The China Agroforestry Programme

The China Agroforestry Programme or World Agroforestry Centre, China Programme, was established in August2002. The World Agroforestry Centre is a centre for learning and, at the same time enabling. It seeks to transformlives and landscapes through agroforestry science in West China. Currently, the Programme has a liaison officein Beijing, established in accordance with an agreement with the Chinese Ministry of Agriculture and the ChineseAcademy of Agricultural Sciences (CAAS), and a Centre for Mountain Ecosystem Studies (CMES), a joint centreof the World Agroforestry Centre and Kunming Institute of Botany, Chinese Academy of Sciences (CAS). Theoverall goal of the Programme is to generate knowledge and innovative options on agroforestry science thatsupport ecosystem services and livelihoods in the mountain areas of West China to benefit both local people andother populations living downstream in Southeast and South Asia and inland and coastal China. China-Agroforestrybrings together a partnership of international, national and local research institutions, development practitioners,government and non-government organizations, and donors with commitment to a “Knowledge and Innovationsto Action”framework to bridge knowledge gaps between science and policy and between science and fieldpractices in the actual mountain environment. Agroforestry science will be integrated into a single system per-spective that places research and development linkages within socio-ecological systems to facilitate its harmoni-zation into society.

Xu Jianchu

© ICRAF China 2007ICRAF Working Paper

The Highlands:A Shared Water Tower in a Changing Climate and Changing Asia

Correspondence: (J.C.Xu@cgiar.org)

©Copyright ICRAF China

ISBN 978-99946-853-6-3Published by: Nagarjuna Publication (P) Ltd.Kathmandu, Nepal, Tel: +977-1-5552118

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World Agroforestry CentreTransforming Lives and Landscapes

ICRAF China, Beijing Office#12 Zhongguancun Nan Dajie, CAAS Mailbox 195Beijing 10081PR ChinaTel: +86-10-62119430, fax: +86-10-62119431

ICRAF China, Kunming OfficeCentre for Mountain Ecosystem StudiesC/O Kunming Institute of BotanyHeilongtan, Kunming, 650204PR ChinaTel: +86-871-5223014, Fax: +86-871-5216350Website: http://cmes.kib.ac.cn

ICRAF Southeast Asia Regional OfficeJl. CIFOR, Situ Gede, Sindang Barang, Bogor 16680PO Box 161, Bogor 16001, IndonesiaTel: +62 251 625415, fax: +62 251 625416Email: icraf-indonesia@cgiar.orgICRAF Southeast Asia website: http://www.worldagroforestrycentre.org/sea

DisclaimerThis text is a ‘working paper’ reflecting research results obtained within the framework of the ICRAF SoutheastAsia project. Full responsibility for the contents remains with the author.

Abstract

The highlands of Asia have an average altitude of 4000 masl; and they extend from an altitude of 3000masl toinclude the whole of the Tibetan Plateau and most parts of the Pamir Plateau. The highlands contain the mostextensive areas of glaciers and permafrost outside high latitudes. The region is often referred to as the ‘Asianwater tower’: the source of Asia’s nine largest rivers the waters of which sustain over 1.3 billion people. Thehighlands of Asia have been ignored in comparison to other natural ecosystems, even though history has shownthat, when ecological change takes place in the highlands, changes soon follow in the valleys and in the lowlandplains. The impacts of climate change are superimposed on a variety of other environmental and social stressesin mountain ecosystems, and many of them have been recognized to be severe and cause uncertainty. Keyimpacts of climate change on the highlands include glacier retreat, shortage of fresh water, natural hazards, soilerosion, ecosystem degradation, and land desertification. The supply of fresh water, or the snow and ice meltwa-ter component, in large river basins is projected to increase over the following decades as perennial snow and icedecrease. Later, however, most scenarios suggest a decrease, even of catastrophic proportions, by the 2050s.

The greatest challenge in the highlands of Asia is the very limited monitoring or understanding of the thresholdsand cascades of climate change on the cryosphere, hydrosphere, biosphere, and on human society in the verticaldimension from highlands to uplands and from lowland plains to coastal areas. Impacts on water resources willdiffer depending upon the importance or influence of different sectors; and between forestry, agriculture, industry,ecosystems, or mitigation measures to reduce water-induced hazards. There are substantial variations within aswell as between these sectors in different countries and valleys. Meanwhile, climate change is superimposed ona variety of other environmental and social stresses that cause uncertainty and lead to contradictory perceptions.Three practical suggestions are a) integrated research to understand highland complexities and reduce scientificuncertainty; b) promotion of regional cooperation and science-based dialogue to regulate blue, green, and virtualwater flows; and c) building of social resilience and offsetting lack of knowledge of diverse human and ecologicalconditions by actively involving local communities; allowing their knowledge, innovations, practices, and con-cerns to inform understanding and help direct responses.

KeywordsClimate Change, Highlands, Water Tower, Ecosystem Services, Asia, Uncertainty

Acknowledgement

This paper is benefit from author’s early work as the Program Manager on Water, Hazards and EnvironmentManagement, International Centre for Integrated Mountain Development, particularly interaction with Dr. MatsEriksson and Dr. Juerg Merz. Thanks also are due to John Dore from Mekong Program on Water Environment& Resilience, Dr. David Thomas from ICRAF-Chiang Mai, Dr. Andreas Wilkes from The Mountain Institute, andDr. Timm Tennigkeit from Centre for Mountain Ecosystem Studies for their valuable comments. Thanks forgreat encouragement from Professor Malin Falkenmark, Dr. Jakob Granit and Dr. Michael Moore from StockholmInternational Water Institute, Dr. Lailai Li from Stockholm Environment Institute. Dr. Xuefei Yang, Mr. JiankunYang and Ms. Qiaohong Li from Kunming Institute of Botany, Chinese Academy of Sciences provide support forillustration of maps and literature study. My colleague, Mr. Dong Chen from ICRAF-China Program compileddata. This research is part of Mekong Program on Water Environment & Resilience. The editing and publicationwas supported by the Ford Foundation, Beijing Office. This paper was improved by professional editing fromGreta Rana.

Content

Abstract…………………………………………………………….........……………....................iAcknowledgement…………………………………………………………….........………….…..ii1.Introduction to the Highlands Of Asia...........................................................................................12.The ‘Asian water tower’ ...............................................................................................................4

The Concept of the ‘Asian Water Tower’...............................................................................................4Towards Integrated Water Tower Management......................................................................................5Regional River Basins..........................................................................................................................8Hydroclimatological Conditions.............................................................................................................8Water Storage in the Highlands ............................................................................................................10Glaciers, Snow, and Iice.....................................................................................................................10High Altitude Wetland..........................................................................................................................12

3.Challenges Of The Climate.........................................................................................................13Intensely Warming Highlands...............................................................................................................13Complex Responses............................................................................................................................13The Constraints of Limited Investigations.............................................................................................16Melting and Retreating Glaciers...........................................................................................................18Impacts on Water Resources...............................................................................................................19Water-induced Natural Hazards............................................................................................................20Impacts on the Natural Ecosystem......................................................................................................21

4. The Societal Challenge................................................................................................................22Land-use and Land-cover Change: the Impact on Water.........................................................................22Increasing Demand for Water and Pollution from Agriculture..................................................................23Competing Use of Water for Hydroelectricity.......................................................................................25

5. Asian Society at the Crossroads................................................................................................27Local Adaptation: the Social Capital......................................................................................................27Planting Trees, Caring for Water.........................................................................................................27Sharing Benefits and Rights.................................................................................................................30Emerging Regional Initiatives...............................................................................................................33

6. Conclusions.................................................................................................................................35Ten Critical Actions: Supporting Land-use Policies and Cooperation in River Basins Based onScientific Knowledge........................................................................................................................38References......................................................................................................................................41

The fourth assessment report of the Intergovernmen-tal Panel on Climate Change (IPCC) excludes the Hi-malayan region because of scientific uncertainty. Thegreater Himalayan region, or the highlands of Asia,called the ‘Third Pole of the World’, which include theinner and south Asian mountains, contain the most ex-tensive and rugged high altitude areas on Earth and themost extensive areas of glaciers and permafrost out-side high latitudes. The highlands occupy about one-fourth of Asia’s land surface, and although they pro-vide a home for less than a tenth of the Asian population,the region is the source of nine of the largest rivers inAsia, the basins of which are home to over 1.3 millionpeople (Xu et al. 2007). The highlands of Asia havebeen ignored in comparison to other natural ecosystems,even though history has shown that when ecologicalchange takes place in the highlands, changes soon fol-low in the valleys and in the lowland plains (Eckholm1975). The impacts of climate change are superimposedon a variety of other environmental and social stressesin mountain ecosystems, and many of them have beenrecognised as severe (Ives and Messerli 1989), caus-ing uncertainty (Thompson and Warburton 1985). The Tibetan Plateau, located at the heart of the high-lands of Asia, plays the role of an ‘Asian water tower’as it supplies water and regulates the climate in uplandand lowland areas of Asia adjacent to it. Geographicallyit covers the high altitude Qinghai-Tibetan Plateau aswell as the Pamir Plateau, Yun-Gui Plateau, and LoessPlateau and other mountain ranges connected to it. TheTibetan Plateau plays a critical role in the cryosphere,hydrosphere, biosphere, and anthrosphere in the conti-nent of Asia, and it also has an impact on the Asianmonsoon. Despite the diversity and complexity of themountains of Asia in terms of the land and peoples ofthree principal zones, viz., the highland Plateau, the up-land watersheds, and the lowland plains1 they presentquite a uniform set of ecological and economic

challenges. The upland watersheds include the moun-tains of central Asia, a narrow belt of the HimalayanMountains, montane mainland Southeast Asia, the Yun-Gui Plateau, and the Loess Plateau of China at eleva-tions of about 2000 masl. The lowland plains coverEast China, lowland mainland Southeast Asia, and a largepart of the Indian subcontinent below 1000 masl (seeMap 1). The total land area of the Tibetan Plateau, thelargest area of in the highlands, is around 2.5 millionsq.km., accounting for about 26% of China’s land mass.The total area of the Tibetan Plateau and its surround-ing provinces in west China is about 6.4 million sq.km., accounting for 69% of China’s land area, twothirds of the entire country, 56% of the runoff, and95% of the hydropower potential of China (Table 1). The highlands of Asia, the largest and most topo-graphically complex ecosystem in the world, play aunique role in global climate and climate changeprocesses. The highland climate is influenced by theAsian Monsoon, the Inner Asian high pressure system,and the winter westerlies. The Tibetan Plateau also hasan important impact on climate circulation in the regionand on the Asian monsoon. The area itself has severaldistinct climatic regions which are characterized byvariations in rainfall. The eastern edge of the TibetanPlateau is relatively humid, with rainfall of from 400-700 mm annually, the southern central area is semi-arid, and the western and northern parts of the TibetanPlateau are arid with rainfall of less than 100 mm peryear. Climate change is not new and can be catastrophicin the highlands since the climate is becoming muchwarmer than global average at increasing altitudes inthe mountain region. Climate change is driven by natural,anthropogenic, biogeochemical, and biogeophysicalprocesses. Human activities in the highlands and thesurrounding mountain regions play a key role in bio-geochemical cycling on earth through land-use prac-tices and land-use changes, both physical and

1. Introduction to the Highlands of Asia

1With an average altitude of 4000 masl, the high plateau extends from 3000masl and includes the whole of the Tibetan Plateau and mostparts of the Pamir Plateau

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Map 1: Tibetan Plateau, montane watersheds, and lowland plains of the Asian Continent

Table 1: Natural Resources of the West China (2005)

Source of data: China Statistical Yearbook 2006, National Bureau of Statistics of China

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socioeconomic. Land-use changes contribute directlyto local and regional climate change, as well as to glo-bal climate warming. In turn, changing biogeochemi-cal cycles strongly impact the human-environmentsystem. The highlands or the ‘Asian Water Towers’ are thesource of the nine largest rivers in Asia. The major riverbasins of the region – west to south, to east and tonorth– are the Indus, Ganges, Brahmaputra, Irrawaddy,Salween, Mekong, Yangtze, Yellow, and Tarim. Unlikethe polar regions, the highlands directly provide water-related environmental services to 1.3 billion peoplewithin nine river basins such as the east coastal area ofChina which is the Chinese economic engine, andmainland Southeast Asia, and South Asia, which to-gether have the largest population globally in terms ofsize and density. Environmental degradation and wide-spread poverty in the headwaters of the mountain re-gions have led them to being identified as areas of emerg-ing water crises as a result of climate change, rapideconomic growth, deteriorating ecosystems, and in-creasing demand for water. There is an increasing need

for integrated water resource management for humanlivelihoods, ecosystems, and economic development.One way forward is to move past realist frameworksof analysis and step forward to paradigms of ‘sharingbenefits, not just sharing water’, ‘sharing riskmanagement,’ and ‘sharing costs to support ecosys-tem services’ at local, national, and transnational level. This paper offers ideas in support of knowledge foraction and cooperation. The assumptions underlying itare as follows: all stakeholders in the ‘Asian Water Tow-ers’ witnessing changes in the mountain environment,relationships, economies, and in the climate. There mayhave been reasons for non-cooperation on some issuesin the past, but there are now reasons to move forwardand seek ways to cooperate considering the uncertaintyof changes in the climate and the environment. All thestakeholders in the ‘Asian Water Tower’ can benefitfrom joint development if the ‘Water Tower’ is main-tained and used carefully. There are many possibilitiesfor shared benefits from cooperation, water being one,but there are also benefits beyond water.

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2. The ‘Asian Water Tower’

Mountains contribute a runoff of up to 60% of the total(Bandyopadhyay et al. 1997). Viviroli and Weingartner(2002) have shown that there is a big difference be-tween the importance of mountain ranges in arid andsemi-arid environments and mountains in humid andsub-humid areas. In arid and semi-arid areas the im-portance of mountain water is much more pronouncedand it provides a lifeline for areas downstream (e.g.,the Indus and Tarim rivers). According to Viviroli andWeingartner (2002) mountains in general provide a) dis-proportionately large amounts of discharge thanks totheir high precipitation and low evaporation rates; b)seasonal retardation of discharge through the accumu-lation of snow and ice; c) highly reliable amounts ofrunoff thanks to the regularity of the melting processand the storage capacity of glaciers. Mountains pro-vide a precipitation barrier which leads to orographicrainfall, and the cool temperatures at high elevationsreduce evaporation rates. This often produces positivewater balances in the mountains, i.e. water inputs arehigher than water outputs and can therewith producerunoff. In the surrounding lowland areas, the inflowfrom rivers upstream is necessary to balance evapora-tion losses and produce an even water balance.

The Concept of the ‘Asian Water Tower’The criteria for the ‘Asian water tower’ are that it shouldbe able to provide water-related services in terms ofboth quality and quantity across space and time for thelarge population of the Asian continent. In order to un-derstand the concept of the highlands as Asian watertowers, we analyze the function, productivity, and pro-cesses of water flow in four broad ecological zonesthat constitute river basins.a)Highland ‘Water Towers’Highland ‘water towers’ refer to the highland plateauxand mountain ranges which cover a total area of 3,846, 131sq.km. at elevations above 3000 masl (Li, et al, 2007).Water is often stored as glaciers, ice, and snow tempo-rally and permanently. The area provides approximately

8.6 x 106 m3 of water annually. It has been estimatedthat about 30% of the water resources of the easternHimalayas are derived from the melting glaciers, snow,and ice: this proportion increases to nearly 50% in theIndus in the western Himalayas and becomes as highas 80% in the upper reaches of the Tarim Basin. Thecomplexity and intensity of high altitude wetlands, lakes,and river network systems enable them to hold waterfor fairly long periods of time. Melting glaciers, ice,and snow replenish freshwaters significantly in earlyspring and summer. Highlands are often a combinationof hilly and flat plateau areas covered with alpinevegetation, bush, and grassland, in many cases para-dises for wildlife. Highland people are either nomads oragropastoralists like the Tibetans who have little ac-cess to social services such as health care and markets.b) Upland WatershedsUpland watersheds refer to the middle areas of largeriver basins between 1000 and 3000 masl where wateris collected in small streams or sub-catchments thatmerge into larger ones and often flow into a reservoiror merge into major rivers. Upland watersheds are typi-cally hilly and mountainous, originally forested or cov-ered with perennial vegetation, and, in many cases. thelocation of protected areas or watershed conservationareas. People in upland watersheds, living in tribes orother minority groupings, are often shifting cultivatorsor composite swiddeners who practice a range of live-lihood activities such as swidden-fallow agriculture,home gardening, and collection of non-timber forestproducts, but they are often poor because they haveless assets than people living downstream.c) Lowland ‘Rice Bowls’Lowland rice bowls, most productive rice producersin the world, are located in areas downstream fromhighland water towers and upland watersheds and up-stream from coastal zones and exclude urban and peri-urban areas. They are often located at less than1000masl and have alluvial and productive soil whichrenders products, from rice to vegetables, from cut-

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ting flowers to fishes, that can be sold nationally orexported to other parts of the world. Lowland farmersengage in intensive agriculture, horticulture (orchards),and aquaculture. They have much better access to so-cial services such as markets, extension services, andinformation.d) Coastal Urban and Peri-urban AreasUrban and peri-urban areas refer to those parts of theriver basin in which population, land ,and water man-agement are strongly affected by large concentrationsof people. Asian mega-cities, lying at less than 300 masl,often have several million people if one includes theareas used for horticulture and animal husbandry sur-rounding them. Most of these cities are located in thecoastal areas in the lower reaches of basins. They arecompletely dependent for water for domestic consump-tion and economic development on the upstream wa-ter towers, watersheds, and water tables. Figure 1 is agraphical representation of the zones.

Towards Integrated Water Tower ManagementThe four broad ecological zones described above areinterconnected and therefore should not be consideredin isolation. The following are suggestions about inte-grated water tower management (IWTM).

More rainfall in highland areas is stored in the formof ice and snow by hours, days, months, years,and centuries than melts into high altitude wetlands,

Figure 1: Highland-upland-lowland linkages of Asian water towers (after Falkenmark 1999)

lakes, and rivers locally and downstream. Thequality of water is in good condition because oflow population density and, therefore, few humanactivities and also because of the alpine vegetationacts as a filter.Fresh water from melting glaciers, snow, and iceflows into the upland watershed zone though riversystems and underground water. Rainfall domi-nated by the Asian monsoon produces substantialsurface runoff and erosion. Water flow and qualityin the watershed are influenced by soil conditions,land use, and land cover.Movement of plant nutrients generally from high-land headwaters and upland watersheds to lowlandplains to urban areas (as food) and the ocean (aspollutants and sediment). Since there are no mecha-nisms to ensure recycling to the place of origin,this process contributes substantially to nutrientdepletion in marginal areas in watersheds, and onthe plains and to pollution in cities and peri-urbanareas.Landscapes in highland Asia are mosaics of forests,home gardens, wetlands, crop lands, and highpastures: a range of habitats for all life forms and adiversity of livelihoods and products, from dairyproducts in alpine areas to tea production in themid mountains, from mushrooms and apples in tem-perate zones to mango and rubber in the tropics,

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and from timber to non-timber forest products.Movement of food from alpine rangelands, uplandwatersheds and lowland rice bowls to urban areasis and important commercial activity in the region.Land-use decisions are also water decisions(Falkenmark et al. 1999). How land is used —whether it is dedicated to agriculture, forestry,rangelands, or urban areas; whether it is left barrenand open to soil erosion, or whether it is subject tointensive crop management — will have substan-tial impact on both water use and the availability ofwater downstream. Land cover, whether land ismanaged or not, will have a great impact on runoffand infiltration as well as water consumption bybiota. Land use and land cover, therefore, will in-fluence both ‘blue’ (water visible in lakes andrivers) and ‘green’ water (water used by plants).The agricultural sector is the largest consumer ofwater. About 70% of the water available in the low-land plains is used for irrigated agriculture. Thisusually competes with water needed to sustainecosystems and their services. A better understand-ing of the relationship of environmental flows andthe health of the ecosystem must be achieved.Food transactions may also affect water

consumption, if the use of water is more efficientat the site of export (often in wet and warmclimates) than at the major importing areas. Inter-connections through infrastructure: roads,channels, housing, dams, airports and recreationalfacilities can have positive effects by making keyinputs available and at reasonable prices (e.g.,fertilizer), by giving farmers different options forincreasing income hence relieving the pressure onland (e.g., high-value vegetables, off-season pro-duction and livestock products, even forest and treeproducts), and by facilitating more commuting andoff-farm activities.Over the centuries, people have used barter to ex-

change goods and services, maintaining genetic di-versity and food security within the parameters oftheir traditional cultures. Merchants from Yunnanin the eastern Himalayas travelled the Tibetanplateau, South-east Asia, and South Asia for a thou-sand years. Caravans served as market structuresand formed a sociocultural network among moun-tain and lowland communities. Mountains were asmuch pathways of migration and trade as barriersbetween highlands and lowlands.Movements of people, particularly the younggeneration, through permanent or temporary mi-gration from the uplands to the lowland is a grow-ing phenomenon as the rural poor seek new oppor-tunities and new ways of life in transition to a mar-ket economy and regionalization. By using resourcesfrom a large, non contiguous area to produce foodand the many other items they consume, they pro-duce a massive ‘ecological footprint’. Increasingly,however, it has been realized that new patterns ofinter-and intra-basin connections are needed whichalso ensure food security and ecosystem servicesprovided throughout the basin are protected.Human activities through land-use and land-coverchanges generate both ‘positive’ benefits (increasesin food and fibre production) and ‘negative’ costs(species’ extinction, soil erosion, land degradation,water pollution, and global warming). The pace,magnitude, and spatial reach of land-cover and land-use changes have increased over the past threecenturies, particularly over the last three decades,in Asia due to an increase in population and eco-nomic growth. Land use affects water resources,human health, and fauna and flora; contributes tolocal, regional, and global climate changes; and isthe primary source of soil, water, and landdegradation.

Table 2 summarises the structure, function, andsocioecological challenges of the Asian water tower.

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Tabl

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Regional River BasinsHighland glaciers, ice, and snow, which represent ma-jor natural reservoirs of frozen water, feed the wet-lands at high altitude and nine of Asia’s great rivers.The Yellow and Yangtze Rivers flow to the coastal ar-eas of China; the Mekong, Irrawaddy and Salween flowto Southeast Asia, and the Indus and Brahmaputra aremajor South Asian river systems. The water tower(natural reservoirs of frozen water and wetlands) servesas a buffer to local climate variation. It compensatesfor the deficit of rainfall and snowmelt during dry anddrought years and stores water from cloudy skies toreduce melting during wet years. Thus stream flowsand discharge are stabilized with recharged melting waterfrom upstream, which is crucial for local agricultureand livelihoods. Table 3 gives indicators of the impor-tance of water resources in the region. In particular, itshows that, in some river systems, glacial melt is animportant source of water for big populationsdownstream. In the long term, glaciers are predicted tomelt and disappear, with major consequences for theavailability of water in these river basins. Climate changewill also have other impacts on the interannual and sea-sonal flows of these rivers, so even where the totalavailability of water is not limited, climate change willcause other impacts such as floods and changes in theseasonality of water flows. For example, 49% of thetotal discharge of the Yellow River is from the TibetanPlateau, 25% of the discharge of the Yangtze River,and 10% of the discharge of the Mekong: water re-sources from the Tibetan Plateau account for 20.23%of China’s total availability of water with a productionof 22.55x104/km2 (Lu et al. 2004, An et al 2007). It isestimated that glacial melt is the principal source ofwater in the dry season for 23% of the population ofwestern China. Changes in glacial water flows will haveimpacts on the availability of water in this critical season.As a high-altitude area, the highlands have several othercryogenic features of importance for water resourcessuch as perennial ice and snow cover, snowfall, rainfall,evaporation, and permafrost. Thus the impacts of cli-mate change on the highlands will have major impactson water resources and on the ecology, human health,

and economic activities not only in the highlands butalso in the river basins dependant on water flows fromthe highlands. Four critical ecological zones directly benefit fromthe Asian water tower as well as from the great riverbasins and they are the a) east coastal areas of China;b) drylands of northwest China; c) mainland SoutheastAsia; and d) Himalayan areas of South Asia. The watertower and its river basins straddle some of the world’spoorest regions, densely populated human settlements,and rapidly growing economies, particularly China andIndia. Within these populations and communities, theimpacts of climate change are not evenly distributed, ineither intensity within the region or among differentsectors of society. The more fragile the ecosystem andthe poorer and more marginalised the people, the ear-lier and greater the impact. This is inevitable unlessconcerted and effective action is taken to engage andassist them to cope with the changes. Continuing climate change is predicted to lead to ma-jor changes in the strength and timing of the Asianmonsoon, inner Asian high pressure systems, and win-ter westerlies, the main systems affecting the highlandclimate. The impacts on river flows, natural hazards,and the ecosystem, as well as on people and theirlivelihoods, are likely to be dramatic, although not thesame in rate, intensity, or direction in all parts of theregion. Given the current state of knowledge, deter-mining the diversity of impacts is a challenge to re-searchers and risk assessment is needed to guide fu-ture actions.

Hydroclimatological ConditionsHydroclimatological conditions vary more sharply withelevation in the highlands and over shorter distancesthan they do with latitude and longitude. The averagetotal annual precipitation on the highland Tibetan Pla-teau is about 8,498x108m3, more than 80% concen-trated in elevations between 3500-5000masl (see table4). Mean temperatures, for example, decline about 1oCper 160m of elevation, compared with about 1oC per150 km by latitude (Hartman 1994). Precipitation in

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Table 3: Principal Rivers of Highland Asia – Basic Statistics

Source: adapted from Xu et al. (2007) based on IUCN/IWMI, 2002; Chalise and Khanal 2001; Merz 2004.

Table 4: Precipitation distribution with elevation on the highland Tibetan Plateau

Source: Lu et al. 2004

highland Asia shows an east-west and north-south varia-tion on the macroscale. The east-west variation is basedon the dominance of different weather systems. In thewestern Tibetan Plateau air masses connected to thewesterlies bring moisture during winter leading to a win-ter peak in rainfall. The eastern highland is influencedby the southwest monsoon with a dominant maximumduring summer. The maximum rainfall in the area andglobally is measured in Cherapunjee, northeast Indiawith annual maxima of more than 10,000mm. Themonsoon rainfall is mainly orographic in nature, whichcauses distinct variations in rainfall with elevation and

distinct differences between the southern rim and therain shadow areas of the Tibetan Plateau behind themain mountain range. Alford (1992) identified the lowerand intermediate altitudes as the main sources of pre-cipitation suggesting that there is an increasing trendwith altitude up to about 3500 m after which rainfallagain decreases. On the mesoscale, climatic effects aredriven mainly by local topographic characteristics suchas ridges, slopes, valleys, and plateaux (Chalise 2001).According to Domroes (1978) the valley bottoms ofthe deep inner valleys in the highlands receive muchless rainfall than the adjacent mountain slopes. This

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would suggest that the current rainfall measurements,which are based mainly on measurements in the valleybottom, are not representative for the area and majorunderestimations result from the use of these data. Theimpacts of climate change, therefore, are expected tointensify in mountain areas, and they are considered tobe unique areas for detection of climate change andrelated impacts (Beniston 2003), but with an uncer-tainty due to limited numbers and poorly representedgeographical locations. The broad predictions of globalclimate change, especially the emphasis on shifts inmean temperature, do not take into account importantregional complexities related to the effects of topogra-phy and elevation in the mountains. If climate changemainly involves vertical shifts in precipitation and ther-mal conditions, ruggedness, elevation, and orientationwill also modify the significance of regional climatechanges. The highest mountains, or those facing orfunnelling the prevailing winds, may retain a substantial,if diminished, glacial cover, whereas lower watershedsor those less favourably oriented may lose theirs.

Water Storage in the HighlandsSeventy per cent of the world’s fresh water is frozenin glaciers. Highland Asia has the largest concentration

of glaciers outside the polar caps. Several of the largestconcentrations of glaciers are found at middle and lowlatitudes, covering a total area of 112,767 sq.km. (Xuet al 2007). Mountains and plateaux often have greaterprecipitation and water storage capacity in terms ofglaciers, ice, and snow as well as large proportions oflakes and wetlands. Mountains provide a proportion of20-50% of total discharge in the humid areas, while inarid areas, the contribution of the mountains, particu-larly from melting glaciers, to total discharge amountsto from 50-90% with extremes of over 95% (Viriroliand Weingartner 2002). Melting glaciers provide 40.2% the river flow in the Tarim Basin, up to 50-80% inthe upstream catchment (Yan et al. 2007, Chen et al.2003) (see map 2). The highly glaciated Tarim Basinsupplies about 137.7x108m3 of fresh water from melt-ing glaciers to areas downstream each summer (Yao etal. 2004). The discharge from highland Asia is an ex-tremely reliable water resource and causes a signifi-cant reduction in the variability of total discharge.

Glaciers, Snow, and IceIn the highlands, a substantial proportion of the annualprecipitation falls as snow. Snowfall builds up fromyear to year to form glaciers that provide long-term

Map 2: Melting glaciers provide vital fresh water for people and ecosystems along the Tarim River in Xinjiang, the most arid basin inAsia (Illustrated by Yang Jiankun)

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reservoirs of water stored as ice and function as regu-lators for stream and river runoff from mountainwatersheds. Most commonly glaciers are thought todelay runoff by preventing precipitation from runningoff directly. Such storage occurs on a sub-seasonaland sub-daily basis and involves both factors associ-ated with snow accumulation and melt on the glacierand the water-storing capacity and characteristics ofthe glacier (Jansson et al. 2003). Storage and release ofwater from glaciers are important for ecosystems, foodproduction, and industrial development (e.g.,hydroelectricity) irrigation; flood forecasting, sea-levelfluctuations, glacial dynamics, sediment transport, andformation of landforms. The Asian highlands have alarge concentration of glaciers with coverage of 112,

767 sq. km. (Dyurgerov and Meier 2005, Xu et al.2007), with wetland coverage of 107,948 sq. km. (Liet al. 2007). China’s glaciers cover a total area of 59,406 sq.km., the fourth largest coverage in the worldafter Canada, Russia and United States; of them, 48%are located within the Tibetan Autonomous Region(TAR), including 21% of China’s total glacier locatedinside of upper Brahmaputra River Basin, Tarim Basinin Xinjiang has 33.5% of total China’s glacier (Wangand Liu, 2001). It has a total water storage capacity of559 billion cubic km., which provides an average of56.3 billion cubic km. of fresh water from melting gla-cial waters (glacial melt) annually. The annual amountof fresh water from melting glacial waters from theTibetan Autonomous Region (TAR) accounts for 60%of the total for China (Yao et al, 2004, Shi, 2001).

Figure 2: Glacial water storage (after Jansson et al. 2003)

Climate controls river flow and glacial mass balancein the Asian water tower, and these vary considerablyfrom west to east. The monsoon from the Bay of Bengal,further developed in the Indian subcontinent, producesheavy precipitation; and this is predominantly in thesoutheast of the Tibetan Plateau. The monsoon weak-ens from east to west of the highlands, penetrating north-wards along the Brahmaputra River into the southeastTibetan Plateau, rarely penetrating as far as theKarakoram (Hofer and Messerli 2006, Rees and Collins2006). Water from both permanent snow and ice andseasonal snow packs is released by melting, giving adistinct seasonal rhythm to annual stream flow regimes.Glaciers undergo winter accumulation and summer ab-lation in the west, but predominantly synchronous sum-mer accumulation and summer melt in the east. Themain melting occurs in high summer but, when this

coincides with the monsoon, it may not be as criticalfor water supply as when the melting occurs in theshoulder seasons: spring and autumn. When the mon-soon is weak, delayed, or fails, melt water from snowand ice may limit or avert catastrophic drought. The contribution of snow and glacial melt to the ma-jor rivers in the region ranges from less than 5 to morethan 45% of the average flow (see table 1). The riversof Nepal that originate in the highland Tibetan Plateaucontribute about 40% of the average annual flow of theGanges Basin. More importantly, they contribute about71% of the flow in the dry season (Alford 1992). Melt-ing snow and ice contribute about 70% of the summerflow of the main Ganges, Indus, and Kabul rivers inthe ‘shoulder seasons’ before and after precipitationfrom the summer monsoon (Kattelmann 1987, Singhand Bengtsson 2004, Barnett et al. 2005). The contri-

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bution to inner Asian rivers, such as the Tarim, is evengreater, more than 40%. The Indus Irrigation Schemein Pakistan depends on approximately 50% of its run-off originating from snowmelt and glacial melt fromthe eastern Hindu Kush, Karakoram, and westernHimalayas (Winiger et al. 2005). Glacial melt providesthe principal water source in dry season for 23% ofthe population living in western China (Gao and Shi1992). The contribution to the Mekong and Salween isless than 10% in the eastern highland region, the mon-soon predominant sub-tropics, and the tropics.

High Altitude WetlandHighland Asia has a wide variety and coverage ofwetlands; and these include peat lands, lakes, and riversystems. They are an important feature of the Asianwater tower and provide water resources, maintain hy-drological cycles, and serve as carbon sinks. RuoergainPeatland, situated at the headwaters of Yellow, Yangtzeand Mekong, is the largest peat land in China and storesseveral billion metric tons of carbon. Little effort hasbeen made, however, to understand wetland ecologicaldynamics and their hydrological processes and carboncycling locally and regionally. Melting glaciers increasewater levels and expand the wetland in the short term,and eventually cause the loss of wetlands and smalllakes in the long term. The water level of Qinghai Lake

has decreased at the rate of 0.769 metres per decadeduring the last 42 years (1961-2002). Some small lakeswill eventually disappear as a result of high rates ofevaporation and a decrease in rainfall, particularly onthe western Tibetan Plateau. There is increasing globaland regional concern about the vulnerability of high al-titude wetlands to climate change and human activities.There are not only many examples of wetlands disap-pearing and decreasing water levels, but also there areexamples of wetlands evolving and expanding whichhave brought significant changes to hydrological pro-cesses such as buffers for floods, groundwaterrecharge, and river flow. High-altitude wetlands have,therefore, become important elements in conservationand water management at national, regional, and inter-national levels with good examples of Himalayaninitiatives. According to a Chinese government inven-tory of high-altitude wetlands in China, there is a totalarea of 92,466 sq.km. of wetland at altitudes above3000 masl, and these are found mostly in the TibetanAutonomous Region, Qinghai, Xinjiang, Gansu,Sichuan, and Yunnan (table 5). The high-altitude lakes,situated mainly between 4000-5000 masl, cover a totalarea of 38,727 sq.km. and have a storage capacity of5,460108m3, accounting for 73% of the total for China(Lu et al. 2004).

Table 5: High-altitude Wetland in China (over 3000 masl)

Source: Ramsar Convention Implementing Office State Forestry Administration, China, 2005

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3. Challenges of the Climate

The anticipated climate change is likely to alter precipi-tation patterns, glacial storage, and river runoff withrespect to timing, volume, and variability from high-land plateaux and upland watersheds, therefore it willinfluence runoff characteristics in the lowland plainsas well (see figure 3). As important as global climatechange seems to be, the increase in population andbooming economy, in important lowland areas ordownstream, will exert heavy pressure on the highlandor upstream river basins for land, water, and otherresources. These pressures will foster the construc-tion of dams for irrigation and hydropower generationand conversion of land for cash crop plantation, whichin turn will have an impact on the availability of waterin the lowlands with the potential to raise political ten-sions between the highlands and lowlands. Highlandpopulations are also likely to intensify land use whichwill need more water and lead to soil erosion and waterdegradation. The possible consequences will occur bothat local and regional levels in the transition to economicglobalization and in the context of climate change. Howto manage the Asian water tower, therefore, is a re-gional challenge for Asia.

Intensely Warming HighlandsIn the highlands, climatic conditions vary more sharplywith elevation and over shorter distances than they dowith latitude. Mean temperatures, for example, declineabout 1oC per 160m of elevation, compared with about1oC per 150 km by latitude (Hartman 1994). The ef-fects of climate change, therefore, are expected to in-tensify at high elevations, and they are considered to beunique areas for detection of climate change and re-lated impacts (Beniston 2003). The global average tem-perature increased by 0.74 °C (0.07 °C per decade) inthe last 100 years (1906 to 2005). Warming over thelast 50 years was almost twice (0.13 °C per decade)that for the last 100 years. Warming in the high plateauhas been much higher than the global average warmingrates, and warming of 0.25°C per decade took placebetween 1961 and 1990 (table 6), suggesting that the

Figure 3: The climate can change in terms of both average andvariability which will alter precipitation patterns and glacialstorage and river runoff from mountain watersheds with respectto timing, volume, and variability.

elevated land masses of the Asian water tower are ex-tremely sensitive to climate change.Extreme events and fluctuation in precipitation-Another feature of climate change is the increasing fre-quency and magnitude of extreme weather events suchas intense rainfall, typhoons, and droughts, which havesubstantial impacts on local economies and human lives.There is also increasing unevenness of rainfall distribu-tion in space; in most cases wet areas have becomewetter and dry zones have become drier (see figure 4).

Complex ResponsesThe broad predictions of global climate change, espe-cially the emphasis on shifts in mean temperature, donot take into account important regional complexitieson the mountain plateaux which are related to the influ-

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ence of topography and elevation. If climate changemainly involves vertical shifts in precipitation and ther-mal conditions, ruggedness, elevation, and orientationalso will modify the significance of regional and localclimate changes. The highest mountains, or those fac-ing or funnelling the prevailing winds, may retainsubstantial, if diminished, glacial cover, whereas loweror less favourably oriented watersheds may lose theirs.Furthermore, intensification of the Asian monsoon ispredicted by most climate models. On a regional scalethis could result in an increase in precipitation, althoughlocal effects are poorly understood. Moreover, climatechange means not only warmer temperatures, but alsochanges in precipitation, evapotranspiration, soil and

air moisture, runoff, and river flow as well as ground-water through water cycles. Climate change is expectedto accelerate water cycles and thereby increase theavailable, renewable freshwater resources (Oki andKanae 2006). Temperature changes have a predomi-nantly regional character, whereas precipitation changesare more locally determined and very difficult to analyseand to predict, especially in mountain areas and riverbasins (Jian et al. 2006). Complexities arise, especially from interactions amongdifferent cold climate elements – freeze-thaw and peri-glacial processes, snowfall, valley wind systems,avalanches, glacial processes, and seasonal or spatialbalance between frozen and liquid precipitation, albedo,

Table 6: Average annual increase in temperature at different altitudes for the plateau andsurrounding areas 1961-1990 (00000C/decade)

Source:Liu and Hou, 1998

Figure 4: Precipitation trend from 1961-2004 on the Tibetan Plateau of China

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and evaporation. Not only are they likely to change withgeneral climate shifts, but also interactions among themcan buffer, exaggerate, or redirect the impacts of changein any one element. The most rapid and varied interac-tions occur through the ‘vertical cascade’ between dif-ferent topoclimates – zones stacked vertically and onslopes of differing orientation – notably transport ofmoisture, runoff, sediment, and dissolved solidsdownslope. The occurrence and impacts of majorhazards, such as avalanches, debris flows, landslides,and flash floods, also have a bearing on downslope,down-glacier, and downstream cascades. Whereassnow avalanches and glacial lake outburst floods(GLOFs) predominate at very high elevations (>3000m), landslides, debris flows, and landslide damoutburst floods (LDOFs or ‘bishyari’) are more com-mon in the middle mountains (1000-3000m). Riverinefloods are the principal hazards in the lower valleys andplains. The causes of these floods are related to cli-matic conditions (Chalise and Khanal 2001, Dixit 2003,Xu and Rana 2005). Equally critical are issues related to the structure,processes, and resilience of ecosystems or biosphereand human adaptations to them; bearing in mind thatecosystems and humans are possibly already stressedby adaptation to topoclimatic diversity. Global warm-ing is predicted to affect vegetation productivity as wellas decomposition (Cornelissen et al, 2007). Dramaticincrease of woody plant biomass occurs in response towarming of highland cold biomes. Increased produc-tivity will probably increase litter production, acceler-ated rate of litter decomposition due to warmer high-land will feedback to climate through carbon cycle.Therefore climate change may turn the highland coldbiomes, including living vegetation, plant litter and storedpeat land, from large carbon sinks into sources. Re-cent study (Cornelissen et al, 2007) the feedback ofdecomposition to climate warming is complex by botha positive and a negative response. The positive feed-back will result from direct temperature effects on de-composition rate, warming will increase the leaf littercarbon released into the atmosphere. There is also,however, a negative feedback that results from thewarming-induced woody vegetation shift to higher

altitude, which shows slower decomposing shrub leaflitter; this reduces the amount of carbon release to theatmosphere, and nutrients released in the soil to sup-port plant production.In general, local impacts of theclimate do not follow single or simple paths, whetherin terms of plant ecology, stream hydrology, erosionand sedimentation, extreme events, or human activities. Much of the cryosphere is sensitive to sustainedchanges in atmospheric temperature. Already many Hi-malayan glaciers are shrinking, some extremely rapidlyin the global context. The widespread consensus is thatclimate change is the main factor in this. Apparently,conversely, in the high Karakoram-Himalayas, the rateof loss of ice cover has been declining in the last half ofthe twentieth century, and evidence is emerging thatsome glaciers are expanding; but this is also due tochanging climatic patterns and unexpected regional con-sequences of ‘warming’ (Archer and Fowler 2004,Hewitt 2005). In the Tien Shan, predominantly sum-mer-fed, continental-type glaciers are situated within100km of predominantly winter-fed, more maritimeones. Although most glaciers in both classes areshrinking, there are significant differences in the ratesand forms of response to warming (Bolch 2006). Al-though studies show marked variations in the local im-pacts of climate change, such as orographic precipita-tion in different valleys and at different elevations withinthe same mountain range, most of the region remainsunstudied in terms of a baseline for assessment or pre-diction of these complexities. Figure 5 illustrates the linkage between atmosphereand other systems such as the cryosphere, hydrosphere,biosphere, and anthrosphere. The change in atmosphere,which is largely driven by human activities in thebiogeophysical environment, has direct impacts on thecryosphere at high altitude and both directly and indi-rectly impacts the biosphere and human society throughhydrological processes in mountain ecosystems. Suchimpacts are manifested by glacial retreat and meltingpermafrost, increasing natural hazards, change in streamand river flows, and biological responses such as shiftof vegetation, migration of species, and phenelogicalchange. The downstream impacts will include rises insea level due to large glaciers melting in the polar re-

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gion and medium and small glaciers melting in moun-tain regions such as the Tibetan Plateau. Human healthin marginal mountain ecosystems will deteriorate as aresult of climate change and its related environmentalimpacts. The consequence, rate, and magnitude of impactsvary in different zones. Key impacts of climate-inducedchanges in the highlands of Asia include vegetation shift,frequent wildfires, changes in freshwater supplies, andproblems to human health caused by environmentaldysfunction. Table 7 depicts the potential impacts ofclimate changes on water resources, agriculture,biodiversity, and human health in different critical zonesfrom the highlands to the uplands, from the lowland tocoastal and urban areas. The general circulation model(GCM) shows that the highlands have experienced adecrease in freshwater runoff in most arid and semi-arid drylands and an increase in the eastern Himalayas;an increase in wildfire frequency and increase in havebeen experienced in most highlands of Asia (Sholze etal. 2006). Furthermore, increasing human activities inthe highlands through land-use and land-cover change,infrastructural development, and tourism have exacer-bated the vicious cycle of climate change.

The Constraints of Limited InvestigationsThe relationship between climate change and thecryosphere on the Tibetan Plateau is not sufficiently

Figure 5: Climate Change and Cascade Amplification of Impacts on in Highland Asia

understood to drive detailed policy responses, eventhough such a relationship has been confirmed by sci-entists in general and farmers and herders over wide-spread areas have been experiencing warmer wintersand longer growing seasons. While in-depth studies ofglaciers, snow packs, and permafrost have been car-ried out in some areas, they have been scattered widelyin space and time. No detailed investigations of snowand ice processes or their relevance to the climate havetaken place in most areas of the Himalayas and otherhigh ranges. For most areas, there are no baselinestudies, particularly for areas higher than 3000 masl,and there has been little long-term monitoring of theinterconnections between climatic variables, perennialsnow and ice, runoff, and hydrology in the context ofthe extraordinary heterogeneity of mountain topogra-phy (Liu and Chen 2000, Rees and Collins 2006, Messerliet al. 2004). Most models and predictions for high-altitude areas (above 3000 masl) are dependent uponextrapolation from climate and stream-gauging stationsat comparatively low altitudes and upon assumptionsbased on other, better studied, parts of the world (Reesand Collins 2004). The importance of the most wide-spread cryogenic processes – avalanches, debris flows,rock glaciers, alpine permafrost, and surging glaciers –has been recognised and their incidence recorded forcertain areas; and yet almost no basic scientific inves-tigations of these cryogenic processes have taken place

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Tabl

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ossib

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pact

s fro

m C

limat

e Cha

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n A

sian

Soci

ety

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Figure 6: Theoretical model of the increase in river dischargefirst, followed by a decrease afterwards while the glacier retreats

in the region, although they involve significant hazards,the patterns and intensities of which will be affected byclimate fluctuations that may increase or decrease riskin given areas. Thus, the immense diversity within the region shouldbe recognised: diversity of climates and topoclimates,hydrology and ecology, and, above all, of human cul-tures and activities. Before effective responses can bemade, much work has to be carried out to identify andpredict the possible impacts of climate change filteredthrough such diverse contexts. In particular, there hasbeen little engagement with local populations so far tolearn from their knowledge and experience in adaptingto unique and changeable environments and to addresstheir concerns and needs (Xu and Rana 2005).

Melting and Retreating GlaciersMany Himalayan glaciers are retreating faster than theworld average (Dyurgerov and Meier 2005) and thin-ning at the rate of 0.3-1 m/year. For example, the rateof retreat for the Gangotri Glacier over the last threedecades has been more than three times the rate duringthe preceding 200 years (Xu et al. 2007). Most glaciersstudied in Nepal are undergoing rapid deglaciation: thereported rate of glacial retreat ranges from several

metres to 20 m/year ( Fujita et al. 2001, Fujita et al.1997, Kadota et al. 1997). In the past half century, 82.2% of glaciers in west China have retreated (Liu et al.2006). While temperature increases, in the earlier stagesthinning prevails and meltwater increases, whereas inthe latter stages, the glacier shrinks, meltwaterdecreases, and some glaciers will disappear. There arewide disparities in the sensitivity and response of gla-ciers to climate warming, depending on the size andtype of glacier. Large glaciers finally attain a new gla-cial mass balance at lower levels (see figure 6). Different types of glaciers have different responsepatterns to increasing temperatures. Glaciers in Chinacan be categorized into 3 types; i.e., the maritime(temperate), sub-continental (sub-polar), and extremecontinental (polar) type; and they cover 22, 46, and32% of the total existing glacial area (59,406 km2)respectively. Since the Maxima of the Little Ice Age(the 17th century), air temperature has risen at a rate of 1.3°C on average and the glacial area decrease corre-sponds to 20% of the present total glacial area in west-ern China (Shi and Liu 2000). Shi and Liu (2000) fur-ther predict shrinkage of 12, 28, and 45% by the 2030s,2070s, and 2100s respectively (see table 8).

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Table 8: Estimated glacial retreat trend in the Tibetan Plateau in the 21st century

Source: Shi and Liu 2000

Impacts on Water ResourcesClimate change presents very serious risks to freshwa-ter resources. The rise in temperature has been muchfaster than the global average in the highlands. Besidesglacial retreat, impacts of climate change include dis-appearance of small wetlands; and this includes lakeswhich are part of the Asian water tower. Glacial meltprovides freshwater, vital for the ecosystem and society,particularly in arid areas of west China and during criti-cal periods from the dry season to monsoon. The sup-ply of freshwater, or meltwater from snow and ice, inlarge river basins is projected to increase over the fol-lowing decades as perennial snow and ice decrease.Later, however, most scenarios suggest a decrease,even of catastrophic proportions, by the 2050s. Cli-mate change may result in increasing temperatures,decreasing snow packs, and earlier snowmelt, and thatwill certainly reduce the flow of water in the riversoriginating from the highlands, particularly in the dryseason. Wang et al (2006) concludes the connectionsbetween decreasing water discharge and global El Niño/Southern Oscillation (ENSO) events in Yellow River ofChina. Shi (2001) predicts that small glaciers (less than2km2) will be more sensitive to climate warming, melt-water will reach its peak value at present, and will de-

crease or even disappear by 2050. Medium-sized gla-ciers of 5-30 km2 will reach their meltwater peak valueby 2050. The larger glaciers (areas exceeding 100 km2)will retreat slowly. Glacial meltwater accounts, atpresent, for 50~80% of the discharge from the Yarkant,Yurunkax, and Aksu rivers and upstream of the Tarim(42% in the Tarim). It is predicted that glacial meltwa-ter will continue to increase before 2050, the increasedvolume may be 25~50% more than that at the begin-ning of this century (Yan et al. 2007). In the short run,animal husbandry and agriculture could benefit fromrises in temperature rise and increases in meltwater dis-charge if good water management practices and properirrigation facilities are introduced, particularly in dry-land and arid areas. Effective and efficient water man-agement technology has still to be introduced and insti-tutionalized in order to cope with long-term decreasesin water supplies. In the eastern Himalayas, however,or the southeastern Tibetan Plateau where there is heavyprecipitation and the temperature of the ice is higherthan in other areas, the temperature rise will acceleratethe ablation and retreat of glaciers, perhaps causing fre-quent flood and debris flow disasters in fragile moun-tain watersheds.

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Water-induced Natural HazardsShifts in rainfall patterns and increase in extreme weatherevents, floods, and droughts: natural hazards are omni-present in highland Asia due to its unique lithosphereand the interaction of the monsoon climate and moun-tain environment. Natural hazards include flash and riv-erine floods, droughts, landslides and debris flows, snowavalanches, and even wildfires when there is insuffi-cient rainfall. Wide fluctuations in the melting of snowand ice can result in excessive or insufficient watersupplies: heavy snowfalls can block roads or overloadstructures. Snowfall on steep slopes and associated con-ditions give rise to avalanches: advancing or retreatingglaciers can interfere with communications or causedangerous impoundments. The action of frost and melt-ing of permafrost pose ecological and technologicaldangers. The most destructive hazards, and those thatcan have impacts far beyond their mountain sources,tend to be the direct consequences of changes in thecryosphere. They include ponding of water by oraround glaciers and subsequent glacial lake outburstfloods (GLOFs), and can involve much more waterthan the amount generated by climatic events alone.Fluctuations in glaciers, especially retreat and thinning,destabilise surrounding slopes, and may give rise tocatastrophic landslides (Ballantyne and Benn 1994,Dadson and Church 2005) damming streams and some-times leading to outbreak floods. Excessive melting oftenin combination with heavy rains may trigger flash floodsor debris flows. In the Karakoram, there is growingevidence that catastrophic rockslides have a substan-tial influence on glaciers and may have triggered glacialsurges (Hewitt 2005). Glacial surges are a particularhazard in the Karakoram and Pamir mountains. Severecold and high winds threaten wild life, domestic animals,and humans. Complexities arise, especially from interactionsamong different elements of the cold climate – freeze-thaw and peri-glacial processes, snowfall, valley windsystems, avalanches, glacial processes, and seasonalor spatial balances between frozen and liquidprecipitation. Not only are they likely to change withgeneral climate shifts, but also interactions among them

can buffer, exaggerate, or redirect the impacts of changein any one element. The most rapid and varied interac-tions occur through the ‘vertical cascade’ between dif-ferent topoclimates – zones stacked vertically and onslopes of differing orientation – notably transport ofmoisture, runoff, sediment, and dissolved solidsdownslope. The occurrence and impacts of majorhazards, such as avalanches, debris flows, landslides,and flash floods, also have a bearing, as mentionedpreviously, on downslope, down-glacier, and down-stream cascades. Whereas snow avalanches and gla-cial lake outburst floods (GLOFs) predominate at veryhigh elevations (>3000masl), landslides, debris flows,and landslide dam outburst floods (LDOFs or ‘bishyari’)are more common in the middle mountains (300-3000masl). Riverine floods are the principal hazards inthe lower valleys and lowland plains. The causes ofthese floods are related to climatic conditions (Chaliseand Khanal 2001, Dixit 2003, Xu and Rana 2005). Inthe eastern and central Himalayas, glacial melt associ-ated with climate change has led to the formation ofglacial lakes in open areas behind exposed end moraines,causing great concern. Many of these high-altitude lakesare potentially dangerous. The moraine dams are com-paratively weak and can breach suddenly, leading tothe sudden discharge of huge volumes of water anddebris. The resulting GLOFs can cause catastrophicflooding downstream, with serious damage to life,property, forests, farms, and infrastructure. Twenty-five GLOFs have been recorded in the last 70 years inNepal, including five in the sixties and four in the eight-ies (Mool 2001, NEA 2004, Yamada 1998). HighlandAsia has a history of disasters triggered by some or allof the cryogenic processes discussed. The main pointis that climate change can alter their frequencies,distribution, mix, and magnitudes – both favourably andadversely. Because of limited investigation into theseprocesses and their relationships to climate, our under-standing of how climate change will affect them (andin different sub-regions) is also limited. We, thus, needto be cautious about making predictions, especiallyalarmist ones, while emphasising that there is cause forconcern.

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Impacts on the Natural EcosystemClimate change may affect the natural ecosystem orbiosphere in a variety of ways, from species’ compo-sition to vegetation distribution, from carbon and nutri-ent cycling to water evapotranspiration, and from pol-lination to phenology. There are widespread reports byTibetan nomads that spring is coming more than a weekearlier than expected and grazing seasons are longerthan usual. The possibility of alterations in overall albedo,water balance, and surface energy balance on alpinegrasslands with increasing degradation and desertifica-tion in the arid areas is causing concern. Signs of theeffects of climate change on the grasslands have beendocumented from the northeast Tibetan Plateau whereexperimental warming caused a 26~36% decrease inspecies richness (Klein et al, 2004), and Kobresia sedgeand alpine turf communities are changing to semi-aridalpine steppe, known in Chinese as ‘black bleaching’ inaddition to overgrazing (Ma and Wang 1999, Miller2000). Qinghai Province in China alone has approxi-mately 20,000 sq.km. of degraded rangeland. Upwardmovements of the tree line and encroachment of woodyvegetation on to alpine meadows are reported widely.In the eastern Himalayas, the tree line is rising at a rateof 5-10 m per decade (Moseley 2006). Although it isdifficult to attribute this to climate change alone as hu-man activities could also be a factor, rapid changes inalpine communities (both structure and species’composition) are expected as the climate changes. Astemperatures rise and glaciers retreat, species shift theirranges to follow their principal habitats and climaticoptima. The ability of species to respond to a changingclimate varies, however. Shifts in species’ ranges dur-ing past major global climate changes indicate that allspecies have climatic limitations beyond which theycannot survive. There is significant uncertainty about the effects of

global warming on vegetation and animal productivityin large dryland ecosystems. Although high altitudedrylands might enjoy increases in net primary produc-tivity (NPP) locally, the greatest confidence is in pre-dicting implications for production of vegetation, withlesser confidence in implications for vegetationcomposition, animal production, and options for adap-tation (Campbell and Stafford Smith 2000). Satelliteobservations suggest that some rangelands might besuffering from processes of degradation due to warmer,windier, and drier trends (Dirnbock et al. 2003). De-graded rangeland already accounts for over 40% ofdryland on the Tibetan Plateau (Zhong et al. 2003,Gaoet al. 2005); and it is expanding at a rate of 3 to 5%each year (Ma and Wang 1999). The culprits are cli-mate warming and overgrazing, as well as the mutualinfluence of human activities and climate change. In-crease in evaporation, reduction in snow cover, andfluctuations in precipitation are key factors contribut-ing to the degradation of dryland ecosystems. In addition,degradation of grassland by overgrazing could increasethe evapotranspiration level, thereby promoting climatewarming and the degradation process (Du et al. 2004). Impacts of climate change on montane forest eco-systems include shifts in forest boundaries by latitudeand the movement of tree lines to higher elevations;changes in species’ composition and vegetation types;and an increase in net primary productivity (NPP)(Ramakrishna et al. 2003). In the eastern Himalayas,forest vegetation will expand significantly; forest pro-ductivity will increase from 1-10%; and it is expectedthat forest fires and pests such as the North Americanpinewood nematode (Bursaphelenchus xylophilus) willincrease as dryness and warmth increase (Rebetez andDobbertin 2004). The overall impact of climate changeon the forest ecosystems can be negative (Siddiqui etal. 1999).

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4.The Societal Challenge

Land-use and Land-Cover Change: the Impacton WaterOver 80% of the population in the Asian mountain re-gion depend either on full- or part- time farming fortheir livelihoods (Thulachan 2001). With population in-creases and economic growth, more and more peoplesearch for land for subsistence production and incomegeneration. The pace, magnitude, and spatial reach ofland-cover and land-use changes in the Asian Conti-nent have increased over the last half century as a re-sult of land reclamation, for example, for rubber plan-tation in Yunnan previously and in northern Laos atpresent, the Green Revolution in India, and fibre pro-duction (e.g., cotton in Xinjiang). Deforestation oc-curred mainly during the ‘Great Leap Forward’ in 1958and forest tenure transition in the early 1980s in westChina, in the large tropical forests of Myanmar, and inmainland Southeast Asia in past decades. Large forestareas have been converted into croplands, particularlyin Ganges, Yangtze, Mekong, Indus, Brahmaputra andYellow river basins (see table 9). Degradation of grassland (e.g., changes in quality andclass of grasslands and desertification) on the TibetanPlateau is attributed to overgrazing. Official statisticsreport that livestock numbers on the plateau are nowthree times higher than in the 1950s. Overgrazing hasadverse impacts on vegetation, on soil system properties,as well as on green water storage in the ecosystem. The

relative contributions of climate change and overgrazingto degradation are hard to quantify. Some studies report,however, that recent grassland management policies –which have encouraged growth in herd sizes and re-duced mobility in grazing systems - have contributed tooverstocking and overgrazing. Paths and rates of land-use change are often driven by the local political economy,mostly by state policies and the market economy. Land-use and land-cover changes affect fauna and flora; con-tribute to local, regional, and global climate changes; andare the primary source of soil, water, and land degrada-tion (Pielke 2005, Sthiannopkao et al. 2007). Land-usedecisions, thus, are also water decisions (Falkenmark1999). Altering ecosystem services from the Asian wa-ter tower—i.e., the provisions people obtain from eco-systems (e.g., food and water), regulating services (e.g., predator-prey relationships and flood and diseasecontrol), cultural services (e.g., spiritual and recreationalbenefits), and support services (e.g., pollination, nutri-ent cycling, and productivity)—that maintain the condi-tions for life on Earth affects the ability of biologicalsystems to support human needs in Asia. While climatewarming reduces the storage of fresh water in glaciers,land use and land cover have contributed greatly to wet-land loss in west China. China has lost 127 cubic km ofwater storage capacity as a result of wetland loss in thewestern plateau in the past 50 years (Wang et al, 2006a)(see table 10).

Table 9: Land-use or -cover in 8 Key River Basins

Source: IUCN, IWMI, Ramsar Convention Bureau and WRI 2002

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Table 10: Loss of glaciers and wetlands in the Chinese highlands

Source: Wang et al. 2006a

Besides climate factors, the quality and flow of wa-ter resources are determined by the management ofland resources. Two types of land-use activities thathave a fundamental impact on livelihoods and, thus, onthe issues outlined above will be addressed: a) land usedependent on drainage and flood protection, or, forexample, dependent on limitations imposed by wateron societal and biomass production. This type of landuse is called ‘water-dependent’ land use. The secondtype, b) land use which has an impact on rainwaterpartitioning through soil and vegetation or impacts re-lated to the function of water as a carrier of solutes andsilt in the landscape. This type of land use is called‘water-impacting’ land use. Managing land-use prac-tices is inextricably linked with water resources. Landuse/cover is intrinsically linked with the hydrologicalcycle and changes in land use and their impacts on thehydrological cycle have been studied in depth fordecades. The best results are obtained by managingboth land and water resources simultaneously within alandscape framework or at river basin level. Good land-use practices can contribute significantly to a) hydro-logical benefits - controlling the timing and volume ofwater flows and the quality of water; b) reducing sedi-mentation - avoiding damage to downstream reservoirsand waterways and hence their uses (hydroelectricpower generation, irrigation, recreation, fisheries, do-mestic water supplies) arising from sedimentation; andc) disaster risk reduction – controlling and preventingdebris flow and landslides. FAO (2002) concluded thatland-use impacts on hydrological parameters and sedi-ment transport are inversely related to the spatial scaleon which the impacts can be observed. In contrast,

impacts of land-use changes on water quality param-eters may be relevant on the meso- and macroscales. Itis important to note that the impact of these land-useand -cover changes are variable in terms of time scale.While the quality of water in rivers and lakes can berestored in quite short time, the biodiversity destroyedwill take several thousands of years to recover to itsoriginal condition. Any planting of trees or currentchanges in land use and cover that involve the naturalgrowth of flora or the natural multiplication of faunatake time and are an investment in the future. The posi-tive benefits of any intervention of this kind will onlybecome effective in years to come. If rapid impactsare required, other means need to be envisaged.

Increasing Demand for Water and Pollutionfrom AgricultureAll countries within continent of Asia have economieswhich are based on agriculture which depends heavilyon water resources for irrigation. The use of water bythe people of Asia is far below the world average. Wa-ter withdrawal for irrigation has, unavoidably, a bigimpact on river flow. Falkenmark (1999) gives an ex-ample from Central Asia where intensified irrigation andincreased extraction of water from the rivers have notonly led to decreased flows in these rivers, but havealso increased salinity in the lakes downstream. Themost famous example of this is the Aral Sea where thetwo tributaries, Amu Darya and Syr Darya, are usedintensively for cotton, fodder, and rice production.Another example comes from the Tarim Basin, on theother side of Tian Shan Mountain. Large wetland areashave been converted to agriculture here through a re-

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settlement programme and agricultural development inthe upper basin has led to decreased flows downstreamthe Tarim River Basin, threatening both the ecosystemand people. Based on an analysis of water distributionand allocation during a period from 1956 and 2000,Chen et al. (2003) show that glacial meltwater fromthe headwaters increased about 10.9% after the 1990s,but the water supply from the upper catchment (theAqsu, Yarkand, and Hetian) downstream has decreasedsignificantly by 18.83%. Increasing use of water in theupper catchment for agriculture and the decreased riverflow downstream have caused soil salinisation,pollution, depletion of groundwater, and destruction ofthe ecosystem in the areas downstream. Desertifica-tion becomes inevitable. Nitrate and phosphorus con-centrations in surface and groundwater continue to bea matter of concern throughout the region. Water qual-ity has been seriously affected by agriculture, mainlyby the application of chemical fertilizers and pesticidesas seen in the Yangtze, Tarim, and Yellow River areas.Increasing accumulation of phosphorus in soil threat-ens rivers, lakes and coastal oceans with eutrophica-tion (Bennett et al, 2001), which has been constantlymoving upwards to high elevations. In the case of amiddle mountain catchment in Nepal also, high nitrate

and phosphate loadings have been observed (Merz etal. 2004). Most lakes in China both on the plateaux andin the lowland plains had to be treated for eutrophication,example of, Dianchi in Kunming and Taihu downstreamfrom the Yangtze Delta. Agricultural mismanagement isseen also as a major cause of soil degradation. This notonly includes soil erosion, but also salinisation and de-cline in soil fertility. Cultivation of cash crops (off-sea-son vegetables, tobacco, and cut flowers in Yunnan)upstream was not only shown to increase sediment yieldbut also to pollute the water. In order to feed about 3 billion people, almost half ofthe world’s population, agriculture consumes the lion’sshare of total water supplies in the region. Water use isexpected to increase rapidly together with populationgrowth, particularly in South Asia (figure 7). As an attempt to lessen the dependence on the mon-soons for agriculture, the Indian government has pro-posed a river-linking project to divert water from thenortheast (including from the Brahmaputra and Ganges)to the west and central parts of country. In generalwater use in Southeast Asia is slightly better than inSouth Asia because of Southeast Asia’s efficiency anddiversification of water use.

Figure 7: Increase in population and the use of water for agriculture in Southand Southeast Asia (Source: Xu and Eriksson 2007)

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China is a country poor in terms of water resources,with an annual storage capacity for fresh water of 2800cubic km and 2300 cubic metres of water available percapita, which is far below the world average. Both wa-ter shortage and inefficient use make modern Chinathirsty. Table 11 shows there is a significant increase indemand for water, particularly for industry and for do-mestic use in East China. Furthermore, the loss of gla-ciers and wetlands from the western plateau where theheadwaters of the major rivers of China are locatedwill exacerbate this thirst in the future. Both scientistsand decision-makers need to review the current watermanagement schemes of linking climate change sce-narios with water availability and allocation among dif-ferent sectors. How to maintain environmental flow inChina’s rivers needs particular attention also. With globalization, water becomes economic goodthrough trade. The water that is used in the productionprocess of a commodity is called the ‘virtual water’contained in the commodity. The volume of virtual wa-ter flow can be quantified by quantity of internationalcrop trade flow. The failure of food production in Chinaor India has not only impacts on water consumption infood export country but also potential impacts othercountries engaged in the food market through interna-tional food prices. China is already a net virtual waterimport country with net import volume of 20x109 m3

yr-1 although India is a net virtual water export withvolume of 32x109 m3 yr-1 (Hoekstra, Hung, 2005).China, India and other countries in Asia will have a sig-nificant increasing water demand for producing more

food in a decreased farmland (due to urbanization) forgrowing population.

Competing Use of Water for HydroelectricityChina, India, and other Southeast Asian countries havebecome crucial parts of the economic powerhouse ofthe world after the slowdown in the American economy,and this has led to their increasing demands for waterfor hydroelectricity. The Ministry of Power, Govern-ment of India, has identified as many as 226 potentialsites for large multipurpose dams on the rivers of North-east India, most of them in the Brahmaputra basin. Someof these are presently in various stages of planning anddevelopment (Brahmaputra Board 2000). China is hometo half the world’s 40,000 large dams, including thelargest which is the Three Gorges’ Dam. Meanwhile aseries of eight dam projects has been under way alongthe upper Mekong (Lancang) River and more along theupper Yangtze (Jinsha) River in Yunnan Province. Thecontroversial 13-dam cascade plan on the upperSalween (Nu Jing) is still under government review.Yunnan, together with other parts of west China is be-coming the ‘powershed’ of east China. Magee (2006)argues that the Western Development campaign in Chinapaves the way to increasingly strong interprovincial link-age and regional integration between the water towerin the mountain region and the economic powerhousein the coastal region. There is growing concern,however, about the possible negative impacts of pro-posed mega dams in terms of their viability andsustainability vis-à-vis the delicately poised geo-envi-

Table 11: Water Demand Forecast for China (2010-2050) (billion cubic metres)

Source: China Statistics Bureau 2007

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ronmental base, ecological balance, ethnoculturalheritage, and the extreme dynamism of geophysical pro-cesses in the region. The wisdom behind constructinga series of big dams in the mountain region raises morequestions than can possibly be answered satisfactorilyat the present stage of knowledge and development.The stakes seem to be too high and risks too great forsuch gigantic ventures which may have too many far-reaching consequences to justify making hastydecisions. Similarly, in Bhutan most of its current power pro-duction is fed into the Indian power grid and therewithprovides important revenue for the Government ofBhutan. Bhutan has a hydropower potential of 30,000MW with an economically feasible potential of as highas 16,000 MW in terms of current technology. Cur-rently only about 350MW are installed, but with thecompletion of the Tala hydropower project (expectedto be completed in 2006), the total installed capacitywill be about 1487MW. The revenue from hydropoweraccounted for about 42% of the total national revenueon the basis of the values from the year 1998/1999.With the increased installed capacity the hydropowersector will finance anything between 30 and 60% ofthe 9th Five-Year Plan from 2002 to 2007. Also, inNepal this may become a substantial future source ofrevenue if power is sold to the adjacent states of India.Large-scale hydropower schemes that are so oftenfound in mountainous regions are important on the na-tional and regional scales, but also small-scale water -powered mills and small hydro plants are important onthe local and community scale. In China 40% of therural townships rely on small hydropower plants, while

in Nepal about 800 plants of different sizes provideenergy to about half a million people not connected tothe national grid (Mountain Agenda 2001). Along the Mekong river, hydropower potential var-ies from 31 200MW to at least 60 000MW. Values givenfor the different countries of the Mekong basin are:Yunnan Province of China 13 000 MW (42%), Laos 13000 MW (42%), Cambodia 2200 MW (7%), Vietnam2000MW (6%), and Thailand 1000MW (3%) (Bakker,1999). Myanmar has no hydropower potential in thisriver system. Several projects are in the pipeline at dif-ferent stages in different countries. The Salween Riveris one of the last untapped rivers, but several projectsare in the pipeline in areas in both China and Myanmar.Myanmar has signed power sale agreements with Thai-land for Thai state agencies to buy 1500MW of energyproduced in the Salween river basin. In the Yangtzebasin the technically feasible hydropower potential isabout 197 000 MW or 52% of China’s total potential(Kajander 2001). In addition another 23% of China’shydropower potential is in the Southwest rivers. Thebiggest project and probably the most controversial aswell is the Three Gorges’ Project. The dam site is situ-ated in Hubei Province on the Yangtze River and has adam, two powerhouses, and navigation facilities(Kajander 2001). The total installed capacity is 18 200MW. In addition to positive impacts such as hydro-power generation, improved navigation, flood control,and others others, there are also several negative as-pects such as environmental impacts, resettlement oflarge numbers of people, and salinity problems in theestuary to mention a few

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Figure 8: The sediment loads of selected South Asian riverscompared to the world average (Ferguson1984 in Alford 1992)

5. Asian Society at the Crossroads

Local Adaptation: the Social CapitalThe Himalayan mountains promote cultural diversity(languages, belief systems, architecture, settlementpatterns), land-use and livelihood practices (nomadicherding, agropastoralism, shifting cultivation, teaplantation, river paddy), niche products (tea, teak, me-dicinal plants, mushroom, spices), as well as merchantswho connect peoples and market places, locally andregionally. Merchants from Yunnan in the easternHimalayas travelled the Tibetan plateau, South-east Asia,and South Asia for a thousand years. Caravans servedas market structures and formed a sociocultural net-work among mountain and lowland communities.Mountains were as much pathways of migration andtrade as barriers between the highlands and lowlands.Mountains were productive and prosperous historicallybecause of their microclimates which made a diversityof products possible, not to mention an environmentfree from malaria. Mountain regions used to be muchmore populated than the plains. The shift from themountains as socioeconomic centres can be dividedinto the following periods: a) pre-colonial, b) colonial,c) post-colonial, and d) post-Cold War and economicliberalisation. Equally critical are issues related to the form and flex-ibility of ecosystems and human adaptations to them;bearing in mind that ecosystems and humans are alreadystressed possibly by having to adapt to topoclimaticdiversity. In general, local impacts of the climate do notfollow single or simple paths, whether in terms of plantecology, stream hydrology, erosion and sedimentation,extreme events, or human activities. Much of the moun-tain cryosphere is sensitive to sustained changes in at-mospheric temperature. Already many Himalayan gla-ciers are shrinking, some extremely rapidly in the globalcontext. The widespread consensus is that climate changeis the main factor behind this.

Planting Trees, Caring for WaterRivers from highland Asia rank among the top rivers in

terms of suspended sediment load (Meybeck and Ragu1995; see also figure 8). In terms of suspended sedi-ment delivery the rivers originating from the CentralHimalayas, such as the Karnali, Sethi Nadi, Tamur, SunKhosi, Arun, and Marsyangdi,, have the highest amountswith values of more than 65 t/ha*y (Lauterburg 1993).In years with high intensity cloudburst, tributaries, suchas those of the Kulekhani catchment in Nepal during the1993 event, have had sediment loads of 500 t/ha*y(Schreier and Shah 1996). Over a period of 13 years,the sediment load is estimated to be about 53 t/ha*y.Western Himalayan rivers, such as the Jhelum, Chenab,and Indus, have low sediment delivery rates of below 15t/ha*y. Locally these rivers may, however, have veryhigh loads, as for example the rivers originating from theKarakoram draining into the upper Indus River. The Hunzaand Gilgit rivers yield above global average sediment yieldsas shown in figure 8. T