A field experiment was conducted at the Shenyang Experimental Station ofEcology, Chinese Academy of Sciences, to study the effects of soil management practices on water useand rice (Oryza sativa L.) yield in an aquic ...A field experiment was conducted at the Shenyang Experimental Station ofEcology, Chinese Academy of Sciences, to study the effects of soil management practices on water useand rice (Oryza sativa L.) yield in an aquic brown soil during 2001 and 2002. A completely randomexperimental design with three replications was employed, having four soil management practices astreatments, namely: an undisturbed plow layer (CK), a thin plastic film (TN), a thick plastic film(TI) and subsoil compacting (CP). Results indicated no significant differences among all treatmentsfor rice biomass and grain yields. Also, water consumption was about the same for treatments TN andCK, however the treatments TI and CP were much lower with more than 45% and 40% of the irrigationwater in the treatments TI and CP, respectively, saved each year compared to CK. Therefore, wateruse efficiency was higher in the treatments TI and CP. These results will provide a scientific basisfor the water-saving rice cultivation.展开更多
Some patients with ascites due to liver cirrhosis become no longer responsive to diuretics. Once other causes of ascites such as portal vein thrombosis, malignancy or infection and non-compliance with medications and ...Some patients with ascites due to liver cirrhosis become no longer responsive to diuretics. Once other causes of ascites such as portal vein thrombosis, malignancy or infection and non-compliance with medications and low sodium diet have been excluded, the diagnosis of refractory ascites can be made based on strict criteria. Patients with refractory ascites have very poor prognosis and therefore referral for consideration for liver transplantation should be initiated. Search for reversible components of the underlying liver pathology should be undertaken and targeted therapy, when available, should be considered. Currently, serial large volume paracentesis (LVP) and transjugular intrahepatic portasystemic stent-shunt (TIPS) are the two mainstay treatment options for refractory ascites. Other treatment options are available but not widely used either because they carry high morlJidity and mortality (most surgical options) rates, or are new interventions that have shown promise but still need further evaluation. In this comprehensive review, we describe the evaluation and management of patients with refractory ascites from the prospective of the practicing physician.展开更多
In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium ...In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium (Cd) content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2+, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.展开更多
Virtual Reality provides a new approach for geographical research. In this paper, a framework of the Virtual Huanghe (Yellow) River System was first presented from the view of technology, which included five main mo...Virtual Reality provides a new approach for geographical research. In this paper, a framework of the Virtual Huanghe (Yellow) River System was first presented from the view of technology, which included five main modules——data sources, 3D simulation terrain database, 3D simulation model database, 3D simulation implementation and application system. Then the key technoiogies of constructing Virtual Huanghe River System were discussed in detail: 1) OpenGL technology, the 3D graphics developing instrument, was employed in Virtual Huanghe River System to realize the function of dynamic real-time navigation. 2) MO and OpenGL technologies were used to make the mutual response between 3D scene and 2D electronic map available, which made use of the advantages of both 3D scene and 2D electronic map, with the macroscopic view, integrality and conciseness of 2D electronic map combined with the locality, reality and visualization of 3D scene. At the same time the disadvantages of abstract and ambiguity of 2D electronic map and the direction losing of virtual navigation in 3D scene were overcome.展开更多
The construction of stone terraces to minimise soil erosion is common throughout Guizhou. This technique, however, has high inherent risk. Stone terraces are usually much higher than those with earth risers. While th...The construction of stone terraces to minimise soil erosion is common throughout Guizhou. This technique, however, has high inherent risk. Stone terraces are usually much higher than those with earth risers. While they trap a greater thickness of soil on the slope they increase the risk of slope failures, reduce moisture and nutrient availability to plants, and thin more soil up slope. The stone risers also threaten long-term productivity. When a riser collapses debris is deposited over the terrace below making farming difficult. These breaches in the terrace focus surface runoff leading to gully formation and increased sediment transport down slope. Artificial drainage systems, often used in conjunction with terracing, compound the risk. These channels prevent precipitation from soaking into the soil. This limits groundwater and soil moisture recharge which reduces the availability of water for crops and the length of the growing season. The rapid drainage of water from the slope reduces the time of concentration of the catchment resulting in an increase in flood activity. Floods are caused by smaller rainstorm events. They arrive faster and peak quicker and higher than before the channels were constructed. Engineering solutions to soil erosion must therefore be used in conjunction with, and are not as a substitute for, good land management strategies. Furthermore, despite changes in land use practices, and the application of new technologies, there is a maximum amount of production that can be obtained from this land on a sustainable basis.展开更多
Mountain catchments are prone to flash flooding due to heavy rainfall. Enhanced understanding of the generation and evolution processes of flash floods is essential for effective flood risk management. However, tradit...Mountain catchments are prone to flash flooding due to heavy rainfall. Enhanced understanding of the generation and evolution processes of flash floods is essential for effective flood risk management. However, traditional distributed hydrological models based on kinematic and diffusion wave approximations ignore certain physical mechanisms of flash floods and thus bear excessive uncertainty. Here a hydrodynamic model is presented for flash floods based on the full two-dimensional shallow water equations incorporating rainfall and infiltration. Laboratory experiments of overland flows were modelled to illustrate the capability of the model. Then the model was applied to resolve two observed flash floods of distinct magnitudes in the Lengkou catchment in Shanxi Province, China. The present model is shown to be able to reproduce the flood flows fairly well compared to the observed data. The spatial distribution of rainfall is shown to be crucial for the modelling of flash floods. Sensitivity analyses of the model parameters reveal that the stage and discharge hydrographs are more sensitive to the Manning roughness and initial water content in the catchment than to the Green-Ampt head. Most notably, as the flash flood augments due to heavier rainfall, the modelling results agree with observed data better, which clearly characterizes the paramount role of rainfall in dictating the floods. From practical perspectives, the proposed model is more appropriate for modelling large flash floods.展开更多
To manage water resources effectively, a multiscale assessment of the vulnerability of water resources on the basis of political boundaries and watersheds is necessary. This study addressed issues on the vulnerability...To manage water resources effectively, a multiscale assessment of the vulnerability of water resources on the basis of political boundaries and watersheds is necessary. This study addressed issues on the vulnerability of water resources and provided a multiscale comparison of spatial heterogeneity under a climate change background. Using improved quantitative evaluation methods of vulnerabil- ity, the Theil index and the Shannon-Weaver index, we evaluated the vulnerability of water resources and its spatial heterogeneity in the Haihe River Basin in four scales, namely, second-class water resource regions (Class II WRRs), third-class water resource regions (Class III WRRs), Province-Class II WRRs, and Province-Class III WRRs. Results show that vulnerability enhances from the north to south in the different scales, and shows obvious spatial heterogeneity instead of moving toward convergence in multiscale assessment results. Among the Class II WRRs, the Tuhai-Majia River is the most vulnerable area, and the vulnerability of the Luanhe River is lower than that of the north of the Haihe River Basin, which in turn is lower than that of the south of the Haihe River Basin. In the scales of Class III WRRs and Province-Class III WRRs, the vulnerability shows obvious spatial heterogeneity and diversity measured by the Theil index and the Shannon-Weaver index. Multiscale vulnerability assessment results based on political boundaries and the watersheds of the Haihe River Basin innovatively provided in this paper are important and useful to characterize the real spatial pattern of the vulnerability of water resources and improve water resource management.展开更多
Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable condit...Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.展开更多
This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of...This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.展开更多
The main aim of this study is to assess various aspects of the current water policy, investigate the perspectives of water saving, evaluate water price elasticity and explore new approaches toward sustainable water ma...The main aim of this study is to assess various aspects of the current water policy, investigate the perspectives of water saving, evaluate water price elasticity and explore new approaches toward sustainable water management in the water sector, through a questionnaire survey that has been performed in the city of Volos, Greece, concerning the residential sector. The appropriate design of water management measures presupposes the investigation of the influence of some selected variables to consumers' behavior. The price of water, the size of the dwelling, the indoor and outdoor uses, the educational level, the income of consumers as well as rainfall and temperature levels are examined, the residential water demand curve is estimated and projections of future water demand under different pricing policies are performed.展开更多
Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix...Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix polymer of coating. In order to obtain such information, the authors investigated the penetration of active substances to the polymer from cross section of specimens introduced by SAICAS (surface and interracial cutting analysis system), followed by FT-IR-ATR (Fourier transform infrared and attenuated total reflectance) spectroscopy analysis from Z direction of cross section. The corrosion test of coating panels by these active substances (control as artificial seawater) has been conducted for 120 days. The results show that the depth profile of each active substance is around few dozens of micrometers from coating surface. The criteria of corrosion test cannot be determined by these results due to lacking in actual corrosion data immersed for 15 years under active substances. However, the authors evaluated the effect on ballast tank coating systems by active substances using analytical methods of SAICAS and FT-IR-ATR spectroscopy.展开更多
Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developin...Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers' response can be grouped into seven major aspects: i) effects on income, ii) effects on production resources, iii) effects on crop management, iv) existing local knowledge about the technology, v) availability of inputs, vi) access to information, and vii) socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers' awareness of ago-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes.展开更多
This paper addresses the change of the river-lake relationship in the Huai River and its causes due to environmental change and human activities. A preliminary analysis is made from three aspects: (1) the natural geog...This paper addresses the change of the river-lake relationship in the Huai River and its causes due to environmental change and human activities. A preliminary analysis is made from three aspects: (1) the natural geographical change particularly captured by the Yellow River, (2) water conservancy project construction, and (3) socioeconomic development in the Huai River Basin. Key problems of changes in this river-lake relationship and the Huai River flood control are tackled, involving flood control and disaster alleviation ability of the Basin, engineering and non-engineering measurements applied to flood control and disaster mitigation, and water governance for adaptive management. Research shows that the Huai River is a rather complex one due to its complex geography with a hybrid wet and dry climate zoon, and higher population density. With the alternation of the river-lake relationship and socioeconomic development in the region, new problems keep arising, imposing new requirements on its sustainable water management. Thus, understanding the Huai River is a long and gradually improving process. Its future planning should keep absorbing new achievements of science and technology development, employing new technologies and methods, and gradually deepening our understanding of its fundamental principles. Water governance and adaptive water management will be new challenges and opportunities for the Basin in its river system change and flood control.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
Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical tec...Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical techniques. It was found that corrosion protective effect was revealed in the range of 2.0 to 2.7 ppm of ozone concentration in seawater. The ratio of the rust area of specimen became 20% in that concentration region. The rusted area is strongly influenced by the ozone concentration and the flow rate determined by FEM (finite element method). Ozone has a good influence for ballast tanks, i.e., ozone can delay the rust of ballast tanks, provided that the suitable concentration of ozone is selected. In this case, ozone may stop the corrosion at the defects, if a part of the paint in ballast tank is peeled off. However, ozone may also promote the corrosion of steel when the ozone concentration is very high, e.g., 10 ppm. Attention should be paid to the ozone concentration, if we use ozone as an active substance for ballast water management systems.展开更多
In Kuwait, wastewater management has gained extra attention in recent years and becomes crucial for sustainable industrial development sector. Among the food industry sector, dairy processing plants generate huge amou...In Kuwait, wastewater management has gained extra attention in recent years and becomes crucial for sustainable industrial development sector. Among the food industry sector, dairy processing plants generate huge amount of wastewater, which is heavily loaded with organic and other toxic compounds. Disposal of dairy wastewater effluent without sufficient treatment can contaminate aquatic ecosystems. Cost efficient treatment processes that are effective in removing organic load and other contaminants are essential to meet stringent environmental regulations applied in Kuwait. A research study was carried out at the KISR (Kuwait Institute for Scientific Research) to assess the technical viability and economic feasibility of combined microfiltration and biological treatment system. This work presents the economic evaluation of the adopted treatment system. The results show that the cost of the integrated system for large scale is estimated to be US$ 1.575/m3, which is 25% less than the cost of wastewater transportation and treatment in conventional sewage plants.展开更多
Three numeric simulation and optimal management models on groundwater resources are introduced in this paper. These models stand for the present developing levels on the technology of groundwater modeling and optimal ...Three numeric simulation and optimal management models on groundwater resources are introduced in this paper. These models stand for the present developing levels on the technology of groundwater modeling and optimal management in China, and show the practical application situations of the technology. Each of the technology of unique characteristics and purposes. According to the tests of the practical engineering, these models have played a very important role in solving the difficult problems of groundwater resources.展开更多
This paper seeks to understand people's perception of "come-we-stay" (CWS) cohabitation in Menchum Division (MD), Cameroon. As in most of Africa, marriage is a valued institution that ensures the continuation o...This paper seeks to understand people's perception of "come-we-stay" (CWS) cohabitation in Menchum Division (MD), Cameroon. As in most of Africa, marriage is a valued institution that ensures the continuation of the family tree. The emergence of CWS is gathering momentum fast in many communities in the country much to the dislike,of the church and custodians of tradition who perceive CWS to be a cheap union form that breaches marriage norms. This paper seeks to address whether the emergence of CWS has affected marriage perceptions in MD. Initially, quantitative data were collected via online survey disseminated via Facebook. The time-efficiency, economic viability, convenience and anonymity of this method made it a viable method for this study. Later, however, due to a low response to the Facebook link, the online survey was constructed into a questionnaire and administered to the same target population. Questionnaires were relevant to this study because they could be self-administered. However, the questionnaires were limited as they did not allow for attention to details. The data were analysed using content analysis.展开更多
Effects of soil management on carbon content in alluvial paddy were investigated using past soil survey data of Niigata prefecture, Japan. The changes of soil management were as follows: (1) slight decrease in nitr...Effects of soil management on carbon content in alluvial paddy were investigated using past soil survey data of Niigata prefecture, Japan. The changes of soil management were as follows: (1) slight decrease in nitrogen and phosphate fertilizer application rates; (2) decrease to half in the application of soil amendments, like calcium silicate; (3) decrease in compost application and increase in rice straw application; (4) increase in pipe drainage. In spite of these changes, negligible change of carbon content in the plow-layer of alluvial paddy soils had been observed for past 25 years. However, without rice straw application and paddy-upland rotations, the soil carbon content had been decreased. Carbon content of alluvial paddy soils classified into Gley Lowland soil (Fluvisol or Gleysol) at the depth of 0-30 cm was calculated about 49-103 g-kg"1 and gross carbon sequestration was calculated 7.68 Mt in the paddy field soils in Niigata prefecture.展开更多
基金Project supported by the Foundation of Shenyang Experimental Station of Ecology, Chinese Academy of Sciences (No. SYZ0203).
文摘A field experiment was conducted at the Shenyang Experimental Station ofEcology, Chinese Academy of Sciences, to study the effects of soil management practices on water useand rice (Oryza sativa L.) yield in an aquic brown soil during 2001 and 2002. A completely randomexperimental design with three replications was employed, having four soil management practices astreatments, namely: an undisturbed plow layer (CK), a thin plastic film (TN), a thick plastic film(TI) and subsoil compacting (CP). Results indicated no significant differences among all treatmentsfor rice biomass and grain yields. Also, water consumption was about the same for treatments TN andCK, however the treatments TI and CP were much lower with more than 45% and 40% of the irrigationwater in the treatments TI and CP, respectively, saved each year compared to CK. Therefore, wateruse efficiency was higher in the treatments TI and CP. These results will provide a scientific basisfor the water-saving rice cultivation.
文摘Some patients with ascites due to liver cirrhosis become no longer responsive to diuretics. Once other causes of ascites such as portal vein thrombosis, malignancy or infection and non-compliance with medications and low sodium diet have been excluded, the diagnosis of refractory ascites can be made based on strict criteria. Patients with refractory ascites have very poor prognosis and therefore referral for consideration for liver transplantation should be initiated. Search for reversible components of the underlying liver pathology should be undertaken and targeted therapy, when available, should be considered. Currently, serial large volume paracentesis (LVP) and transjugular intrahepatic portasystemic stent-shunt (TIPS) are the two mainstay treatment options for refractory ascites. Other treatment options are available but not widely used either because they carry high morlJidity and mortality (most surgical options) rates, or are new interventions that have shown promise but still need further evaluation. In this comprehensive review, we describe the evaluation and management of patients with refractory ascites from the prospective of the practicing physician.
文摘In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium (Cd) content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2+, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.
基金Under the auspices of the Science Data Sharing Pilot Project of Ministry of Science and Technology of China (No. 2003DEA2C010), Natural Science Fund of Henan University on Virtual City Construction Method (No. 04YBRW026)
文摘Virtual Reality provides a new approach for geographical research. In this paper, a framework of the Virtual Huanghe (Yellow) River System was first presented from the view of technology, which included five main modules——data sources, 3D simulation terrain database, 3D simulation model database, 3D simulation implementation and application system. Then the key technoiogies of constructing Virtual Huanghe River System were discussed in detail: 1) OpenGL technology, the 3D graphics developing instrument, was employed in Virtual Huanghe River System to realize the function of dynamic real-time navigation. 2) MO and OpenGL technologies were used to make the mutual response between 3D scene and 2D electronic map available, which made use of the advantages of both 3D scene and 2D electronic map, with the macroscopic view, integrality and conciseness of 2D electronic map combined with the locality, reality and visualization of 3D scene. At the same time the disadvantages of abstract and ambiguity of 2D electronic map and the direction losing of virtual navigation in 3D scene were overcome.
文摘The construction of stone terraces to minimise soil erosion is common throughout Guizhou. This technique, however, has high inherent risk. Stone terraces are usually much higher than those with earth risers. While they trap a greater thickness of soil on the slope they increase the risk of slope failures, reduce moisture and nutrient availability to plants, and thin more soil up slope. The stone risers also threaten long-term productivity. When a riser collapses debris is deposited over the terrace below making farming difficult. These breaches in the terrace focus surface runoff leading to gully formation and increased sediment transport down slope. Artificial drainage systems, often used in conjunction with terracing, compound the risk. These channels prevent precipitation from soaking into the soil. This limits groundwater and soil moisture recharge which reduces the availability of water for crops and the length of the growing season. The rapid drainage of water from the slope reduces the time of concentration of the catchment resulting in an increase in flood activity. Floods are caused by smaller rainstorm events. They arrive faster and peak quicker and higher than before the channels were constructed. Engineering solutions to soil erosion must therefore be used in conjunction with, and are not as a substitute for, good land management strategies. Furthermore, despite changes in land use practices, and the application of new technologies, there is a maximum amount of production that can be obtained from this land on a sustainable basis.
基金funded by Natural Science Foundation of China (Grants Nos. 51279144 and 11432015)Chinese Academy of Sciences (Grant No. KZZD-EW-05-01-03)
文摘Mountain catchments are prone to flash flooding due to heavy rainfall. Enhanced understanding of the generation and evolution processes of flash floods is essential for effective flood risk management. However, traditional distributed hydrological models based on kinematic and diffusion wave approximations ignore certain physical mechanisms of flash floods and thus bear excessive uncertainty. Here a hydrodynamic model is presented for flash floods based on the full two-dimensional shallow water equations incorporating rainfall and infiltration. Laboratory experiments of overland flows were modelled to illustrate the capability of the model. Then the model was applied to resolve two observed flash floods of distinct magnitudes in the Lengkou catchment in Shanxi Province, China. The present model is shown to be able to reproduce the flood flows fairly well compared to the observed data. The spatial distribution of rainfall is shown to be crucial for the modelling of flash floods. Sensitivity analyses of the model parameters reveal that the stage and discharge hydrographs are more sensitive to the Manning roughness and initial water content in the catchment than to the Green-Ampt head. Most notably, as the flash flood augments due to heavier rainfall, the modelling results agree with observed data better, which clearly characterizes the paramount role of rainfall in dictating the floods. From practical perspectives, the proposed model is more appropriate for modelling large flash floods.
基金Under the auspices of National Natural Science Foundation of China(No.51279140,51249010)National Basic Research Program of China(No.2010CB428406)
文摘To manage water resources effectively, a multiscale assessment of the vulnerability of water resources on the basis of political boundaries and watersheds is necessary. This study addressed issues on the vulnerability of water resources and provided a multiscale comparison of spatial heterogeneity under a climate change background. Using improved quantitative evaluation methods of vulnerabil- ity, the Theil index and the Shannon-Weaver index, we evaluated the vulnerability of water resources and its spatial heterogeneity in the Haihe River Basin in four scales, namely, second-class water resource regions (Class II WRRs), third-class water resource regions (Class III WRRs), Province-Class II WRRs, and Province-Class III WRRs. Results show that vulnerability enhances from the north to south in the different scales, and shows obvious spatial heterogeneity instead of moving toward convergence in multiscale assessment results. Among the Class II WRRs, the Tuhai-Majia River is the most vulnerable area, and the vulnerability of the Luanhe River is lower than that of the north of the Haihe River Basin, which in turn is lower than that of the south of the Haihe River Basin. In the scales of Class III WRRs and Province-Class III WRRs, the vulnerability shows obvious spatial heterogeneity and diversity measured by the Theil index and the Shannon-Weaver index. Multiscale vulnerability assessment results based on political boundaries and the watersheds of the Haihe River Basin innovatively provided in this paper are important and useful to characterize the real spatial pattern of the vulnerability of water resources and improve water resource management.
文摘Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.
基金the Dyn Fluid Laboratory at Arts et Métiers Paris Tech
文摘This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.
文摘The main aim of this study is to assess various aspects of the current water policy, investigate the perspectives of water saving, evaluate water price elasticity and explore new approaches toward sustainable water management in the water sector, through a questionnaire survey that has been performed in the city of Volos, Greece, concerning the residential sector. The appropriate design of water management measures presupposes the investigation of the influence of some selected variables to consumers' behavior. The price of water, the size of the dwelling, the indoor and outdoor uses, the educational level, the income of consumers as well as rainfall and temperature levels are examined, the residential water demand curve is estimated and projections of future water demand under different pricing policies are performed.
文摘Sodium hypochlorite and ozone are the principal active substances and usually employed in ballast water management systems. In the present study, the authors focus on the effect of these active substances to the maaix polymer of coating. In order to obtain such information, the authors investigated the penetration of active substances to the polymer from cross section of specimens introduced by SAICAS (surface and interracial cutting analysis system), followed by FT-IR-ATR (Fourier transform infrared and attenuated total reflectance) spectroscopy analysis from Z direction of cross section. The corrosion test of coating panels by these active substances (control as artificial seawater) has been conducted for 120 days. The results show that the depth profile of each active substance is around few dozens of micrometers from coating surface. The criteria of corrosion test cannot be determined by these results due to lacking in actual corrosion data immersed for 15 years under active substances. However, the authors evaluated the effect on ballast tank coating systems by active substances using analytical methods of SAICAS and FT-IR-ATR spectroscopy.
基金Project supported by the University of Wolverhampton, UK.
文摘Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers' response can be grouped into seven major aspects: i) effects on income, ii) effects on production resources, iii) effects on crop management, iv) existing local knowledge about the technology, v) availability of inputs, vi) access to information, and vii) socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers' awareness of ago-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes.
基金The National Basic Research Program of China (2010CB428406)the National Natural Science Foundation of China (No. 41071025/40730632) & National Key Water Project (No.2009ZX07210-006)
文摘This paper addresses the change of the river-lake relationship in the Huai River and its causes due to environmental change and human activities. A preliminary analysis is made from three aspects: (1) the natural geographical change particularly captured by the Yellow River, (2) water conservancy project construction, and (3) socioeconomic development in the Huai River Basin. Key problems of changes in this river-lake relationship and the Huai River flood control are tackled, involving flood control and disaster alleviation ability of the Basin, engineering and non-engineering measurements applied to flood control and disaster mitigation, and water governance for adaptive management. Research shows that the Huai River is a rather complex one due to its complex geography with a hybrid wet and dry climate zoon, and higher population density. With the alternation of the river-lake relationship and socioeconomic development in the region, new problems keep arising, imposing new requirements on its sustainable water management. Thus, understanding the Huai River is a long and gradually improving process. Its future planning should keep absorbing new achievements of science and technology development, employing new technologies and methods, and gradually deepening our understanding of its fundamental principles. Water governance and adaptive water management will be new challenges and opportunities for the Basin in its river system change and flood control.
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.
文摘Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical techniques. It was found that corrosion protective effect was revealed in the range of 2.0 to 2.7 ppm of ozone concentration in seawater. The ratio of the rust area of specimen became 20% in that concentration region. The rusted area is strongly influenced by the ozone concentration and the flow rate determined by FEM (finite element method). Ozone has a good influence for ballast tanks, i.e., ozone can delay the rust of ballast tanks, provided that the suitable concentration of ozone is selected. In this case, ozone may stop the corrosion at the defects, if a part of the paint in ballast tank is peeled off. However, ozone may also promote the corrosion of steel when the ozone concentration is very high, e.g., 10 ppm. Attention should be paid to the ozone concentration, if we use ozone as an active substance for ballast water management systems.
文摘In Kuwait, wastewater management has gained extra attention in recent years and becomes crucial for sustainable industrial development sector. Among the food industry sector, dairy processing plants generate huge amount of wastewater, which is heavily loaded with organic and other toxic compounds. Disposal of dairy wastewater effluent without sufficient treatment can contaminate aquatic ecosystems. Cost efficient treatment processes that are effective in removing organic load and other contaminants are essential to meet stringent environmental regulations applied in Kuwait. A research study was carried out at the KISR (Kuwait Institute for Scientific Research) to assess the technical viability and economic feasibility of combined microfiltration and biological treatment system. This work presents the economic evaluation of the adopted treatment system. The results show that the cost of the integrated system for large scale is estimated to be US$ 1.575/m3, which is 25% less than the cost of wastewater transportation and treatment in conventional sewage plants.
文摘Three numeric simulation and optimal management models on groundwater resources are introduced in this paper. These models stand for the present developing levels on the technology of groundwater modeling and optimal management in China, and show the practical application situations of the technology. Each of the technology of unique characteristics and purposes. According to the tests of the practical engineering, these models have played a very important role in solving the difficult problems of groundwater resources.
文摘This paper seeks to understand people's perception of "come-we-stay" (CWS) cohabitation in Menchum Division (MD), Cameroon. As in most of Africa, marriage is a valued institution that ensures the continuation of the family tree. The emergence of CWS is gathering momentum fast in many communities in the country much to the dislike,of the church and custodians of tradition who perceive CWS to be a cheap union form that breaches marriage norms. This paper seeks to address whether the emergence of CWS has affected marriage perceptions in MD. Initially, quantitative data were collected via online survey disseminated via Facebook. The time-efficiency, economic viability, convenience and anonymity of this method made it a viable method for this study. Later, however, due to a low response to the Facebook link, the online survey was constructed into a questionnaire and administered to the same target population. Questionnaires were relevant to this study because they could be self-administered. However, the questionnaires were limited as they did not allow for attention to details. The data were analysed using content analysis.
文摘Effects of soil management on carbon content in alluvial paddy were investigated using past soil survey data of Niigata prefecture, Japan. The changes of soil management were as follows: (1) slight decrease in nitrogen and phosphate fertilizer application rates; (2) decrease to half in the application of soil amendments, like calcium silicate; (3) decrease in compost application and increase in rice straw application; (4) increase in pipe drainage. In spite of these changes, negligible change of carbon content in the plow-layer of alluvial paddy soils had been observed for past 25 years. However, without rice straw application and paddy-upland rotations, the soil carbon content had been decreased. Carbon content of alluvial paddy soils classified into Gley Lowland soil (Fluvisol or Gleysol) at the depth of 0-30 cm was calculated about 49-103 g-kg"1 and gross carbon sequestration was calculated 7.68 Mt in the paddy field soils in Niigata prefecture.