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Spatial Downscaling of the Tropical Rainfall Measuring Mission Precipitation Using Geographically Weighted Regression Kriging over the Lancang river Basin, China

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Chinese Geographical Science 2019年第3期29卷 446-462页

作者： LI Yungang ZHANG Yueyuan HE Daming LUO Xian JI Xuan institute of international rivers and eco-security Yunnan University Yunnan Key Laboratory of international rivers and Transboundary eco-security Yunnan University

Satellite-based precipitation products have been widely used to estimate precipitation, especially over regions with sparse rain gauge networks. However, the low spatial resolution of these products has limited their application in localized regions and *** study investigated a spatial downscaling approach, Geographically Weighted Regression Kriging(GWRK), to downscale the Tropical Rainfall Measuring Mission(TRMM) 3 B43 Version 7 over the Lancang river Basin(LRB) for 2001–2015. Downscaling was performed based on the relationships between the TRMM precipitation and the Normalized Difference Vegetation Index(NDVI), the Land Surface Temperature(LST), and the Digital Elevation Model(DEM). Geographical ratio analysis(GRA) was used to calibrate the annual downscaled precipitation data, and the monthly fractions derived from the original TRMM data were used to disaggregate annual downscaled and calibrated precipitation to monthly precipitation at 1 km resolution. The final downscaled precipitation datasets were validated against station-based observed precipitation in 2001–2015. Results showed that: 1) The TRMM 3 B43 precipitation was highly accurate with slight overestimation at the basin scale(i.e., CC(correlation coefficient) = 0.91, Bias = 13.3%). Spatially, the accuracies of the upstream and downstream regions were higher than that of the midstream region. 2) The annual downscaled TRMM precipitation data at 1 km spatial resolution obtained by GWRK effectively captured the high spatial variability of precipitation over the LRB. 3) The annual downscaled TRMM precipitation with GRA calibration gave better accuracy compared with the original TRMM dataset. 4) The final downscaled and calibrated precipitation had significantly improved spatial resolution, and agreed well with data from the validated rain gauge stations, i.e., CC = 0.75, RMSE(root mean square error) = 182 mm, MAE(mean absolute error) = 142 mm, and Bias = 0.78%for annual precipitation and CC = 0.9

关键词： precipitation Tropical Rainfall Measuring Mission(TRMM) 3B43 Geographically Weighted Regression Kriging(GWRK) spatial downscaling the Lancang river Basin,China

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Distribution and Susceptibility Assessment of Collapses and Landslides in the Riparian Zone of the Xiaowan Reservoir

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Chinese Geographical Science 2019年第1期29卷 70-85页

作者： ZHONG Ronghua HE Daming HU Jinming DUAN Xingwu HUANG Jiangcheng CHENG Xupeng institute of international rivers and eco-security Yunnan University Yunnan Key Laboratory of international rivers and Transboundary eco-security Yunnan University

The southwest alpine gorge region is the major state base of hydropower energy development in China and hence planned many cascading hydropower stations. After the reservoir impoundment, the intense water level fluctuations under the interaction of cascade dams operating and the mountainous flooding, usually cause bank collapse, landslide and debris flow hazards. The Xiaowan reservoir(XWR), for example, as the ‘dragon head' meg reservoir located in the middle mainstream of Lancang river, have resulted in a series of geohazards during its building and operating. In this study, we investigated the number and surface area of collapses and landslides(CLs) occurred in the water level fluctuations zone(WLFZ) of XWR using remote sensing images of Gaofen-1 and Google Earth; evaluated the CLs susceptibility using information value method. The results presented that the total WLFZ area of 87.03 km2 and 804 CLs masses with a total area of 1.98 km2 were identified in the riparian zone of XWR. CLs mainly occurred at an elevation of 1190–1240 m, and the CLs density increased with an increase in altitude. The WLFZ with a slope gradient of 25°– 45° is the main CLs distribution area that accounts for more than half of the total CLs area. The susceptibility assessment revealed that high and very high susceptibility zones are generally distributed along zones with an elevation of 1210–1240 m, a slope degree of 25°–45° and a slope aspect perpendicular to the direction of Lancang river. Furthermore, these susceptible zones are close in distance to the dam site and tend to be in the riparian zones with the formation lithology of Silurian strata. These results provide a valuable contribution to prevent and control geohazards in the XWR area. Moreover, this study offers a constructive sample of geohazards assessment in the riparian zone of large reservoirs throughout the mountains of southwest China.

关键词： susceptibility assessment collapses and landslides water level fluctuations Xiaowan Reservoir Lancang-Mekong river

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Global Trends in Dam Removal and Related Research: A Systematic Review Based on Associated Datasets and Bibliometric Analysis

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Chinese Geographical Science 2019年第1期29卷 1-12页

作者： DING Liuyong CHEN Liqiang DING Chengzhi TAO Juan Yunnan Key Laboratory of international rivers and Transboundary eco-security Yunnan University institute of international rivers and eco-security Yunnan University

Dam removal has been increasingly reported globally and is becoming an important approach for river management, restoration and environmental conservation in damming rivers. However, current limited knowledge of global trends in dam removal and related research may be potentially biased in terms of the geographic distribution and organisms studied. Such bias could mislead dam removal planning and management in different areas and ecological conservation for different taxa. In this study, we quantitatively and qualitatively analyzed datasets of dam removal and publications of dam removal research using bibliometric methods. A total of 1449 dam removal documents were published from 1953 to 2016. Trends, current hotspots and future directions of dam removal research were identified. The results from this study reveal that dam removal largely occurred in the North America and Europe, and most of the removed dams were small and old dams. With respect to the topic analysis, more dam removal studies should focus on the responses of a wide range of organisms, not only fish, as well as the interspecies relationships, food webs and ecosystem structures and functions. Based on our findings, we also provide some suggestions for future dam removal planning and analysis.

关键词： dam demolition literature research topics weir

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Estimation of glacier ice storage in western China constrained by field ground-penetrating Radar surveys

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Advances in Climate Change Research 2022年第3期13卷 359-374页

作者： Peng-Bin LIANG Li-De TIAN institute of international rivers and eco-security Yunnan UniversityKunming 650500China Yunnan Key Laboratory of international rivers and Transboundary eco-security Kunming 650091China

Recent decades have witnessed the accelerated retreat of alpine glaciers,which likely portends a decline in the glacial ice melt on which large downstream populations rely for ***,estimating water storage in alpine glaciers is critical for predicting the trend of glacier *** study compiled a rich set of ice thickness observations for glaciers of varying sizes in western *** here presented a first-order assessment of the various errors involved in interpreting ice thickness from ground-penetrating radar(GPR)*** empirical Bayesian kriging(EBK)method was used for ice thickness interpolation and volume *** then established a new volume-scaling law specific to western China glaciers based on these 36 volume-area *** together with the Second Chinese Glacier Inventory(SCGI),we obtain a regional volume estimate of 4451±298 km^(3).By comparison,we believed that this result is the most reliable estimate of the total ice storage in western China and more reliably predicts gross glacier ***,our results show that the method of glacier division can strongly affect the total volume estimation,which previous studies *** emphasizes the need for more surveyed glaciers data and more accurate glacier inventory to improve the evaluation of the climate impact on glacier melting water resources and to help ensure the future survival of these alpine glaciers.

关键词： Ground-penetrating radar Glacier thickness survey Glacier volume volume-area scaling law Distributed model Western China

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Forest disturbances and the attribution derived from yearly Landsat time series over 1990–2020 in the Hengduan Mountains Region of Southwest China

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Forest ecosystems 2021年第4期8卷 974-990页

作者： Yating Li Zhenzi Wu Xiao Xu Hui Fan Xiaojia Tong Jiang Liu institute of international rivers and eco-security Yunnan UniversityKunming 650091China Yunnan Key Laboratory of international rivers and Transboundary eco-security Kunming 650091China

Background:Natural forests in the Hengduan Mountains Region(HDMR)have pivotal ecological functions and provide diverse ecosystem *** long-term forest disturbance and drivers at a regional scale is crucial for sustainable forest management and biodiversity ***:We used 30-m resolution Landsat time series images and the LandTrendr algorithm on the Google Earth Engine cloud platform to map forest disturbances at an annual time scale between 1990 and 2020 and attributed causal agents of forest disturbance,including fire,logging,road construction and insects,using disturbance properties and spectral and topographic variables in the random forest ***:The conventional and area-adjusted overall accuracies(OAs)of the forest disturbance map were 92.3% and 97.70%±0.06%,respectively,and the OA of mapping disturbance agents was 85.80%.The estimated disturbed forest area totalled 3313.13 km^(2)(approximately 2.31% of the total forest area in 1990)from 1990 to 2020,with considerable interannual fluctuations and significant regional *** predominant disturbance agent was fire,which comprised approximately 83.33% of the forest area disturbance,followed by logging(12.2%),insects(2.4%)and road construction(2.0%).Massive forest disturbances occurred mainly before 2000,and the post-2000 annual disturbance area significantly dropped by 55% compared with the pre-2000 ***:This study provided spatially explicit and retrospective information on annual forest disturbance and associated agents in the *** findings suggest that China’s logging bans in natural forests combined with other forest sustainability programmes have effectively curbed forest disturbances in the HDMR,which has implications for enhancing future forest management and biodiversity conservation.

关键词： Change detection Disturbance attribution Landsat LandTrendr Hengduan Mountains region

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Hydrologic Response to Future Climate Change in the Dulong-Irra-waddy river Basin Based on Coupled Model Intercomparison Project 6

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Chinese Geographical Science 2024年第2期34卷 294-310页

作者： XU Ziyue MA Kai YUAN Xu HE Daming institute of international rivers and eco-security Yunnan UniversityKunming 650500China Yunnan Key Laboratory of international rivers and Transboundary eco-security Kunming 650500China

Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)river,an international river among China,India and Myanmar,plays a significant role as both a valuable hydro-power resource and an essential ecological ***,the water resources and security exhibit a high degree of vulnerabil-ity to climate change *** research evaluates climate impacts on the hydrology of the Dulong-Irrawaddy river Basin(DIRB)by using a physical-based hydrologic *** crafted future climate scenarios using the three latest global climate models(GCMs)from Coupled Model Intercomparison Project 6(CMIP6)under two shared socioeconomic pathways(SSP2-4.5 and SSP5-8.5)for the near(2025-2049),mid(2050-2074),and far future(2075-2099).The regional model using MIKE SHE based on historical hydrologic processes was developed to further project future streamflow,demonstrating reliable performance in streamflow simulations with a val-idation Nash-Sutcliffe Efficiency(NSE)of *** showed that climate change projections showed increases in the annual precip-itation and potential evapotranspiration(PET),with precipitation increasing by 11.3%and 26.1%,and PET increasing by 3.2%and 4.9%,respectively,by the end of the century under SSP2-4.5 and *** changes are projected to result in increased annual streamflow at all stations,notably at the basin’s outlet(Pyay station)compared to the baseline period(with an increase of 16.1%and 37.0%at the end of the 21st century under SSP2-4.5 and SSP5-8.5,respectively).Seasonal analysis for Pyay station forecasts an in-crease in dry-season streamflow by 31.3%-48.9%and 22.5%-76.3%under SSP2-4.5 and SSP5-8.5,respectively,and an increase in wet-season streamflow by 5.8%-12.6%and 2.8%-33.3%,***,the magnitude and frequency of flood events are pre-dicted to escalate,potentially impacting hydropower production and food security *** res

关键词： climate change hydrologic response Coupled Model Intercomparison Project 6(CMIP6) MIKE SHE(Système Hydrologique Europeén) Dulong-Irrawaddy river Basin

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Spatiotemporal variation of snow cover and its relationship with temperature and precipitation in the Yarlung Tsangpo-Brahmaputra river Basin

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Journal of Mountain Science 2022年第7期19卷 1901-1918页

作者： GUO Ruo-yu JI Xuan LIU Chun-yu LIU Chang JIANG Wei YANG Lu-yi institute of international rivers and eco-security Yunnan UniversityKunming650091China Yunnan Key Laboratory of international rivers and Transboundary eco-security Yunnan UniversityKunming650091China

The snow cover over the Qinghai-Tibet Plateau(QTP)and its surrounding areas is very sensitive to climate *** to the complexity of geographical environment in this large region,the response of snow cover to climate change should exhibit spatiotemporal *** this study,the spatiotemporal variations of snow cover from 2002-2015 in the Yarlung Tsangpo-Brahmaputra river Basin(YBRB)were analyzed using an optimized fractional snow cover(FSC)product derived from Moderate Resolution Imaging Spectroradiometer(MODIS).Additionally,the effects of temperature and precipitation on the variability of snow cover were also *** results showed that:(1)The snow cover exhibited large spatial and temporal heterogeneity in the *** FSC was observed in the northeast of the basin and the south slope of Himalaya,while the lowest was concentrated in the broad valley of the upstream of *** FSC value reached its highest in winter and dropped to its lowest in summer,but the monthly change processes were different between upstream and downstream regions.(2)A slightly increasing tendency(3.76%/10 a)of snow cover was observed on basin-wide,but the changes varied through time and *** FSC increased significantly in the source and midstream regions during winter to spring(10.5%-18.0%/10 a),while it changed slightly in summer over all parts of the basin(-0.4%-4.3%/10 a).(3)The study area generally became warm and wet,and the change trend of temperature was more significant than that of *** cover changes were weakly correlated with temperature in winter and precipitation in *** in spring and autumn,both precipitation and temperature were significantly related to snow cover change in most regions of the basin.(4)The dominant factor driving the changes of snow cover varied in *** area dominated by temperature was slightly larger than that dominated by precipitation in spring,except that precipitation significantly dominated the sno

关键词： Yarlung Tsangpo-Brahmaputra river Basin MODIS Fractional snow cover Climate change international rivers

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GIS and DEM based analysis of incision and drainage reorganization of the Buyuan river basin in the upper Lancang-Mekong of China since the Late Pleistocene

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Journal of Geographical Sciences 2020年第9期30卷 1495-1506页

作者： GU Zhenkui FAN Hui YANG Kun Yunnan Key Laboratory of In ternational rivers and Tran sbo un dary eco-security Institute of International Rivers and Eco-SecurityYunnan UniversityKunming 650091China

river incision and drainage reorganization have an important impact on the site selection of many major projects including city,road and others,and are the key issues of Quaternary environmental *** of river incision and river-network adjustment have traditionally been based on extensive field evidence,such as sediment age and beheaded river *** Buyuan river basin is a large sub-basin of the upper Lancang-Mekong,with high mountains and extremely active *** latter affects the preservation of the Quaternary period sediments leading to difficulties in understanding the main evolution characteristics of the *** study investigates differences in the equilibrium state of the longitudinal profile,infers incision rates,and evaluates drainage divide migration timelines using the stream-power incision model,the latest morphological dating,and Chi-plots(χ–z) based on digital elevation models(DEMs) on the GIS software *** final results show that two significant erosion base-level decreases occurred in the Late Pleistocene at *** incision rate of the mainstream might have been 0–2.99 mm/yr since 100 ka BP and 0–3.28 mm/yr since 46 ka *** Chi-values across the divides suggest that space limited(or constrained) river reorganization and that there is no severe reorganization in the basin;the imbalance of traceable erosion only exists in local *** main driving force for the geomorphologic evolution of the Buyuan river basin is likely climate fluctuations rather than strong tectonic uplift since the Late Pleistocene.

关键词： incision rate river reorganization morphometric dating Buyuan river Lancang-Mekong

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Controls on geomorphic characteristics of the Xiaohei river basin in the upper Lancang-Mekong, China

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Journal of Mountain Science 2020年第5期17卷 1032-1044页

作者： GU Zhen-kui FAN Hui LOU Jun-peng YANG Kun Yunnan Key Laboratory of international rivers and Transboundary eco-security Institute of International Rivers and Eco-SecurityYunnan UniversityKunming 650091China Department of Hydraulic Engineering Tsinghua UniversityBeijing 10084China

Understanding the evolution of the fluvial geomorphology in an orogenic belt provides valuable insight into the relationship between upper crustal deformation and surface *** upper Lancang-Mekong river is in an area experiencing both uplift and *** related processes provide a steady sediment supply to the lower reaches of the river and play an important role in the regional environmental *** Xiaohei(Weiyuan)river Basin is an important sub-basin in this area,which is characterized by large-scale topographic fluctuations,active tectonics and erosion,and anthropogenic *** different factors introduce numerous complexities to the local surface *** this study,we investigate and quantify the controls of geomorphic evolution of the Xiaohei river *** located and mapped the main knick-zones within the channels and examined the main genetic factors,such as faults and stratigraphic *** results show that the areas with the lowest uplift rates are characterized by a low steepness index and are located in the southeastern part of the *** stream power of the mainstream increases downstream,with an average value of^122 W/*** erosional activity of the various stream channels is ***,the basin tends to expansion,with only local instances of inward *** analysis confirms that a number of the geomorphic evolutionary characteristics of the Xiaohei river Basin are *** addition,the future potential for the increasing the number of dams and the hydropower development in the basin may weaken the expansion trend of the basin over a long period of time.

关键词： Longitudinal profile Steepness Divide migration Stream power Hydropower development Lancang

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Surrogacy of bird species in systematic conservation planning and conservation assessments in Yunnan Province,China

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Journal of Mountain Science 2022年第10期19卷 2861-2873页

作者： ZHOU Jian YANG Fei-ling ZHONG Zi-jie ZHANG Ji LENG Xian YE Jin WU Rui-dong Conservation Biogeography Research Group Institute of International Rivers and Eco-securityYunnan UniversityKunming 650091China Yunnan Key Laboratory of international rivers and Transboundary eco-security Yunnan UniversityKunming 650091China

Bird diversity is often used as surrogates for other species diversity,but there is a limited understanding of the extent of this surrogate in identifying representative priority conservation areas(PCAs).We used Yunnan Province in China as a case to measure the surrogacy of birds in systematic conservation ***,we collected distribution records of mammals,amphibians,reptiles,and birds from public databases and literature,and applied systematic conservation planning methods to identify *** targeted four taxonomic groups at conservation targets of 17%,31%,and 50%of the total study area,and used the Jaccard similarity index to evaluate the surrogate extent of bird PCAs for the other three ***,we overlapped different portfolios of PCAs with six categories of protected areas(PAs)in Yunnan,calculated the protection rates,and evaluated the effect of sustainable-use PAs on improving the protection rate of strict Nature *** results showed that bird PCAs generally had the highest surrogacy for representing PCAs of the other three *** the 50%conservation target,the Jaccard indices between birds and the other taxa reached about ***,amphibian PCAs had a good surrogacy for conserving reptiles,with a Jaccard index of 0.30,0.44 and 0.51 at the 17%,31%and 50%conservation targets,*** existing PA system had quite low coverages for PCAs of these four taxa,and the average protection rates were 22.97%,19.78%and 16.52%at the three levels of conservation targets,*** sustainable-use PAs can greatly complement the strict Nature Reserves by achieving average increased PA coverages of 10.00%,9.20%and 7.90%at the three conservation *** findings provide a basis for surrogate-based conservation planning for areas with insufficient biodiversity information.

关键词： Biodiversity surrogates Priority conservation areas Protected areas Systematic conservation planning Threatened species Yunnan

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