ABOUT NEPAL

Nepal is divided into five physiographic regions (and three agro-ecological zones), which are almost parallel to each other, running from west to east. They are: the high Himalayan region, mountains, mid hills, Siwaliks and Terai.

High Himalayan Region:

This region, which is always covered by snow, occupies 23.7% of the total land – 3,447 500 ha. Its altitude ranges from 3,000 m to 8,848 m. The mountains are very steep with active glacier systems. The geology consists of gneiss, schist, limestone and shale of different ages. Physical weathering predominates and soils are very stony. This region falls largely within the alpine and arctic climate regimes, so there are active glacier systems where there is enough precipitation in high catchments. The climate is dependent on elevation and location in the mountain massifs. The few pockets of arable land of Solukhumbu, Mustang, Manang and Dolpa are the result of a unique combination of aspect, shelter from wind and availability of water for irrigation.

Characteristic landforms are glaciers, cirque basins, moraines, U-shaped valleys and avalanche slopes. Bedrock in most of the areas is exposed at or near the surface including gneisses, schist and the Tethys sediments. Less than 1% of the region has soil and climate suited to crop production and then only where irrigation is available.

Mountain Region:

The altitude of this region ranges from 2,000 m to 2,500 m and it lies below the permanent snow line. This region occupies 2,899,500 ha making up 19.7% of the country. It has a cool climate and receives heavy to moderate snow in winter. Mountain slopes are very steep but there are some flat valleys as well. The geology is characterized by phyllite, schists, gneiss and quartzite of different ages. Soil formation on the slopes is slow and they are rocky.

This region borders the mid hills to the south and the high Himal to the north. The boundaries are defined by changes in geomorphic processes, bedrock geology, climate and relative relief. This region has more metamorphosed and structurally consolidated rocks. Gneisses and garnetiferous mica schists are common. Most of the major valleys have been glaciated. High river gradients and enhanced river down-cutting resulted in the formation of deep canyons since glaciation. Agriculturally this region is of lesser importance. After the snow melts the mountains are covered with thick grasses and livestock like sheep, yak, and other mountain animals graze in this region. In the valleys, in summer, one crop a year can be harvested. The crops are potato, naked barley, buckwheat, and maize. Food grown here is not enough to support the population and more has to bring in.

Mid Hills Region:

This region includes a wide range of physiography. Its area is 4,350,300 ha. – about 29.5% of the area of the country. Mountain peaks range up to 2,000 m with narrow river valleys. The mountains are the Mahabharat Range. The geology consists of a complex of phyllite, schists, quartzite of Cambrian to Precambrian ages and granites and limestones of different ages. The climate ranges from warm subtropical to warm temperate. The higher peaks receive occasional snow whereas some lower parts receive occasional frost in winter, which causes damage to crops. Soils are extremely variable because of the differences in bedrock, geomorphology and microclimate. The southern margin mostly consists of a prominent belt of uplifted mountains known as Mahabharat Lekh. This belt is made up of deeply weathered granite, limestone, dolomite, shale, sandstone, slate and quartzite; is intensively cultivated and is home for more than 60% of the population. It produces most of its food, yet food is always transported from surplus regions to this area. Subtropical dense forest occupies the non-agricultural land.

Siwalik Region:

This region lies at the foot of the Mahabharat Range. Its area is 1,888 600 ha: 12.7% of the total land. Altitudes range from 300 m to 1,800 m. The geology mainly consists of tertiary mudstone, sandstone, siltstones and conglomerate. Soils vary depending on the materials from which they are developed. There are several inner valleys or duns, which are densely populated. Because of alluvial deposition these valleys are very fertile. The landscape is very rugged and unstable, consisting of weakly consolidated Tertiary sediments with gentle to strongly sloping dip slope. Siwalik soils are unable to retain high precipitation which frequently occurs resulting in flash floods. Duns, a very important part of the Siwalik landscape, are structurally stable and sometimes, in the past, their outlets were blocked by rapid tectonic uplift of the Siwalik range. The major dun valleys are: Chitwan, Dang, Deokhuri, Surkhet, Trijuga and Kamala. Climate in the duns is modified by the regular occurrence of winter fogs; otherwise it is very dry.

The Terai Region:

The Terai, a flat extension of the southern Indo-Gangetic plain, occupies 2,142,200 ha, 14.4% of the country. Altitudes range from 66 m to 300 m. The region enjoys a warm sub-tropical climate and its alluvial soils are fertile. Wherever irrigation is available the land is intensively cultivated. It consists of recent and post-Pleistocene alluvial deposits forming a piedmont plain adjacent to the Himalayan ranges. Although the whole length of the Terai has a common geomorphology, it has obvious differences in land use due to presence of different land systems and land units. The obvious difference is the increased amount of rice cultivation in the eastern Terai indicating a greater proportion of higher quality alluvial soils and more availability of water/rainfall compared to the west.

Forests

The entire country lies within the latitude of the subtropical region but variation in elevation, slope rainfall, temperature and, to a large extent, soil and drainage determines the location of major forest types. The vegetation varies from tropical moist forests to alpine scrub.