Volume 17,Issue 3,2019 Table of Contents
2019, 17(3):1-6.
Abstract:
In order to improve the accuracy of medium and long term wet season rainfall forecasting,a Hybrid models based on the Grain in Ear and BP neural network is established in this study,and applied to the forcasting of rainfall in mid and long term wet seasons in Beijing.The results show that the hybrid model can effectively improve the accuracy of the rainfall forecasting,in comparison with the traditional BP model.The correlation coefficient between the simulated and the measured rainfall is 0.78,which is much better than the traditional BP model of 0.42.The hybrid model also has a 40% improvement in terms of the forecasting pass rate over the traditional BP model.The Grain in Ear can fully explore the useful information hidden in the original data,reduce interfere of noise data (e.g.,extreme values),and effectively improve the forecasting accuracy.This study combines the traditional 24 solar terms with artificial intelligence forecasting technology and provides a new idea for medium and long term wet season rainfall forecasting.
In order to improve the accuracy of medium and long term wet season rainfall forecasting,a Hybrid models based on the Grain in Ear and BP neural network is established in this study,and applied to the forcasting of rainfall in mid and long term wet seasons in Beijing.The results show that the hybrid model can effectively improve the accuracy of the rainfall forecasting,in comparison with the traditional BP model.The correlation coefficient between the simulated and the measured rainfall is 0.78,which is much better than the traditional BP model of 0.42.The hybrid model also has a 40% improvement in terms of the forecasting pass rate over the traditional BP model.The Grain in Ear can fully explore the useful information hidden in the original data,reduce interfere of noise data (e.g.,extreme values),and effectively improve the forecasting accuracy.This study combines the traditional 24 solar terms with artificial intelligence forecasting technology and provides a new idea for medium and long term wet season rainfall forecasting.
2019, 17(3):7-15.
Abstract:
The flood disasters are frequent in the Huaihe River Basin,and Hongze Lake plays a key role in flood control.It is ofgreat practical significance for water resources management,streamflow and sediment regulation to detect the trend and changing points of streamflow and sediment in the Hongze Lake.The temporal characteristics of streamflow and sediment in the Hongze Lake were investigated with observed annual streamflow and sediment discharge data at representative hydrological stations from 1975 to 2015.The Mann Kendall trend test and the Pettit change point detection method were used to explore temporal trend and changing points of streamflow and sediment.The main influencing factors of streamflow and sediment changes in the Hongze Lake were identified from the aspects of river water resources development and utilization,basin rainfall and sediment retaining of reservoir.The research showed that the annual variations of inflows and outflows of the Hongze Lake was consistent,and there was not statistically significant trend or changing point.There was a slight and insignificant decreasing trend for the amount of sediment inflows at 0.05 significance level,but a statistically significant decreasing trend for the sediment outflows.Sediment inflows and outflows both had a changing point in 1991.Rainfall was the most important factor affecting the variation of streamflow.The streamflow showed a decreasing trend from 1993 to 2015,which was related to the increasing development and utilization of water resources in the basin.Decrease in sediment was mainly from the upstream reservoir constructions.The main reasons for the changing points were the engineering projects of the Huaihe River started in 1991,which included the reconstruction of reservoirs and conservation countermeasures of water and soil.
The flood disasters are frequent in the Huaihe River Basin,and Hongze Lake plays a key role in flood control.It is ofgreat practical significance for water resources management,streamflow and sediment regulation to detect the trend and changing points of streamflow and sediment in the Hongze Lake.The temporal characteristics of streamflow and sediment in the Hongze Lake were investigated with observed annual streamflow and sediment discharge data at representative hydrological stations from 1975 to 2015.The Mann Kendall trend test and the Pettit change point detection method were used to explore temporal trend and changing points of streamflow and sediment.The main influencing factors of streamflow and sediment changes in the Hongze Lake were identified from the aspects of river water resources development and utilization,basin rainfall and sediment retaining of reservoir.The research showed that the annual variations of inflows and outflows of the Hongze Lake was consistent,and there was not statistically significant trend or changing point.There was a slight and insignificant decreasing trend for the amount of sediment inflows at 0.05 significance level,but a statistically significant decreasing trend for the sediment outflows.Sediment inflows and outflows both had a changing point in 1991.Rainfall was the most important factor affecting the variation of streamflow.The streamflow showed a decreasing trend from 1993 to 2015,which was related to the increasing development and utilization of water resources in the basin.Decrease in sediment was mainly from the upstream reservoir constructions.The main reasons for the changing points were the engineering projects of the Huaihe River started in 1991,which included the reconstruction of reservoirs and conservation countermeasures of water and soil.
2019, 17(3):16-22.
Abstract:
The water balance of lakes in the plain areas is difficult to estimate due to the influences of human activities.In the paper,a distributed hydrological model was constructed and the water balance was calculated for the Wolong Lake,an inland lake in the plain area.The model simulation results had a Nash coefficient being greater than 0.75 and a relative runoff error of being less than 3%. The water balance was further investigated for typical years,such as,wet year,normal year,dry year and extreme dry year.The results showed that under natural conditions,the lake storage were 20442 million m3、7911 million m3、1655 million m3、 6.87 million m3,respectively.If water was interrupted in the upstream section,the lake storage would reduce to 15424 million m3 for wet year,and to 1943 million m3 for the normal year.Under the dry year and the extreme dry year,there was no flow in the East and West Malian River,causing the lake to be extremely drought.
The water balance of lakes in the plain areas is difficult to estimate due to the influences of human activities.In the paper,a distributed hydrological model was constructed and the water balance was calculated for the Wolong Lake,an inland lake in the plain area.The model simulation results had a Nash coefficient being greater than 0.75 and a relative runoff error of being less than 3%. The water balance was further investigated for typical years,such as,wet year,normal year,dry year and extreme dry year.The results showed that under natural conditions,the lake storage were 20442 million m3、7911 million m3、1655 million m3、 6.87 million m3,respectively.If water was interrupted in the upstream section,the lake storage would reduce to 15424 million m3 for wet year,and to 1943 million m3 for the normal year.Under the dry year and the extreme dry year,there was no flow in the East and West Malian River,causing the lake to be extremely drought.
2019, 17(3):23-30.
Abstract:
An index reduction method was proposed to eliminate unnecessary indexes and to establish a simple and practical water resources carrying capacity (WRCC) model,based on sensitivity analysis and dynamic cluster analysis.It overcame the shortcomings of the traditional WRCC model,such as,many quantities,fine classifications,rich data requirements and not independence or indirect correlations.Firstly,the sensitivity analysis was used to screen the indexes initially.Secondly,the correlation coefficient was used to cluster the indexes dynamically.According to the clustering results,the number of index was further reduced,and the effective reduction of indexes was achieved.This model was then used in Huzhou City to calculate its WRCC from 2011 to 2016.The results showed that the WRCC states of Huzhou has been developed well from 2011 to 2016,which was basically consistent with the actual conditions,which verified the rationality and effectiveness of the model.Meanwhile,the proposed method provided some new aspects of the WRCC evaluation and can be used in other regions of the country to estimate WRCC.
An index reduction method was proposed to eliminate unnecessary indexes and to establish a simple and practical water resources carrying capacity (WRCC) model,based on sensitivity analysis and dynamic cluster analysis.It overcame the shortcomings of the traditional WRCC model,such as,many quantities,fine classifications,rich data requirements and not independence or indirect correlations.Firstly,the sensitivity analysis was used to screen the indexes initially.Secondly,the correlation coefficient was used to cluster the indexes dynamically.According to the clustering results,the number of index was further reduced,and the effective reduction of indexes was achieved.This model was then used in Huzhou City to calculate its WRCC from 2011 to 2016.The results showed that the WRCC states of Huzhou has been developed well from 2011 to 2016,which was basically consistent with the actual conditions,which verified the rationality and effectiveness of the model.Meanwhile,the proposed method provided some new aspects of the WRCC evaluation and can be used in other regions of the country to estimate WRCC.
2019, 17(3):31-39.
Abstract:
Based on the hydrological and meteorological data and land types in the upper reaches of Heihe River basin,variations and attribution of runoff over the study area were investigated using several statistical methods and Zhang Lu's empirical formula under Budyko framework.The results showed that:(1) The runoff increased significantly from 1960 to 2015 and changed abruptly in 1997 and 2004.The study period was divided into three stages:the base period of 1960-1997,the abrupt change period I of 1998-2004,and the abrupt change period II of 2005-2015;(2) The changes of precipitation,potential evapotranspiration and permanent glacial snow area were consistent with the changes of runoff to a certain extent.The increase of precipitation and the decrease of permanent glacial snow area had positive effects on runoff generation,while the increase of potential evapotranspiration had negative effects on runoff generation;(3) The contribution rates of precipitation,potential evapotranspiration and other factors (mainly the permanent glacial snowmelt) to runoff changes during abrupt change period I were 149%,-83% and 34%,respectively;and decreased to 138%、-35% and -3%,respectively,during abrupt change period II.
Based on the hydrological and meteorological data and land types in the upper reaches of Heihe River basin,variations and attribution of runoff over the study area were investigated using several statistical methods and Zhang Lu's empirical formula under Budyko framework.The results showed that:(1) The runoff increased significantly from 1960 to 2015 and changed abruptly in 1997 and 2004.The study period was divided into three stages:the base period of 1960-1997,the abrupt change period I of 1998-2004,and the abrupt change period II of 2005-2015;(2) The changes of precipitation,potential evapotranspiration and permanent glacial snow area were consistent with the changes of runoff to a certain extent.The increase of precipitation and the decrease of permanent glacial snow area had positive effects on runoff generation,while the increase of potential evapotranspiration had negative effects on runoff generation;(3) The contribution rates of precipitation,potential evapotranspiration and other factors (mainly the permanent glacial snowmelt) to runoff changes during abrupt change period I were 149%,-83% and 34%,respectively;and decreased to 138%、-35% and -3%,respectively,during abrupt change period II.
2019, 17(3):40-47.
Abstract:
A case study was conducted in the Jinjiang River basin,which is located in south east coast of China,in order to explore how the spatial variations of the natural conditions and the human activities like large reservoir affect the temporalspatial variations of the distributed hydrological model parameters.Three hydrological stations and the dam of Shanmei Reservoir were used to separate the watershed into four subareas and the method of multi sites calibration and validation was used to set up the HEC-HMS model.The annual largest flood series from 1996 to 2014 were selected and two key parameters,the initial loss rate (λ) and the flood wave velocity (V),were calibrated in each sub area with approximate circulation method.The results showed that:(1) The multisites calibration method was effective to obtain the values of key parameters in each subarea.(2) The temporal spatial variation of parameters was clear.The annual average of the initial loss rates at four sub area were 0.33,0.54,0.559 and 0.571,respectively,being affected by the land use and water conservancy project.The initial loss rate at reservoir catchment area was the lowest one among the four sub areas,which indicated that woodland increasing and reservoir storage decreased the initial loss rate.The temporal variation of initial loss rate was dependent on the initial discharge.The greater the initial discharge was,the smaller the initial loss rate was.The annual averages of flood wave velocity at different sub area were 3.218,2.241,1.95,1.427 and 1.217 m/s,respectively,and it decreased from upstream to downstream.The spatial variation of flood wave velocity was related to the average slope of the watershed while the temporal variation was related to the largest 6 h areal rainfall and upstream runoff.A larger of the average slope and areal rainfall leads into a greater of wave velocity.(3) The method of multi sites calibration for setting up of HEC-HMS made it possible to reveal the differences of hydrologic processes in different region of the basin.
A case study was conducted in the Jinjiang River basin,which is located in south east coast of China,in order to explore how the spatial variations of the natural conditions and the human activities like large reservoir affect the temporalspatial variations of the distributed hydrological model parameters.Three hydrological stations and the dam of Shanmei Reservoir were used to separate the watershed into four subareas and the method of multi sites calibration and validation was used to set up the HEC-HMS model.The annual largest flood series from 1996 to 2014 were selected and two key parameters,the initial loss rate (λ) and the flood wave velocity (V),were calibrated in each sub area with approximate circulation method.The results showed that:(1) The multisites calibration method was effective to obtain the values of key parameters in each subarea.(2) The temporal spatial variation of parameters was clear.The annual average of the initial loss rates at four sub area were 0.33,0.54,0.559 and 0.571,respectively,being affected by the land use and water conservancy project.The initial loss rate at reservoir catchment area was the lowest one among the four sub areas,which indicated that woodland increasing and reservoir storage decreased the initial loss rate.The temporal variation of initial loss rate was dependent on the initial discharge.The greater the initial discharge was,the smaller the initial loss rate was.The annual averages of flood wave velocity at different sub area were 3.218,2.241,1.95,1.427 and 1.217 m/s,respectively,and it decreased from upstream to downstream.The spatial variation of flood wave velocity was related to the average slope of the watershed while the temporal variation was related to the largest 6 h areal rainfall and upstream runoff.A larger of the average slope and areal rainfall leads into a greater of wave velocity.(3) The method of multi sites calibration for setting up of HEC-HMS made it possible to reveal the differences of hydrologic processes in different region of the basin.
2019, 17(3):48-55.
Abstract:
The spatial and temporal variations of meteorological drought on the north and south slopes of Tianshan mountains in Xinjiang from 1960 to 2016 were investigated with three sets of standardized precipitation evapotranspiration index (SPEI),based on three different methods to estimate the potential evapotranspiration (PET).They were Penman Monteith method (SPEI-PM),instrument measurement (SPEI-SJ) and Thornthwaite method (SPEI-TH).The results showed:(1) Both the SPEI-SJ and SPEI-PM indexes showed a wetting trend and a decrease of drought area,but the SPEI-TH index showed an opposite trend;(2) The SPEI-SJ and SPEI-PM indexes had the same occurrence frequency of drought on the annual and seasonal scales,i.e.,drought occurred more frequently in the spring and summer seasons,followed by autumn,and the least in winter season.However,the drought frequency of SPEI-TH did not show significant differences in various time scales.The spatial patterns of drought frequency from the SPEI-SJ and SPEI-PM indices were consistent.There was a difference of drought frequency in local regions,which was the same as drought intensity variation;(3) SPEI-PM had a relatively higher accuracy before 1986,while SPEI-SJ only had a higher accuracy after 1990 in comparison with observed drought events.SPEI-TH was the worst index to reflect drought events.Overall,SPEI-PM was the most suitable index for monitoring historical drought events,and SPEI-SJ could add some values for monitoring drought after 1990s.
The spatial and temporal variations of meteorological drought on the north and south slopes of Tianshan mountains in Xinjiang from 1960 to 2016 were investigated with three sets of standardized precipitation evapotranspiration index (SPEI),based on three different methods to estimate the potential evapotranspiration (PET).They were Penman Monteith method (SPEI-PM),instrument measurement (SPEI-SJ) and Thornthwaite method (SPEI-TH).The results showed:(1) Both the SPEI-SJ and SPEI-PM indexes showed a wetting trend and a decrease of drought area,but the SPEI-TH index showed an opposite trend;(2) The SPEI-SJ and SPEI-PM indexes had the same occurrence frequency of drought on the annual and seasonal scales,i.e.,drought occurred more frequently in the spring and summer seasons,followed by autumn,and the least in winter season.However,the drought frequency of SPEI-TH did not show significant differences in various time scales.The spatial patterns of drought frequency from the SPEI-SJ and SPEI-PM indices were consistent.There was a difference of drought frequency in local regions,which was the same as drought intensity variation;(3) SPEI-PM had a relatively higher accuracy before 1986,while SPEI-SJ only had a higher accuracy after 1990 in comparison with observed drought events.SPEI-TH was the worst index to reflect drought events.Overall,SPEI-PM was the most suitable index for monitoring historical drought events,and SPEI-SJ could add some values for monitoring drought after 1990s.
2019, 17(3):56-66.
Abstract:
Rainfall infiltration is one of the main sources of water for the underground reservoir.The influence of rainfall on the groundwater reservoir water level and the water storage capacity of the groundwater reservoir are investigated in this study with a single reservoir of single channel anti seepage underground dam and a reservoir group of multi channel anti seepage underground dam.A two dimensional finite element model was established to estimate the unsteady seepage field of the groundwater reservoir under different rainfall intensities and different rainfall patterns,with the Seep/W module in GeoStudio finite element software.Rainfall intensity was chosen by taking into account annual average rainfall and annual maximum rainfall for a period of 1 year.Rainfall types include average type,forward type,center type and post peak type,with a total rainfall of 100 mm.The simulation results show that the upstream water level of the single base underground dam increased by 71.1% and the downstream water level increased by 11.7% under different rainfall intensities.The water level changes are mainly occurred in the #1 and #6 water storage spaces under multiple water storage spaces in an actual underground reservoir group,and the maximum water level changes are 8.8 m and 12.5 m under average rainfall and maximum rainfall,respectively.The water level in the middle storage space has only a minor change.The single reservoir has little changes of an overall water level.The installation of the reservoir group has a great influence on the water level for each water storage space,which might be beneficial to the water intake.Under different rainfall patterns,the pressures of the upper and lower surface pores of the single reservoir and the reservoir group reached their maximum.The peaks of the surface water content could be affected,and the maximum water content lasts the longest time with forwardtype rainfall.The research results provide a reference for the groundwater reservoir to store water under different rainfall conditions.
Rainfall infiltration is one of the main sources of water for the underground reservoir.The influence of rainfall on the groundwater reservoir water level and the water storage capacity of the groundwater reservoir are investigated in this study with a single reservoir of single channel anti seepage underground dam and a reservoir group of multi channel anti seepage underground dam.A two dimensional finite element model was established to estimate the unsteady seepage field of the groundwater reservoir under different rainfall intensities and different rainfall patterns,with the Seep/W module in GeoStudio finite element software.Rainfall intensity was chosen by taking into account annual average rainfall and annual maximum rainfall for a period of 1 year.Rainfall types include average type,forward type,center type and post peak type,with a total rainfall of 100 mm.The simulation results show that the upstream water level of the single base underground dam increased by 71.1% and the downstream water level increased by 11.7% under different rainfall intensities.The water level changes are mainly occurred in the #1 and #6 water storage spaces under multiple water storage spaces in an actual underground reservoir group,and the maximum water level changes are 8.8 m and 12.5 m under average rainfall and maximum rainfall,respectively.The water level in the middle storage space has only a minor change.The single reservoir has little changes of an overall water level.The installation of the reservoir group has a great influence on the water level for each water storage space,which might be beneficial to the water intake.Under different rainfall patterns,the pressures of the upper and lower surface pores of the single reservoir and the reservoir group reached their maximum.The peaks of the surface water content could be affected,and the maximum water content lasts the longest time with forwardtype rainfall.The research results provide a reference for the groundwater reservoir to store water under different rainfall conditions.
2019, 17(3):67-78.
Abstract:
The potential evapotranspiration is an important basis for determining the crop water demand.Accurate estimation and attribution its meteorological influencing factors are of great significances for optimizing the adjustment of agricultural planting structure and rational allocation of water and soil resources.The spatiotemporal variations of potential evapotranspiration and its climate influencing factors in Hebei Province were investigated based on daily weather data from 1960-2016 at 24 meteorological stations in Hebei Province and adjacent administrative regions,Penman Monteith formula sensitivity coefficient,and contribution rate.Results showed that the average ET0 in Hebei Province was 1095.70 mm in the past 57 years.It showed an overall downward trend with an average magnitude of -8.905 mm/（10a）.The ET0 change rate of was the highest in summer season and the lowest in winter season.The spatial distribution showed a general semi circular decreasing trend from west to east,and its seasonal variations were basically consistent with that of annual scale.The annual average ET0 was negatively sensitive to relative humidity and positively to other meteorological factors.The sensitivity of each meteorological factor was:relative humidity>maximum temperature>average wind speed>sunshine hours>average temperature>minimum temperature.The average wind speed was the dominant factor for the change of ET0 in the whole year and in spring,autumn and winter seasons.Sunshine hours were the dominant factor for the change of summer ET0.In terms of spatial distribution,the dominant factor of ET0 variation in the northwestern region was the average temperature,the northeastern region the sunshine hours,and the central and southern regions the average wind speed.The results can provide theoretical supports for the optimal allocation of water resources and regional drought assessment.
The potential evapotranspiration is an important basis for determining the crop water demand.Accurate estimation and attribution its meteorological influencing factors are of great significances for optimizing the adjustment of agricultural planting structure and rational allocation of water and soil resources.The spatiotemporal variations of potential evapotranspiration and its climate influencing factors in Hebei Province were investigated based on daily weather data from 1960-2016 at 24 meteorological stations in Hebei Province and adjacent administrative regions,Penman Monteith formula sensitivity coefficient,and contribution rate.Results showed that the average ET0 in Hebei Province was 1095.70 mm in the past 57 years.It showed an overall downward trend with an average magnitude of -8.905 mm/（10a）.The ET0 change rate of was the highest in summer season and the lowest in winter season.The spatial distribution showed a general semi circular decreasing trend from west to east,and its seasonal variations were basically consistent with that of annual scale.The annual average ET0 was negatively sensitive to relative humidity and positively to other meteorological factors.The sensitivity of each meteorological factor was:relative humidity>maximum temperature>average wind speed>sunshine hours>average temperature>minimum temperature.The average wind speed was the dominant factor for the change of ET0 in the whole year and in spring,autumn and winter seasons.Sunshine hours were the dominant factor for the change of summer ET0.In terms of spatial distribution,the dominant factor of ET0 variation in the northwestern region was the average temperature,the northeastern region the sunshine hours,and the central and southern regions the average wind speed.The results can provide theoretical supports for the optimal allocation of water resources and regional drought assessment.
10 Remote sensing estimation of evapotranspiration in large scale basin based on surface energy balance
2019, 17(3):79-88.
Abstract:
Evapotranspiration (ET) is the key link between land surface energy balance and water movement.Accurate estimation of ET on basin scale is of great significance to climate change studies,water resources management,crop yield estimation and environmental protection.Combining the climate characteristics,land use types and vegetation dynamics in the middle and high latitudes of China,an ET estimation model was proposed based on Surface Energy Balance System (SEBS)..The model was then applied to the Songhua River basin to estimate ET.The estimation accuracy of the model was validated by the water balance and ecological observations in the basin,and MTE data of global flux observation network.The simulation accuracy of the model was also evaluated by cross-validation of a land surface process model and NASA MOD16 ET .The results show that the improved SEBS model has a high accuracy in estimating the ET in Songhua River and Liaohe River basins in China,but the accuracy is not uniform in the whole country;The model is a reasonable method for estimating the ET in the middle and high latitudes of China;The spatial and temporal changes of the Songhua River basin show that the total ET in the basin has been relatively stable in recent years,but with a spatial variation.
Evapotranspiration (ET) is the key link between land surface energy balance and water movement.Accurate estimation of ET on basin scale is of great significance to climate change studies,water resources management,crop yield estimation and environmental protection.Combining the climate characteristics,land use types and vegetation dynamics in the middle and high latitudes of China,an ET estimation model was proposed based on Surface Energy Balance System (SEBS)..The model was then applied to the Songhua River basin to estimate ET.The estimation accuracy of the model was validated by the water balance and ecological observations in the basin,and MTE data of global flux observation network.The simulation accuracy of the model was also evaluated by cross-validation of a land surface process model and NASA MOD16 ET .The results show that the improved SEBS model has a high accuracy in estimating the ET in Songhua River and Liaohe River basins in China,but the accuracy is not uniform in the whole country;The model is a reasonable method for estimating the ET in the middle and high latitudes of China;The spatial and temporal changes of the Songhua River basin show that the total ET in the basin has been relatively stable in recent years,but with a spatial variation.
2019, 17(3):89-96.
Abstract:
In this article,the spatiotemporal pattern of resources and environment carrying capacity in the Yangtze River economic belt was investigated by constructing an evaluation index system of resource and environment carrying capacity,using the entropy theory to quantify the index value,and adopting the spatial data exploratory analysis method..The results show that the overall index value of resources and environmental carrying capacity of the Yangtze River economic belt in the 2005-2016 displayed a moderate upward trend,but the index value of urban resources and environmental carrying capacity gradually decreased from the east to west,which was consistent with the levels of economic development.The overall Moran′s I value of the resource and environment carrying capacity in the Yangtze River economic belt keeps on increasing.In terms of local scale evolution,the distribution of hot spots were relatively stable,while those of sub hot spots,sub cold spots and cold spots were relatively unstable.Therefore,cities in the Yangtze River economic belt should achieve self improvement and co development in the future development in order to promote the improvement of resources and environmental carrying capacity of the Yangtze River economic belt and to achieve high quality development.
In this article,the spatiotemporal pattern of resources and environment carrying capacity in the Yangtze River economic belt was investigated by constructing an evaluation index system of resource and environment carrying capacity,using the entropy theory to quantify the index value,and adopting the spatial data exploratory analysis method..The results show that the overall index value of resources and environmental carrying capacity of the Yangtze River economic belt in the 2005-2016 displayed a moderate upward trend,but the index value of urban resources and environmental carrying capacity gradually decreased from the east to west,which was consistent with the levels of economic development.The overall Moran′s I value of the resource and environment carrying capacity in the Yangtze River economic belt keeps on increasing.In terms of local scale evolution,the distribution of hot spots were relatively stable,while those of sub hot spots,sub cold spots and cold spots were relatively unstable.Therefore,cities in the Yangtze River economic belt should achieve self improvement and co development in the future development in order to promote the improvement of resources and environmental carrying capacity of the Yangtze River economic belt and to achieve high quality development.
2019, 17(3):97-104.
Abstract:
Nine groundwater samples in the Liuli River and its surrounding areas in Beijing were taken to investigate the effects of characteristics of regional groundwater chemistry on microbial community.Characteristics of groundwater chemistry were examined,and the V4-V5 region of 16S rRNA was scanned by the high throughput sequencing.The correlation between groundwater chemical characteristics and microbial community structure were then explored.The results of hydrochemistry showed that HCO_3-Ca·Mg、HCO_3·Cl-Ca、HCO_3·Cl·SO_4-Ca and HCO_3-Ca were found and the main type is HCO_3-Ca·Mg in the study area.Microbial analysis results showed that Proteobacteria was the predominant phylum and predominant gene was not found in the study area.The microbial diversity from different types of groundwater showed that the level of microbial diversity increased with complexity of groundwater chemical types.A total of 113 genera were found in the four chemical types of groundwater,and the numbers of microorganisms in HCO_3-Ca·Mg、HCO_3·Cl-Ca、HCO_3·Cl·SO_4-Ca and HCO_3-Ca were 186,32,33 and 2,respectively.The order of groundwater impact on microbial community was turbidity>EC>DO>pH.The turbidity,Pseudomonas,Vogesella and Hydrogenophaga were benefited from Higher EC and DO values,and the Gallionella and Nitrospira were stimulated by moderate increase of pH.In summary, the characteristics of regional groundwater chemistry had significant effects on microbial community.
Nine groundwater samples in the Liuli River and its surrounding areas in Beijing were taken to investigate the effects of characteristics of regional groundwater chemistry on microbial community.Characteristics of groundwater chemistry were examined,and the V4-V5 region of 16S rRNA was scanned by the high throughput sequencing.The correlation between groundwater chemical characteristics and microbial community structure were then explored.The results of hydrochemistry showed that HCO_3-Ca·Mg、HCO_3·Cl-Ca、HCO_3·Cl·SO_4-Ca and HCO_3-Ca were found and the main type is HCO_3-Ca·Mg in the study area.Microbial analysis results showed that Proteobacteria was the predominant phylum and predominant gene was not found in the study area.The microbial diversity from different types of groundwater showed that the level of microbial diversity increased with complexity of groundwater chemical types.A total of 113 genera were found in the four chemical types of groundwater,and the numbers of microorganisms in HCO_3-Ca·Mg、HCO_3·Cl-Ca、HCO_3·Cl·SO_4-Ca and HCO_3-Ca were 186,32,33 and 2,respectively.The order of groundwater impact on microbial community was turbidity>EC>DO>pH.The turbidity,Pseudomonas,Vogesella and Hydrogenophaga were benefited from Higher EC and DO values,and the Gallionella and Nitrospira were stimulated by moderate increase of pH.In summary, the characteristics of regional groundwater chemistry had significant effects on microbial community.
2019, 17(3):105-114.
Abstract:
Groundwater recharge can not only cover the deficit of groundwater resources,but also dilute and purify contaminated groundwater.The recharge experiments at Beijing Water Source No.4 Plant and the PHREEQC simulation software were used in this study for water quality mixing simulations and water quality prediction.The results showed that the recharge has a great impact on the water quality of South Well,but limited impacts on that of North Well and East Well.The water quality of South Well was upgraded from Class Ⅲ to Class Ⅱ.The chloride,sulfate,nitrate and bicarbonate were recharged and their the concentration.at the end were very close to those of the recharge wells.The final concentrations of potassium,calcium and magnesium were slightly lower than those of the recharge wells,probably due to cation exchanges.The simulated water quality of mixed water had a good correlation with the observations,and a linear equation of the simulation mixing ratio and recharge time of South Well were obtained.Its coefficient of determination (R2) was as high as 0.999.It predicted that the groundwater in Beijing needed 11 days to be recharged under the same conditions for the water quality being upgraded from the Class Ⅳ to Class Ⅱ.The water quality prediction method of this study can effectively improve the efficiency of groundwater recharge and has useful guideline for groundwater recharge prediction.
Groundwater recharge can not only cover the deficit of groundwater resources,but also dilute and purify contaminated groundwater.The recharge experiments at Beijing Water Source No.4 Plant and the PHREEQC simulation software were used in this study for water quality mixing simulations and water quality prediction.The results showed that the recharge has a great impact on the water quality of South Well,but limited impacts on that of North Well and East Well.The water quality of South Well was upgraded from Class Ⅲ to Class Ⅱ.The chloride,sulfate,nitrate and bicarbonate were recharged and their the concentration.at the end were very close to those of the recharge wells.The final concentrations of potassium,calcium and magnesium were slightly lower than those of the recharge wells,probably due to cation exchanges.The simulated water quality of mixed water had a good correlation with the observations,and a linear equation of the simulation mixing ratio and recharge time of South Well were obtained.Its coefficient of determination (R2) was as high as 0.999.It predicted that the groundwater in Beijing needed 11 days to be recharged under the same conditions for the water quality being upgraded from the Class Ⅳ to Class Ⅱ.The water quality prediction method of this study can effectively improve the efficiency of groundwater recharge and has useful guideline for groundwater recharge prediction.
2019, 17(3):115-120.
Abstract:
The variation characteristics of soil bulk density at different depths of collapse fissures is studied at Fuxin in this study in order to quantify the effects of coal mining subsidence on soil moisture. The relationships between the width of the collapse fracture,the distance from the crack and the water content of the soil were explored with hierarchical clustering,the Mann-Kendall rank correlation and the multiple linear regression.The results indicate that the soil bulk density increases linearly with the depth in the study area,and there are obvious changing points.The locations of these changing points of connected cracks,concealed cracks and non-collapse areas are 50 cm,70 cm and 150 cm,respectively.The effects of crack width on soil water content decrease with the depth at different depth cracks with the same width.Under the condition of the same crack and depth,the soil moisture content will then increases with the distance from the crack.The crack width obviously enhance the soil moisture content,and an increase in the crack width usually leads to an increase of the average soil moisture content.
The variation characteristics of soil bulk density at different depths of collapse fissures is studied at Fuxin in this study in order to quantify the effects of coal mining subsidence on soil moisture. The relationships between the width of the collapse fracture,the distance from the crack and the water content of the soil were explored with hierarchical clustering,the Mann-Kendall rank correlation and the multiple linear regression.The results indicate that the soil bulk density increases linearly with the depth in the study area,and there are obvious changing points.The locations of these changing points of connected cracks,concealed cracks and non-collapse areas are 50 cm,70 cm and 150 cm,respectively.The effects of crack width on soil water content decrease with the depth at different depth cracks with the same width.Under the condition of the same crack and depth,the soil moisture content will then increases with the distance from the crack.The crack width obviously enhance the soil moisture content,and an increase in the crack width usually leads to an increase of the average soil moisture content.
2019, 17(3):121-127.
Abstract:
Taihu lake dredged sediment was selected as raw material to produce smallsize (＜12 mm) wrapshell lightweight aggregates (WSLAs) from unburned process.The unburned coarse and lightweight aggregates (UCLAs) was obtained by bonding and shell wrapping process from WSLAs.The effects of WSLAs gradation on UCLAs density,particle size distribution and particle strength were then investigated with 20~25 mm UCLAs in this study.The characteristics,such as size distribution,packing density,water adsorption,cylinder compressive strength,crushing value and freezingthawing resistance of UCLAs,were examined and compared with natural coarse aggregates (NCAs) in accordance with the Chinese National Standards (GB/T 14685-2011).The results showed that the best performance UCLAs were WSLAs1~3 mm accounting for 10%,3~5 mm for 25%,5~8 mm for 50%,and 8~12 mm for 15%.The density and particle strength of this best performance UCLAs obtained from this WSLAs combination were 1.644 g/cm3 and 2.75 MPa,respectively.At the same time, the internal structure of UCLAs was stable and the shell structure was dense.The water absorption rate was only 189%,which showed a durability being comparable to that of NCAs.There was not mass loss in 25 days of salt solution erosion and 25 cycles of freezethaw resistance.The crushing value of UCLAs was 18.6%,which was higher than that of NCAs (9.5%),but meets the requirement of GB/T 14685-2011 for class Ⅱ coarse aggregate.Therefore, it can be used as skeleton support in building concrete.
Taihu lake dredged sediment was selected as raw material to produce smallsize (＜12 mm) wrapshell lightweight aggregates (WSLAs) from unburned process.The unburned coarse and lightweight aggregates (UCLAs) was obtained by bonding and shell wrapping process from WSLAs.The effects of WSLAs gradation on UCLAs density,particle size distribution and particle strength were then investigated with 20~25 mm UCLAs in this study.The characteristics,such as size distribution,packing density,water adsorption,cylinder compressive strength,crushing value and freezingthawing resistance of UCLAs,were examined and compared with natural coarse aggregates (NCAs) in accordance with the Chinese National Standards (GB/T 14685-2011).The results showed that the best performance UCLAs were WSLAs1~3 mm accounting for 10%,3~5 mm for 25%,5~8 mm for 50%,and 8~12 mm for 15%.The density and particle strength of this best performance UCLAs obtained from this WSLAs combination were 1.644 g/cm3 and 2.75 MPa,respectively.At the same time, the internal structure of UCLAs was stable and the shell structure was dense.The water absorption rate was only 189%,which showed a durability being comparable to that of NCAs.There was not mass loss in 25 days of salt solution erosion and 25 cycles of freezethaw resistance.The crushing value of UCLAs was 18.6%,which was higher than that of NCAs (9.5%),but meets the requirement of GB/T 14685-2011 for class Ⅱ coarse aggregate.Therefore, it can be used as skeleton support in building concrete.
2019, 17(3):128-138.
Abstract:
The influences of bolt and lining on the stability of its surrounding rock are investigated in this study for the diversion tunnel of Danba Hydropower Station.The thickness of tunnel lining under different buried depths are investigated,and the safety of lining under different working conditions is analyzed.The reinforcement and the crack width are checked,and the influences of different lining application time on the force and displacement of the tunnel are taken into consideration.It is found that the bolt supporter can make the distribution of the plastic zone of its surrounding rocks more uniform and the force is more reasonable,which could control the deformation of the surrounding rock better.The maximum compressive stress in the lining will increases with depth,and decreases with the lining thickness.An effective decompression zone is proposed,which should be selected within the effective decompression zone.The lining thickness is preferred at 1.5 m.In the most dangerous conditions,a reasonable design scheme of reinforcement is given.By comparing and analyzing the safety of lining under different displacement and different models,85% displacement reserve is chosen for lining reinforcement,and the deformation and maximum internal force of surrounding rock can be obviously controlled.
The influences of bolt and lining on the stability of its surrounding rock are investigated in this study for the diversion tunnel of Danba Hydropower Station.The thickness of tunnel lining under different buried depths are investigated,and the safety of lining under different working conditions is analyzed.The reinforcement and the crack width are checked,and the influences of different lining application time on the force and displacement of the tunnel are taken into consideration.It is found that the bolt supporter can make the distribution of the plastic zone of its surrounding rocks more uniform and the force is more reasonable,which could control the deformation of the surrounding rock better.The maximum compressive stress in the lining will increases with depth,and decreases with the lining thickness.An effective decompression zone is proposed,which should be selected within the effective decompression zone.The lining thickness is preferred at 1.5 m.In the most dangerous conditions,a reasonable design scheme of reinforcement is given.By comparing and analyzing the safety of lining under different displacement and different models,85% displacement reserve is chosen for lining reinforcement,and the deformation and maximum internal force of surrounding rock can be obviously controlled.
2019, 17(3):139-146.
Abstract:
Large scale water conveyance canal lining is easy to erode and damage under freezethaw cycles and the drainage system at the bottom of the canal may fail during the operation processes.These disadvantages need to be improved.Large scale water diversion projects generally do not have the conditions of waterstopping or water level reduction.Therefore,the repairing techniques of the defects and damages under the condition of non-stop water are one of the key and difficult problems in the operational and maintenance of largescale water diversion projects.Based on the field testing of lining repair of main canal in the middle route of South to North Water Diversion Project,the structure design of an underwater 3.0~3.5 meter steel cofferdam was carried out.A set of self-balanced combined cofferdam techniques,which were easy to install and had effective water stopping,was proposed in this study through further researches of water retaining panel,supporting force transfer system and new water stopping types of structures in different parts..Construction technology of water surface assembly,waterentry and dismantling transfer site of steel cofferdam have also been proposed.The results can provide useful references for underwater repair of dry land with lining of large water conveyance projects.
Large scale water conveyance canal lining is easy to erode and damage under freezethaw cycles and the drainage system at the bottom of the canal may fail during the operation processes.These disadvantages need to be improved.Large scale water diversion projects generally do not have the conditions of waterstopping or water level reduction.Therefore,the repairing techniques of the defects and damages under the condition of non-stop water are one of the key and difficult problems in the operational and maintenance of largescale water diversion projects.Based on the field testing of lining repair of main canal in the middle route of South to North Water Diversion Project,the structure design of an underwater 3.0~3.5 meter steel cofferdam was carried out.A set of self-balanced combined cofferdam techniques,which were easy to install and had effective water stopping,was proposed in this study through further researches of water retaining panel,supporting force transfer system and new water stopping types of structures in different parts..Construction technology of water surface assembly,waterentry and dismantling transfer site of steel cofferdam have also been proposed.The results can provide useful references for underwater repair of dry land with lining of large water conveyance projects.
18 Experimental study on erosion of sand beds with different slopes by plane jet with inclined angles
2019, 17(3):147-154.
Abstract:
The utility of jet dredging has been widely used and played an important role in dredging projects.It is important to explore its results with different jet factors and dredging factors,which can improve dredging efficiency.In this paper,the erosion processes of sand beds with different slopes by the plane jet with inclined angles were investigated with different jet velocities,jet angles and slopes of sand bed,shapes of scour holes,and characteristics of turbid flow outside the crater.The results showed that:(1) There were geometric similarities of the scour holes with asymmetrical geometry and downstreamtoward profiles;(2) The development processes of the scour holes can be divided into three stages:initial stage,development stage and stable stage;(3) The depth of the scour holes developed with time as a logarithmic relationshp,and the erosion rate reached the largest when the crater depth reaches half of the maximum depth;(4) With the increase of jet angle,the areas of twodimensional crater decreased firstly and then increased.It reached its minimum value when the jet angle was at 45°;(5) The volumes of sediment erosion and the speed of turbid flow outside the crater increased with the slopes of the sand bed.However,the growth trend slowed down after the slope was greater than 10‰.
The utility of jet dredging has been widely used and played an important role in dredging projects.It is important to explore its results with different jet factors and dredging factors,which can improve dredging efficiency.In this paper,the erosion processes of sand beds with different slopes by the plane jet with inclined angles were investigated with different jet velocities,jet angles and slopes of sand bed,shapes of scour holes,and characteristics of turbid flow outside the crater.The results showed that:(1) There were geometric similarities of the scour holes with asymmetrical geometry and downstreamtoward profiles;(2) The development processes of the scour holes can be divided into three stages:initial stage,development stage and stable stage;(3) The depth of the scour holes developed with time as a logarithmic relationshp,and the erosion rate reached the largest when the crater depth reaches half of the maximum depth;(4) With the increase of jet angle,the areas of twodimensional crater decreased firstly and then increased.It reached its minimum value when the jet angle was at 45°;(5) The volumes of sediment erosion and the speed of turbid flow outside the crater increased with the slopes of the sand bed.However,the growth trend slowed down after the slope was greater than 10‰.
2019, 17(3):155-162.
Abstract:
The traditional energy dissipation and diversion measures of the curved spillway are mostly applicable to the curves with a smaller breadthdepth ratio (e.g.,the ratio of spillway breadth to average water depth),however,the problems of energy dissipation and diversion for the curved spillway with larges breadthdepth ratio have been reported in the literature.The new type of rough strips energy dissipator was proposed in this study based on the general engineering measures to solve the transverse circulation in curved spillway and combination with 635 Spillway Regulation Project in Xinjiang..In order to further explore the hydraulic characteristics and the diversion mechanism of the roughstrips,numerical simulations and experimental studies were used in this study,i.e.,numerical simulation on the seven working conditions of the bending based on the RNG k-εturbulence model.The results showed that the new type of rough strips had the advantages over the traditional auxiliary energy dissipator,which is not applicable to energy dissipation and the curved spillway with larges width to depth ratio.The flow patterns of water surface was also superior to that of traditional energy dissipator,while solving the circulation current in river bend, reducing the transverse slope of water surface and shortening the distance of downstream adjustment section.
The traditional energy dissipation and diversion measures of the curved spillway are mostly applicable to the curves with a smaller breadthdepth ratio (e.g.,the ratio of spillway breadth to average water depth),however,the problems of energy dissipation and diversion for the curved spillway with larges breadthdepth ratio have been reported in the literature.The new type of rough strips energy dissipator was proposed in this study based on the general engineering measures to solve the transverse circulation in curved spillway and combination with 635 Spillway Regulation Project in Xinjiang..In order to further explore the hydraulic characteristics and the diversion mechanism of the roughstrips,numerical simulations and experimental studies were used in this study,i.e.,numerical simulation on the seven working conditions of the bending based on the RNG k-εturbulence model.The results showed that the new type of rough strips had the advantages over the traditional auxiliary energy dissipator,which is not applicable to energy dissipation and the curved spillway with larges width to depth ratio.The flow patterns of water surface was also superior to that of traditional energy dissipator,while solving the circulation current in river bend, reducing the transverse slope of water surface and shortening the distance of downstream adjustment section.
2019, 17(3):163-170.
Abstract:
In order to address the problem of pore seepage and plugging in pervious concrete,a pervious concrete plugging test device was used to simulate the flow and distribution of surface micro particles through concrete in the initial stage of rainfall.The pore structure was reconstructed by CT scanning technology and avizo software.The surface micro particles in Kunming were modeled by DEM model in CFD.Particles were simulated by multiphase flow through the process of permeable concrete.The results showed that the CFD numerical simulated results were in good agreement with the experimental results.The surface micro particles with particle size rangeing100～500 μm had a certain degree of blockage to the concrete,and still had a good permeability (higher permeability coefficient).The blockage of particles below 100 μm was more significant,and the permeability coefficient approached to the basic level of zero ;More importantly,it was found that the seepage velocity of 0～50 μm particles passing through concrete was slow and partially adhered to the wall of the tunnel,leading to the decrease of the diameter,which affected the seepage.
In order to address the problem of pore seepage and plugging in pervious concrete,a pervious concrete plugging test device was used to simulate the flow and distribution of surface micro particles through concrete in the initial stage of rainfall.The pore structure was reconstructed by CT scanning technology and avizo software.The surface micro particles in Kunming were modeled by DEM model in CFD.Particles were simulated by multiphase flow through the process of permeable concrete.The results showed that the CFD numerical simulated results were in good agreement with the experimental results.The surface micro particles with particle size rangeing100～500 μm had a certain degree of blockage to the concrete,and still had a good permeability (higher permeability coefficient).The blockage of particles below 100 μm was more significant,and the permeability coefficient approached to the basic level of zero ;More importantly,it was found that the seepage velocity of 0～50 μm particles passing through concrete was slow and partially adhered to the wall of the tunnel,leading to the decrease of the diameter,which affected the seepage.
2019, 17(3):171-176.
Abstract:
In order to improve the multiobjective decision effectively in water conservancy project management,an improved ant colony optimization algorithm was proposed.In this algorithm,pheromone was initialized using the global search ability of genetic algorithm,and the mutation operation and crossover operation were introduced to improve the efficiency of the optimal solution.Engineering case study showed that the improved algorithm can quickly converge to achieve optimal solution and guarantee the quality of solution.In comparison with the genetic algorithm and ant colony algorithm,it has better optimization ability for multi objective decision making problem.This study provides a new method for water conservancy project management.
In order to improve the multiobjective decision effectively in water conservancy project management,an improved ant colony optimization algorithm was proposed.In this algorithm,pheromone was initialized using the global search ability of genetic algorithm,and the mutation operation and crossover operation were introduced to improve the efficiency of the optimal solution.Engineering case study showed that the improved algorithm can quickly converge to achieve optimal solution and guarantee the quality of solution.In comparison with the genetic algorithm and ant colony algorithm,it has better optimization ability for multi objective decision making problem.This study provides a new method for water conservancy project management.
2019, 17(3):177-184.
Abstract:
Both Simulation and Flow Simulation modules within Solidworks software were used to build finite element static and CFD numerical simulation for a Y type branch pipe.The Ytype branch pipe was chosen because it was used for the tunnel exit of a water delivery project in Liaoning Province..The results showed that,for the Y type internal crescent rib branch pipe,the large deformation is generally located at the intersection of the two branches and the crescent rib when the rib breadth ratio is≤0.12.The distribution was symmetric around its horizontal axis,and the displacement was large and concentrated.The greater stress was located at the inner center of the rib,the upper and lower sides of the shell near the end of the rib and the junction of main pipe and branch pipe.When the rib breadth ratio was≥0.24,the large deformation was generally located at the intersection of the main pipe and the branch pipe on the upper and lower sides of the branch pipe.It was also symmetrically distributed in the left and right,and the displacement was large and concentrated.The maximum stress was located on the shell,which was near the end of the rib.The width and thickness of the ribs had little effects on the stress of the shell,the flow states of the water and the hydraulic loss in the branch pipe.Increasing the width and thickness of the ribs can effectively reduce the stress of the crescent rib.The results can provide a reference for the design and promotion of similar branch pipes.
Both Simulation and Flow Simulation modules within Solidworks software were used to build finite element static and CFD numerical simulation for a Y type branch pipe.The Ytype branch pipe was chosen because it was used for the tunnel exit of a water delivery project in Liaoning Province..The results showed that,for the Y type internal crescent rib branch pipe,the large deformation is generally located at the intersection of the two branches and the crescent rib when the rib breadth ratio is≤0.12.The distribution was symmetric around its horizontal axis,and the displacement was large and concentrated.The greater stress was located at the inner center of the rib,the upper and lower sides of the shell near the end of the rib and the junction of main pipe and branch pipe.When the rib breadth ratio was≥0.24,the large deformation was generally located at the intersection of the main pipe and the branch pipe on the upper and lower sides of the branch pipe.It was also symmetrically distributed in the left and right,and the displacement was large and concentrated.The maximum stress was located on the shell,which was near the end of the rib.The width and thickness of the ribs had little effects on the stress of the shell,the flow states of the water and the hydraulic loss in the branch pipe.Increasing the width and thickness of the ribs can effectively reduce the stress of the crescent rib.The results can provide a reference for the design and promotion of similar branch pipes.
2019, 17(3):185-192.
Abstract:
The Ezhai Village landslide is one of the large landslides along the upper of the Minjiang River and the Chengdu Lanzhou railway.It is very important for early identifying the geohazards and reducing the harm to explore the causes and stability prediction.On the basis of expounding the geological background and development characteristics of the landslide,this study analyzes its genetic mechanism and evolution process,and investigates the mechanism of landslide accumulation stability and deformation damage by engineering geological analysis,quantitative calculation and numerical simulation.The results show that the Ezhai Village landslide is a large rock landslide with 739×10 4 m 3 volume,and an old push down landslide induced by rainfall.It has been through four stages:deformation and crack by tension,crack penetration,push down and stagnation accumulation.The formation of the landslide is related to the steep terrain condition,the type of broken rock and soil,and the type of slope structure.It is also closely related to the active fault and the strong earthquake,induced by rainfall.The Ezhai Village landslide is stable now as a whole but is not stable at local scale,which implies that it may be unstable in some areas under heavy rainfall or earthquake conditions.
The Ezhai Village landslide is one of the large landslides along the upper of the Minjiang River and the Chengdu Lanzhou railway.It is very important for early identifying the geohazards and reducing the harm to explore the causes and stability prediction.On the basis of expounding the geological background and development characteristics of the landslide,this study analyzes its genetic mechanism and evolution process,and investigates the mechanism of landslide accumulation stability and deformation damage by engineering geological analysis,quantitative calculation and numerical simulation.The results show that the Ezhai Village landslide is a large rock landslide with 739×10 4 m 3 volume,and an old push down landslide induced by rainfall.It has been through four stages:deformation and crack by tension,crack penetration,push down and stagnation accumulation.The formation of the landslide is related to the steep terrain condition,the type of broken rock and soil,and the type of slope structure.It is also closely related to the active fault and the strong earthquake,induced by rainfall.The Ezhai Village landslide is stable now as a whole but is not stable at local scale,which implies that it may be unstable in some areas under heavy rainfall or earthquake conditions.
2019, 17(3):193-200.
Abstract:
The impacts of component structures of axial flow pump on its performance were investigated based on the k-s epsilon turbulent flow model and the Reynolds averaged N-S equation with CFX software to numerically simulate threedimensional flow.It can help us to find key components in the pump design.The results showed that an elbow shape flow inlet can ensure continuously water movement,makes the flow uniformity of impeller reach 90 or more and the efficiency of the impeller about 92%.The hydraulic loss of the entire inlet passage depends on the hydraulic loss of the elbow and accordingly the hydraulic loss generated by the outlet passage is the largest among the entire pump.The main hydraulic losses mainly come from the bend and the outlet.Therefore,inflow bend section and the outlet are the key components of the pump design.In the outlet channel,the vorticity decreases along the path,and reached its maximum magnitude in the curved section where the flow rate also reached its smallest.
The impacts of component structures of axial flow pump on its performance were investigated based on the k-s epsilon turbulent flow model and the Reynolds averaged N-S equation with CFX software to numerically simulate threedimensional flow.It can help us to find key components in the pump design.The results showed that an elbow shape flow inlet can ensure continuously water movement,makes the flow uniformity of impeller reach 90 or more and the efficiency of the impeller about 92%.The hydraulic loss of the entire inlet passage depends on the hydraulic loss of the elbow and accordingly the hydraulic loss generated by the outlet passage is the largest among the entire pump.The main hydraulic losses mainly come from the bend and the outlet.Therefore,inflow bend section and the outlet are the key components of the pump design.In the outlet channel,the vorticity decreases along the path,and reached its maximum magnitude in the curved section where the flow rate also reached its smallest.
2019, 17(3):201-208.
Abstract:
Identifying drivers for industrial water efficiency can provide a scientific basis for industrial water conservation.The added value of water abstraction per ten thousand Yuan industrial outputs was used to measure industrial water use efficiency (IE).A new model was developed to quantitatively identify the drivers of IE using Logarithmic Mean Divisia Index (LMDI) method,including fresh water abstraction,water reuse and production process water use.The change of IE was decomposed into three drivers,i.e.,water reuse rate (P),water use efficiency in production process (IW) and industrial structure(S).The model was then applied to Shandong province and compared with the fresh[JP] water model.These two models were equivalent when water reuse rate did not change.The fresh water model could not reflect the effects of water reuse and cannot accurately attribute the contributions of different drives.In terms of contribution,IW was the dominant driver leading to the increase of IE, while P was the secondary driver and the contribution of S was very limited.The increasing IE during 2005 to 2010 was greatly reduced because the contribution of IW significantly decreased and the contribution of P changed from positive to negative.It should comprehensively increase the water reuse rate for the industrial sector in Shandong province,explore the water saving potential of high water consumption industries,optimize the industrial structure,and continue to reduce the proportion of highwater consumption industries.
Identifying drivers for industrial water efficiency can provide a scientific basis for industrial water conservation.The added value of water abstraction per ten thousand Yuan industrial outputs was used to measure industrial water use efficiency (IE).A new model was developed to quantitatively identify the drivers of IE using Logarithmic Mean Divisia Index (LMDI) method,including fresh water abstraction,water reuse and production process water use.The change of IE was decomposed into three drivers,i.e.,water reuse rate (P),water use efficiency in production process (IW) and industrial structure(S).The model was then applied to Shandong province and compared with the fresh[JP] water model.These two models were equivalent when water reuse rate did not change.The fresh water model could not reflect the effects of water reuse and cannot accurately attribute the contributions of different drives.In terms of contribution,IW was the dominant driver leading to the increase of IE, while P was the secondary driver and the contribution of S was very limited.The increasing IE during 2005 to 2010 was greatly reduced because the contribution of IW significantly decreased and the contribution of P changed from positive to negative.It should comprehensively increase the water reuse rate for the industrial sector in Shandong province,explore the water saving potential of high water consumption industries,optimize the industrial structure,and continue to reduce the proportion of highwater consumption industries.
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