Land Cover Status in the Koshi River Basin, Central Himalayas

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1 Jan., 2017 Journal of Resources and Ecology Vol. 8 No.1 J. Resour. Ecol (1) DOI: /j.issn x Land Cover Status in the Koshi River Basin, Central Himalayas WU Xue 1,2, GAO Jungang 1, ZHANG Yili 1,2,*, LIU Linshan 1, ZHAO Zhilong 1,2, Basanta PAUDEL 1,2 1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing , China; 2. University of the Chinese Academy of Sciences, Beijing , China Abstract: The Koshi River Basin is in the middle of the Himalayas, a tributary of the Ganges River and a very important cross-border watershed. Across the basin there are large changes in altitude, habitat complexity, ecosystem integrity, land cover diversity and regional difference and this area is sensitive to global climate change. Based on Landsat TM images, vegetation mapping, field investigations and 3S technology, we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics. We found that from source to downstream, land cover in the Koshi River Basin in 2010 was composed of water body (glacier), bare land, sparse vegetation, grassland, wetland, shrubland, forest, cropland, water body (river or lake) and built-up areas. Among them, grassland, forest, bare land and cropland are the main types, accounting for 25.83%, 21.19%, 19.31% and 15.09% of the basin s area respectively. The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes. The north slope is dominated by grassland, bare land and glacier; forest, bare land and glacier are mainly found on northern slopes. Northern slopes contain nearly seven times more grassland than southern slopes; while 97.13% of forest is located on southern slopes. Grassland area on northern slope is 6.67 times than on southern slope. The vertical distribution of major land cover types has obvious zonal characteristics. Land cover types from low to high altitudes are cropland, forest, Shrubland and mixed cropland, grassland, sparse vegetation, bare land and water bodies. These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection, sustainability and management in this and other alpine transboundary basins. Key words: Himalayas; Koshi River Basin; land cover pattern; vertical distribution; object-oriented method 1 Introduction Global environmental change and sustainable development have become major issues, to which growing attention is being paid worldwide, especially regarding mountain regions (Zheng 2002; Turner et al. 2007). Land use and land cover change (LUCC) is the main cause of changes in the land surface environment and has become an important component of research on global environmental change and sustainable development (Li 1996, 1999). The basis and premise of land cover change and analysis is the study of land cover patterns. Accurate global and regional land cover data is an important foundation in the study of land surface processes. Based on this, many countries and organizations have used different image processing technologies and data to carry out land cover remote sensing systems at regional, continental and global scales. Up to now, six global scale data sets have been established, including the GLOB- COVER land cover product (GlobCover) (Patrice et al., 2008), University of Maryland land cover product (UMd) (Hansen et al., 2000), and GlobeLand30 (Chen et al., 2010). In general, the accuracy of global land cover data is increasing, and Chen s (2010) data provided a leap in global land cover data accuracy. However, while global land cover data is of good quality and accuracy as a whole, for local and marginal areas the information is low quality, especially Received: Accepted: Foundation: National Natural Science Foundation of China ( ); Australian Government-funded Koshi Basin Programme at the International Centre for Integrated Mountain Development (ICIMOD); Key Research Program of the Chinese Academy of Sciences (ZDRW-ZS ). *Corresponding author: ZHANG Yili. zhangly@igsnrr.ac.cn. Citation: WU Xue, GAO Jungang, ZHANG Yili, et al Land Cover Status in the Koshi River Basin, Central Himalayas. Journal of Resources and Ecology. 8(1):

2 WU Xue, et al.: Land Cover Status in the Koshi River Basin, Central Himalayas 11 for high altitude areas. The accuracy of global land cover data is relatively coarse if applied at the regional scale. GlobelLand30 has a higher precision, but it has a first classification only, helpful when examining the overall land cover situation but limited in classification and precision for deeper research. The Koshi River Basin is a very important cross-border river system in the Central Himalayas, South Asia. Land cover data in the watershed is mainly at a national scale. One set is the China 1:10 million land use data by the Institute of Geographical Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences (CAS); another is Nepal 30 m land cover data. The data source, classification system and classification methods of these two sets are inconsistent and cannot be used to synthesize land cover data for the KRB. Coupled with high elevation terrain and road inaccessibility, reasonable and effective high resolution land cover type data in this region is lacking. This study attempts to construct high-accuracy land cover data based on multiple field surveys and existing land survey data and knowledge. A systematic study is made of the overall land cover pattern, together with the first exploration of the vertical distribution characteristics of the basin s land cover. This research will provide basic high-precision data for research on land cover change and in-depth study of the relationship between land change and climate change in the KRB. Our approach will provide a scientific basis for exploring the vertical distribution of land cover in high altitude areas in the context of high-mountain cross-border land resource utilization, management and sustainable development. 2 Study area and Methods 2.1 Study area The Koshi River Basin is located in the Central Himalayas include China, Nepal and India. In this paper, the Koshi River Basin (KRB) refers only about the China and Nepal parts. KRB ranges from E and N. It stretches from south of the Brahmaputra River in the north to the southern frontier of Nepal in the south, and from Kathmandu in the west to the eastern border of Nepal in the east. The total area of km 2 includes km 2 in the Tibet Autonomous Region of China and km 2 in Nepal (Zhang et al. 2013) (Fig. 1). The average elevation in the KRB is 3783 m, with nearly 51% of the area Fig.1 Location of study area and field routes in the Koshi River Basin

3 12 Journal of Resources and Ecology Vol. 8 No. 1, 2017 being at an altitude of m and 28% at m. Of the world s fourteen highest peaks above 8000 m, six are in the KRB, including Mount Qomolangma (Sagarmatha/ Everest, 8844 m), Kanchenjunga (8586 m) and Lhotse (8516 m). The elevation gap in the KRB is huge, from the highest spot on Mount Qomolangma at 8844 m to the lowest at 96 m. This leads to complex vertical natural zones and distinct regional differences among varieties of landscape types (Zhang et al. 2013). The KRB is a global biodiversity hotspot (core region of the Eastern Himalayas). There is a rich variety of flora and fauna, including 6244 species of vascular plants (Manandhar 2010). Weather station records in the KRB show that the annual average temperature is 5.1 C with average annual rainfall of mm in the northern KRB in China (Nie 2010); the annual average temperature is 10.5 C and average annual precipitation is mm in the southern KRB in Nepal. 2.2 Data sources Remote sensing data were obtained from the US Geological Survey (USGS) and included eight scenes from 30 m-resolution Landsat remote sensing data. To reduce errors resulting from images being taken at different periods, data were acquired at a similar season in April 2010 and images from other periods were used for secondary data interpretation. Parts of images 141/40 (Path/Row) and 141/41 were used for corresponding images in 2009 because of cloud factors. Auxiliary data were topographic maps at a scale of 1: in China and 1: in Nepal and from the latest 30 m ASTER Global Digital Model (DEM) provided by the Ministry of Economy, Trade, and Industry of Japan and the United States National Aeronautics and Space Administration. Over the same period, glacier and glacial lake (vector data) data were provided by the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI) of CAS. A vegetation map of the Tibet Plateau (1: ) was provided by IGSNRR of CAS. In addition, investigation data in 2010, 2011, 2013 and 2014 were used. 2.3 Methods Land cover mapping and evaluation of accuracy (1) Land cover classification system On the basis of the Food and Agriculture Organization and United Nations Environment Programme Land Cover Classification System (LCCS) (Di-Gregorio et al. 2000), our research group developed land use and cover classification for the Qomolangma region (Zhang et al. 2006, 2010; Birendra 2010; Nie 2010; Zhang 2010; Gao 2012) and referred to Nepal land use and land cover classification from the International Centre for Integrated Mountain Development (ICIMOD) (Kabir et al. 2015). Considering the spatial resolution of remote sensing data, reference to other land cover system results combined with KRB land cover distribution and field land cover investigations, vegetation distribution maps, land use maps and soil map data, our group developed a LCCS for the KRB (Table 1). (2) Mapping An object-oriented method was using for land cover mapping, combined with the results of remote-sensingbased glacier and glacial lake special mapping (Shangguan et al. 2014) and systematically modified with the help of field surveys and knowledge. The processing steps of the object-oriented method of land cover mapping were as follows. (1) Remote sensing image preprocessing using a 1: topographic map for geometric correction of remote sensing images. On examination, the correction kept the error to within a pixel. (2) Object-oriented image classification using ENVI5.1 for feature extraction from land cover information, involving four processes: image segmentation, merger, imposition of rules, and output of results. After experimentation, the segmentation parameter was set at 30 and merger at 70. This completed the preliminary extraction of information for land cover classification in the KRB (Gao 2012). (3) Assessment of accuracy and evaluation of results To further improve the accuracy of data we enhanced the visual intensity for the later period in combination with data from multiple sources to provide a revised classification. First, with reference to remote sensing images and Google Earth, an overall wide range of polygonal amendments have been made to the basin. The second correction combines glacier and lake data provided by the Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences. With reference to remote sensing images, high-precision amendments to glacier and lake types have been made, improving the accuracy for glaciers and lakes to more than 95%. Finally, determination of the altitudinal distribution of land cover types has been emphasized. Combining climate and soil characteristics, the vegetation distribution, natural zone features and field investigated data, we analyzed the upper limits of distribution of some land cover types (Table 2). A revision of these upper limits improved the overall accuracy of determination of land cover types at high altitude and reduced uncertainty. The land cover classification results of the study were then evaluated. After classification and correction of land use and land cover data, we used stratified random sampling for an analysis of the accuracy of land cover data interpretation. Topographic maps, Google Earth high resolution images, and other thematic maps together with field investigations at different places at the same time were used to evaluate the test sample. A total of 869 uniformly distributed sample points were selected and investigated during the field survey. The overall accuracy was 83.36% and that for the glacier and glacial lakes was 95% (Table 1) Extraction of land cover elevation, slope and aspect In extracting slope and aspect we first converted land cover

4 WU Xue, et al.: Land Cover Status in the Koshi River Basin, Central Himalayas 13 Table 1 Land cover classification system and accuracy of land cover mapping Level one Forest Shrubland Grassland Land cover type Level two Broadleaved Evergreen Closed Forest Topographic Field reference map reference point point Google Earth reference point Reference total Classified total Number correct Producer s accuracy (%) User s accuracy (%) Broadleaved Evergreen/ Deciduous Mixed Forest Broadleaved Deciduous Forest Mixed Forest Needleleaved Evergreen Forest Broadleaved Evergreen Shrubland Broadleaved Deciduous Shrubland Mixed Shrubland Needleleaved Evergreen Shrubland Forest Grassland Shrubland Grassland Alpine Grassland Wetland Swamp Wetland Sparse vegetation Sparse vegetation Bare land Bare Soil Bare Rock Cropland Cropland Water body River Lake Glacial Lake Glacier/Nival Zone Built-up area Built-up area Total Table 2 Distribution of land cover with elevation Data source Spatial resolution Year Forestupper limit (m) Grasslandupper limit (m) Croplandupper limit (m) Remarks European Communities 1 km Gao (2012) Chen et al. (2014) 30 m Present analysis Uddin et al. (2014) 30 m Present study 30 m Whole of Nepal, present analysis vector data into raster data based on the 30 m GDEM with a resolution of 30 m. We then imposed a reclassification into a total of nine classes, using ArcGIS software to make divisions into flat, north, northeast, east, southeast, south, southwest, west and northwest. Following the Second National Land Survey Technology Procedures, slope data from the cropland grade classification were combined with terrain data for the KRB, and the slopes were divided into 12 classes at intervals of 4. A raster calculator was then used to overlay the results of the classification of slope and aspect pect on land cover data. Finally, statistical data were overlaid to analyze terrain characteristics of land cover. 3 Results analysis 3.1 Land cover pattern and distribution characteristics in the KRB Composition and distribution of land cover Land cover in the KRB is composed of nine categories: forest, shrubland, grassland, wetland, cropland, built-up areas, sparse vegetation, bare land and water body. Grassland, for-

5 14 Journal of Resources and Ecology Vol. 8 No. 1, 2017 est, bare land, and cropland are the main land cover types, accounting for 25.83%, 21.19%, 19.31%, and 15.09%, respectively, of the total area of the KRB (Table 3). The glacier/nival zone area (sensitive to climate change and an important characteristic of land cover composition) occupies km 2, accounting for 5.72% of the total area of the KRB. The proportion of built-up land is the smallest. The distribution of the main land cover types in the KRB is consistent with the distributions of soil, terrain (altitude) and gradients in temperature and precipitation. From the southwest to the northeast, the pattern of distribution is as follows: plain cropland; low mountain forest and cropland; middle mountain forest and shrubland; alpine shrubland and grassland; extremely high-mountain bare land and glacier/nival zone; plateau slope grassland; and plateau valley cropland. These are distributed in a strip-like manner (Fig. 2). Swamp wetland shows a concentrated distribution along rivers in valleys and around lakes. Glacial lakes are distributed at the ends of extremely high mountain glaciers. Taking the Himalayas as the boundary, the southern slope is mainly covered by forest (37.76%), cropland (26.84%) and glacier/nival zones (9.01%) (Table 2). From low altitude to high altitude the pattern of land cover distribution is: cropland; (wetland); forest; shrubland; grassland; bare land; and glacier/nival zone. The built-up area is mainly distributed along both sides of rivers and highways. In the northern part of the basin, grassland (49.37%), bare land (31.64%), and glacier/nival zones (5.23%) dominate. From low to high altitude, the pattern of distribution is: forest; cropland; shrubland; swamp wetland; cropland; grassland; bare land; and glacier/nival zone Distribution characteristics of the main land cover types Grassland is the largest land cover type in the KRB, with an area of km 2 mainly distributed in the Arun River sub-basin in the high mountains and the middle mountain area. Its area of distribution on the northern slope of the Himalayas is much higher than that on the southern slope, by a ratio of 6.67:1. Grassland is subdivided into forest grassland, shrubland grassland and alpine grassland. Alpine grassland is the largest grassland type in the KRB, accounting for 95.75% of grassland, and 54.38% of the alpine grassland is distributed on the northern slope in the Tibetan Plateau. Grassland in the KRB is basically natural grassland, mostly distributed in pastoral areas of the basin. Forest is the second largest land cover type by area at km 2. It is mainly distributed on the southern slope of the Himalayas in Nepal, accounting for 97.66% of the whole forest area. In the central valley region and southern plains region, forest is in a staggered distribution with cropland. The area of forest on the northern slope is less, and is mainly concentrated in the Chentang ditch of the core area of Mount Qomolangma Nature Reserve. Among forest types, the largest areas are of broadleaved evergreen forest and broadleaved evergreen/deciduous mixed forest, accounting for % and % of the total forest area, respectively. Broadleaved evergreen/deciduous mixed forest is mainly distributed in the central valley of Nepal, and broadleaved evergreen forest in Sankhuwasabha (the northern part of the Kosi zone) and the Bhojpur District in the southern part of the basin. Shrubland is mainly distributed in the central basin and is small (3.88% of the total area). In the Chinese part of the KRB it is mainly concentrated in the valley region and the Camphor, Rongxia and Chentang ditches. However, it has a scattered distribution in Nepal, mainly on both sides of rivers in the mountains of northern Nepal. Table 3 Composition of land cover types in the Koshi River Basin Land cover type KRB Northern slope Southern slope Area (km 2 ) Percentage (%) Area (km 2 ) Percentage (%) Area (km 2 ) Percentage (%) Broadleaved Evergreen Closed Forest Broadleaved Evergreen and Deciduous Mixed Forest Broadleaved Deciduous Forest Mixed Forest Needleleaved Evergreen Forest Shrubland Grassland Sparse vegetation Wetland Cropland River Lake glacier/nival Zone Bare Land Built-up Area Total

6 WU Xue, et al.: Land Cover Status in the Koshi River Basin, Central Himalayas 15 Fig.2 Land cover map of the Koshi River Basin in 2010 The cropland area in the KRB is km 2, 96.95% of which is distributed on the southern slope of the Himalayas on southern plains and the middle valley of Nepal. It has a sparse distribution on the northern slope where it is mostly in valley areas. The area of cropland in the Nepalese part of the KRB accounts for 18.24% of total cropland in Nepal (Uddin et al., 2014, Paudel et al, 2016) and is an important food production area for that country. However, agriculture in the KRB is greatly influenced by natural precipitation because of limited water conservancy facilities for cropland irrigation (Ghimire et al., 2010). In addition, crop yield is sensitive to climate change (Raut et al., 2011; Schroeder, 1985). Bare land is one of the main land cover types in the KRB, with an area of km 2. It is mainly distributed on the northern slope, accounting for 75.56% of the total bare land area. Bare land is also distributed in the northern parts of the southern slope. Most bare land is distributed in front of the Himalayan glaciers and as unused land in alpineharsh environments on the Tibetan Plateau. Glaciers form an important component of land cover in the KRB at km 2. They are mainly distributed on the southern slope, with an area 1.41 times bigger than that on the northern slope. They are mostly distributed around the center of Mount Qomolangma, Kanchenjunga, Lhotse, Makalu, Cho Oyu and Xixiabangma. Changes in mountain glaciers are indicative of global climate change, especially in the Himalayas because of sensitivity to climate change (Nie 2010). Rivers make up km 2 of the KRB. They are distributed more in the Nepalese side, the ratio being 1.84:1 (Nepal:China). Himalayan rivers are the cradles of Southeast Asia s major rivers and play an important role in the ecological environment and economic development of downstream regions. Lakes in the basin are formed mostly from glacial meltwater and have an area of km 2. They are distributed to the north of the Himalayas making up an area of km 2. Plateau lakes and glacier lakes are a sensitive indicator of climate change (Shi, 1990; Liu et al. 2009; Nie et al. 2016) and are subject to influence by human activities (Nie et al. 2014, 2016). The area of swamp wetland in the KRB is smaller, but plateau wetlands occupy a special position in global climate change research (Bai et al. 2004; Zhao et al. 2014). They are mainly distributed on the plateau area to the north of the Himalayas, occurring at river bends and confluences. There is less swamp wetland on the southern slope of the KRB, the proportions on the northern and southern slopes occurring at

7 16 Journal of Resources and Ecology Vol. 8 No. 1, 2017 a ratio of 2.82:1. The area of sparse vegetation is km 2, mainly distributed on the northern slope of the Himalayas in China and on the southern slope in northern Nepal. The areas on both sides of the basin are almost the same. The built-up area is the smallest at km 2, of which 94.42% is located on the southern slope of the Himalayas Vertical distribution of land cover The vertical distribution of primary land cover types in the KRB has zonal characteristics. From low to high elevation, the land cover distribution is: cropland; forest; shrubland and cropland; grassland; sparse vegetation; bare land; and glacial/nival zones (Fig. 3). The distribution belt elevations of each land cover type on the northern slope of the KRB are higher than those on the southern slope. In contrast, level two land cover types on the northern slope tend to exhibit simple distributions with no structural complexity. Cropland occurs mostly below 4500 m, with a distribution of double-center type ( , ) (Fig. 4). The land cover at these elevations should be forest but this has now been replaced by cropland. The distributions of most human residents and built-up areas are consistent with that of cropland, more or less coinciding in space. A small area of industrial land is distributed in non-agricultural areas. The distribution range of forest is basically below 4000 m. In terms of level-two forest classification, five main forest types are distributed from low to high elevation as follows: broadleaved evergreen ( m); broadleaved evergreen/deciduous mixed ( m); needleleaved ( m); broadleaved deciduous ( m); mixed ( m); and needleleaved again ( m) (Fig. 5). Grassland is mainly distributed at m. Sparse vegetation in the Himalayas is distributed at m (Wang et al. 1988), whereas in the KRB it is mainly distributed at m. Corresponding to the tundra belt of the Himalaya natural zone, bare land is distributed between m. Glaciers appear above 4000 m and are concentrated at m. The distributions of wetland, water bodies and other types of land cover show nonzonal characteristics Terrain characteristics of land cover distribution (1) Aspect characteristic Spatial statistics show that forest is mainly located on northwest, north, west and southwest aspects, while cropland Fig.3 Vertical distribution structure of land cover in the Koshi River Basin Fig.5 Elevation gradient distribution of typical land cover types Fig.4 Elevation gradient distribution of each land cover types in the Koshi River Basin is concentrated on southeast, south, east and southwest aspects (Fig. 6). This is because local cropland occupies a lot of space in the south (where there are sunny slopes) and there has been much effort in some areas to retain a large amount of unspoiled forest. The distribution of grassland shows a uniform aspect overall. Forest grassland and shrub grassland are distributed on sunny slopes. However, the distribution of alpine grassland

8 WU Xue, et al.: Land Cover Status in the Koshi River Basin, Central Himalayas 17 Fig.6 Aspect distribution of land cover types in the Koshi River Basin does not show any preference with regard to aspect. This may be because alpine grassland is mainly distributed on the northern slope of the Himalayas with a cold climate and less rainfall, and therefore the slope distribution will not show the same pattern as forest grassland and shrub grassland, which are mainly distributed in dry hot valleys of the southern slopes. Forest grassland grows on shady slopes because of good hydrothermal conditions. Shrub grassland is mostly distributed on sunny slopes and evergreen shrubland on shady slopes. One possible reason is that many of the areas with a shrubland distribution are strongly illuminated, and soil moisture conditions on sunny slopes are not as good as those on shady slopes. Sunny slopes are suitable for some broadleaved deciduous and evergreen, hardy and needle evergreen shrubland plants. Shady slopes are suitable for some hygrophilous evergreen shrubland plants. Sparse vegetation is mainly distributed on sunny slopes. Wetland and glaciers are mainly distributed on the northern, northeastern, and northwestern slopes (which are shady). Lakes are found on the southern slope, especially glacial lakes, which are mostly formed by meltwater. (2) Slope characteristics The range of slope gradients in the KRB is not wide, owing to the mountainous nature of the basin. Spatial statistical results show that forests are mainly distributed on slopes, which are less common in the low-elevation zone. Alpine grassland is mainly distributed 2 18 and forest grassland and shrub grassland on slopes greater than 22, with most on slopes greater than 42. Glaciers are also concentrated on slopes greater than 42. Cropland is concentrated on slopes Most cropland is in the form of terraces on slopes, with crop types such as rice, millet and maize. Wetland, rivers and lakes are widely distributed on slopes 0 14, related to the effects of gravity on water. Built-up areas are distributed on slopes less than 18. The majority of bare land is concentrated on slopes With regard to the behavior of the distributions of different land cover types with increasing slope (Fig. 7), there are four major trends: (1) a gradual increase in distribution with increasing slope, as exhibited by glaciers; (2) an initial increase followed by a decrease, as exhibited by forest, cropland, sparse vegetation and bare land, with the largest proportion of forest appearing at 22 30, that of cropland at and that of sparse vegetation at ; (3) a gradual decrease, as exhibited by grassland, wetland, rivers, lakes and built-up areas; (4) irregularity, as exhibited by mixed forest and shrubland, which show two peaks of almost the same magnitude, one at and the other above Conclusions The main land use cover types in the KRB are grassland, forest, bare land and cropland. Due to differences in altitude, air temperature and precipitation between southern and northern slopes, land cover types are completely different. The southern slope is dominated by forest, cropland and glaciers, the northern slope by grassland, bare land and glaciers. The belt altitude distribution of each land cover type on the northern slope is higher than for the southern slope. Level-two land cover types have simpler distributions, and

9 18 Journal of Resources and Ecology Vol. 8 No. 1, 2017 Fig.7 Slope characteristics of land cover in the Koshi River Basin their structural complexity is decreased on the northern slope. There is a low altitude area in which human activity has led to large areas of forest being replaced by cropland. Wetland and water bodies show non-zonal distributions. The vertical distribution characteristics of land cover in the basin follow the usual pattern for most land cover types at given ranges of altitude. Land cover types are distributed from low to high elevation as follows: cropland; forest; shrubland (and crop land); grassland; sparse vegetation; bare land; and glacier/nival zone. The belt altitude distribution of each land cover type on the northern slope is higher than that on the southern slope. Level-two land cover types have simpler distributions and their structural complexity is decreased on the northern slope. There is a low altitude area in which human activity has led to large areas of forest being replaced by cropland. Wetland and water bodies show non-zonal distributions and their distribution along with cropland and built-up areas is similar to that of rivers. Forest is distributed on northwest, north, west and southwest aspects on slopes Cropland is distributed on southeast and southern aspects on slopes. With regard to the behavior of the distributions of different land cover types with increasing slope, four major trends are seen: an increasing distribution with increasing slope (glacier/nival zone); an increase followed by a decrease (forest, cropland, sparse vegetation and bare land); a gradual decrease (grassland, wetland, rivers, lakes and built-up areas); and irregularity (mixed forest and shrubland). Acknowledgement The authors are grateful to Basanta SHRESTHA, Arun B. SHRESTHA, SM WAHID, MSR MURTHY and Kabir UDDIN of ICIMOD, Nepal for sharing valuable datasets. We sincerely thank to SHANGGUAN Donhui from CAREERI of CAS for providing valuable data on glaciers and lakes. We are grateful to anonymous reviewers for constructive comments and suggestions regarding this paper. References Ali J, Benjaminsen T A, Hammad A, et al The road to deforestation: An assessment of forest loss and its causes in Basho Valley, Northern Pakistan. Global Environmental Change, 15(4): Bai J H, Ou Y H, Xu H F Advances in studies of wetlands in Qinhai-Tibet Plateau, Progress in geography, (4): 1 9. (in Chinese) Bajracharya B, Uddin K, Chettri N, et al Understanding Land Cover Change Using a Harmonized Classification System in the Himalaya. International Journal of Remote Sensing, 30(2): Bartholome E, and Belward A S GLC2000: a new approach to global land cover mapping from Earth observation data. International Journal of Remote Sensing, 26 (9): Di-Gregorio A, Jansen L Land cover classification system, LCCS: classification concepts and user manual, Food and Agriculture Organization of the United Nations, Rome. Gao J G Land cover change and its relationship with climate change in Koshi river basin of the central Himalaya. Institute of geographic sciences and natural resources research, Chinese academy of sciences. (in Chinese) Ghimire Y N, Shivakoti G P, Perret S R Household-level vulnerability to drought in hill agriculture of Nepal: implications for adaptation planning. International Journal of Sustainable Development & World Ecology, 17(3): Hansen M. C., Defries R. S., Townshend J. R. G. et al Global land cover classification at 1km spatial resolution using a classification tree approach. International Journal of Remote Sensing, 21 (6-7): Kabir U, Him L S, Murthy MSR, et al Development of 2010 national land cover database for the Nepal. Journal of Environmental Management, 148: Li X B A review of the international researches on land use/land cover change. Acta Geographica Sinica, 51(6): (in Chinese) Li X B International research of environmental consequence of land use/cover change. Advance In Earth Sciences, 14(4): (in Chinese) Liu J, Wang S, Yu S, et al Climate warming and growth of highelevation inland lakes on the Tibetan Plateau. Global & Planetary Change, 67(3 4): Manandhar R, Emeishan meeting report, Kunming. Nani Raut, Bishal K. Sitaula, Jens B. Aune, et al Evolution and future direction of intensified agriculture in the central mid-hills of Nepal. International Journal of Agricultural Sustainability, 9(4): Nie Y, Sheng Y W, Liu Q, et al A regional-scale assessment of Hi-

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