This study proposes a novel form of environmental reservoir operation through integrating environmental flow supply,drought analysis,and evolutionary optimization.This study demonstrates that simultaneous supply of do...This study proposes a novel form of environmental reservoir operation through integrating environmental flow supply,drought analysis,and evolutionary optimization.This study demonstrates that simultaneous supply of downstream environmental flow of reservoir as well as water demand is challenging in the semi-arid area especially in dry years.In this study,water supply and environmental flow supply were 40%and 30%in the droughts,respectively.Moreover,mean errors of supplying water demand as well as environmental flow in dry years were 6 and 9 m3/s,respectively.Hence,these results highlight that ecological stresses of the downstream aquatic habitats as well as water supply loss are considerably escalated in dry years,which implies even using environmental optimal operation is not able to protect downstream aquatic habitats properly in the severe droughts.Moreover,available storage in reservoir will be remarkably reduced(averagely more than 30×106 m3 compared with optimal storage equal to 70×106 m3),which implies strategic storage of reservoir might be threatened.Among used evolutionary algorithms,particle swarm optimization(PSO)was selected as the best algorithm for solving the novel proposed objective function.The significance of this study is to propose a novel objective function to optimize reservoir operation in which environmental flow supply is directly addressed and integrated with drought analysis.This novel form of optimization system can overcome uncertainties of the conventional objective function due to considering environmental flow in the objective function as well as drought analysis in the context of reservoir operation especially applicable in semi-arid areas.The results indicate that using either other water resources for water supply or reducing water demand is the only solution for managing downstream ecological impacts of the river ecosystem.In other words,the results highlighted that replanning of water resources in the study area is necessary.Replacing the conventional optimization system for reservoir operation in the semi-arid area with proposed optimization system is recommendable to minimize the negotiations between stakeholders and environmental managers.展开更多
In recent decades,a series of policies and practices for environmental flows(e-flows)have been implemented in China,with the sustainable development goal of balancing the utilization and protection of water resources ...In recent decades,a series of policies and practices for environmental flows(e-flows)have been implemented in China,with the sustainable development goal of balancing the utilization and protection of water resources among social,economic,and ecological needs.The aims of this study were to determine the main challenges and issues in e-flows implementation at different scales by analyzing policies and practices for eflows in China,and to propose some recommendations for bridging the gaps between the science and implementation of e-flows.The gaps between the science and implementation of e-flows were found after review of literature,policies,and practices,and it was found that ecological flow was a more widely used term by the government,rather than e-flows,in implementation.The plans and effects of e-flows implementation are discussed in this paper and challenges of e-flows implementation are recognized:(1)limited water resources and uneven spatial and temporal distribution,(2)a weak scientific basis for e-flows implementation,(3)poor operability of e-flows science,and(4)ineffective supervision and guarantee measures.The recommendations are(1)to strengthen the scientific foundation of e-flows,(2)to improve effectiveness in application of e-flows science,and(3)to propose operable and effective supervision and guarantee measures.This paper elaborates the current understanding of e-flows science and provides practical recommendations for implementing e-flows and for improving the effectiveness in e-flows implementation.To bridge the gaps between science and implementation of e-flows and improve the operability of policies in future practices,more scientific research on practices is recommended through adaptive management.展开更多
Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban rivers.In addition to known reasons such as ever-increasing competition among water ...Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban rivers.In addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans,we propose that designing weir heights without explicitly considering e-flows is another major cause of this problem.In this paper,we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design stage.We establish a new weir height determination framework that would more effectively satisfy the required e-flows.The new framework differs from previous frameworks,in which flood control and water retention are the major concerns and the flow during floods is set as the inflow.In the new framework,e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the inflow.As a case study of the new framework’s effectiveness,we applied it to the Shiwuli River,a typical channelized urban river in Hefei,China.The old framework specified too-high weir height to meet the e-flow requirements,whereas the new framework offered more reasonable heights that improved e-flow provision.展开更多
It is difficult to scale up measurements of the sap flux density(J_S) for the characterization of tree or stand transpiration(E) due to spatial variations in J_S and their temporal changes.To assess spatial variations...It is difficult to scale up measurements of the sap flux density(J_S) for the characterization of tree or stand transpiration(E) due to spatial variations in J_S and their temporal changes.To assess spatial variations in the sap flux density of Korean pine(Pinus koraiensis) and their effects on E estimates,we measured the J_S using Granier-type sensors.Within trees,the J_S decreased exponentially with the radial depth,and the J_S of the east aspects were higher than those of the west aspects.Among trees,there was a positive relationship between J_S and the tree diameter at breast height,and this positive relationship became stronger as the transpiration demand increased.The spatial variations that caused large errors in E estimates(i.e.,up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors.However,changes in these variations did not generate substantial errors in the E estimates.For our study periods,the differences in the daily E(E_D) calculated by ignoring radial,azimuthal and tree-to-tree variations and the measured E_D were fairly constant,especially when the daily vapor pressure deficit(D_D)was higher than 0.6 k Pa.These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations(radial,azimuthal and tree-to-tree variations) when considering E estimates.展开更多
With the implementation of the Official Mexican Standard NOM-011-CONAGUA-2000 [1], the water balance of 730 basins has been calculated and its water availability agreement is published. This rule points out to allocat...With the implementation of the Official Mexican Standard NOM-011-CONAGUA-2000 [1], the water balance of 730 basins has been calculated and its water availability agreement is published. This rule points out to allocate water for the environment only as an annual volume since methods for estimating environmental flows were not standardized in the country. For this reason, The Water Agency (CONAGUA) issued the standard NMX-AA-159-SCFI-2012 [2], to assess environmental flows needed both, at the strategic level in Integrated Water Resources Management (IWRM), or as part of the Environmental Impact Assessment (EIA) of large hydraulic projects. For over ten years, this standard was developed and finally published in September 2012 [3]. It explains different methods from hydrological to holistic approaches, with examples for the country. Its application will cover the urgent need to preserve water for ecosystems in watersheds with high ecological importance and low stress for water use. In this paper, an analysis of the environmental flow standard and examples of the suggested hydrological methods are presented. For its implementation, some steps are taking place, mainly establishing environmental water reserves and building capacities. In addition, environmental allocations are becoming a common practice for all water projects, as well as setting limits to hydrological alterations by hydroelectric dams. The standard promotes the use of technical integration tools to analyze the responses of ecosystems to changes in the flow regime and adaptive management under different scenarios of water use. Although the main steps have been taken, its implementation as mandatory rule will take time.展开更多
To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrient...To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrients,temperature,dissolved oxygen,p H,conductivity,turbidity,chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s,which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light,resulting in a dramatic shift in phytoplankton composition,from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However,flow rate significantly enhanced the inter-relationships among environmental variables,in particular by inducing higher water turbidity and vegetative reproduction of periphyton( Spirogyra). These changes were accompanied by a decrease in underwater light intensity,which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist,because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.展开更多
Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap fl...Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R^2=0.76, P=0.01 at Hetou and R^2=0.7021, P=0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y=-17585X^3+15147X^2-1250.7X+2278.4 (R^2=0.68; P=0.01) at Hetou and Y=-101.67X^3-1.65X^2-376.4X+1914.8(R^2=0.40, P=0.05) at Jijia, where Ywas daily SFD, Xwas daily wind speed. Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2kPa, within which daily SFD varied from 540±70L/(m^2·d) to 4739±115L/(m^2·d) at Hetou site, from 397±26L/(m^2·d) to 3414±191L/(m^2·d) at Jijia site; (2) Diurnal SFDs at Hetou site were much higher under low relative humidity (<30%) and slightly lower under high relative humidity (>80%) compared with those at the Jijia site; (3) The upper and lower threshold of daily and diurnal RAD for the optimal water use of E. urophylla plantations were 18±2.7 and 2±1MJ/(m^2·d), 669 and 0J/(cm^2·h) during the observation period.展开更多
Increasing demand for water from all sectors presents a challenge for policy makers to improve water allocation policies for storage reservoirs. In addition, there are many other organisms and species present in river...Increasing demand for water from all sectors presents a challenge for policy makers to improve water allocation policies for storage reservoirs. In addition, there are many other organisms and species present in river waters that also require water for their survival. Due to the lack of awareness many times the minimum required quantity and quality of water for river ecosystem is not made available at downstream of storage reservoirs. So, a sustainable approach is required in reservoir operations to maintain the river ecosystem with environmental flow while meeting the other demands. Multi-objective, multi-reservoir operation model developed with Python programming using Fuzzy Linear Programing method incorporating environmental flow requirement of river is presented in this paper. Objective of maximization of irrigation release is considered for first run. In second run maximization of releases for hydropower generation is considered as objective. Further both objectives are fuzzified by incorporating linear membership function and solved to maximize fuzzified objective function simultaneously by maximizing satisfaction level indicator (λ). The optimal reservoir operation policy is presented considering constraints including Irrigation release, Turbine release, Reservoir storage, Environmental flow release and hydrologic continuity. Model applied for multi-reservoir system consists of four reservoirs, i.e., Jayakwadi Stage-I Reservoir (R1), Jayakwadi Stage-II Reservoir (R2), Yeldari Reservoir (R3), Siddheshwar Reservoir (R4) in Godavari River sub-basin from Marathwada region of Maharashtra State, India.展开更多
Water is the soul of the world. It is the most important element for the survival of humans, animals, birds, plants and all other living things on earth. Water is essential for the beginning of life as well as regular...Water is the soul of the world. It is the most important element for the survival of humans, animals, birds, plants and all other living things on earth. Water is essential for the beginning of life as well as regular availability of water ensuring the survival, growth and overall nourishment. Thus, proper planning and use of reservoir water are essential for all. To tackle this issue different optimization techniques underline their need and importance in the reservoir operations. In the present study, multi-reservoir optimization model is developed using Python programing language considering the objective of maximization of total annual release for hydropower generation. Model is applied to 3 reservoirs from Godavari River basin from Maharashtra state India. Water essential for conservation of environment has also been made available in river as environmental flow as per the recommendations of Central Water Commission (CWC) India. Developed optimization model provides optimal monthly operation policies.展开更多
Land use policy involves allocating land between production alternatives to meet society’s wants and desires. Increase in the affluence in the United States has increased the demand for environmental flows that could...Land use policy involves allocating land between production alternatives to meet society’s wants and desires. Increase in the affluence in the United States has increased the demand for environmental flows that could be met from public ownership or as joint products of private ownerships. The empirical results of this study indicated that land use patterns remained relatively unchanged between 1947 and 2007. The lack of change suggests that a large part of the demand for environmental services is being as byproducts of other commercial decisions.展开更多
Environmental issue has been considered more significant in many aspects of engineering decision-making process particularly in river management. There is an increasing effort to conserve functioning of rivers for hum...Environmental issue has been considered more significant in many aspects of engineering decision-making process particularly in river management. There is an increasing effort to conserve functioning of rivers for human use as well as nature, therefore environmental flow assessment has been widely developed. This paper discusses on environmental flow assessment of the Sekampung River, particularly on its middle reach. A new analytical approach based on water-sediment equations was introduced in order to determine a minimum environmental flow at the certain cross section of a river. The result of the new method was then compared with a minimum environmental flow provided by using two hydrological based methods, namely, Tennant and Flow Duration Curve Analysis (FDCA) method. The result shows that the concerned discharge provided by the water-sediment method (3.5 m3/s) is the smallest compare with a minimum environmental flow that is provided by both Tennant (5.7 m3/s) and FDCA method (4.5 m3/s). It is promising that the water-sediment method can be used as a simple approach on preliminary state of environmental flow assessment. The method involves not only water discharge but also its related sediment flow of the river in order to mitigate further ecological and morphological risks.展开更多
The Early Jurassic volcanic sequence of the Central Atlantic Magmatic Province(CAMP)of Morocco is classically subdivided into four stratigraphic units:the Lower,Middle,Upper and Recurrent Formations separated
Using the T63L16 analysis data with the resolution of 1.875╳1.875 degree of latitude and lon-gitude obtained from National Meteorological Center (NMC) and the real central position information of tropi-cal cyclone (r...Using the T63L16 analysis data with the resolution of 1.875╳1.875 degree of latitude and lon-gitude obtained from National Meteorological Center (NMC) and the real central position information of tropi-cal cyclone (referred to as TC hereafter) numbered by NMC, the basic environmental geostrophic flow at 126 time levels of 25 TCs in 1996 are calculated. The vertical distribution features of the flows are analyzed. Be-sides, the deviation of real TC tracks from the flows (referred as steering deviation hereafter, namely, the de-viation between the real central position of TC and the position calculated according to the steering flow) is also investigated. The result shows that the steering deviation would be different if the domain used to calculate the steering flow is different. The present paper obtains the optimum domain size to calculate the steering flow. It is found that the steering deviation is related to the velocity of steering flow and the initial latitude and intensity of TC itself, and that TC motion has relationship with the vertical shear structure of environmental geostrophic flow. The result also shows that the optimum steering flow is the deep-layer averaged basic flow from 1000 hPa to 200 hPa. Having the knowledge of these principle and features would help make accurate forecast of TC motion.展开更多
A simple on-line sonodigestion system was successfully used for breakdown organic nickel complexes in environmental waters acidified with diluted nitric acid prior to flow injection total dissolved nickel preconcentra...A simple on-line sonodigestion system was successfully used for breakdown organic nickel complexes in environmental waters acidified with diluted nitric acid prior to flow injection total dissolved nickel preconcentration in a microcolumn containing a chelating resin (Chelite Che with iminodiacetic acid groups) and determination by flame atomic absorption spectrometry. For the determination of the dissolved labile nickel fraction, microcolumns packed with the chelating resin were loaded in-situ with the sample without sample pH modification, and once in the laboratory were inserted in the flow injection device where nickel elution-detection was carried out. The performance of the chelating resin was investigated in order to elucidate its behavior in the presence of dissolved nickel species. The results obtained reveal that the resin, at the experimental employed conditions, retained only dissolved free nickel ions and nickel bound to weak complexes (labile fraction). The figures of merit for determinations in both nickel fractions are given and the obtained values are discussed. The speciation scheme is applied to the analysis of nickel in river and seawater samples collected in Galicia (Northwest, Spain). The results of fractionation showed that Ni are mainly in the dissolved labile fraction in river water, while in seawater samples analyzed was mainly present in the organic fraction.展开更多
文摘This study proposes a novel form of environmental reservoir operation through integrating environmental flow supply,drought analysis,and evolutionary optimization.This study demonstrates that simultaneous supply of downstream environmental flow of reservoir as well as water demand is challenging in the semi-arid area especially in dry years.In this study,water supply and environmental flow supply were 40%and 30%in the droughts,respectively.Moreover,mean errors of supplying water demand as well as environmental flow in dry years were 6 and 9 m3/s,respectively.Hence,these results highlight that ecological stresses of the downstream aquatic habitats as well as water supply loss are considerably escalated in dry years,which implies even using environmental optimal operation is not able to protect downstream aquatic habitats properly in the severe droughts.Moreover,available storage in reservoir will be remarkably reduced(averagely more than 30×106 m3 compared with optimal storage equal to 70×106 m3),which implies strategic storage of reservoir might be threatened.Among used evolutionary algorithms,particle swarm optimization(PSO)was selected as the best algorithm for solving the novel proposed objective function.The significance of this study is to propose a novel objective function to optimize reservoir operation in which environmental flow supply is directly addressed and integrated with drought analysis.This novel form of optimization system can overcome uncertainties of the conventional objective function due to considering environmental flow in the objective function as well as drought analysis in the context of reservoir operation especially applicable in semi-arid areas.The results indicate that using either other water resources for water supply or reducing water demand is the only solution for managing downstream ecological impacts of the river ecosystem.In other words,the results highlighted that replanning of water resources in the study area is necessary.Replacing the conventional optimization system for reservoir operation in the semi-arid area with proposed optimization system is recommendable to minimize the negotiations between stakeholders and environmental managers.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFE0196000)
文摘In recent decades,a series of policies and practices for environmental flows(e-flows)have been implemented in China,with the sustainable development goal of balancing the utilization and protection of water resources among social,economic,and ecological needs.The aims of this study were to determine the main challenges and issues in e-flows implementation at different scales by analyzing policies and practices for eflows in China,and to propose some recommendations for bridging the gaps between the science and implementation of e-flows.The gaps between the science and implementation of e-flows were found after review of literature,policies,and practices,and it was found that ecological flow was a more widely used term by the government,rather than e-flows,in implementation.The plans and effects of e-flows implementation are discussed in this paper and challenges of e-flows implementation are recognized:(1)limited water resources and uneven spatial and temporal distribution,(2)a weak scientific basis for e-flows implementation,(3)poor operability of e-flows science,and(4)ineffective supervision and guarantee measures.The recommendations are(1)to strengthen the scientific foundation of e-flows,(2)to improve effectiveness in application of e-flows science,and(3)to propose operable and effective supervision and guarantee measures.This paper elaborates the current understanding of e-flows science and provides practical recommendations for implementing e-flows and for improving the effectiveness in e-flows implementation.To bridge the gaps between science and implementation of e-flows and improve the operability of policies in future practices,more scientific research on practices is recommended through adaptive management.
基金We thank the National Key Research and Development Program of China(2017YFC0404504)the Fund for Innovative Research Group of the National Natural Science Foundation of China(51721093)the National Natural Science Foundation of China(71861137001)for their financial support.
文摘Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban rivers.In addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans,we propose that designing weir heights without explicitly considering e-flows is another major cause of this problem.In this paper,we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design stage.We establish a new weir height determination framework that would more effectively satisfy the required e-flows.The new framework differs from previous frameworks,in which flood control and water retention are the major concerns and the flow during floods is set as the inflow.In the new framework,e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the inflow.As a case study of the new framework’s effectiveness,we applied it to the Shiwuli River,a typical channelized urban river in Hefei,China.The old framework specified too-high weir height to meet the e-flow requirements,whereas the new framework offered more reasonable heights that improved e-flow provision.
基金supported by both the Korea Forest Service(S211315L020120,S111215L020110)the Korea Meteorology Agency(KMIPA-20120001-2)the support of the Mt.Teahwa Seoul National University Forest
文摘It is difficult to scale up measurements of the sap flux density(J_S) for the characterization of tree or stand transpiration(E) due to spatial variations in J_S and their temporal changes.To assess spatial variations in the sap flux density of Korean pine(Pinus koraiensis) and their effects on E estimates,we measured the J_S using Granier-type sensors.Within trees,the J_S decreased exponentially with the radial depth,and the J_S of the east aspects were higher than those of the west aspects.Among trees,there was a positive relationship between J_S and the tree diameter at breast height,and this positive relationship became stronger as the transpiration demand increased.The spatial variations that caused large errors in E estimates(i.e.,up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors.However,changes in these variations did not generate substantial errors in the E estimates.For our study periods,the differences in the daily E(E_D) calculated by ignoring radial,azimuthal and tree-to-tree variations and the measured E_D were fairly constant,especially when the daily vapor pressure deficit(D_D)was higher than 0.6 k Pa.These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations(radial,azimuthal and tree-to-tree variations) when considering E estimates.
文摘With the implementation of the Official Mexican Standard NOM-011-CONAGUA-2000 [1], the water balance of 730 basins has been calculated and its water availability agreement is published. This rule points out to allocate water for the environment only as an annual volume since methods for estimating environmental flows were not standardized in the country. For this reason, The Water Agency (CONAGUA) issued the standard NMX-AA-159-SCFI-2012 [2], to assess environmental flows needed both, at the strategic level in Integrated Water Resources Management (IWRM), or as part of the Environmental Impact Assessment (EIA) of large hydraulic projects. For over ten years, this standard was developed and finally published in September 2012 [3]. It explains different methods from hydrological to holistic approaches, with examples for the country. Its application will cover the urgent need to preserve water for ecosystems in watersheds with high ecological importance and low stress for water use. In this paper, an analysis of the environmental flow standard and examples of the suggested hydrological methods are presented. For its implementation, some steps are taking place, mainly establishing environmental water reserves and building capacities. In addition, environmental allocations are becoming a common practice for all water projects, as well as setting limits to hydrological alterations by hydroelectric dams. The standard promotes the use of technical integration tools to analyze the responses of ecosystems to changes in the flow regime and adaptive management under different scenarios of water use. Although the main steps have been taken, its implementation as mandatory rule will take time.
基金Supported by the National Natural Science Foundation of China(Nos.51379146,51409190)the National Science Foundation for Post-Doctoral Scientists of China(No.2013M531218)
文摘To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrients,temperature,dissolved oxygen,p H,conductivity,turbidity,chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s,which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light,resulting in a dramatic shift in phytoplankton composition,from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However,flow rate significantly enhanced the inter-relationships among environmental variables,in particular by inducing higher water turbidity and vegetative reproduction of periphyton( Spirogyra). These changes were accompanied by a decrease in underwater light intensity,which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist,because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.
基金Project supported by Knowledge Innovation Funds from Chinese Academy of Sciences (Nos. KSCX2-SW-120, KZCX1-SW-01-01A3)the Key Project of Guangdong Natural Science Foundation (No. 010567), China Author for correspondence
文摘Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R^2=0.76, P=0.01 at Hetou and R^2=0.7021, P=0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y=-17585X^3+15147X^2-1250.7X+2278.4 (R^2=0.68; P=0.01) at Hetou and Y=-101.67X^3-1.65X^2-376.4X+1914.8(R^2=0.40, P=0.05) at Jijia, where Ywas daily SFD, Xwas daily wind speed. Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2kPa, within which daily SFD varied from 540±70L/(m^2·d) to 4739±115L/(m^2·d) at Hetou site, from 397±26L/(m^2·d) to 3414±191L/(m^2·d) at Jijia site; (2) Diurnal SFDs at Hetou site were much higher under low relative humidity (<30%) and slightly lower under high relative humidity (>80%) compared with those at the Jijia site; (3) The upper and lower threshold of daily and diurnal RAD for the optimal water use of E. urophylla plantations were 18±2.7 and 2±1MJ/(m^2·d), 669 and 0J/(cm^2·h) during the observation period.
文摘Increasing demand for water from all sectors presents a challenge for policy makers to improve water allocation policies for storage reservoirs. In addition, there are many other organisms and species present in river waters that also require water for their survival. Due to the lack of awareness many times the minimum required quantity and quality of water for river ecosystem is not made available at downstream of storage reservoirs. So, a sustainable approach is required in reservoir operations to maintain the river ecosystem with environmental flow while meeting the other demands. Multi-objective, multi-reservoir operation model developed with Python programming using Fuzzy Linear Programing method incorporating environmental flow requirement of river is presented in this paper. Objective of maximization of irrigation release is considered for first run. In second run maximization of releases for hydropower generation is considered as objective. Further both objectives are fuzzified by incorporating linear membership function and solved to maximize fuzzified objective function simultaneously by maximizing satisfaction level indicator (λ). The optimal reservoir operation policy is presented considering constraints including Irrigation release, Turbine release, Reservoir storage, Environmental flow release and hydrologic continuity. Model applied for multi-reservoir system consists of four reservoirs, i.e., Jayakwadi Stage-I Reservoir (R1), Jayakwadi Stage-II Reservoir (R2), Yeldari Reservoir (R3), Siddheshwar Reservoir (R4) in Godavari River sub-basin from Marathwada region of Maharashtra State, India.
文摘Water is the soul of the world. It is the most important element for the survival of humans, animals, birds, plants and all other living things on earth. Water is essential for the beginning of life as well as regular availability of water ensuring the survival, growth and overall nourishment. Thus, proper planning and use of reservoir water are essential for all. To tackle this issue different optimization techniques underline their need and importance in the reservoir operations. In the present study, multi-reservoir optimization model is developed using Python programing language considering the objective of maximization of total annual release for hydropower generation. Model is applied to 3 reservoirs from Godavari River basin from Maharashtra state India. Water essential for conservation of environment has also been made available in river as environmental flow as per the recommendations of Central Water Commission (CWC) India. Developed optimization model provides optimal monthly operation policies.
文摘Land use policy involves allocating land between production alternatives to meet society’s wants and desires. Increase in the affluence in the United States has increased the demand for environmental flows that could be met from public ownership or as joint products of private ownerships. The empirical results of this study indicated that land use patterns remained relatively unchanged between 1947 and 2007. The lack of change suggests that a large part of the demand for environmental services is being as byproducts of other commercial decisions.
文摘Environmental issue has been considered more significant in many aspects of engineering decision-making process particularly in river management. There is an increasing effort to conserve functioning of rivers for human use as well as nature, therefore environmental flow assessment has been widely developed. This paper discusses on environmental flow assessment of the Sekampung River, particularly on its middle reach. A new analytical approach based on water-sediment equations was introduced in order to determine a minimum environmental flow at the certain cross section of a river. The result of the new method was then compared with a minimum environmental flow provided by using two hydrological based methods, namely, Tennant and Flow Duration Curve Analysis (FDCA) method. The result shows that the concerned discharge provided by the water-sediment method (3.5 m3/s) is the smallest compare with a minimum environmental flow that is provided by both Tennant (5.7 m3/s) and FDCA method (4.5 m3/s). It is promising that the water-sediment method can be used as a simple approach on preliminary state of environmental flow assessment. The method involves not only water discharge but also its related sediment flow of the river in order to mitigate further ecological and morphological risks.
文摘The Early Jurassic volcanic sequence of the Central Atlantic Magmatic Province(CAMP)of Morocco is classically subdivided into four stratigraphic units:the Lower,Middle,Upper and Recurrent Formations separated
基金The Program of Research on Weather Forecasting Methods and Operational Systems by the National Meteorological Center (ZX95-02)
文摘Using the T63L16 analysis data with the resolution of 1.875╳1.875 degree of latitude and lon-gitude obtained from National Meteorological Center (NMC) and the real central position information of tropi-cal cyclone (referred to as TC hereafter) numbered by NMC, the basic environmental geostrophic flow at 126 time levels of 25 TCs in 1996 are calculated. The vertical distribution features of the flows are analyzed. Be-sides, the deviation of real TC tracks from the flows (referred as steering deviation hereafter, namely, the de-viation between the real central position of TC and the position calculated according to the steering flow) is also investigated. The result shows that the steering deviation would be different if the domain used to calculate the steering flow is different. The present paper obtains the optimum domain size to calculate the steering flow. It is found that the steering deviation is related to the velocity of steering flow and the initial latitude and intensity of TC itself, and that TC motion has relationship with the vertical shear structure of environmental geostrophic flow. The result also shows that the optimum steering flow is the deep-layer averaged basic flow from 1000 hPa to 200 hPa. Having the knowledge of these principle and features would help make accurate forecast of TC motion.
文摘A simple on-line sonodigestion system was successfully used for breakdown organic nickel complexes in environmental waters acidified with diluted nitric acid prior to flow injection total dissolved nickel preconcentration in a microcolumn containing a chelating resin (Chelite Che with iminodiacetic acid groups) and determination by flame atomic absorption spectrometry. For the determination of the dissolved labile nickel fraction, microcolumns packed with the chelating resin were loaded in-situ with the sample without sample pH modification, and once in the laboratory were inserted in the flow injection device where nickel elution-detection was carried out. The performance of the chelating resin was investigated in order to elucidate its behavior in the presence of dissolved nickel species. The results obtained reveal that the resin, at the experimental employed conditions, retained only dissolved free nickel ions and nickel bound to weak complexes (labile fraction). The figures of merit for determinations in both nickel fractions are given and the obtained values are discussed. The speciation scheme is applied to the analysis of nickel in river and seawater samples collected in Galicia (Northwest, Spain). The results of fractionation showed that Ni are mainly in the dissolved labile fraction in river water, while in seawater samples analyzed was mainly present in the organic fraction.