By using remote sensing and GIS technologies, spatial analysis and statistic analysis, we calculated the water area and volume variations of the Nam Co Lake from 1971−2004, and discussed their influence factors from the viewpoints of climatic change and water balance. Data source in this study includes bathymetric data of the lake, aerial surveyed topographic maps of 1970, remote sensing images of 1991 and 2004 in the lake catchment, meteorological data from 17 stations within 1971−2004 in the adjacent area of the lake catchment. The results showed that the lake area expanded from 1920 km 2 to 2015 km 2 during 1971 to 2004 with the mean annual increasing rate (MAIR) of 2.81 km 2 a −1 , and the lake volume augmented from 783.23×10 8 m 3 to 863.77×10 8 m 3 with the MAIR of 2.37×10 8 m 3 . Moreover, the MAIR of the lake area and volume are both higher during 1992 to 2004 (4.01 km 2 a −1 and 3.61×10 8 m 3 a −1 ) than those during 1971 to 1991 (2.06 km 2 a −1 and 1.60×10 8 m 3 a −1 ). Analyses of meteorological data indicated that the continue rising of air temperature conduced more glacier melting water. This part of water supply, together with the increasing precipitation and the descending evaporation, contributed to the enlargement of Nam Co Lake. The roughly water balance analyses of lake water volume implied that, in two study periods (1971−1991 and 1992−2004), the precipitation supplies (direct precipitations on the lake area and stream flow derived from precipitations) accounted for 63% and 61.92% of the whole supplies, while the glacier melting water supplies occupied only 8.55% and 11.48%, respectively. This showed that precipitations were main water supplies of the Nam Co Lake. However, for the reason of lake water increasing, the increased amount from precipitations accounted for 46.67% of total increased water supplies, while the increased amount from glacier melting water reached 52.86% of total increased water supplies. The ratio of lake evaporation and lake volume augment showed that 95.71% of total increased water supplies contributed to the augment of lake volume. Therefore, the increased glacier melting water accounted for about 50.6% of augment of the lake volume, which suggested that the increased glacier melting water was the main reason for the quickly enlargement of the Nam Co lake under the continuous temperature rising.Tibetan Plateau, Nam Co Lake, lake area variation, remote sensing, water balance Citation:Zhu L P, Xie M P, Wu Y H. Quantitative analysis of lake area variations and the influence factors from 1971

2018) Trophic state assessment of global inland waters using a MODIS-derived Forel-Ule index.Abstract 13 Eutrophication of inland waters is considered a serious global environmental 14 problem. Satellite remote sensing (RS) has been established as an important source of 15 information to determine the trophic state of inland waters through the retrieval of 16 optically active water quality parameters such as chlorophyll-a (Chl-a). However, the 17 use of RS techniques for assessment of the trophic state of inland waters on a global 18 scale is hindered by the performance of retrieval algorithms over highly dynamic and 19 complex optical properties that characterize many of these systems. In this study, we 20 developed a new RS approach to assess the trophic state of global inland water bodies 21 based on Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and the 22Forel-Ule index (FUI). First, the FUI was calculated from MODIS data by dividing 23 2 natural water colour into 21 indices from dark blue to yellowish-brown. Then the 24 relationship between FUI and the trophic state index (TSI) was established based on in-25 situ measurements and MODIS products. The water-leaving reflectance at 645 nm band 26 was employed to distinguish coloured dissolved organic matter (CDOM)-dominated 27 systems in the FUI-based trophic state assessment. Based on the analysis, the FUI-based 28 trophic state assessment method was developed and applied to assess the trophic states 29 of 2058 large inland water bodies (surface area > 25 km 2 ) distributed around the world 30 using MODIS data from the austral and boreal summers of 2012. Our results showed 31 that FUI can be retrieved from MODIS with a considerable accuracy (92.5%, R 2 =0.92) 32 by comparing with concurrent in situ measurements over a wide range of lakes, and the 33 overall accuracy of the FUI-based trophic state assessment method is 80.0% (R 2 = 0.75) 34 validated by an independent dataset. Of the global large water bodies considered, 35 oligotrophic large lakes were found to be concentrated in plateau regions in central Asia 36 and southern South America, while eutrophic large lakes were concentrated in central 37 Africa, eastern Asia, and mid-northern and southeast North America. 38

Glaciers in the Yarlung Zangbo River witness severe glacial retreat nowadays, which gives important influence on lake processes in the region. We have studied glacial distribution, glacial mass balance and found large deficit in glacial mass and its impact in the region. Our study also integrated the variation in glacial-fed lakes of the Nam Co and Ranwu Lake, and presented an initial assessment of the impact of glacial mass balance on lakes. The study has shown a significant contribution of glacial melting to recent lake expansion and lake level rising. Yarlung Zangbo River, glacial distribution, glacial mass balance, lake variation Citation:Yao T D, Li Z G, Yang W, et al. Glacial distribution and mass balance in the Yarlung Zangbo River and its influence on lakes.

The Yarlung Zangbo River (YR) is the highest great river in the world, and its basin is one of the centers of human economic activity in Tibet. Using 10 meteorological stations over the YR basin in 1961-2005, the spatial and temporal characteristics of temperature and precipitation as well as potential evapotranspiration are analyzed. The results are as follows.(1) The annual and four seasonal mean air temperature shows statistically significant increasing trend, the tendency is more significant in winter and fall. The warming in Lhasa river basin is most significant. (2) The precipitation is decreasing from the 1960s to the 1980s and increasing since the 1980s. From 1961 to 2005, the annual and four seasonal mean precipitation is increasing but not statistically significant, especially in fall and spring. The increasing precipitation rates are more pronounced in Niyangqu and Palong Zangbo river basins, the closer to the upper YR is, the less precipitation increasing rate would be. (3) The annual and four seasonal mean potential evapotranspiration has decreased, especially after the 1980s, and most of it happens in winter and spring. The decreasing trend is most significant in the middle YR and Nianchu river basin. (4) Compared with the Mt. Qomolangma region, Tibetan Plateau, China and global average, the magnitudes of warming trend over the YR basin since the 1970s exceed those areas in the same period, and compared with the Tibetan Plateau, the magnitudes of precipitation increasing and potential evapotranspiration decreasing are larger, suggesting that the YR basin is one of the most sensitive areas to global warming.