The 5.12 Wenchuan Earthquake and the subsequent rainstorms induced a large number of landslides, which later were transformed into debris flows. To evaluate the effect of the earthquake on the sediment supply of debri...The 5.12 Wenchuan Earthquake and the subsequent rainstorms induced a large number of landslides, which later were transformed into debris flows. To evaluate the effect of the earthquake on the sediment supply of debris flows, eight debris flow basins near Beichuan City, Sichuan Province, China were chosen as the study area. The area variations of the debris flow source after the Wenchuan Earthquake and the subsequent rainstorm are analyzed and discussed in this paper. Interpretations of aerial photographs (after the 5.12 Wenchuan Earthquake) and SPOT5 images (after the rainstorm event of September 24, 2008) as well as field investigations were compared to identify the transformation of landslide surface in the study area, indicating that the landslide area in the eight debris flow basins significantly increased. The loose sediment area on the channel bed increased after the rainstorm event. In order to estimate the relationship of the landslide area with the rainfall intensity in different return periods, a model proposed by Uchihugi was adopted. Results show that new landslide area induced by heavy rainfall with 50-year and 100-year return period will be 0.87 km2 and 1.67 km2, respectively. The study results show the Wenchuan earthquake had particular influences on subsequent rainfall-induced debris flow occurrence.展开更多
The relationship between the groundwater and the surface eco-environment in arid area is very close. In this paper, the authors extracted normalized difference vegetation index （NDVI） and vegetation conditional rat...The relationship between the groundwater and the surface eco-environment in arid area is very close. In this paper, the authors extracted normalized difference vegetation index （NDVI） and vegetation conditional ratio （VCR） from MODIS images, and analyzed the relationships among NDVI, VCR and the measured data of groundwater of the same location in the research region. Based on this, the depth of groundwater suitable for vegetation growth in the upper-middle reaches of the Yellow River basin has been calculated. The results show that the depth of groundwater suitable for vegetation growth in the research region ranges from 0.8 to 4.5m, and the optimal groundwater depth is 1.2m. The method developed in this study is applicable to research the relationship between the groundwater and land surface vegetation environment on large-scale in arid area.展开更多
During the last decade, there has been an intensive research activity concerning the concept of the Water Footprint （WF） approach, which was firstly introduced by Arjen Hoekstra in 2002. WF is an indicator of direct...During the last decade, there has been an intensive research activity concerning the concept of the Water Footprint （WF） approach, which was firstly introduced by Arjen Hoekstra in 2002. WF is an indicator of direct and indirect freshwater use of a consumer or producer that takes into account water consumption in every step （intermediate and final） along the production chain and services. The concept can be implemented in various levels such as products, consumers, producers, nations and river basins etc.. The water footprint within a geographically delineated area equals the sum of the process water footprints of all processes taking place in the area. The aim of current research is a review of the most important WF studies, with a special focus on applications within regional, basin and administrative unit level. National and global scales are not included in the current paper. The article presents the most widespread methodologies and approaches that attempt to evaluate water footprints of specific defined areas and highlights their recent advances as well as shortcomings in the constantly evolving research efforts.展开更多
The results presented in this paper are a part of the research results of the thesis ＂research on scientific basis and practice of develop a system of monitoring the impacts of climate change on surface water and gro...The results presented in this paper are a part of the research results of the thesis ＂research on scientific basis and practice of develop a system of monitoring the impacts of climate change on surface water and groundwater＂. Case study： Ma river basin in Vietnam. The results were implemented： （i） data collection, fieldwork survey, synthesis and analysis of information and data; （ii） partitioning the influence degree of climate change and sea level rise to groundwater; （iii） determining criteria to select monitoring routes, location of monitoring groundwater in the condition of climate change and sea level rise and （iv） developing the monitoring system. The research＇s results have practical implications for the water resources management in the context of climate change and sea level rise in Ma river basin.展开更多
Comparative performance analysis of four irrigation schemes within Cagayan River Basin was assessed using comparative performance indicators between the years 2008 and 2012. The objectives were to establish benchmarks...Comparative performance analysis of four irrigation schemes within Cagayan River Basin was assessed using comparative performance indicators between the years 2008 and 2012. The objectives were to establish benchmarks for both productivity and performance of irrigation schemes along the valley and to inquire whether small schemes function better than large schemes. The performance evaluation study of the systems composed of three general performance indicators, based on three domains-（1） system operation performance; （2） agricultural productivity and economics; （3） financial performance. Each indicator was assessed based on the prescribed descriptors used by the International Water Management Institute （IWMI） and Food and Agriculture Organization （FAO）. Analysis showed an overall system performance efficiency of 59%, 55%, 47% and 36% for Magat River Integrated Irrigation System （MARI1S）, Lucban, Garab and Divisoria Communal Irrigation Systems （CIS）, respectively. In terms of annual productivity performance, Lucban CIS dominates the three other systems with 0.35 kg/m3, which was classified as moderately performing system, while the rest were classified with low productivity index. Financial sustainability of the systems were extremely poor with cost recovery ratio of 0, 0.33, 0.41 and 0.49 for Divisoria, Garab, Lucban and MARIIS, respectively, which were exceptionally below the standard value of at least one. Also, analysis of the indicators revealed that on average, large schemes performed similarly to small-scale schemes, but small schemes were more variable, particularly in input-use efficiency. The benchmarking study will provide strategic information to policy makers of agricultural and irrigation agencies on the existing weaknesses of irrigation systems in the country and determine in a more quantifiable terms levels of potential improvement and intervention targets.展开更多
We discuss the concepts, research methods, and infrastructure of watershed science. A watershed is a basic unit and possesses all of the complexities of the land surface system, thereby making it the best unit for pra...We discuss the concepts, research methods, and infrastructure of watershed science. A watershed is a basic unit and possesses all of the complexities of the land surface system, thereby making it the best unit for practicing Earth system science. Watershed science is an Earth system science practiced on a watershed scale, and it has developed rapidly over the previous two decades. The goal of watershed science is to understand and predict the behavior of complex watershed systems and support the sustainable development of watersheds. However, watershed science confronts the difficulties of understanding complex systems, achieving scale transformation, and simulating the co-evolution of the human-nature system. These difficulties are fundamentally methodological challenges. Therefore, we discuss the research methods of watershed science, which include the self-organized complex system method, the upscaling method dominated by statistical mechanics, Darwinian approaches based on selection and evolutionary principles, hydro-economic and eco-economic methods that emphasize the human-nature system co-evolution, and meta-synthesis for addressing unstructured problems. These approaches together can create a bridge between holism and reductionism and work as a group of operational methods to combine hard and soft integrations and capture all aspects of both natural and human systems. These methods will contribute to the maturation of watershed science and to a methodology that can be used throughout land-surface systems science.展开更多
基金supported by Research Fund of the State Key Laboratory of Geo-Hazard Prevention (Grant SKLGP2009Z004)the National Basic Research Program of China (also called 973 Program) (Grant No. 2011CB409903)
文摘The 5.12 Wenchuan Earthquake and the subsequent rainstorms induced a large number of landslides, which later were transformed into debris flows. To evaluate the effect of the earthquake on the sediment supply of debris flows, eight debris flow basins near Beichuan City, Sichuan Province, China were chosen as the study area. The area variations of the debris flow source after the Wenchuan Earthquake and the subsequent rainstorm are analyzed and discussed in this paper. Interpretations of aerial photographs (after the 5.12 Wenchuan Earthquake) and SPOT5 images (after the rainstorm event of September 24, 2008) as well as field investigations were compared to identify the transformation of landslide surface in the study area, indicating that the landslide area in the eight debris flow basins significantly increased. The loose sediment area on the channel bed increased after the rainstorm event. In order to estimate the relationship of the landslide area with the rainfall intensity in different return periods, a model proposed by Uchihugi was adopted. Results show that new landslide area induced by heavy rainfall with 50-year and 100-year return period will be 0.87 km2 and 1.67 km2, respectively. The study results show the Wenchuan earthquake had particular influences on subsequent rainfall-induced debris flow occurrence.
文摘The relationship between the groundwater and the surface eco-environment in arid area is very close. In this paper, the authors extracted normalized difference vegetation index （NDVI） and vegetation conditional ratio （VCR） from MODIS images, and analyzed the relationships among NDVI, VCR and the measured data of groundwater of the same location in the research region. Based on this, the depth of groundwater suitable for vegetation growth in the upper-middle reaches of the Yellow River basin has been calculated. The results show that the depth of groundwater suitable for vegetation growth in the research region ranges from 0.8 to 4.5m, and the optimal groundwater depth is 1.2m. The method developed in this study is applicable to research the relationship between the groundwater and land surface vegetation environment on large-scale in arid area.
文摘During the last decade, there has been an intensive research activity concerning the concept of the Water Footprint （WF） approach, which was firstly introduced by Arjen Hoekstra in 2002. WF is an indicator of direct and indirect freshwater use of a consumer or producer that takes into account water consumption in every step （intermediate and final） along the production chain and services. The concept can be implemented in various levels such as products, consumers, producers, nations and river basins etc.. The water footprint within a geographically delineated area equals the sum of the process water footprints of all processes taking place in the area. The aim of current research is a review of the most important WF studies, with a special focus on applications within regional, basin and administrative unit level. National and global scales are not included in the current paper. The article presents the most widespread methodologies and approaches that attempt to evaluate water footprints of specific defined areas and highlights their recent advances as well as shortcomings in the constantly evolving research efforts.
文摘The results presented in this paper are a part of the research results of the thesis ＂research on scientific basis and practice of develop a system of monitoring the impacts of climate change on surface water and groundwater＂. Case study： Ma river basin in Vietnam. The results were implemented： （i） data collection, fieldwork survey, synthesis and analysis of information and data; （ii） partitioning the influence degree of climate change and sea level rise to groundwater; （iii） determining criteria to select monitoring routes, location of monitoring groundwater in the condition of climate change and sea level rise and （iv） developing the monitoring system. The research＇s results have practical implications for the water resources management in the context of climate change and sea level rise in Ma river basin.
文摘Comparative performance analysis of four irrigation schemes within Cagayan River Basin was assessed using comparative performance indicators between the years 2008 and 2012. The objectives were to establish benchmarks for both productivity and performance of irrigation schemes along the valley and to inquire whether small schemes function better than large schemes. The performance evaluation study of the systems composed of three general performance indicators, based on three domains-（1） system operation performance; （2） agricultural productivity and economics; （3） financial performance. Each indicator was assessed based on the prescribed descriptors used by the International Water Management Institute （IWMI） and Food and Agriculture Organization （FAO）. Analysis showed an overall system performance efficiency of 59%, 55%, 47% and 36% for Magat River Integrated Irrigation System （MARI1S）, Lucban, Garab and Divisoria Communal Irrigation Systems （CIS）, respectively. In terms of annual productivity performance, Lucban CIS dominates the three other systems with 0.35 kg/m3, which was classified as moderately performing system, while the rest were classified with low productivity index. Financial sustainability of the systems were extremely poor with cost recovery ratio of 0, 0.33, 0.41 and 0.49 for Divisoria, Garab, Lucban and MARIIS, respectively, which were exceptionally below the standard value of at least one. Also, analysis of the indicators revealed that on average, large schemes performed similarly to small-scale schemes, but small schemes were more variable, particularly in input-use efficiency. The benchmarking study will provide strategic information to policy makers of agricultural and irrigation agencies on the existing weaknesses of irrigation systems in the country and determine in a more quantifiable terms levels of potential improvement and intervention targets.
基金supported by Prof.Chen Fahurepresented by this paper was funded by the Major Research Plan of the National Natural Science Foundation of China(Grant Nos.91225302,91425303)the Cross-disciplinary Collaborative Teams Program for Science,Technology,and Innovation of the Chinese Academy of Sciences
文摘We discuss the concepts, research methods, and infrastructure of watershed science. A watershed is a basic unit and possesses all of the complexities of the land surface system, thereby making it the best unit for practicing Earth system science. Watershed science is an Earth system science practiced on a watershed scale, and it has developed rapidly over the previous two decades. The goal of watershed science is to understand and predict the behavior of complex watershed systems and support the sustainable development of watersheds. However, watershed science confronts the difficulties of understanding complex systems, achieving scale transformation, and simulating the co-evolution of the human-nature system. These difficulties are fundamentally methodological challenges. Therefore, we discuss the research methods of watershed science, which include the self-organized complex system method, the upscaling method dominated by statistical mechanics, Darwinian approaches based on selection and evolutionary principles, hydro-economic and eco-economic methods that emphasize the human-nature system co-evolution, and meta-synthesis for addressing unstructured problems. These approaches together can create a bridge between holism and reductionism and work as a group of operational methods to combine hard and soft integrations and capture all aspects of both natural and human systems. These methods will contribute to the maturation of watershed science and to a methodology that can be used throughout land-surface systems science.
