Global reanalysis precipitation products could provide valuable meteorological information for flow forecasting in poorly gauged areas, helping to overcome a long-standing challenge in the field. But not all data sour...Global reanalysis precipitation products could provide valuable meteorological information for flow forecasting in poorly gauged areas, helping to overcome a long-standing challenge in the field. But not all data sources are suitable for all regions or perform the same way in hydrological modeling, so it is essential to test the suitability of precipitation products before applying them. In this study, five widely used global high-resolution precipitation products—Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of Water Resources(APHRODITE), National Centers for Environmental Prediction Climate Forecast System Reanalysis(NCEP-CFSR), Climate Hazards Group InfraRed Precipitation with Station Data(CHIRPS), China Gauge-based Daily Precipitation Analysis developed by China Meteorological Administration(CMA) and Agricultural Model Intercomparison and Improvement Project based on the NASA Modern-Era Retrospective Analysis for Research and Applications(AgMERRA)—were evaluated using statistical methods and a hydrological approach for their suitability for the Lancang River Basin. The results indicated that APHRODITE, CMA, AgMERRA and CHIRPS were more accurate precipitation indicators than NCEP-CFSR in terms of the multiyear average and seasonal spatial distribution pattern, all of the CHIRPS, Ag MERRA and APHRODITE perform better than CMA and NCEP-CFSR at the small, medium and high precipitation intensities ranges in subbasin11 and sunbabsin46. All five products performed better in subbasin46(a low-altitude region) than in subbasin11(a high-altitude region) on the daily and monthly scales. In addition to NCEP-CFSR, the other four products all presented encouraging potential for streamflow simulation at daily(Yunjinghong) and monthly(Yunjinghong, Jiuzhou and Gajiu) scale. Hydrological simulations forced with APHRODITE were the best of the five for the Yunjinghong station in capturing daily and monthly measured streamflow. Except for NCEP-CFSR, all products were very good for hydrological simulations for the Gajiu and Jiuzhou stations.展开更多
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 ...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 watersheds.This 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 = 0.95, RMSE = 25 mm, MAE = 16 mm, and Bias = 0.67% for monthly precipitation.展开更多
The Lancang River Watershed is one of the most biologically diverse areas in the world. The river flows through Yunnan Province, China, which suffered serious deforestation since the 1980s;this in turn led to increase...The Lancang River Watershed is one of the most biologically diverse areas in the world. The river flows through Yunnan Province, China, which suffered serious deforestation since the 1980s;this in turn led to increased soil erosion in the region. To investigate the influence of the spatial distribution of land use and slope on soil erosion in the Lancang River Watershed, the Soil and Water Assessment Tool (SWAT) model was used to establish hydrological models using two-phase land use maps (1975 and 1985), a soil map, and meteorological data from 11 gauging stations. The satisfactory values of Nash-Sutcliffe efficiency Ens and correlation coefficient R2 during the calibration and validation period indicated that SWAT can be used in this area to simulate the average annual soil erosion under different land use scenarios change. By comparing soil erosion rate under different land use scenarios change, forests and grasslands had similar effects on preventing soil erosion. A parameter, soil erosion increment (Ei), was used to assess the effects of slope on soil erosion. The results revealed that variation in sediment yield was more sensitive to land use change for slopes exceeded 25° than for slopes being 0° - 15°. The spatial distribution of land use also had a relationship to soil erosion. Compared with the soil erosion rate in each sub-watershed using two-phase land use maps, the soil erosion rate increased when the percent cover of natural vegetation decreased. The results of this study provide baseline data for soil conservation and protection of the environment and ecology of the Lancang River Watershed in Yunnan Province.展开更多
The Lancang-Mekong River has attracted much attention from researchers, but the cooperation on water issues in this river basin has been limited, even after the establishment of the Mekong River Commission(MRC). Coope...The Lancang-Mekong River has attracted much attention from researchers, but the cooperation on water issues in this river basin has been limited, even after the establishment of the Mekong River Commission(MRC). Cooperation on water resources has been determined as one of the key priority areas in the Lancang-Mekong Cooperation Mechanism, but there are no details of targets. In order to establish the priorities of water cooperation under the mechanism, we adopted nine categories to classify the objectives of 87 water cooperation events based on the ‘Lancang-Mekong Water Cooperative Events Database' from 1995 to 2015. Based on the occurrence of cooperative events, cooperative objectives, cooperative scales, and approaches to cooperation, we conducted statistical, correlation, and text analyses. Our analyses indicated the following results: under the impact of economic conditions inside and outside the river basin, full cooperation appeared more difficult than bilateral and multilateral cooperation. Each of the partners adopted different preferences for cooperation targets. Cooperation with more definite objectives was easier to establish than cooperation with broader and more complex objectives. The potential objectives for water cooperation were navigation, hydropower, joint management, data sharing, flood control and water use. Because hydropower development is controversial, and because water cooperation is avoided by most existing regional cooperation mechanisms due to its complexity, we suggest the following priority areas for water cooperation in the Lancang-Mekong River Basin. 1) Navigation and flood control/drought relief are attractive objectives for all the riparian countries across the whole watershed. 2) Data sharing should be a priority for cooperation in the watershed due to its laying the foundation for the equitable and reasonable utilization of transboundary waters. 3) Hydropower is an objective best implemented mainly through bilateral cooperation, and on tributaries.展开更多
The Lancang–Mekong River basin(LMRB) is under increasing threat from global warming. In this paper, the projection of future climate in the LMRB is explored by focusing on the temperature change and extreme temperatu...The Lancang–Mekong River basin(LMRB) is under increasing threat from global warming. In this paper, the projection of future climate in the LMRB is explored by focusing on the temperature change and extreme temperature events. First, the authors evaluate the bias of temperature simulated by the Weather Research and Forecasting model. Then, correction is made for the simulation by comparing with observation based on the non-parametric quantile mapping using robust empirical quantiles(RQUANT) method. Furthermore, using the corrected model results, the future climate projections of temperature and extreme temperature events in this basin during 2016–35, 2046–65, and 2080–99 are analyzed. The study shows that RQUANT can effectively reduce the bias of simulation results. After correction, the simulation can capture the spatial features and trends of mean temperature over the LMRB, as well as the extreme temperature events. Besides, it can reproduce the spatial and temporal distributions of the major modes. In the future, the temperature will keep increasing, and the warming in the southern basin will be more intense in the wet season than the dry season. The number of extreme high-temperature days exhibits an increasing trend, while the number of extreme low-temperature days shows a decreasing trend. Based on empirical orthogonal function analysis, the dominant feature of temperature over this basin shows a consistent change. The second mode shows a seesaw pattern.展开更多
According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and devel...According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.展开更多
Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of ...Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the surface sediments of 11 sections in the lower Lancang River during flood season are analyzed, as well as the distribution of phosphorus in different forms. The main sources of TOC and its correlation with TN and TP are discussed and, finally, the pollution levels of the surface sediments are evaluated. The results show that the average content of TOC in the surface sediments of the lower Lancang River is 9003.75 mg/kg. The average TN content is 893.79 mg/kg, while the average TP content is 521.35 mg/kg. The TOC in the surface sediments of the lower Lancang River is derived mainly from algae and plankton in the river, and the TN and TP have similar sources. The total phosphorus in the surface sediments of the lower Lancang River is composed mainly of calcium-bound phosphorus (Ca-P). The evaluations of the organic pollution index and comprehensive pollution index show that the surface sediment pollution degree at the upper sections of the Nuozhadu and Jinghong Dams are more serious than those below the dams. Furthermore, the tributary sections are all slightly polluted, with the exception of the Mengyang River, which is considered moderately polluted.展开更多
It remains unclear whether the elevational diversity gradients observed in seed plants across different taxonomic levels (family, genus, and species) are driven by the same macro-environmental variables. In this stu...It remains unclear whether the elevational diversity gradients observed in seed plants across different taxonomic levels (family, genus, and species) are driven by the same macro-environmental variables. In this study, seed plant elevational distribution data from the Lancang River Nature Reserve (Yunnan, China) were used to investigate spatial patterns in diversity and their environ- mental correlates, comparing across taxonomic levels. Environmental variables included energy availability, climate seasonality and environmental heterogeneity. All taxonomic levels (family, genus, and species) were found to have strong elevational richness gradients, with the strength of the gradient weakening at higher taxonomic levels. Spatial patterns in richness were explained by a combination of contemporary environmental variables and the mid-domain effect at all taxonomic levels. The independent effects of temperature- and precipitation-related variables were similar in explaining geographical patterns of family, genus and species richness. Energy, seasonality and heterogeneity variables influenced seed plant spatial richness at different taxonomic levels in similar ways.展开更多
Satellite-based products with high spatial and temporal resolution provide useful precipitation information for data-sparse or ungauged large-scale watersheds. In the Lower Lancang-Mekong River Basin, rainfall station...Satellite-based products with high spatial and temporal resolution provide useful precipitation information for data-sparse or ungauged large-scale watersheds. In the Lower Lancang-Mekong River Basin, rainfall stations are sparse and unevenly distributed, and the transboundary characteristic makes the collection of precipitation data more difficult, which has restricted hydrological processes simulation. In this study, daily precipitation data from four datasets(gauge observations, inverse distance weighted(IDW) data, Tropical Rainfall Measuring Mission(TRMM) estimates, and Climate Hazards Group InfraRed Precipitation with Stations(CHIRPS) estimates), were applied to drive the Soil and Water Assessment Tool(SWAT) model, and then their capability for hydrological simulation in the Lower Lancang-Mekong River Basin were examined. TRMM and CHIRPS data showed good performances on precipitation estimation in the Lower Lancang-Mekong River Basin, with the better performance for TRMM product. The Nash-Sutcliffe efficiency(NSE) values of gauge, IDW, TRMM, and CHIRPS simulations during the calibration period were 0.87, 0.86, 0.95, and 0.93 for monthly flow, respectively, and those for daily flow were 0.75, 0.77, 0.86, and 0.84, respectively. TRMM and CHIRPS data were superior to rain gauge and IDW data for driving the hydrological model, and TRMM data produced the best simulation performance. Satellite-based precipitation estimates could be suitable data sources when simulating hydrological processes for large data-poor or ungauged watersheds, especially in international river basins for which precipitation observations are difficult to collect. CHIRPS data provide long precipitation time series from 1981 to near present and thus could be used as an alternative precipitation input for hydrological simulation, especially for the period without TRMM data. For satellite-based precipitation products, the differences in the occurrence frequencies and amounts of precipitation with different intensities would affect simulation results of water balance components, which should be comprehensively considered in water resources estimation and planning.展开更多
The Lancnag Mekong River is the most important international river across China and Southeast Asia, If it is developed according to 'Great Mekong Subregional Cooperation Plan' [9] prepared by ADB, the area di...The Lancnag Mekong River is the most important international river across China and Southeast Asia, If it is developed according to 'Great Mekong Subregional Cooperation Plan' [9] prepared by ADB, the area directly affected will be up to over 2.32 million km 2, the population over 220 million, and the natural environment, and socio-economic conditions within a large area will be greatly changed. 'Agreement on Cooperation for Sustainable Development of Mekong Basin' signed by the four riparian countries along the lower Mekong River on April 5, 1995 provides a new opportunity for sustainable development of the Basin. According to preliminary analysis, if the multipurpose utilization of the water resources is the target for carrying out integrated planning and management, and the efforts are made 1) to focus on energy exploitation on the Lancang River Mainstream and the tributaries of the lower Mekong River; 2) to build gated weirs at Tonle Sam; 3) to construct spillways at the Mekong Delta; 4) to facilitate flood dykes in big cities and on both banks of the mainstream which are concentrated with population and farmland and liable to be flooded, and 5) to strengthen networks for forecasting hydrological and meteorological conditions, then all problems such as power demand, irrigation, flood, salt water intrusion as well as acid water erosion to soil could be solved without constructing large cascaded stations and dams on the lower Mekong Mainstream. This will not only avoid input of great number of fund, large scale resettlement and land inundation, but also prevent aquatic organisms living in Mekong River from being injured due to dam construction, and promote the sustainable development of the Basin.展开更多
The Jinsha River-Lancang River-Nujiang River area is one of the important prospect areas for noble metal and nonferous metal deposits of China. Of a great variety of gold deposits present in this area, the following t...The Jinsha River-Lancang River-Nujiang River area is one of the important prospect areas for noble metal and nonferous metal deposits of China. Of a great variety of gold deposits present in this area, the following types seem to be economically most valuable and promising: tectonic alteration type in ophiolitic melange; polymetallic quartz vein type related to intermediate-acid intrusions; finely disseminated type in fracture zones; mixed hydrothermal type in tectonic fractures of carbonate rocks; hydrothermal type related to subvolcanic rocks; volcanic-hot spring type; submarine volcano exhalation-sedimentary-hydrothermal reformation type. Metallogenic epochs are exclusively Mesozoic and Cenozoic, and ore deposits and orebodies are controlled by linear structures. Magmatic activity has affected gold mineralization in varying degrees, and gold deposits are basically of mesothermal-epithermal type with ubiquitous and intense alterations. Ore-forming materials and hydrothermal solutions show multi-source character.展开更多
Specialists think tectonic mixtite zone in Lancang River, which lies in southern and eastern fringe of Qingzang plateau, is the suture line (or contact strip) between Gondwana Land and Yangtz block (Fan Chengjun, 1982...Specialists think tectonic mixtite zone in Lancang River, which lies in southern and eastern fringe of Qingzang plateau, is the suture line (or contact strip) between Gondwana Land and Yangtz block (Fan Chengjun, 1982; Liu Zhengqian, etc, 1991; Fang Runsen,1993).By regional geological study (Legend:1∶50000) in Tu’e, western Yunnan, the author think major fracture zone about 6\|8km from western Lancang River is fragile\|ductile shear zone between batholithic granite of Biluo snow mountain and Jurassic\|Cretaceous slight curdle strata. The zone is a very complicated tectonic mixtite zone (width:0.7\|6km; strike: SN\|direction). Study based on geometric structure, constitution, metamorphism, deformation and kinematic characteristics, the author sum up the following features about the complex deformation zone.(1) Tectonic mixtite zone is a very complicate blocks made up of curdle blocks and residual blocks of granite. Its’ geometric structure is a net\|shape structure composed of matrixes and chaotic blocks in plane and have two kinds of structure types (obduction schists in early diagenesis and heteroploytypes in late diagenesis) in section.展开更多
Carbon cycle is one of the focuses of climate change, river carbon is an important part, while dissolved inorganic carbon (DIC) has a high proportion of river carbon flux. In this study, we did the research on the Lan...Carbon cycle is one of the focuses of climate change, river carbon is an important part, while dissolved inorganic carbon (DIC) has a high proportion of river carbon flux. In this study, we did the research on the Lancang River, an important international river in the southwest of China. Water samples were obtained from 16 sections of the middle and lower reaches of the Lancang River in 2016 (11 months), then we monitored some water quality indicators and DIC content, finally analyzed the temporal-spatial distribution characteristics of DIC and the relationship between DIC content and water environment factors. The results showed that: (1) DIC contents in the middle and lower reaches of the Lancang River varied from 1.1840 mmol/L to 3.1440 mmol/L, with a mean value of about 2.2155 mmol/L. (2) At a time scale, DIC contents of dry season (spring, autumn and winter) were higher than rainy season (summer). At a space scale, DIC contents of the middle and lower reaches of the Lancang River gradually decreased from north to south, and each reservoir had the same characteristics, that is, DIC contents at upstream of the dam was lower than those at downstream of the dam. Compared to other rivers with cascade dams around the world, DIC contents within studied river were at similar level. And the reservoir’s effect of the Lancang River were not obvious, however, DIC contents in the water sampled upstream the dams had a slight stratification. (3) Water temperature, conductivity, turbidity were important factors affecting DIC content of water, and the effect of oxidation and reduction potential (ORP) and pH on DIC was relatively small.展开更多
Drought is one of the main natural disasters that cause economic loss in the basins of international rivers such as Nujiang and Lancang rivers. Based on the monthly precipitation and temperature data of 31 meteorologi...Drought is one of the main natural disasters that cause economic loss in the basins of international rivers such as Nujiang and Lancang rivers. Based on the monthly precipitation and temperature data of 31 meteorological stations in Nujiang and Lancang river basins in Yunnan Province during 1965-2013, the standardized precipitation evapotranspiration index(SPEI) in each of the two bio-climate zones was calculated. In addition, the drought process in annual, seasonal and monthly scale was analyzed respectively to reveal the spatial and temporal characteristics and the intensity variation of meteorological drought in Nujiang and Lancang river basins in Yunnan Province. The results showed that there was a significant increasing trend in seasonal(especially winter's) and monthly drought since the late 1970 s; the drought occurred in the two bio-climate zones showed no obvious spatial distinction, and it was synchronized with that occurred throughout Yunnan Province; and in the recent 50 years, the significant increase of drought in the study area may be attributed to the significant rise in temperature, rather than the slight decline of the precipitation.展开更多
Based on high-resolution Google Earth images,settlements in Yunnan section of the Lancang River basin were extracted.We use the kernal density and the optimized hot spot analysis methods to display spatial pattern of ...Based on high-resolution Google Earth images,settlements in Yunnan section of the Lancang River basin were extracted.We use the kernal density and the optimized hot spot analysis methods to display spatial pattern of the settlements.Random forest model is used to explore the natural environmental impact factors of residential areas distribution.The results show that settlements in Yunnan section of the Lancang River basin are mainly distributed in the middle reaches and the upper reaches along the river.The random forest model contains 11 environmental factors,and the top three factors in importance are the nearest distance to forest,altitude and the nearest distance to glacier/snow.The partial dependence plots show the response trend of settlements to environmental factors.This research results could provide guidance for rational use of land resources,making regional development and construction plans,and coordinating the relationship between humans and the environment.展开更多
In this paper, we conduct research on the national traditional sports resources in Lancang river valley under culture oriented background. Really in Chinese traditional sports culture must be confirmed and reflect on ...In this paper, we conduct research on the national traditional sports resources in Lancang river valley under culture oriented background. Really in Chinese traditional sports culture must be confirmed and reflect on the moment, only a clear definition of the concept of national traditional sports and category, figuring out what is the Chinese nationality traditional sports activity, which is a folk activity, and modern competitive sports, we can suit the remedy to the case, targeted, heritage and development path of the respective work, realize the diversification of the Chinese nation traditional culture heritage and development. Specifically the Lancang river valley region sports should be payed special attention for the preservation of the tradition.展开更多
Groundwater is an important and readily available source of fresh water in the Mekong-Lancang River Basin. With a rapid population growth and increasing human activities, an increasing number of countries in the Mekon...Groundwater is an important and readily available source of fresh water in the Mekong-Lancang River Basin. With a rapid population growth and increasing human activities, an increasing number of countries in the Mekong-Lancang River Basin are experiencing depleted and degraded groundwater supplies. In transboundary river basins, such as the Mekong-Lancang River, prioritizing the use of the shared aquifer by one riparian government may affect the opportunities of other riparian governments and lead to potential water conflicts between neighboring countries. To promote the sharing of strategies and information for the sustainable and equitable use of water resources of the shared basin, international collaborative workshops on groundwater resources have been organized for all Mekong-Lancang River countries. These workshops provide an opportunity to communicate and discuss nationally sensitive issues on groundwater by the associated countries, with topics covering multiple aspects of groundwater, such as the groundwater status in the basin, quality issues, water use conflicts, hydrological information gaps, management policies and capacity building for successful water resource management. Consensus has been reached by all countries on the importance of catchment-based groundwater management and the need for close communication among the countries. Strategies for managing transboundary aquifer issues must foster international collaboration based on the regional network, influence national networks and enhance the capacity to building maps and monitoring systems based on associated databases. The sustainability of water resources cannot be achieved without the integrated involvement and contributions by multiple countries and various stakeholders. Therefore, collaborative workshops provide a great opportunity to further our understanding of the hydrologic processes of the Mekong River Basin, share the benefits of the aquifer and provide a strategy and vision for sustainable water resource management in the Mekong-Lancang River countries.展开更多
The Lancang-Mekong River in China, Laos, Thailand, Myanmar, Cambodia, and Vietnam is the soul and heart of mainland Southeast Asia. Over 60 million people depend on the river and its tributaries for food, transportati...The Lancang-Mekong River in China, Laos, Thailand, Myanmar, Cambodia, and Vietnam is the soul and heart of mainland Southeast Asia. Over 60 million people depend on the river and its tributaries for food, transportation, water, and other necessities of life. The river supports one of the world’s most diverse fisheries, second only to Brazil’s Amazon River. Lancang-Mekong and tributaries are already heavily dammed primarily in China, Laos, Thailand, and Cambodia, with many more dams planned or under construction. Dams can worsen the impact of periodic droughts in the Lancang-Mekong basin and block the river’s “pulse effect” that spreads water and nutrients needed for fishing and farming onto the floodplains and delta. The headwaters of the Lancang are in China and its waters are considered a national resource. China regards the Lancang, Yangtze and Yellow rivers as a free resource rather than a shared resource. The primary difference between these rivers is the Lancang flows from China into and through other countries and not directly into a sea or ocean. China and Myanmar have not joined the Mekong River Commission (MRC) as full members but have been Dialogue Partners since 1996. Over the past thirty years, China’s Lancang policies and actions have reflected its national resource interests. China has actively engaged with individual transboundary countries at various levels including environmental, conservation, and economic agreements. The primary objective of this study is to assess the environmental and human impacts of all Lancang-Mekong mainstem and tributary dams and the plans by many countries for more hydropower utilizing the potential of the river as the continent’s energy lifeline. Future dams need to include fish ladders and navigation locks to reduce the environmental impacts on fish populations, natural resources, navigation, and livelihoods. Strengthening of international collaboration via the MRC or by individual or multiple country agreements to address Lancang-Mekong’s sustainable transboundary development goals is recommended. When new Lancang-Mekong and tributary dams are built within any of the transboundary watershed countries, additional communities will need to be resettled. Significant environmental and human impacts are observed. Steps will have to be taken by all the concerned countries to prevent these problems and to ensure that people’s livelihoods are restored after resettlement.展开更多
The western part of China borders on South and Southeast Asia. Of the numerous well known international rivers sharing with the two regions, the Lancang Mekong River has been most extensively studied in the world fo...The western part of China borders on South and Southeast Asia. Of the numerous well known international rivers sharing with the two regions, the Lancang Mekong River has been most extensively studied in the world for its important strategic position, rich resources, prosperous potential market as well as considerable opportunities for investment and development. The sustainable multipurpose development in this area has increasingly become the focus of international regional cooperation, and great attention has been paid to this area by the international society. Up to now, at least 10 major actions in the international regional cooperation are expected in this area. This paper intends, at the angle of geography and with the overall target of promoting the sustainable development in the basin through international cooperations, to study the international position, the potential and the prospects for development of the Lancang Mekong River, to analyze the main problems in this international cooperation, to propose targets and prospects for such cooperation, and to indicate the way for geographers to participate in such research.展开更多
基金National Key Research and Development Programs of China(No.2016YFA0601601,2016YFA0601501)National Natural Science Foundation of China(No.41330854,51779144,51779146)
文摘Global reanalysis precipitation products could provide valuable meteorological information for flow forecasting in poorly gauged areas, helping to overcome a long-standing challenge in the field. But not all data sources are suitable for all regions or perform the same way in hydrological modeling, so it is essential to test the suitability of precipitation products before applying them. In this study, five widely used global high-resolution precipitation products—Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of Water Resources(APHRODITE), National Centers for Environmental Prediction Climate Forecast System Reanalysis(NCEP-CFSR), Climate Hazards Group InfraRed Precipitation with Station Data(CHIRPS), China Gauge-based Daily Precipitation Analysis developed by China Meteorological Administration(CMA) and Agricultural Model Intercomparison and Improvement Project based on the NASA Modern-Era Retrospective Analysis for Research and Applications(AgMERRA)—were evaluated using statistical methods and a hydrological approach for their suitability for the Lancang River Basin. The results indicated that APHRODITE, CMA, AgMERRA and CHIRPS were more accurate precipitation indicators than NCEP-CFSR in terms of the multiyear average and seasonal spatial distribution pattern, all of the CHIRPS, Ag MERRA and APHRODITE perform better than CMA and NCEP-CFSR at the small, medium and high precipitation intensities ranges in subbasin11 and sunbabsin46. All five products performed better in subbasin46(a low-altitude region) than in subbasin11(a high-altitude region) on the daily and monthly scales. In addition to NCEP-CFSR, the other four products all presented encouraging potential for streamflow simulation at daily(Yunjinghong) and monthly(Yunjinghong, Jiuzhou and Gajiu) scale. Hydrological simulations forced with APHRODITE were the best of the five for the Yunjinghong station in capturing daily and monthly measured streamflow. Except for NCEP-CFSR, all products were very good for hydrological simulations for the Gajiu and Jiuzhou stations.
基金Under the auspices of the National Natural Science Foundation of China(No.41661099)the National Key Research and Development Program of China(No.Grant 2016YFA0601601)
文摘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 watersheds.This 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 = 0.95, RMSE = 25 mm, MAE = 16 mm, and Bias = 0.67% for monthly precipitation.
文摘The Lancang River Watershed is one of the most biologically diverse areas in the world. The river flows through Yunnan Province, China, which suffered serious deforestation since the 1980s;this in turn led to increased soil erosion in the region. To investigate the influence of the spatial distribution of land use and slope on soil erosion in the Lancang River Watershed, the Soil and Water Assessment Tool (SWAT) model was used to establish hydrological models using two-phase land use maps (1975 and 1985), a soil map, and meteorological data from 11 gauging stations. The satisfactory values of Nash-Sutcliffe efficiency Ens and correlation coefficient R2 during the calibration and validation period indicated that SWAT can be used in this area to simulate the average annual soil erosion under different land use scenarios change. By comparing soil erosion rate under different land use scenarios change, forests and grasslands had similar effects on preventing soil erosion. A parameter, soil erosion increment (Ei), was used to assess the effects of slope on soil erosion. The results revealed that variation in sediment yield was more sensitive to land use change for slopes exceeded 25° than for slopes being 0° - 15°. The spatial distribution of land use also had a relationship to soil erosion. Compared with the soil erosion rate in each sub-watershed using two-phase land use maps, the soil erosion rate increased when the percent cover of natural vegetation decreased. The results of this study provide baseline data for soil conservation and protection of the environment and ecology of the Lancang River Watershed in Yunnan Province.
基金the National Key R&D Program of China(No.2016YFA0601601)Natural Science Foundation of China-International Center for Integrated Mountain Development(NSFC-ICIMOD)Joint Research Program(No.41661144044)
文摘The Lancang-Mekong River has attracted much attention from researchers, but the cooperation on water issues in this river basin has been limited, even after the establishment of the Mekong River Commission(MRC). Cooperation on water resources has been determined as one of the key priority areas in the Lancang-Mekong Cooperation Mechanism, but there are no details of targets. In order to establish the priorities of water cooperation under the mechanism, we adopted nine categories to classify the objectives of 87 water cooperation events based on the ‘Lancang-Mekong Water Cooperative Events Database' from 1995 to 2015. Based on the occurrence of cooperative events, cooperative objectives, cooperative scales, and approaches to cooperation, we conducted statistical, correlation, and text analyses. Our analyses indicated the following results: under the impact of economic conditions inside and outside the river basin, full cooperation appeared more difficult than bilateral and multilateral cooperation. Each of the partners adopted different preferences for cooperation targets. Cooperation with more definite objectives was easier to establish than cooperation with broader and more complex objectives. The potential objectives for water cooperation were navigation, hydropower, joint management, data sharing, flood control and water use. Because hydropower development is controversial, and because water cooperation is avoided by most existing regional cooperation mechanisms due to its complexity, we suggest the following priority areas for water cooperation in the Lancang-Mekong River Basin. 1) Navigation and flood control/drought relief are attractive objectives for all the riparian countries across the whole watershed. 2) Data sharing should be a priority for cooperation in the watershed due to its laying the foundation for the equitable and reasonable utilization of transboundary waters. 3) Hydropower is an objective best implemented mainly through bilateral cooperation, and on tributaries.
基金This work was supported by the External Cooperation Program of Bureau of International Co-operation,Chinese Academy of Sciences[grant number GJHZ1729]the Key Program of the Natural Science Foundation of Yunnan Province of China[grant number 2016FA041].
文摘The Lancang–Mekong River basin(LMRB) is under increasing threat from global warming. In this paper, the projection of future climate in the LMRB is explored by focusing on the temperature change and extreme temperature events. First, the authors evaluate the bias of temperature simulated by the Weather Research and Forecasting model. Then, correction is made for the simulation by comparing with observation based on the non-parametric quantile mapping using robust empirical quantiles(RQUANT) method. Furthermore, using the corrected model results, the future climate projections of temperature and extreme temperature events in this basin during 2016–35, 2046–65, and 2080–99 are analyzed. The study shows that RQUANT can effectively reduce the bias of simulation results. After correction, the simulation can capture the spatial features and trends of mean temperature over the LMRB, as well as the extreme temperature events. Besides, it can reproduce the spatial and temporal distributions of the major modes. In the future, the temperature will keep increasing, and the warming in the southern basin will be more intense in the wet season than the dry season. The number of extreme high-temperature days exhibits an increasing trend, while the number of extreme low-temperature days shows a decreasing trend. Based on empirical orthogonal function analysis, the dominant feature of temperature over this basin shows a consistent change. The second mode shows a seesaw pattern.
文摘According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.
文摘Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the surface sediments of 11 sections in the lower Lancang River during flood season are analyzed, as well as the distribution of phosphorus in different forms. The main sources of TOC and its correlation with TN and TP are discussed and, finally, the pollution levels of the surface sediments are evaluated. The results show that the average content of TOC in the surface sediments of the lower Lancang River is 9003.75 mg/kg. The average TN content is 893.79 mg/kg, while the average TP content is 521.35 mg/kg. The TOC in the surface sediments of the lower Lancang River is derived mainly from algae and plankton in the river, and the TN and TP have similar sources. The total phosphorus in the surface sediments of the lower Lancang River is composed mainly of calcium-bound phosphorus (Ca-P). The evaluations of the organic pollution index and comprehensive pollution index show that the surface sediment pollution degree at the upper sections of the Nuozhadu and Jinghong Dams are more serious than those below the dams. Furthermore, the tributary sections are all slightly polluted, with the exception of the Mengyang River, which is considered moderately polluted.
基金supported by the Key Project of National Key Research and Development Plans(Grant No.2016YFC0503106)
文摘It remains unclear whether the elevational diversity gradients observed in seed plants across different taxonomic levels (family, genus, and species) are driven by the same macro-environmental variables. In this study, seed plant elevational distribution data from the Lancang River Nature Reserve (Yunnan, China) were used to investigate spatial patterns in diversity and their environ- mental correlates, comparing across taxonomic levels. Environmental variables included energy availability, climate seasonality and environmental heterogeneity. All taxonomic levels (family, genus, and species) were found to have strong elevational richness gradients, with the strength of the gradient weakening at higher taxonomic levels. Spatial patterns in richness were explained by a combination of contemporary environmental variables and the mid-domain effect at all taxonomic levels. The independent effects of temperature- and precipitation-related variables were similar in explaining geographical patterns of family, genus and species richness. Energy, seasonality and heterogeneity variables influenced seed plant spatial richness at different taxonomic levels in similar ways.
基金National Key R&D Program of China(No.2016YFA0601601)National Natural Science Foundation of China(No.41601026,41661099)Science and Technology Planning Project of Yunnan Province,China(No.2017FB073)
文摘Satellite-based products with high spatial and temporal resolution provide useful precipitation information for data-sparse or ungauged large-scale watersheds. In the Lower Lancang-Mekong River Basin, rainfall stations are sparse and unevenly distributed, and the transboundary characteristic makes the collection of precipitation data more difficult, which has restricted hydrological processes simulation. In this study, daily precipitation data from four datasets(gauge observations, inverse distance weighted(IDW) data, Tropical Rainfall Measuring Mission(TRMM) estimates, and Climate Hazards Group InfraRed Precipitation with Stations(CHIRPS) estimates), were applied to drive the Soil and Water Assessment Tool(SWAT) model, and then their capability for hydrological simulation in the Lower Lancang-Mekong River Basin were examined. TRMM and CHIRPS data showed good performances on precipitation estimation in the Lower Lancang-Mekong River Basin, with the better performance for TRMM product. The Nash-Sutcliffe efficiency(NSE) values of gauge, IDW, TRMM, and CHIRPS simulations during the calibration period were 0.87, 0.86, 0.95, and 0.93 for monthly flow, respectively, and those for daily flow were 0.75, 0.77, 0.86, and 0.84, respectively. TRMM and CHIRPS data were superior to rain gauge and IDW data for driving the hydrological model, and TRMM data produced the best simulation performance. Satellite-based precipitation estimates could be suitable data sources when simulating hydrological processes for large data-poor or ungauged watersheds, especially in international river basins for which precipitation observations are difficult to collect. CHIRPS data provide long precipitation time series from 1981 to near present and thus could be used as an alternative precipitation input for hydrological simulation, especially for the period without TRMM data. For satellite-based precipitation products, the differences in the occurrence frequencies and amounts of precipitation with different intensities would affect simulation results of water balance components, which should be comprehensively considered in water resources estimation and planning.
文摘The Lancnag Mekong River is the most important international river across China and Southeast Asia, If it is developed according to 'Great Mekong Subregional Cooperation Plan' [9] prepared by ADB, the area directly affected will be up to over 2.32 million km 2, the population over 220 million, and the natural environment, and socio-economic conditions within a large area will be greatly changed. 'Agreement on Cooperation for Sustainable Development of Mekong Basin' signed by the four riparian countries along the lower Mekong River on April 5, 1995 provides a new opportunity for sustainable development of the Basin. According to preliminary analysis, if the multipurpose utilization of the water resources is the target for carrying out integrated planning and management, and the efforts are made 1) to focus on energy exploitation on the Lancang River Mainstream and the tributaries of the lower Mekong River; 2) to build gated weirs at Tonle Sam; 3) to construct spillways at the Mekong Delta; 4) to facilitate flood dykes in big cities and on both banks of the mainstream which are concentrated with population and farmland and liable to be flooded, and 5) to strengthen networks for forecasting hydrological and meteorological conditions, then all problems such as power demand, irrigation, flood, salt water intrusion as well as acid water erosion to soil could be solved without constructing large cascaded stations and dams on the lower Mekong Mainstream. This will not only avoid input of great number of fund, large scale resettlement and land inundation, but also prevent aquatic organisms living in Mekong River from being injured due to dam construction, and promote the sustainable development of the Basin.
文摘The Jinsha River-Lancang River-Nujiang River area is one of the important prospect areas for noble metal and nonferous metal deposits of China. Of a great variety of gold deposits present in this area, the following types seem to be economically most valuable and promising: tectonic alteration type in ophiolitic melange; polymetallic quartz vein type related to intermediate-acid intrusions; finely disseminated type in fracture zones; mixed hydrothermal type in tectonic fractures of carbonate rocks; hydrothermal type related to subvolcanic rocks; volcanic-hot spring type; submarine volcano exhalation-sedimentary-hydrothermal reformation type. Metallogenic epochs are exclusively Mesozoic and Cenozoic, and ore deposits and orebodies are controlled by linear structures. Magmatic activity has affected gold mineralization in varying degrees, and gold deposits are basically of mesothermal-epithermal type with ubiquitous and intense alterations. Ore-forming materials and hydrothermal solutions show multi-source character.
文摘Specialists think tectonic mixtite zone in Lancang River, which lies in southern and eastern fringe of Qingzang plateau, is the suture line (or contact strip) between Gondwana Land and Yangtz block (Fan Chengjun, 1982; Liu Zhengqian, etc, 1991; Fang Runsen,1993).By regional geological study (Legend:1∶50000) in Tu’e, western Yunnan, the author think major fracture zone about 6\|8km from western Lancang River is fragile\|ductile shear zone between batholithic granite of Biluo snow mountain and Jurassic\|Cretaceous slight curdle strata. The zone is a very complicated tectonic mixtite zone (width:0.7\|6km; strike: SN\|direction). Study based on geometric structure, constitution, metamorphism, deformation and kinematic characteristics, the author sum up the following features about the complex deformation zone.(1) Tectonic mixtite zone is a very complicate blocks made up of curdle blocks and residual blocks of granite. Its’ geometric structure is a net\|shape structure composed of matrixes and chaotic blocks in plane and have two kinds of structure types (obduction schists in early diagenesis and heteroploytypes in late diagenesis) in section.
文摘Carbon cycle is one of the focuses of climate change, river carbon is an important part, while dissolved inorganic carbon (DIC) has a high proportion of river carbon flux. In this study, we did the research on the Lancang River, an important international river in the southwest of China. Water samples were obtained from 16 sections of the middle and lower reaches of the Lancang River in 2016 (11 months), then we monitored some water quality indicators and DIC content, finally analyzed the temporal-spatial distribution characteristics of DIC and the relationship between DIC content and water environment factors. The results showed that: (1) DIC contents in the middle and lower reaches of the Lancang River varied from 1.1840 mmol/L to 3.1440 mmol/L, with a mean value of about 2.2155 mmol/L. (2) At a time scale, DIC contents of dry season (spring, autumn and winter) were higher than rainy season (summer). At a space scale, DIC contents of the middle and lower reaches of the Lancang River gradually decreased from north to south, and each reservoir had the same characteristics, that is, DIC contents at upstream of the dam was lower than those at downstream of the dam. Compared to other rivers with cascade dams around the world, DIC contents within studied river were at similar level. And the reservoir’s effect of the Lancang River were not obvious, however, DIC contents in the water sampled upstream the dams had a slight stratification. (3) Water temperature, conductivity, turbidity were important factors affecting DIC content of water, and the effect of oxidation and reduction potential (ORP) and pH on DIC was relatively small.
基金Sponsored by Project of Baoshan Municipal Science and Technology Bureau"Study on Ecological Security Pattern of Baoshan City Based on ANNs"
文摘Drought is one of the main natural disasters that cause economic loss in the basins of international rivers such as Nujiang and Lancang rivers. Based on the monthly precipitation and temperature data of 31 meteorological stations in Nujiang and Lancang river basins in Yunnan Province during 1965-2013, the standardized precipitation evapotranspiration index(SPEI) in each of the two bio-climate zones was calculated. In addition, the drought process in annual, seasonal and monthly scale was analyzed respectively to reveal the spatial and temporal characteristics and the intensity variation of meteorological drought in Nujiang and Lancang river basins in Yunnan Province. The results showed that there was a significant increasing trend in seasonal(especially winter's) and monthly drought since the late 1970 s; the drought occurred in the two bio-climate zones showed no obvious spatial distinction, and it was synchronized with that occurred throughout Yunnan Province; and in the recent 50 years, the significant increase of drought in the study area may be attributed to the significant rise in temperature, rather than the slight decline of the precipitation.
文摘Based on high-resolution Google Earth images,settlements in Yunnan section of the Lancang River basin were extracted.We use the kernal density and the optimized hot spot analysis methods to display spatial pattern of the settlements.Random forest model is used to explore the natural environmental impact factors of residential areas distribution.The results show that settlements in Yunnan section of the Lancang River basin are mainly distributed in the middle reaches and the upper reaches along the river.The random forest model contains 11 environmental factors,and the top three factors in importance are the nearest distance to forest,altitude and the nearest distance to glacier/snow.The partial dependence plots show the response trend of settlements to environmental factors.This research results could provide guidance for rational use of land resources,making regional development and construction plans,and coordinating the relationship between humans and the environment.
文摘In this paper, we conduct research on the national traditional sports resources in Lancang river valley under culture oriented background. Really in Chinese traditional sports culture must be confirmed and reflect on the moment, only a clear definition of the concept of national traditional sports and category, figuring out what is the Chinese nationality traditional sports activity, which is a folk activity, and modern competitive sports, we can suit the remedy to the case, targeted, heritage and development path of the respective work, realize the diversification of the Chinese nation traditional culture heritage and development. Specifically the Lancang river valley region sports should be payed special attention for the preservation of the tradition.
文摘Groundwater is an important and readily available source of fresh water in the Mekong-Lancang River Basin. With a rapid population growth and increasing human activities, an increasing number of countries in the Mekong-Lancang River Basin are experiencing depleted and degraded groundwater supplies. In transboundary river basins, such as the Mekong-Lancang River, prioritizing the use of the shared aquifer by one riparian government may affect the opportunities of other riparian governments and lead to potential water conflicts between neighboring countries. To promote the sharing of strategies and information for the sustainable and equitable use of water resources of the shared basin, international collaborative workshops on groundwater resources have been organized for all Mekong-Lancang River countries. These workshops provide an opportunity to communicate and discuss nationally sensitive issues on groundwater by the associated countries, with topics covering multiple aspects of groundwater, such as the groundwater status in the basin, quality issues, water use conflicts, hydrological information gaps, management policies and capacity building for successful water resource management. Consensus has been reached by all countries on the importance of catchment-based groundwater management and the need for close communication among the countries. Strategies for managing transboundary aquifer issues must foster international collaboration based on the regional network, influence national networks and enhance the capacity to building maps and monitoring systems based on associated databases. The sustainability of water resources cannot be achieved without the integrated involvement and contributions by multiple countries and various stakeholders. Therefore, collaborative workshops provide a great opportunity to further our understanding of the hydrologic processes of the Mekong River Basin, share the benefits of the aquifer and provide a strategy and vision for sustainable water resource management in the Mekong-Lancang River countries.
文摘The Lancang-Mekong River in China, Laos, Thailand, Myanmar, Cambodia, and Vietnam is the soul and heart of mainland Southeast Asia. Over 60 million people depend on the river and its tributaries for food, transportation, water, and other necessities of life. The river supports one of the world’s most diverse fisheries, second only to Brazil’s Amazon River. Lancang-Mekong and tributaries are already heavily dammed primarily in China, Laos, Thailand, and Cambodia, with many more dams planned or under construction. Dams can worsen the impact of periodic droughts in the Lancang-Mekong basin and block the river’s “pulse effect” that spreads water and nutrients needed for fishing and farming onto the floodplains and delta. The headwaters of the Lancang are in China and its waters are considered a national resource. China regards the Lancang, Yangtze and Yellow rivers as a free resource rather than a shared resource. The primary difference between these rivers is the Lancang flows from China into and through other countries and not directly into a sea or ocean. China and Myanmar have not joined the Mekong River Commission (MRC) as full members but have been Dialogue Partners since 1996. Over the past thirty years, China’s Lancang policies and actions have reflected its national resource interests. China has actively engaged with individual transboundary countries at various levels including environmental, conservation, and economic agreements. The primary objective of this study is to assess the environmental and human impacts of all Lancang-Mekong mainstem and tributary dams and the plans by many countries for more hydropower utilizing the potential of the river as the continent’s energy lifeline. Future dams need to include fish ladders and navigation locks to reduce the environmental impacts on fish populations, natural resources, navigation, and livelihoods. Strengthening of international collaboration via the MRC or by individual or multiple country agreements to address Lancang-Mekong’s sustainable transboundary development goals is recommended. When new Lancang-Mekong and tributary dams are built within any of the transboundary watershed countries, additional communities will need to be resettled. Significant environmental and human impacts are observed. Steps will have to be taken by all the concerned countries to prevent these problems and to ensure that people’s livelihoods are restored after resettlement.
文摘The western part of China borders on South and Southeast Asia. Of the numerous well known international rivers sharing with the two regions, the Lancang Mekong River has been most extensively studied in the world for its important strategic position, rich resources, prosperous potential market as well as considerable opportunities for investment and development. The sustainable multipurpose development in this area has increasingly become the focus of international regional cooperation, and great attention has been paid to this area by the international society. Up to now, at least 10 major actions in the international regional cooperation are expected in this area. This paper intends, at the angle of geography and with the overall target of promoting the sustainable development in the basin through international cooperations, to study the international position, the potential and the prospects for development of the Lancang Mekong River, to analyze the main problems in this international cooperation, to propose targets and prospects for such cooperation, and to indicate the way for geographers to participate in such research.