The 3rd International Symposium on Watershed Geographic Sciences (ISWSGS2020)

  ISWSGS2020 (the 3rd International Symposium on Watershed Geographic Sciences) will be held online from October 17 to 18, 2020. This symposium is organized by the Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences. The theme of the symposium is “Watershed geography and interdisciplinary sciences”. This symposium aims to provide a forum for the exchange of the latest research achievements on watershed geography and other related sciences. World leading scientists are invited to present keynotes covering the latest advances in soil and water processes, human geography, remote sensing and watershed management.
  Topics include
  1. Observation and monitoring at multiple scales
  2. Integrated watershed modeling of multi-processes
  3. Watershed soil and water processes and their environmental impacts
  4. Human activities, processes and driving mechanism in watersheds
  5. Sustainable development and watershed planning
  6. Watershed integrated management and spatial optimization
  7. Other topics relevant to watershed geography
  October 17 2020 for local participants’ arrival
  October 18 2020 for keynote speeches online
  Information and contacts
  Tel: +86 25 8688 2083
  Fax: +86 25 5771 4759
  Add: 73 East Beijing Road, Nanjing, China
  General enquiry:

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Prof. Qin Boqiang and Prof. Zhang Yunlin of our institute were selected as the top 2% scientists in the world

  Stanford University recently released the latest 2020 World’s Top 2% Scientists. Prof. Qin Boqiang and Prof. Zhang Yunlin of our institute made the list.
  The World’s Top 2% Scientists was published by the team of Professor John P.A. Ioannidis of Stanford University. The top 2% scientists in the world were selected by the team from nearly 7 million scientists, based on citations, h-index, co-authorship adjusted hm-index, citations to papers in different authorship positions and a composite indicator. The ranking list was divided into 22 fields and 176 sub-fields, including a total of about 160,000 famous scientists from various fields. Among them, Prof. Qin Boqiang and Prof. Zhang Yunlin were selected in the field of Environmental Sciences, ranked 179 and 747 respectively in the 1,400 scientists in the field.
  Prof. Qin Boqiang has been engaged in lake ecological environment research for a long time. He is the PI of the Science Fund for Creative Research Group and the Distinguished Young Scholar of the National Natural Science Foundation of China. He also serves as the associate editor of many famous domestic and foreign journals such as Science Bulletin. In the Web of Science database, Qin Boqiang is ranked first by the number of SCI papers with “shallow lake” as the subject term with an H index of 49 and more than 9,300 citations.
  Prof. Zhang Yunlin has long been engaged in remote sensing of physical lakes and water color and biogeochemical cycle of chromophoric dissolved organic matter research. He is the Distinguished Young Scholar and the deputy editor of many famous journals, such as Limnology and Oceanography. In the Web of Science database, the SCI papers of Zhang Yunlin ranked first worldwide with “chromophoric dissolved organic matter” or “CDOM” as the subject term, with an H index of 41 and more than 6000 citations.
Nature: Lake heatwaves under climate change

  Lake ecosystems, and the organisms that live within them, are vulnerable to temperature change, including the increased occurrence of thermal extremes. However, very little is known about lake heatwaves—periods of extreme warm lake surface water temperature—and how they may change under global warming. Here the researchers use satellite observations and a numerical model to investigate changes in lake heatwaves for hundreds of lakes worldwide from 1901 to 2099. The researchers show that lake heatwaves will become hotter and longer by the end of the twenty-first century. For the high-greenhouse-gas-emission scenario (Representative Concentration Pathway (RCP) 8.5), the average intensity of lake heatwaves, defined relative to the historical period (1970 to 1999), will increase from 3.7 ± 0.1 to 5.4 ± 0.8 degrees Celsius and their average duration will increase dramatically from 7.7 ± 0.4 to 95.5 ± 35.3 days. In the low-greenhouse-gas-emission RCP 2.6 scenario, heatwave intensity and duration will increase to 4.0 ± 0.2 degrees Celsius and 27.0 ± 7.6 days, respectively. Surface heatwaves are longer-lasting but less intense in deeper lakes (up to 60 metres deep) than in shallower lakes during both historic and future periods. As lakes warm during the twenty-first century, their heatwaves will begin to extend across multiple seasons, with some lakes reaching a permanent heatwave state. Lake heatwaves are likely to exacerbate the adverse effects of long-term warming in lakes and exert widespread influence on their physical structure and chemical properties. Lake heatwaves could alter species composition by pushing aquatic species and ecosystems to the limits of their resilience. This in turn could threaten lake biodiversity and the key ecological and economic benefits that lakes provide to society.
  R. Iestyn Woolway, Eleanor Jennings, Tom Shatwell, Malgorzata Golub, Don C. Pierson & Stephen C. Maberly. Lake heatwaves under climate change. Nature. 589,402-407 (2021). doi: 10.1038/s41586-020-03119-1. (

Int’l Cooperation News

Radiation dimming and decreasing water clarity fuel underwater darkening in lakes

  Long-term decreases in the incident total radiation and water clarity might substantially affect the underwater light environment in aquatic ecosystems. However, the underlying mechanism and relative contributions of radiation dimming and decreasing water clarity to the underwater light environment on a national or global scale remains largely unknown. Here, we present a comprehensive dataset of unprecedented scale in China’s lakes to address the combined effects of radiation dimming and decreasing water clarity on underwater darkening. Long-term total radiation and sunshine duration showed 5.8% and 7.9% decreases, respectively, after 2000 compared to 1961–1970, resulting in net radiation dimming. An in situ Secchi disk depth (SDD) dataset in 170 lakes showed that the mean SDD significantly decreased from 1.80 ± 2.19 m before 1995 to 1.28 ± 1.82 m after 2005. SDD remote sensing estimations for 641 lakes with areas ≥ 10 km2 showed that SDD markedly decreased from 1.26 ± 0.62 m during 1985–1990 to 1.14 ± 0.66 m during 2005–2010. Radiation dimming and decreasing water clarity jointly caused an approximately 10% decrease in the average available photosynthetically active radiation (PAR) in the euphotic layer. Our results revealed a more important role of decreasing water clarity in underwater darkening than radiation dimming. A meta-analysis of long-term SDD observation data from 61 various waters further elucidated a global extensive underwater darkening. Underwater darkening implies a decrease in water quality for potable water supplies, recession in macrophytes and benthic algae, and decreases in benthic primary production, fishery production, and biodiversity.
  Spatial distribution of SDD differences during 2005–2016 compared to the 1960s–1995 (a), comparison of SDDs before 1995 to after 2005 according to the five geographic lake zones and the Hu Huanyong Line (b and c) for the dataset of 170 lakes.
  All: all lakes; EPL: Eastern Plain Lake zone; YGPL; Yunnan-Guizhou Plateau Lake zone; NPL: Northeast Plain Lake zone; IMXL: Inner Mongolia-Xinjiang Lake zone; TPL: Tibetan Plateau Lake zone; NW and SE represent results for lakes in the northwestern and southeastern regions of the Hu Huanyong Line.
  Yunlin Zhang, Boqiang Qin, Kun Shi, Yibo Zhang, Jianming Deng, Martin Wild et al., 2020. Science Bulletin. DOI:
Climate mediates continental scale patterns of stream microbial functional diversity

  Understanding the large-scale patterns of microbial functional diversity is essential for anticipating climate change impacts on ecosystems worldwide. However, studies of functional biogeography remain scarce for microorganisms, especially in freshwater ecosystems. Here we study 15,289 functional genes of stream biofilm microbes along three elevational gradients in Norway, Spain and China.
  We find that alpha diversity declines towards high elevations and assemblage composition shows increasing turnover with greater elevational distances. These elevational patterns are highly consistent across mountains, kingdoms and functional categories and exhibit the strongest trends in China due to its largest environmental gradients. Across mountains, functional gene assemblages differ in alpha diversity and composition between the mountains in Europe and Asia. Climate, such as mean temperature of the warmest quarter or mean precipitation of the coldest quarter, is the best predictor of alpha diversity and assemblage composition at both mountain and continental scales, with local non-climatic predictors gaining more importance at mountain scale. Under future climate, we project substantial variations in alpha diversity and assemblage composition across the Eurasian river network, primarily occurring in northern and central regions, respectively.
  We conclude that climate controls microbial functional gene diversity in streams at large spatial scales; therefore, the underlying ecosystem processes are highly sensitive to climate variations, especially at high latitudes. This biogeographical framework for microbial functional diversity serves as a baseline to anticipate ecosystem responses and biogeochemical feedback to ongoing climate change.
  Félix Picazo, Annika Vilmi, Juha Aalto, Janne Soininen, Emilio O. Casamayor, Yongqin Liu, Qinglong Wu, Lijuan Ren, Jizhong Zhou, Ji Shen & Jianjun Wang*. Microbiome. 2020. DOI:10.1186/s40168-020-00873-2
China's inland water dynamics: The significance of water body types

  The recent paper by Feng et al. analyzes the changes of China’s inland water bodies (WBs) between 1985-1999 and 2000-2015 based on the Global Surface Water Dataset (GSWD). They quantify the area and number of changes of WBs in different hydrological regions of China, and discuss the possible driving factors. Although this study provides a synoptic view of China’s WB dynamics at basin scales, we here convey a caveat that their basin-scale statistics aggregate the changes in various types of WBs, and, consequently, mask divergent changing patterns among the WB types that are critical for attributing causality.
  An explicit consideration of WB types is essential for understanding large-scale water dynamics. This is especially true for China, a vastly diverse country that descends from the “Roof of the World” to coastal deltas, and is a global hotspot of booming dam construction. In such a complex setting, WB types provide indispensable insight on sorting out water change mechanisms. To elucidate our point, we categorized China’s WBs larger than 1 km2 (~123,150 km2) into saline lakes (42%), freshwater lakes (35%), and artificial reservoirs (23%) based on national lake/reservoir surveys, and reexplored their area changes between the two 15-y epochs using GSWD. 
  China at a national scale, as reported in ref. 1, owned more WB area during this century than previously. Nevertheless, the increased WB area mainly stems from a net expansion of saline lakes (5,572.0 km2) and the reservoirs (3,925.8 km2). In contrast, China’s natural freshwater lakes underwent a net shrinkage of 324.8 km2. Most of the expanded saline lakes are distributed in remote endorheic regions such as the Changtang Plateau, indicating a dominant contribution of climate change. The shrinkage of freshwater lakes, however, mainly occurred in densely populated regions such as the Yangtze River basin (YZR) and the Hai River basin, due to extensive impoldering and rising human water consumption. This contrast implicates an aggravated unevenness of China’s natural freshwater accessibility despite a net national WB gain.
  At least 3,665 reservoirs (≥1 km2) have been added to mitigate freshwater stress in populated basins. About one-third of the newly impounded area (1,219.5 km2) occurred in the upper YZR, largely owing to the construction of monumental reservoirs such as the Three Gorges Reservoir and the Xiluodo Reservoir. Newly impounded reservoirs contribute over half of the total freshwater increase in several major basins such as YZR, the Pearl River basin, and the Yellow River basin, suggesting that human water regulation, rather than increased precipitation, was the first-order driver of the recent WB increase in China’s populated basins.
  Reporting aggregated water changes, as in ref. 1, is an important initiative, but we have to ask, Can the implemented analysis better address the ultimate purposes of WB monitoring, such as understanding causations? Unequivocally, WB variations of different types are driven by different mechanisms. Without an explicit consideration of WB types, regional aggregates not only obscure a thorough attribution of the spatially variable water dynamics but may lead to misinterpreted ramifications to water resource management.
  Fig 1. China's inland WBs (salt lakes, freshwater lakes, and reservoirs) and their area changes during 1985–2015.
  (A) Distribution of natural freshwater and saline lakes, with 1° latitude/longitude histograms of “absolutely increased (AI) area” and “absolutely decreased (AD) area.” AI and AD areas are referred to in Feng et al., which indicates water occurrence change intensity of 100% and ?100%, respectively. Saline lakes were identified from the Second China Lake Survey.
  (B) Distribution of natural freshwater lakes and artificial reservoirs, with 1° latitude/longitude histograms of AI and AD areas. Reservoirs were identified from the Global Reservoir and Dam Database and Almanac of China’s water power.
  (C) WB area changes in the same 11 basins/regions as defined in Feng et al.
  作者:Jingying Zhu, Chunqiao Song et al. PNAS. 2020. DOI: 10.1073/pnas.2005584117
Spatial variations of hydrochemistry and stable isotopes in mountainous river water from the Central Asian headwaters of the Tajikistan Pamirs
Water resources in Central Asia from the mountainous headwater catchments is changing due to the shrinkage of glaciers in the Tian Shan and Pamir mountain systems. In order to predict future changes in water quality, it is crucial to understand what factors are governing the spatial variations of water chemistry and hydrological processes in mountainous headwater catchments. In this study, water chemistry including major ions and stable isotopes in the headwaters of major Tajikistan rivers was studied. Results showed that Tajikistan river water had an alkaline pH value (mean: 8.2) and total dissolved solids (mean: 368.5mg/L) were higher than the global average value. Ca2+, Na+, HCO3-, and SO42- in the rivers were the most abundant cations and anions, controlled by the rock weathering process and evaporation-crystallization processes. The hydrochemical facies of river water was dominated by Ca-HCO3 (71.7%) and exhibited spatial heterogeneity, which was related to the lithologic compositions and water source across Tajikistan. A significant negative correlation of river water δ18O with elevation was observed with a vertical lapse rate of 0.17‰/100 m. The more negative δ18O values in rivers from eastern Tajikistan were scattered in the lower left corner of the δ18O-δ2H plot, implying that the rivers were primarily supplied by snow/glacier meltwater because of the substantial number of glaciers and high elevation mountain in eastern regions. The drinking and irrigation suitability from ionic compositions revealed that the water quality of Tajikistan rivers was naturally good, though some sites posed a safety concern. These findings can provide new insights into sustainable management of water quality in the climatically and lithologically distinct segments of headwater regions in the Tajikistan Pamirs.
  Spatial variations of δ18O (a) and d-excess (b) values in river water across Tajikistan
  Huawu Wu, Jinglu Wu, Jing Li, Congsheng Fu. 2020. Catena. DOI: