Physiography and Resources

Abstract

The HKH Region can conveniently be divided into four distinct zones such as the outer southern part called “Shiwaliks”, the lesser Himalayas, the higher Himalayas, and the Tibetan-Tethys. The Shiwalik Hills form the southern stretch of the Himalayas starting from the Indus River to about 2,400 km eastwards, spanning across the northern parts of PakistanPakistan, India,India and Nepal. It is 10–50 km wide with an average elevation of 1,500–2,000 m. The Lesser Himalaya lies in between the Sub-Himalayas and Higher Himalayas separated by the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT), respectively. The total width ranges from 60 to 80 km. The rocks in the lesser Himalaya range in age from Precambrian to Miocene. The northernmost boundary of the Shiwaliks Group is marked by the Main Boundary Thrust (MBT), over which the low-grade metasedimentary rocks of the Lesser Himalaya overlie. The higher Himalayas extend from the main central thurst to Tibetan-Tethys Zone and consists of about 10 km-thick succession of crystalline rocks, known as the Himal Group. The Tibetan-Tethys Himalayas generally begins from the top of the Higher Himalayan Zone and extends to the north of TibetTibet (China). This zone is about 40 km wide. The Himalayas are the tallest mountain ranges in the world spread across 8 countries and can conveniently be categorized as (a) Western Himalayas (AfghanistanAfghanistan, PakistanPakistan, IndiaIndia), (b) Central Himalayas (India, NepalNepal, TibetTibet (China) Autonomous Region of China), (c) Eastern Himalayas (India, China, BhutanBhutan), and (d) Far-eastern Himalayas (IndiaIndia, MyanmarMyanmar, China, BangladeshBangladesh). The Hindu Kush Himalayas mountain ranges function as water towers, providing water to people throughout much of Asia. The glacier-fed rivers originating from the Himalayan mountain ranges surrounding the Tibetan Plateau comprise the largest river runoff from any single location in the world. The rivers shape the landscape and ecosystems and are important in terms of biodiversity. The high mountain ranges strongly influence atmospheric circulation and meteorological patterns across the region. As a result of its varied topography, the HKH is endowed with rich biodiversity and diverse ecosystems, which provide a basis for the livelihoods of the many people who live there. Its physical characteristics, however, also make the Hindu Kush Himalayas one of the most hazard-prone regions in the world. Heavy rains, steep slopes, weak geological formations, accelerated rates of erosion, and high seismicity contribute to serious flooding and mass movements of rock and sediment affecting the lives and livelihoods of millions. The rivers flowing from the Hindu Kush Himalayas provide the region with one of the most valuable resources, that is, freshwater. Besides huge water resourcesWater resources of India, the HKH Region is endowed with sufficient human, animal, land, soil, vegetation, rangelands, grasslands, pasture, and mineral resources.