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accounting for about 1.5 per cent of the\u00a0country\u2019s total surface area (DIIR 1992).\u00a0The catchment area ecology of most of\u00a0the lakes is relatively unknown and\u00a0utilization of their waters has remained low\u00a0until recent times. Many of these lakes\u00a0have been receding slowly due to natural processes for\u00a0thousands of years.\u00a0According to Chinese surveys, there are 71 species and\u00a0sub-species of fish in the \u2018Tibet Autonomous Region\u2019 (\u2018TAR\u2019).<\/p>\n
This constitutes 63 per cent of the species and sub-species\u00a0on the entire Tibetan Plateau. Among these are various species\u00a0of: Schizothoracinae, Nemacheilinae and Sissoridae (Zhang\u00a01997).\u00a0There were no cases of Tibetan rivers being diverted,\u00a0polluted or extensively fished before 1949. A small hydro power\u00a0station was built in 1928 in the Togde Gully on the Kyichu\u00a0with an installed capacity of 92 kw (Yan 1998).<\/p>\n
Diversions\u00a0for irrigation were also minimal. In this period, Tibet\u2019s\u00a0agriculture was dependent on monsoon rains and small-scale\u00a0river diversions organised on a village basis. These would have had a negligible impact on the flows of Tibet\u2019s rivers. The absence of any modern industry at this time, and the low population density, meant that it was unlikely that wastes entering Tibet\u2019s rivers caused any significant pollution. For devout Tibetan Buddhists eating fish is a sacrilege. There is a saying: \u201cBecause a fish is without a tongue, killing is unforgivable\u201d (Duncan 1961).<\/p>\n
Fish were not an important part of the Tibetan diet. Therefore, few people engaged themselves in fishing. The fishing activity around Yamdrok Tso in southern Tibet was regulated by the central government in Lhasa as the lake is of great spiritual significance. The Kashag (Cabinet of the Tibetan Government) regulated the size of fishing net holes so that young\u00a0fish and other non-edible creatures were protected (Tsering\u00a01996). Therefore the exploitation of fish resources prior to\u00a01949 was minimal and so where harvests were cpmsequently.<\/p>\n
WATER FOR THE MILLIONS<\/strong><\/p>\nAs mentioned above, rivers originating in Tibet flow into various regions in Asia. In some cases the distance traversed by these rivers through Tibet is short, while for many of them Tibetan terrain constitutes a large proportion of the rivers\u2019 total length and contributes largely to the rivers\u2019 perennial flow. Since Asia is dominated by monsoon patterns of rainfall, bringing rain for only a few months (usually three months) of the year, the perennial flow of its rivers relies upon the constant flux of glaciers on the Tibetan Plateau. Tibet\u2019s high altitude causes extreme diurnal variation in temperature, so that every day, winter or summer, glaciers can partially melt and refreeze. This daily snow melt feeds the river systems.<\/p>\n
From Tibet\u2019s Rivers Flows Asia\u2019s Survival<\/strong><\/p>\nFor 1,600 km of its total 4,500 km length, the Mekong\u00a0traverses through Tibetan territory (Lafitte 1996). Beginning\u00a0in Amdo, the Mekong passes through the eastern side of\u00a0Tibet near Sangang and Chamdo and flows near the Tibetan\u00a0town Jol and then Balang to the Chinese town Lajing in\u00a0Yunnan Province. It then continues in a south southeasterly\u00a0direction through Yunnan and on into Southeast Asia. After\u00a0leaving China, the Mekong flows through Laos, Thailand,\u00a0Cambodia and Vietnam.
\nThe Salween begins in Thangla Mt. (Ch. Tanggula) in\u00a0Tibet and flows east towards the Mekong. It then travels in\u00a0an almost parallel gorge just west of the Mekong in the
\nKhawakarpo Mountains. Once in Kham, the two river valleys\u00a0diverge and the Salween heads southwest into Burma, where\u00a0it becomes the country\u2019s primary river.
\nThe two great rivers of China, the Yangtze and the Yellow,\u00a0originate high up on the plateau in Amdo. The Yellow River\u00a0travels northeast through Amdo before entering the Loess\u00a0Plateau and the North China Plain. This region of China\u00a0supports 550 million people and two thirds of the country\u2019s\u00a0cropland. However, the watershed only supplies one fifth\u00a0of the country\u2019s water. The Yangtze watershed and the region\u00a0to its south supports slightly more people (700 million),\u00a0accounting for four fifths of China\u2019s total water yet only\u00a0one third of the country\u2019s cropland (Brown & Halweil 1998).<\/p>\n
The imbalance of water resources to cropland between these\u00a0two major watersheds of China is emerging as one of the\u00a0Beijing\u2019s biggest ecological problems. As groundwater and\u00a0river water is becoming exhausted in the north, Chinese\u00a0engineers are contemplating massive inter-basin water\u00a0transfer projects.\u00a0In the southwest of Tibet, four major rivers originate\u00a0around Mt. Tesi (Kailash). One is the Yarlung Tsangpo which\u00a0travels for over 2,200 km within Tibet.<\/p>\n
Its easterly course\u00a0skirts north of the Himalayan divide before turning sharply\u00a0south into the plains of Arunachal Pradesh, India, where it\u00a0becomes known as the Brahmaputra. After flowing through\u00a0the Assam Plain in India, the Yarlung Tsangpo enters\u00a0Bangladesh to irrigate the fields of the country\u2019s 128 million\u00a0people, before joining the Ganges and the Meghna to form\u00a0the great delta of northeastern India known\u00a0as the Sunderbans.\u00a0The Senge Khabab (Indus) has its source\u00a0north of Tesi mountains (Kailash).<\/p>\n
It then\u00a0passes west into Ladakh as the Senge Tsangpo\u00a0and then to Kashmir and continues to become\u00a0Pakistan\u2019s principle river. The Langchen\u00a0Khabab (Sutlej) begins west of Tesi mountains, crossing the\u00a0Himalayas into Himachal Pradesh in northwest India, passing\u00a0through the Punjab region before joining the Indus in\u00a0Pakistan. The Macha Khabab (Karnali) originates from Mt.\u00a0Tesi Range (Kailash Range), crosses the Himalayas into\u00a0western Nepal and then into India where it joins the River\u00a0Ganges.\u00a0Fertile River Valleys\u00a0Every year the major rivers flowing out of Tibet flood when\u00a0the spring sun melts the winters\u2019 snow and then again when\u00a0the monsoon rains arrive \u2014 mostly between July and\u00a0September.<\/p>\n
At times these floods are severe, often wreaking\u00a0havoc downstream as they did in China and Bangladesh in\u00a01998 and 1999. Nevertheless, a regular annual flood can be\u00a0a beneficial function of a healthy river. As these rivers\u00a0cascade down into the foothills and plains of Asia they bring\u00a0with them more than just water. The silt loads of Tibet\u2019s\u00a0rivers deposit millions of tons of silt and sediment to create\u00a0fertile river valleys and flood plains in the downstream regions\u00a0in Asia. This is the key to maintaining the viability of\u00a0downstream ecosystems.<\/p>\n
The fertile river valleys of\u00a0Brahmaputra, Yellow and Mekong are cases in point.\u00a0As the floods recede they leave behind silt which\u00a0replenishes the topsoil with vital trace elements such as silica\u00a0and iron. This sedimentation process also maintains the deltas\u00a0of major rivers. The annual flood also facilitates the breeding\u00a0of freshwater fish. While the floods are at their peak, fish\u00a0swim into the shallows and lay their eggs in still waters where\u00a0they can develop without disturbance. As the floodwaters\u00a0recede, the hatchlings find their way into the main streams.<\/p>\n
These benefits are not always appreciated by agro-scientists\u00a0and developers and, perhaps not surprisingly, by those\u00a0affected by the floods. Catastrophic floods appear to be\u00a0becoming more regular and more severe. This is a possible\u00a0consequence of the interference in hydrological systems,\u00a0climate change and continuing deforestation.\u00a0It is becoming increasingly clear that rivers have more\u00a0ecological functions than just the provision of water. The\u00a0interaction of flood plains and rivers is one such vital\u00a0function. The Tibetan Plateau \u2014 with its weather patterns,\u00a0hydrological system, glacial conditions,\u00a0forest, and soil functions \u2014 has an essential\u00a0influence over Asia (with high population\u00a0densities) and which also provide sustenance\u00a0to some of the world\u2019s most productive\u00a0agricultural zones.<\/p>\n
Source: Tibet 2000 Environment and Development Issues, Environment and Development Desk, DIIR<\/strong><\/p>\n\u00a0<\/strong><\/p>\n <\/p>\n
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THE MOUNTAINS of Tibet constitute the headwaters of many\u00a0of Asia\u2019s major rivers. Tibet\u2019s high altitude, huge landmass\u00a0and vast glaciers endows it with the greatest river system in\u00a0the world.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-513","post","type-post","status-publish","format-standard","hentry","category-water-resources"],"_links":{"self":[{"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/posts\/513","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/comments?post=513"}],"version-history":[{"count":9,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/posts\/513\/revisions"}],"predecessor-version":[{"id":551,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/posts\/513\/revisions\/551"}],"wp:attachment":[{"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/media?parent=513"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/categories?post=513"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tibetnature.net\/en\/wp-json\/wp\/v2\/tags?post=513"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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