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
Mekong River is one of the major international freshwater sources in the world. The Lower Mekong Basin (LMB) comprised of four downstream countries, including Thailand, Lao PDR, Cambodia, and Vietnam. The utilization ...Mekong River is one of the major international freshwater sources in the world. The Lower Mekong Basin (LMB) comprised of four downstream countries, including Thailand, Lao PDR, Cambodia, and Vietnam. The utilization of the basin’s water brings not only substantial benefits to the region ranging from hydropower to navigation, but also negative impacts caused by the unbalanced water using. The essential role of Mekong River requires all member nations to cooperate effectively for the sustainable development of the region. One of the most popular methods in the field of water resource management is a trustable tool called the Analytical Hierarchy Process (AHP). AHP is much appropriate for water resource policymaking. The literature, however, points out that there is no study to both structure the water using hierarchy and employ quantitative (objective) criteria to the AHP model in LMB case. With regard to water resource management, there are no previous studies applying AHP models to evaluating sustainable development of transboundary water resource in LMB case. This paper explores the evolution of water cooperation among Mekong countries and subsequently evaluates the water development scenarios in the LMB based on the water cooperation preferences of four LMB countries This study proposes a novel approach to analyzing, assessing water resource development scenarios characterized by sustainability indicators and to assisting in developing a suitable water policy in LMB according to the best cooperation scenario.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 transboundary Mekong River is shared by six SE Asia countries (China, Myanmar, Thailand, Lao PDR, Cambodia, and Vietnam). In this paper the livelihoods of farmers and fishers of Lao PDR, Cambodia and Vietnam are e...The transboundary Mekong River is shared by six SE Asia countries (China, Myanmar, Thailand, Lao PDR, Cambodia, and Vietnam). In this paper the livelihoods of farmers and fishers of Lao PDR, Cambodia and Vietnam are examined to assess impacts of Mekong River development and modernization projects on the rural peoples of the Mekong River and Delta. A high proportion of the 190 million rural people of the Mekong basin are dependent on the diverse and abundant resources of the Mekong River and its tributaries for food security and basic necessities, livelihoods, and cultural identities. Although rice farming and fisheries occupations are primary income sources, many livelihoods involve a diversity of on-farm and off-farm activities. Agricultural specialization and intensification and hydropower dam construction on the Mekong main stem and tributaries are altering traditional rural patterns of household food security, income, and cultural ways of living at an increasingly rapid pace. Rural transformation projects must better assess how these modernization efforts change the ecology of the Mekong River and in turn affect the capacity of rural people to adapt in ways that ensure food security and improve household livelihoods. It will be critical that development efforts recognize, value, and invest in rural people’s roles in producing a stable, affordable food system and managing the integrity of river ecosystems upon which future prosperity depends. Interventions are needed to prevent degradation of the Mekong Basin soil and water resources from large-scale agricultural intensification, water diversion and overbuilding of hydropower dams which are threats to small-scale land holdings and farmers and fishers capacities to provide daily food for their own consumption and to feed SE Asia’s growing urban populations.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 Lower Mekong River basin (LMB) covers the lower part of the Mekong river basin, including Laos, Thailand, Cambodia and Vietnam. Due to numerous pressures from high population growth and intensive hydropower develo...The Lower Mekong River basin (LMB) covers the lower part of the Mekong river basin, including Laos, Thailand, Cambodia and Vietnam. Due to numerous pressures from high population growth and intensive hydropower development, the LMB has been facing significant challenges concerning its biodiversity and ecosystem. In 2017, Mekong River Commission (MRC), an intergovernmental organisation founded in 1995 among LMB countries, established the Council Study, which analysed the impacts of water development scenarios concerning the environmental, socioeconomic aspects of the LMB. This paper explores the nature of risks to the LMB water development and subsequently evaluates LMB’s water development scenarios described in the Council Study by using a multi-criteria decision analysis (MCDA) method. MCDA method has been widely applied in the field of water resource management in order to assist the decision-making process by systematically evaluating a certain number of alternatives against well-selected criteria through a preference rating scheme. By implementing a risk-based comprehensive assessment of the LMB transboundary water, this study provides insights into the impacts of the increasing risks to the ecosystem and human beings on the water development of the basin over time, which assists to change the awareness and the perspective toward humans’ risks and transboundary river ecosystem of decision-makers. This paper provides valuable recommendations for MRC to improve their policy concerning benefit-sharing scheme, water planning and risk mitigation strategies.展开更多
The societal impact of extreme winds induced by tropical cyclones(TCs)is a major concern in the Mekong River Basin(MRB).Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed s...The societal impact of extreme winds induced by tropical cyclones(TCs)is a major concern in the Mekong River Basin(MRB).Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed since the 1970 s,climate models project an increasing TC intensity in the 21 st century over the Western North Pacific,which is the primary TC source region influencing the MRB.Yet,how future TC activities will affect extreme winds quantitatively in the MRB remains unclear.By employing a novel dynamical downscaling technique using a specialized,coupled ocean-atmospheric model,shorter return periods of maximum wind speed in the MRB for 2081–2100 compared with 1981–2000 are projected based on five global climate models under the RCP8.5 scenario,suggesting increases in the future tropical cyclone intensity.The results point to consistently elevated future TC-related risks that may jeopardize sustainable development,disrupt food supply,and exacerbate conflicts in the region and beyond.展开更多
In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for u...In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for understanding the challenges.In this study,the Weather Research and Forecasting(WRF)model was applied to project the LMRB precipitation.Comparing with the historical period(1986e2005),we analyzed the changes of both the projected precipitation amount and the frequency of rainless(<0.1 mm d1),light rain(0.1e10 mm d1),moderate rain(10e25 mm d1),heavy rain(25e50 mm d1),rainstorm(50e100 mm d1),and heavy rainstorm(>100 mm d1)for three periods,namely the near-term(2016e2035),mid-term(2046e2065),and long-term(2080e2099).The results indicate that the precipitation amount during the wet season(AprileOctober)is expected to increase in most areas of the basin for the three periods.As for the precipitation during the dry season(NovembereMarch),an increase is projected in most areas for the near-term,while an increase in the lower reach of the basin and a decrease in the upper and middle reach for the mid-term and long-term.The precipitation reduction is expected to be greatest in Myanmar,Laos,Thailand,and Yunnan province of China for the mid-term.The frequency of precipitation in different intensities has prominent regional and temporal differences.During the wet season,the days of rainless and light rain are expected to decrease in the middle reach,whereas the days of rainstorm and heavy rainstorm increase.This feature is especially strong in southern Thailand,southern Laos and Cambodia in the near-term and in Laos and Thailand for the mid-term and long-term.During the dry season,there are projected increasing rainless days and decreasing days of precipitation for the other intensities in the middle reach,and opposite in the rest area of the basin.These projected precipitation changes have potential various impact in different parts of the basin.The middle reach would likely face increasing flood risks because of more days of rainstorm and heavy rainstorm,as well as more precipitation.Yunnan,Myanmar,Thailand and Laos would probably be the center of drought threatens during the dry season due to the increment of rainless days and the precipitation reduction.Besides,the seawater intrusion during the dry season in the near-term and mid-term would be more serious as a result of the precipitation decrease in southern Vietnam.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
Concern on alteration of sediment natural flow caused by developments of water resources system, has been addressed in many river basins around the world especially in developing and remote regions where sediment data...Concern on alteration of sediment natural flow caused by developments of water resources system, has been addressed in many river basins around the world especially in developing and remote regions where sediment data are poorly gauged or ungauged. Since suspended sediment load (SSL) is predominant, the objectives of this research are to: 1) simulate monthly average SSL (SSLm) of four catchments using artificial neural network (ANN);2) assess the application of the calibrated ANN (Cal-ANN) models in three ungauged catchment representatives (UCR) before using them to predict SSLm of three actual ungauged catchments (AUC) in the Tonle Sap River Basin;and 3) estimate annual SSL (SSLA) of each AUC for the case of with and without dam-reservoirs. The model performance for total load (SSLT) prediction was also investigated because it is important for dam-reservoir management. For model simulation, ANN yielded very satisfactory results with determination coefficient (R2) ranging from 0.81 to 0.94 in calibration stage and 0.63 to 0.87 in validation stage. The Cal-ANN models also performed well in UCRs with R2 ranging from 0.59 to 0.64. From the result of this study, one can estimate SSLm and SSLT of ungauged catchments with an accuracy of 0.61 in term of R2 and 34.06% in term of absolute percentage bias, respectively. SSLA of the AUCs was found between 159,281 and 723,580 t/year. In combination with Brune’s method, the impact of dam-reservoirs could reduce SSLA between 47% and 68%. This result is key information for sustainable development of such infrastructures.展开更多
【目的】研究澜沧江—湄公河跨境流域土地利用变化及生态环境质量地域分异。【方法】运用动态度模型和地学信息图谱理论,基于Global Land 30、全球30 m精细地表覆盖数据集等,分析澜沧江—湄公河跨境流域在2000—2010年和2010—2020年2...【目的】研究澜沧江—湄公河跨境流域土地利用变化及生态环境质量地域分异。【方法】运用动态度模型和地学信息图谱理论,基于Global Land 30、全球30 m精细地表覆盖数据集等,分析澜沧江—湄公河跨境流域在2000—2010年和2010—2020年2个时序单元的土地利用变化;构建生态环境质量评价体系,采用探索性空间数据分析方法探究其分异。【结果】澜沧江—湄公河跨境流域土地利用类型变动速率差异明显;在图谱空间中,长期稳定型的分布最广,图谱变化类型呈片状零散分布;2000—2020年,研究区土地利用类型转移呈多样性和不均衡性,林地为主要转出类型,贡献了总转出面积的46%以上。2000—2010年,研究区不同土地利用类型空间呈南北弱、中间强的散点分散格局;2010—2020年,则呈南北强、中间弱的片状集中格局,且不同类型的涨落势具有显著的相似性。生态环境质量空间格局总体呈南高北低的片状分布,具有较弱的空间正相关性,生态环境发展水平的空间俱乐部收敛特征显著性较低。【结论】澜沧江—湄公河跨境流域土地利用具有图谱变化稳定性、地域分异国别性和生态质量差异性,耕地和草地转变为林地有助于改善生态环境,但林地转为耕地以及城镇化导致了生态环境恶化。展开更多
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Mekong River is one of the major international freshwater sources in the world. The Lower Mekong Basin (LMB) comprised of four downstream countries, including Thailand, Lao PDR, Cambodia, and Vietnam. The utilization of the basin’s water brings not only substantial benefits to the region ranging from hydropower to navigation, but also negative impacts caused by the unbalanced water using. The essential role of Mekong River requires all member nations to cooperate effectively for the sustainable development of the region. One of the most popular methods in the field of water resource management is a trustable tool called the Analytical Hierarchy Process (AHP). AHP is much appropriate for water resource policymaking. The literature, however, points out that there is no study to both structure the water using hierarchy and employ quantitative (objective) criteria to the AHP model in LMB case. With regard to water resource management, there are no previous studies applying AHP models to evaluating sustainable development of transboundary water resource in LMB case. This paper explores the evolution of water cooperation among Mekong countries and subsequently evaluates the water development scenarios in the LMB based on the water cooperation preferences of four LMB countries This study proposes a novel approach to analyzing, assessing water resource development scenarios characterized by sustainability indicators and to assisting in developing a suitable water policy in LMB according to the best cooperation scenario.
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 transboundary Mekong River is shared by six SE Asia countries (China, Myanmar, Thailand, Lao PDR, Cambodia, and Vietnam). In this paper the livelihoods of farmers and fishers of Lao PDR, Cambodia and Vietnam are examined to assess impacts of Mekong River development and modernization projects on the rural peoples of the Mekong River and Delta. A high proportion of the 190 million rural people of the Mekong basin are dependent on the diverse and abundant resources of the Mekong River and its tributaries for food security and basic necessities, livelihoods, and cultural identities. Although rice farming and fisheries occupations are primary income sources, many livelihoods involve a diversity of on-farm and off-farm activities. Agricultural specialization and intensification and hydropower dam construction on the Mekong main stem and tributaries are altering traditional rural patterns of household food security, income, and cultural ways of living at an increasingly rapid pace. Rural transformation projects must better assess how these modernization efforts change the ecology of the Mekong River and in turn affect the capacity of rural people to adapt in ways that ensure food security and improve household livelihoods. It will be critical that development efforts recognize, value, and invest in rural people’s roles in producing a stable, affordable food system and managing the integrity of river ecosystems upon which future prosperity depends. Interventions are needed to prevent degradation of the Mekong Basin soil and water resources from large-scale agricultural intensification, water diversion and overbuilding of hydropower dams which are threats to small-scale land holdings and farmers and fishers capacities to provide daily food for their own consumption and to feed SE Asia’s growing urban populations.
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 Lower Mekong River basin (LMB) covers the lower part of the Mekong river basin, including Laos, Thailand, Cambodia and Vietnam. Due to numerous pressures from high population growth and intensive hydropower development, the LMB has been facing significant challenges concerning its biodiversity and ecosystem. In 2017, Mekong River Commission (MRC), an intergovernmental organisation founded in 1995 among LMB countries, established the Council Study, which analysed the impacts of water development scenarios concerning the environmental, socioeconomic aspects of the LMB. This paper explores the nature of risks to the LMB water development and subsequently evaluates LMB’s water development scenarios described in the Council Study by using a multi-criteria decision analysis (MCDA) method. MCDA method has been widely applied in the field of water resource management in order to assist the decision-making process by systematically evaluating a certain number of alternatives against well-selected criteria through a preference rating scheme. By implementing a risk-based comprehensive assessment of the LMB transboundary water, this study provides insights into the impacts of the increasing risks to the ecosystem and human beings on the water development of the basin over time, which assists to change the awareness and the perspective toward humans’ risks and transboundary river ecosystem of decision-makers. This paper provides valuable recommendations for MRC to improve their policy concerning benefit-sharing scheme, water planning and risk mitigation strategies.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20060401)the China Scholarship Council+2 种基金the National Natural Science Foundation of China(91537210)the Swedish STINT(CH2015-6226)the Swedish VR(2017-03780).
文摘The societal impact of extreme winds induced by tropical cyclones(TCs)is a major concern in the Mekong River Basin(MRB).Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed since the 1970 s,climate models project an increasing TC intensity in the 21 st century over the Western North Pacific,which is the primary TC source region influencing the MRB.Yet,how future TC activities will affect extreme winds quantitatively in the MRB remains unclear.By employing a novel dynamical downscaling technique using a specialized,coupled ocean-atmospheric model,shorter return periods of maximum wind speed in the MRB for 2081–2100 compared with 1981–2000 are projected based on five global climate models under the RCP8.5 scenario,suggesting increases in the future tropical cyclone intensity.The results point to consistently elevated future TC-related risks that may jeopardize sustainable development,disrupt food supply,and exacerbate conflicts in the region and beyond.
基金the model data,and the support from Li Chongyin Academician Workstation of Yunnan province.This work was supported by the National Natural Science Foundation of China(U1902209)the Chinese Academy of Sciences and the Key Science Foundation of Yunnan Province(2016FA041)+1 种基金the External Cooperation Program of Bureau of International Cooperation(GJHZ1729)the Science and Technology Project of SGCC(State Grid Corporation of China)[Research and application of multi-spatial scale variation of photovoltaic output characteristics considering complex factors such as cloud and floating dust](NY71-19-013).
文摘In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for understanding the challenges.In this study,the Weather Research and Forecasting(WRF)model was applied to project the LMRB precipitation.Comparing with the historical period(1986e2005),we analyzed the changes of both the projected precipitation amount and the frequency of rainless(<0.1 mm d1),light rain(0.1e10 mm d1),moderate rain(10e25 mm d1),heavy rain(25e50 mm d1),rainstorm(50e100 mm d1),and heavy rainstorm(>100 mm d1)for three periods,namely the near-term(2016e2035),mid-term(2046e2065),and long-term(2080e2099).The results indicate that the precipitation amount during the wet season(AprileOctober)is expected to increase in most areas of the basin for the three periods.As for the precipitation during the dry season(NovembereMarch),an increase is projected in most areas for the near-term,while an increase in the lower reach of the basin and a decrease in the upper and middle reach for the mid-term and long-term.The precipitation reduction is expected to be greatest in Myanmar,Laos,Thailand,and Yunnan province of China for the mid-term.The frequency of precipitation in different intensities has prominent regional and temporal differences.During the wet season,the days of rainless and light rain are expected to decrease in the middle reach,whereas the days of rainstorm and heavy rainstorm increase.This feature is especially strong in southern Thailand,southern Laos and Cambodia in the near-term and in Laos and Thailand for the mid-term and long-term.During the dry season,there are projected increasing rainless days and decreasing days of precipitation for the other intensities in the middle reach,and opposite in the rest area of the basin.These projected precipitation changes have potential various impact in different parts of the basin.The middle reach would likely face increasing flood risks because of more days of rainstorm and heavy rainstorm,as well as more precipitation.Yunnan,Myanmar,Thailand and Laos would probably be the center of drought threatens during the dry season due to the increment of rainless days and the precipitation reduction.Besides,the seawater intrusion during the dry season in the near-term and mid-term would be more serious as a result of the precipitation decrease in southern Vietnam.
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Concern on alteration of sediment natural flow caused by developments of water resources system, has been addressed in many river basins around the world especially in developing and remote regions where sediment data are poorly gauged or ungauged. Since suspended sediment load (SSL) is predominant, the objectives of this research are to: 1) simulate monthly average SSL (SSLm) of four catchments using artificial neural network (ANN);2) assess the application of the calibrated ANN (Cal-ANN) models in three ungauged catchment representatives (UCR) before using them to predict SSLm of three actual ungauged catchments (AUC) in the Tonle Sap River Basin;and 3) estimate annual SSL (SSLA) of each AUC for the case of with and without dam-reservoirs. The model performance for total load (SSLT) prediction was also investigated because it is important for dam-reservoir management. For model simulation, ANN yielded very satisfactory results with determination coefficient (R2) ranging from 0.81 to 0.94 in calibration stage and 0.63 to 0.87 in validation stage. The Cal-ANN models also performed well in UCRs with R2 ranging from 0.59 to 0.64. From the result of this study, one can estimate SSLm and SSLT of ungauged catchments with an accuracy of 0.61 in term of R2 and 34.06% in term of absolute percentage bias, respectively. SSLA of the AUCs was found between 159,281 and 723,580 t/year. In combination with Brune’s method, the impact of dam-reservoirs could reduce SSLA between 47% and 68%. This result is key information for sustainable development of such infrastructures.
文摘【目的】研究澜沧江—湄公河跨境流域土地利用变化及生态环境质量地域分异。【方法】运用动态度模型和地学信息图谱理论,基于Global Land 30、全球30 m精细地表覆盖数据集等,分析澜沧江—湄公河跨境流域在2000—2010年和2010—2020年2个时序单元的土地利用变化;构建生态环境质量评价体系,采用探索性空间数据分析方法探究其分异。【结果】澜沧江—湄公河跨境流域土地利用类型变动速率差异明显;在图谱空间中,长期稳定型的分布最广,图谱变化类型呈片状零散分布;2000—2020年,研究区土地利用类型转移呈多样性和不均衡性,林地为主要转出类型,贡献了总转出面积的46%以上。2000—2010年,研究区不同土地利用类型空间呈南北弱、中间强的散点分散格局;2010—2020年,则呈南北强、中间弱的片状集中格局,且不同类型的涨落势具有显著的相似性。生态环境质量空间格局总体呈南高北低的片状分布,具有较弱的空间正相关性,生态环境发展水平的空间俱乐部收敛特征显著性较低。【结论】澜沧江—湄公河跨境流域土地利用具有图谱变化稳定性、地域分异国别性和生态质量差异性,耕地和草地转变为林地有助于改善生态环境,但林地转为耕地以及城镇化导致了生态环境恶化。
