Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

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.

Distribution and Influencing Factors of Residential Areas in Yunnan Section of the Lancang River Basin

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.

Soil Erosion and Its Relationship to the Spatial Distribution of Land Use Patterns in the Lancang River Watershed, Yunnan Province, China

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.

CHARACTERISTICS OF TECTONIC MIXTITE ZONE IN THE LANCANG RIVER,WESTERN YUNNAN

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.

PRELIMINARY DISCUSSION ON METALLOGENESIS OF LANCANGJIANG RIVER TRANSITIONAL FIELD TECTONIC ZONE IN WESTERN YUNNAN

Applying the crustobody geotectonic theory to geological prospecting at the Lancangjiang river metallogenic belt in western Yunnan province, and on the basis of the basic geological background of western Yunnan and the space-time evolution-movement historical-dynamic features of the Lancangjiang river tectonic belt, the author has discussed firstly the metallogenesis of the Lancangjiang river transitional field tectonic zone, which can provide a new theoretical foundation for exploring the space-time laws of mineralization in this region.

Soil Erosion under Different Land Use Types and Zones of Jinsha River Basin in Yunnan Province,China

Severe soil erosion in the middle and upper reaches of Yangtze River has been regarded as a major environmental problem. The on-site impact of soil erosion on agricultural production and the off-site impact on floods and sedimentation in Yangtze Rive are well known. A quantitative assessment of soil erosion intensity is still scanty for developing appropriate soil erosion control measures for different land use types and zones in this region. This article constructs a localized USLE and estimates the average soil loss in the Jinsha River Region in Yunnan Province, one of the priority areas for soil erosion control in the middle and upper reaches of Yangtze River. The estimation is done under different land uses and zones in this basin. The estimation shows that while soil erosion in the cultivated land is the most severe, 36～40% of the garden and forest land suffers from soil erosion of various degrees due to lack of ground cover and other factors. Soil erosion in the pasture is modest when the ground cover is well maintained. It also confirmed that terracing can reduce soil erosion intensity significantly on the cultivated land. Research findings suggest that sufficient attention must be paid to regeneration of the ground cover in reforestation programs. In addition to mass reforestation efforts, restoration of grassland and terracing of the cultivated land should also play an important role in erosion control.

Elevational diversity gradients across seed plant taxonomic levels in the Lancang River Nature Reserve： role of temperature, water and the mid-domain effect

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.

Frequency, Duration and Intensity of Dengue Fever Epidemic Risk in Townships in Pearl River Delta and Yunnan in China, 2013

Dengue fever （DF）, one of the neglected tropical diseases also known as breakbone fever, is a mosquito-borne disease common in the tropics and subtropics. Dengue fever is transmitted primarily by A.aegypti, resulting in infection with any of four distinct but closely related virus serotypes. The majority of infected people experience a self-limiting clinical course. A small proportion of cases develop into life-threatening Dengue Hemorrhagic Fever or Dengue Shock Syndrome.

A New Species of Japalura(Squamata, Agamidae) from the Nu River Valley in Southern Hengduan Mountains, Yunnan, China

A population of Japalura from Yunnan Province, China, previously assigned to Japalura splendida, is described as a new species. The new species has been recorded between 1 138–2 500 m in the Nu River drainage between the towns of Liuku and Binzhongluo, and on the lower western slopes of the Nushan and eastern slopes of the Goaligongshan. The new species can be distinguished from other species of Japalura, except J. dymondi, by the following combination of characters： exposed tympani, prominent dorso-lateral stripes, and small gular scales. It is very similar with but differs from J. dymondi by having smooth or feebly keeled dorsal head scales, three relatively enlarged spines on either side of the post-occiput area, strongly keeled and mucronate scales on occiput area and within the lateral stripes, back of arm and leg green, higher number of dorsal-ridge scales（DS） and fourth toe subdigital scales（T4S）. A principal component analysis of body measurements of adult male specimens of the new species and J. dymondi showed principal component 1 loading highest for upper arm length, fourth toe length and snout to eye length and principal component 2 loading highest for head width, head length and fourth toe length.

Types and Ore-forming Conditions of Gold Deposits in the Jinsha River-Lancang River-Nujiang River Area

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.

Meteorological Drought in Nujiang and Lancang River Basins during Recent 50 Years

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.

Research and Exploration on the National Traditional Sports Resources in Lancang River Valley under Culture Oriented Background

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.

Groundwater status and associated issues in the Mekong-Lancang River Basin： International collaborations to achieve sustainable groundwater resources

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.

Three Parallel Rivers of Yunnan

Listed as a Natural Cultural Heritage Site in 2003 Location： Crossing Lijiang Prefecture, Diqing Tibetan Autonomous Prefecture and Nujiang Lisu Autonomous Prefecture, Yunan Province, southwest China Best Time to Visit： Anytime

Evaluating Suitability of Multiple Precipitation Products for the Lancang River Basin

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.

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

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.

Spatial Distribution of Carbon, Nitrogen and Phosphorus within Surface Sediments in the Lower Lancang River: Pollution Assessment Related to Dams

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.

Geochemical discrimination of the geotectonic environment of basaltic-andesitic volcanic rocks associated with the Laochang polymetallic ore deposit at Lancang, Yunnan

The Laochang polymetallic ore deposit at Lancang is one of the well known ancient ore deposits associated with volcanic rocks in the Sanjiang (Tri-river) region of Southwest China. Volcanic rocks are dominated by alkali basalt and trachyte basalt. There has long been a controversy on the environment of formation of basalts. Some scholars hold that the basalts were formed in a continental environment, some thought they were formed in an oceanic environment and others considered that the basalts were emplaced in a back-arc basin. This study focuses on the geochemical characteristics of the basalts on the basis of their major elements, REEs and trace elements. At the same time, strongly incompatible elements such as Ta, Th and Hf and their ratios were used to differentiate the geotectonic settings of basalts. The results showed that the basalts in the region studied were formed in a continental rift environment.

Dissolved Inorganic Carbon (DIC) Contents in Middle and Lower Reaches of Lancang River: Related to Water Environments and Dams

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.