 2.5 provides a comparison of two altitudinal gradients that summarize the work of Schweinfurth (1957) and Troll (1959), and four deriving from the extensive Japanese research in the Central and Eastern Himalaya (Nakao, 1957; Kawakita, 1956; Kanai, 1966; and Numata, 1966).

So far we have restricted ourselves to the simplest possible phytogeographic description using basically south-facing slopes in central Nepal. To take the next, more complicating, step, it must be emphasized that each east-west crestline separates a wetter, south-facing, and a drier, north-facing slope. Precipitation from the summer monsoon, as the moist air is forced to rise against each successively higher ridge, is generally much heavier to the south of the major topographic alignments. In contrast, the succession of northfacing slopes experience rain-shadow effects to varying degrees.

Figure 2.4 Schematic representation of major vegetation communities as a function of altitude in Nepal. The stippled boundaries correspond to the four phytogeographic regions of Nepal: from left to right, Northwest Nepalese, West Nepalese, Central Nepalese, and East Nepalese. From J-F. Dobremez, 1976: 244, Figure 169.

Figure 2.5 Schematic representation of climatic zones and vegetation belts
a) after Schweinfurth (1957) and Troll (1959);
b) 1 after Nakao (1957), 2 after Kawakita (1956), 3 after Kanai (1966), and 4 after Numata (1966). Reproduced from J-F. Dobremez, 1976: 248, Figures 172, 174 and 249.

Annual rainfall totals appear to increase with increasing altitude in the Himalaya of central Nepal to about 3,000 m; thereafter, with increasing altitude (and increasing northerly latitude) annual totals diminish. Above about 5,500 m all precipitation is in the form of snow. The most complete topographical barrier, the Greater Himalaya, produces a major rain shadow on its northern side. Thus, annual precipitation totals show marked differences over very short horizontal distances. One of the most dramatic examples is provided by a pair of climatic stations (Lumle, altitude 1,642 m, and Jomosom, altitude 2,650 m) to the south and north of the Annapurna massif respectively and only 50 km apart. The former recorded 5,964 mm in 1961 and a five-year average (197175) of 5,551 mm; the latter has a mean annual precipitation of 255 mm.

Even in a relatively simple transect through the central Nepal Himalaya, however, extremely sparse data, especially long time series, render generalizations rather dangerous. The increasing aridity with increasing altitude and latitude, especially on north-facing slopes, reaches its most pronounced development north of the Greater Himalaya on the Tibetan Plateau and in the trans-Himalayan valleys. Thus Dobremez has added a 'steppe belt' to the simplified altitudinal vegetation-climate belts outlined above. Until recently much of our generalized climatic knowledge of the Himalayan region was based upon inferences drawn from the mapping of vegetation (Schweinfurth, 1957; Ohsawa et a/., 1986). Recently, data from newly established climatic stations are beginning to indicate the presence of 'pockets' of extremely high annual precipitation totals. One such pocket has been identified north of Pokhara in Nepal on the lower flanks of the Annapurna massif, which includes the Lumle record over five years (5,000+ mm) introduced above (Dhar and Mandal, 1986). The results of Dhar and Mandal's appraisal of Nepal's precipitation pattern is provided in Figure 2.6. Equally important, however, are the pockets of very low precipitation receipts. These also have long been recognized from vegetation mapping (Schweinfurth, 1957), and also from the travels of F. Kingdon Ward in the eastern Himalaya and in the Hengduan Mountains that resulted in the description of the 'dry valleys' (Wissman, 1959; Schweinfurth, 1985; Zhang Yongzu, personal communication, May 1985). Thus the large number of examples of precipitation data that can be found in the standard climatological references can only be regarded as providing a rough scale of the range of variation. Other important climatic parameters, usually noticeable by unavailability of relevant data, are annual variability, short-term rainfall intensities, and pronounced variations over very short horizontal and vertical distances.

The scatter, and the great range of climatic data, can best be viewed in the context of the general rhythm of the monsoon climate at large. A good general account is given by Das (1983) who provides a breakdown of the seasonal rhythm as:

April-May provides the highest temperatures, with maxima exceeding 40°C at many lowland stations. Of the total annual precipitation, 70-85 percent falls during June-September, depending upon location. The highest totals, according to available statistics, occur between the Annapurna massif and the eastern end of the Himalaya sensu stricto, with the highest amounts being recorded north of the Bay of Bengal and in Assam-Arunachal Pradesh (Cherrapungi: altitude 1,326 m, annual precipitation 11,615mm). With increasing distance along the Himalayan front toward the west-northwest, total annual precipitation decreases and the occasional winter westerly disturbances become more important. At the western end of the Himalaya, sensu stricto, and more particularly in the Karakorum and Hindu Kush, a winter maximum regime predominates with most precipitation occurring in the form of snow. The lower valleys and gorges are very dry and local agriculture is dependent upon snow-melt and glacial-melt irrigation. Summer monsoon influences here are slight or absent. This overall trend was noted by Troll (1938, 1939) while mapping altitudinal vegetation transects in the Nanga Parbat area (see also Troll's north-south reconstruction of the altitude of the regional snowline - Figure 2.7). Troll's work ws greatly expanded by Schweinfurth (1957), who produced the first composite vegetation map for the entire Himalaya. This map, a fundamental research resource to this day, reflects the parallelism between the climate and vegetation trends from north to south and from east to west.

This same pattern is also important in terms of the region's glacio-hydrology and the associated variation in water source and availability throughout the year (Young, 1982; Hewitt, 1985). The eastern Himalaya, in general, provide moisture surpluses from direct runoff of the abundant summer monsoon rainfall; the snow-melt contribution is comparatively insignificant. With increasing distance toward the west-northwest meltwater becomes critically important. A particularly heavy summer monsoon, for instance, which produces excess water (and flooding) in the eastern half of the region, may only serve to lower the summer flow of the western rivers since the increased cloud cover (with little or no rain/snow) will serve to reduce incoming solar radiation and thus limit meltwater production. Additionally, summer snow at high altitudes in the northwest, by greatly increasing surface reflectance (albedo), will curtail melting. A general lack of systematic studies in glacio-hydrology is a serious deficiency in terms of the great importance attached to hydroelectric and irrigation schemes by several governments of the region as well as United Nations and bilateral aid agencies (cf. the Canadian-Pakistan collaboration: Hewitt, 1986, 1987).

So far we have referred mainly to the impacts of the summer monsoon as a mass of warm moist air flowing northward from the Bay of Bengal and moving predominantly westward along the mountain front. While the mountains and valleys of the northwest are influenced mainly by winter westerlies, the easternmost ranges, the Hengduan Mountains, have their own predominating monsoon regime. In this case, however, the influence of the Bay of Bengal monsoon flow (southwesterly) and the southeasterly monsoon flow from the South China Sea are both important. But again, sparsity of climatic stations, and especially lack of data from higher altitudes, in this equally complex mountain system, inhibits any level of detail. Figure 2.8 provides some information for the Gongga Shan and Yulongxue Shan areas of western Sichuan and northwestern Yunnan respectively (Messerli and Ives, 1984). The Yulongxue Shan (Jade Dragon Mountain) is of special climatic interest as it is the site of the most southerly glaciers in Asia, and some of the highest known rice culture is to be found in its vicinity (Uhlig, 1978; Messerli and Ives, 1984). For a more complete discussion of the complexities of mountain weather and climate the reader is referred to Barry (1981).

Figure 2.6 Mean annual precipitation for Nepal, showing 500mm isopleths. The 'pocket' of very high precipitation near Pokhara (5,000mm) is based upon recent data from newly established climatic stations (after Dhar and Mandal in Joshi, 1 986a).

Figure 2.7 Topographic and climatic profile from south to north across the Himalaya and the Qinghai-Xizang (Tibet) Plateau. The broken line shows the average altitude of the regional snowline (after Troll, 1960).

Figure 2.8 The pattern of vertical belts: forest, vegetation, and land use, Gongga Shan and Yulongxue Shan, southwestern China (after Messerli and Ives in Lauer, Natural Environment and Man in Tropical Mountain Ecosystems 1984:63 Figure 5)

People and population

Complicated as the physical geography of our region is, the present-day cultural, economic, and ethnic patterns, not to mention the many rivalries at the state level, defy easy description. This in turn is partly due to the influence of the physical base and partly a result of the very long and complicated history.

Our knowledge of the pattern and extent of prehistoric settlement in the Himalaya, based upon archaeological evidence, remains very sparse. There are only a very few palaeolithic and neolithic sites scattered, for instance, throughout the eastern basin of the Brahmaputra. Consequently, attempts to reconstruct the social and intellectual forces that have shaped contemporary society in northern India and the Himalaya rely heavily upon the great body of Sanskrit epic literature, the earliest fragments of which date from 1200 BC. Much of this literature is derived from an oral tradition that had been continually modified over several thousand years before being committed to writing (O'Flaherty, 1975). This, and other evidence, indicates a continuous political and cultural relationship between the Himalayan foothills and the Ganges plains from at least the fourth century BC to the reign of Ashoka Maurya, the great patron of Buddhism (Rose, 1971).

These introductory remarks are taken from English (1985: 65), who proceeds to outline the cultural and economic history of the Himalaya with emphasis on state formation and the impact of British Rule during the nineteenth century. English describes three patterns of settlement. The western Himalaya was widely settled from 1500 BC onward by a population of nomadic warriors called Khas who were part of a succession of waves of Aryan migration into India from the northwest. The Khas are believed to have subjugated the indigenous inhabitants and to have relegated them to a rigidly inferior social status. The Khas gradually became acculturated to the predominant Hindu influences of the northern plains.

The developing pattern of settlement of the central and eastern Himalaya appears as a migration of Tibeto-Burman tribal peoples from Southeast Asia who moved westward along the mountains north of the Brahmaputra in the early millenia BC. They were reputed to be great hunters, skilled in the arts of magic, and are believed to have practiced cannibalism. They were referred to in Sanskrit writings as Kirata.

The third pattern is the settlement of the Bhotias and related peoples in the high Himalayan valleys dating from the early centuries AD. Successive waves of these nomads appear to have occurred, transforming in the process to a more settled life combining agriculture, pastoralism, and trade, and coming to occupy what is now northern and central Nepal.

The emergence of a powerful centralized Tibetan monarchy patronizing Buddhist monasticism dates from the seventh century AD (Beckwith, 1987). During the course of two hundred years this monarchy expanded the frontiers of Tibet from western China to Kashmir and northward into Central Asia. Unseated nobles and adherents of the pre-Buddhist Bon religion migrated southward to take refuge in the Himalaya where they established semiautonomous kingdoms. Those kingdoms south of the Sutlej River were eventually absorbed by the Khas Malla dynasty which, following upon the eclipse of Tibetan power, unified the Garhwal-Kumaun region and much of western Nepal into an integrated Hindu polity based upon trade and agricultural revenues (Pant, 1935). The kingdoms of Mustang and Dolpo, in northern Nepal, and the later Sherpa entity, remained virtually independent of Hindu domination until well into the present century.

The Muslim conquest of northern India during the fourteenth century led to widespread movements of Hindu and Buddhist populations into the northern mountains in the wake of massive religious persecution. The high-caste refugees, who migrated into the western foothills, claimed descent from the Rajputs, who were legendary for their resistance to a succession of TurkoAfghan invasions. Over the next three centuries, these Rajput nobles displaced the ruling Khas lineages in the hills and extended their control of the Himalaya from Kashmir to the eastern Terai of present-day Nepal. The fortunes of many princely states waxed and waned and the political landscape remained extremely fragmented. At the time of the Gorkhali conquest, late in the eighteenth century, there were about eighty separate principalities in this section of the Himalaya, sensu stricto, alone (Stiller, 1975).

Sikkim was settled in the thirteenth century by herders from eastern Tibet, and Bhutan became unified in the early decades of the seventeenth century. The expansion of the hill state of Gorkha culminated with the conquest of the Newar city-kingdoms of the Kathmandu Valley in 1769. King Prithivi Narayan Shah extended his empire to embrace a 1,500 km area of the Himalaya from the Sutlej to the Teesta. At its short-lived maximum extent it included Sikkim, and the Darjeeling area of present-day West Bengal, the southern tracts of Tibet, and a large section of the Ganges Plain (Figure 2.9) before coming into violent contact with the expanding territorialism of the British East India Company.

This somewhat fragmentary 'history' of settlement can be summed up with the statement that the northwestern part of the region evolved under Muslim influence, the southern flanks of the centre and east under Hindu influence, and the northern fringe under Buddhist influence. This broadly sweeping overlay conceals innumerable small ethnic groupings and says little about the independent entities such as Hunza, the great complexity of settlement of the Arunachal Pradesh Himalaya, and the several dozen distinct ethnic and linguistic groups of the Hengduan Mountains, which were eventually infiltrated along the main valleys by Han agricultural settlers and traders. Karan (1987b) has sought to generalize the major religious-ethnic patterns of the Himalaya, sensu stricto (Figure 2.10), while Figure 2.11 provides greater detail for Nepal (after Dobremez, 1976 (Figure 117): 108).

Figure 2.9 Nepal at the maximum extent of the Gorkhali Empire in 1814 (after English, 1985).

Karan (1987b) claims a total 1981 population of about 33 million for the Himalaya, sensu stricto. This includes the entire population of Nepal (15 million) so that, strictly speaking, this takes in a significant number of lowlanders, since about 7 million inhabit the Nepalese Terai (including the inner terse: Goldstein et al., 1983). Our overall estimate of about 50 million for the mountain (plus Terai) region, sensu lato, is probably of the correct order of magnitude, although presumably this has increased at a rate of about 2 percent per annum, or more, since 1981.

Figure 2.10 'Cultural regions" of the Himalaya, sensu stricto (after Karan 1987b).

Figure 2.11 Ethnic groups of Nepal. Wide diagonal lines show the extent of ethnic groups under the Nepalese caste system; close diagonal lines indicate the extent of groups of Tibetan origin; between these and within the heavy black lines are shown the Tibeto-Burman groups (after Dobremez, 1976: 108, Figure 117).

Karan's (1987b) study indicates that the population of the Himalaya, sensu stricto, has trebled between 1901 and 1981 (from 11 million to over 33 million: Table 2.2). He provides an annual growth rate of 1.26 percent for the region as a whole, for the first five decades of this century, and a rate of 2.7 percent between 1951 and 1981. Broken down into different regions, this gives especially high annual rates of growth (1901-51) for Sikkim (5.8 percent), Darjeeling (3 percent), and Kumaun (2.6 percent). Since 1951 high rates have characterized Sikkim and the Eastern Himalaya (4.3 percent), Kashmir and Kumaun (2.7 percent), and the Punjab and Nepal Himalaya (2.5 percent). In recent years it would appear that the annual growth rate has exceeded 2 percent in all areas of the Himalaya, except Bhutan. It seems reasonable to extend this estimate to the wider region, with the exception of Afghanistan, where 'normal' population trends will have been obliterated by the massive flow of refugees into northern Pakistan and Iran.

When these growth estimates and absolute 1981 population numbers are converted into densities, allowance must be made for the large proportion of land that cannot be used for agriculture or pastoralism (high mountains and land under permanent snow and ice) and the probably equally large amount of marginal land (on account of a combination of altitude and steep slopes). Thus, as has been repeated in many publications, it is necessary to convert population densities into numbers of people per hectare of arable land, or even irrigated khet land. While it is difficult to do this with any degree of accuracy, it is reasonable to conclude that such 'real' densities would greatly exceed those of the rich farmlands of the plains. This comparison is made the more striking if we bear in mind that triple cropping has become a widespread practice in the plains, a form of intensification that is not practiced at higher altitudes (most of the Middle Mountains) because of lower temperatures.

Table 2.2 Himalaya, sensu stricto: area and population of different sub-regions (1901, 1951, 1981) and percentage growth (1901 51, 1951-81) (after Karan, 1987:272).

Sources: Census of India, 1901, 1951, and 1981; Central Bureau of Statistics, Kathmandu, Nepal; Planning Commission, Royal Government of Bhutan, Thtmphu.
Notes: Kumaun a. 1961 data; b. 1901-61 growth; c. 1961 81 growth. Nepal d. 1911 data, e. 1952/54 data, f. 1911-52/54 growth, g. 1952/54-81 growth. Sikkim h. 1891 data; i. 1891 1951 growth. Arunachal Pradeshj. 1961 data; k. 1961 81 growth. n.d. = no data.

As Karan (1987b: 272) points out, despite its rugged terrain, the Himalaya is also a region of extensive population movement. Migration is constantly occurring, from one rural area to another, from urban to urban areas, and from rural to urban areas. Goldstein et al., (1983), for instance, have characterized Nepal as showing a distinct trend in transformation from a highland rural society to a lowland urban one; although the total urban population remains very small it is beginning to grow with increasing rapidity. Nor do these remarks take into account the massive amount of seasonal migration and the day-to-day movement of young males from rural areas seeking wage labour in the nearest towns, and on the plains. This is as characteristic of the Indian Himalaya as it is of Nepal. Karan (1987b) indicates that the two major areas of permanent outmigration are Nepal and Kumaun. There are indications of extensive reverseflow migration into the mountains - from Assam into Arunachal Pradesh (Goswami, personal communication, October 1987).

Breakdown into regions

Different attempts have been made over the past three decades to provide a regional breakdown of the Himalaya and contiguous areas. Schweinfurth (1957) has demonstrated in his seminal treatise the great variability of the natural vegetation cover. His approach is based upon a massive literature review without any first-hand experience in the field. Troll (1967) subsequently synthesized his own extensive experience gained during his scientific expeditions to different parts of the Himalaya and produced a climo-ecological regionalization. Uhlig (1978), as a third example of the long tradition of German research, compares the natural altitudinal differentiations with sociocultural altitudinal systems. The approach introduced here is a new attempt undertaken by the Geographical Institute of the University of Berne. Figure 2.12 provides a summary of the steps used in this procedure.

By extrapolating the annual precipitation amounts for more than 200 climatic stations, the mean annual precipitation pattern for the region (Figure 2.13) was produced with the aid of a computer programme. Next, using a method developed by FAO (1982) to calculate humidity available (moisture) for vegetation, or agricultural production, the monthly precipitation amounts were compared with the potential evapotranspiration amounts (Step I in Figure 2.12). To delineate the actual thermic situation three different isotherm maps were superimposed (Voeikow, 1981). These were: mean annual temperature; mean temperature of the coldest month; mean temperature of the warmest month (Step 2 in Figure 2.12).

The temperature classes for the map (Figure 2.14) were made to correspond with the altitudinal ranges of different types of vegetation. Next, the definition of soil units (Figure 2. 15) follows in a generalized way the FAO soil map of the world (FAO, 1977). In taking the world soil map as an overview of the edaphic situation, however, two limitations need to be considered: (1) the FAO information on soils is based upon very limited field data; and (2) the map projection for the soils of the Himalayan Region is not compatible with those of other maps that were used. To overcome, at least in part, this latter limitation the soil map was redrawn using a more compatible scale and projection. This was accomplished by computer-aided design (Auto CAD).

Figure 2.12 Schematic procedure for the regionalization process, showing Steps I to 4 as discussed in the text (prepared by Markus Wyss, Geographical Institute, University of Berne, 1988).

Figure 2.13 Mean annual precipitation (prepared by Markus Wyss, Geographical Institute, University of Berne, 1988).

Figure 2.14 Temperature classes (prepared by Markus Wyss, Geographical Institute, University of Berne, 1988).

The three maps showing precipitation (Figure 2.13), temperature classes (Figure 2.14), and soil units (Figure 2.15) provide a general overview of the physical base of the Himalayan Region and serve at the same time as intermediate steps for the regional breakdown. However, the several limitations introduced by this approach must be indicated. First, accuracy and detail of information that can be shown are obviously restricted by the small scale of the maps and by the fact that data from some parts of the area are missing. This is especially critical in high mountain areas where site differences can be much more important than sub-regional differences. In particular, the maps cannot take into account the great variability that occurs within short horizontal and vertical distances in mountainous regions.

The next step (3 in Figure 2.12) involved the delineation of natural landscape types by superimposing the three base maps (Figures 2.13-15). For ease of interpretation, this procedural step was taken at the enlarged scale of 1:2,000,000 and, in turn, was used for the final step (4 in Figure 2.12): delineation of the seventeen regions. Figure 2.16 depicts the seventeen regions, and the corresponding legend provides a summary of the ecological situation of each. In considering humidity (available moisture) we differentiate between the annual precipitation, the season of maximum rainfall, and the length of the period suitable for plant growth. The effects of vertical gradients and different aspects are particularly important in this exercise and are probably under-estimated. Nevertheless, the final product (Figure 2.16) provides a coherent and basically rational overview of the major subregions of the Himalayan region, sensu lato. It should serve as a framework for the discussion that follows and, regardless of its limitations, enables us to focus our attention on some of the aspects of the physical diversity of the Himalaya. We have not attempted to superimpose the cultural and historical diversity since that would carry the burden of complexity beyond our cartographic competence.

Figure 2.15 Soil units (prepared by Markus Wyss, Geographical Institute, University of Berne, 1988, generalized from FAO, 1997)

Figure 2.16 A proposed regional breakdown for the Himalayan region, sensu lato (prepared by Markus Wyss, Geographical Institute, University of Berne, 1987).

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