Hydropower development changes the river hydrological regime,thereby altering river ecosystem significantly.One important measure for reducing degradation of ecosystem is to determine ecological flow and implement it ...Hydropower development changes the river hydrological regime,thereby altering river ecosystem significantly.One important measure for reducing degradation of ecosystem is to determine ecological flow and implement it by reservoir operation.This paper described a method to calculate river ecological flow based on fish habitat conservation and applied it to Jinping River Bend of Yalong River.Schizothorax chongi was selected as target species,and the fish habitat model coupling with water environmental model was developed according to the relationship between fish and water environment factors.Moreover,improved hydraulic habitat suitability index(IHHS) and habitat fragment index(HFI) varying with discharge were discussed in this paper.Habitat area representing average annual flow was taken as a reference,and then ecological hydrographs under different habitat conservation levels were calculated considering season variation and life stages of fish.Compared to the natural condition,the model results indicated that the reservoir operation clearly influenced the habitat of the target fish.It was proposed to ensure flow releases to maintain 70%-90% habitat in section after joint while about 60% before joint.展开更多
Bamako’s geographic and demographic expansion is sure to increase the need for water, and the slow development of the water supply network seems unable to meet this need. The knowledge of the approximate quantity of ...Bamako’s geographic and demographic expansion is sure to increase the need for water, and the slow development of the water supply network seems unable to meet this need. The knowledge of the approximate quantity of water reaching the groundwater is crucial, given the high dependence of this city and its surrounding area on groundwater. The aim of this study is to estimate the average groundwater recharge on a monthly scale, based on measurements taken over a 24-month period by using Water Table Fluctuation (WTF). The monthly recharge values obtained from the 15 piezometers in the study area by using WTF method vary from 1.04 to 38.81 mm with an average value of 9.74 mm. As part of the precipitations, these values represent respectively 1.29%, 48.52% and 12.17% of monthly average precipitation. It appears in this study that despite the piezometers belonging to the same climatic zone, the recharge rate can be different because of many factors such as the thickness of the aquifers, the soil and geology type, the local land cover and land use activities.展开更多
The deficiencies of basic particle swarm optimization （bPSO） are its ubiquitous prematurity and its inability to seek the global optimal solution when optimizing complex high-dimensional functions. To overcome such ...The deficiencies of basic particle swarm optimization （bPSO） are its ubiquitous prematurity and its inability to seek the global optimal solution when optimizing complex high-dimensional functions. To overcome such deficiencies, the chaos-PSO （COSPSO） algorithm was established by introducing the chaos optimization mechanism and a global particle stagnation-disturbance strategy into bPSO. In the improved algorithm, chaotic movement was adopted for the particles＇ initial movement trajectories to replace the former stochastic movement, and the chaos factor was used to guide the particles＇ path. When the global particles were stagnant, the disturbance strategy was used to keep the particles in motion. Five benchmark optimizations were introduced to test COSPSO, and they proved that COSPSO can remarkably improve efficiency in optimizing complex functions. Finally, a case study of COSPSO in calculating design flood hydrographs demonstrated the applicability of the improved algorithm.展开更多
This paper firstly described the dam break in the aspects of theories and models. Break parameters prediction, the understanding of dam break mechanics, peak outflow prediction were shown as the essential for the dam ...This paper firstly described the dam break in the aspects of theories and models. Break parameters prediction, the understanding of dam break mechanics, peak outflow prediction were shown as the essential for the dam break analysis, and eventually determined the loss of the damages. Secondly, as an application example, Foster Joseph Sayers Dam break was further modeled and analyzed using USACE Hydrologic Engineering Center’s River Analysis System (HEC-RAS) model based on available geometry data. The results show that dam break is a complicated and comprehensive process involving lots of principles. Combination of mechanics and case studies, reflection of predominant mechanisms of headcut erosion, more specific categorization of dam, prudent investigation and inference of dam break process are needed in developing a satisfactory dam break simulation model. Foster Joseph Sayers Dam break due to piping elongates the time period of high water surface level, which increases the duration of risk. However, the dam break does not increase the downstream maximum water surface elevation (Max. W.S. Elev) significantly at previous design Probable Maximum Flood (PMF). Dam break has a greater impact on the downstream location where is closer to the dam in accordance with the comparison of the hydrographs at different downstream locations. Sensitivity analysis demonstrates that the changes of dam break parameters had no much influence on the downstream Max. W.S. Elev.展开更多
Floods are one of the most common natural hazards occurring all around the world.However,the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet.This lack of understandi...Floods are one of the most common natural hazards occurring all around the world.However,the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet.This lack of understanding is particularly acute in mountainous regions with large degrees in Sichuan Province,China,where runoff is seldom measured.The nature of streamflow in a region is related to the time and spatial distribution of rainfall quantity and watershed geomorphology.The geomorphologic characteristics are the channel network and surrounding landscape which transform the rainfall input into an output hydrograph at the outlet of the watershed.With the given geomorphologic properties of the watershed,theoretically the hydrological response function can be determined hydraulically without using any recorded data of past rainfall or runoff events.In this study,a kinematic-wave-based geomorphologic instantaneous unit hydrograph (KW-GIUH) model was adopted and verified to estimate runoff in ungauged areas.Two mountain watersheds,the Yingjing River watershed and Tianquan River watershed in Sichuan were selected as study sites.The geomorphologic factors of the two watersheds were obtained by using a digital elevation model (DEM) based on the topographic database obtained from the Shuttle Radar Topography Mission of US's NASA.The tests of the model on the two watersheds were performed both at gauged and ungauged sites.Comparison between the simulated and observed hydrographs for a number of rainstorms at the gauged sites indicated the potential of the KW-GIUH model as a useful tool for runoff analysis in these regions.Moreover,to simulate possible concentrated rainstorms that could result in serious flooding in these areas,synthetic rainfall hyetographs were adopted as input to the KW-GIUH model to obtain the flow hydrographs at two ungauged sites for different return period conditions.Hydroeconomic analysis can be performed in the future to select the optimum design return period for determining the flood control work展开更多
Flood wave propagation modeling is of critical importance to advancing water resources management and protecting human life and property. In this study, we investigated how the advection-diffusion routing model perfor...Flood wave propagation modeling is of critical importance to advancing water resources management and protecting human life and property. In this study, we investigated how the advection-diffusion routing model performed in flood wave propagation on a 16 km long downstream section of the Big Piney River, MO. Model performance was based on gaging station data at the upstream and downstream cross sections. We demonstrated with advection-diffusion theory that for small differences in watershed drainage area between the two river cross sections, inflow along the reach mainly contributes to the downstream hydrograph＇s rising limb and not to the falling limb. The downstream hydrograph＇s falling limb is primarily determined by the propagated flood wave originating at the upstream cross section. This research suggests the parameter for the advectiondiffusion routing model can be calibrated by fitting the hydrograph falling limb. Application of the advection diffusion model to the flood wave of January 29, 2013 supports our theoretical finding that the propagated flood wave determines the downstream cross section falling limb, and the model has good performance in our test examples.展开更多
Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of fla...Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of flash flood hazard mapping. In this study, the headwater catchment of the Xiapu River Basin in central China was selected as a pilot study area for flash flood hazard mapping. A conceptual distributed hydrological model was developed for flood calculation based on the framework of the Xinanjiang model, which is widely used in humid and semi-humid regions in China. The developed model employs the geomorphological unit hydrograph method, which is extremely valuable when simulating the overland flow process in ungauged catchments, as compared with the original Xinanjiang model. The model was tested in the pilot study area, and the results agree with the measured data on the whole. After calibration and validation, the model is shown to be a useful tool for flash flood calculation. A practicable method for flash flood hazard mapping using the calculated peak discharge and digital elevation model data was presented, and three levels of flood hazards were classified. The resulting flash flood hazard maps indicate that the method successfully predicts the spatial distribution of flash flood hazards, and it can meet the current requirements in China.展开更多
Channel roughness is a sensitive parameter in development of hydraulic model for flood forecasting and flood inundation mapping. The requirement of multiple channel roughness coefficient Mannnig’s ‘n’ values along ...Channel roughness is a sensitive parameter in development of hydraulic model for flood forecasting and flood inundation mapping. The requirement of multiple channel roughness coefficient Mannnig’s ‘n’ values along the river has been spelled out through simulation of floods, using HEC-RAS, for years 1998 and 2003, supported with the photographs of river reaches collected during the field visit of the lower Tapi River. The calibrated model, in terms of channel roughness, has been used to simulate the flood for year 2006 in the river. The performance of the calibrated HEC-RAS based model has been accessed by capturing the flood peaks of observed and simulated floods;and computation of root mean squared error (RMSE) for the intermediated gauging stations on the lower Tapi River.展开更多
Cryospheric meltwater is an important runoff component and it profoundly influences changes in water resources in the Tibetan Plateau.Significant changes in runoff components occur in the three-river headwater region(...Cryospheric meltwater is an important runoff component and it profoundly influences changes in water resources in the Tibetan Plateau.Significant changes in runoff components occur in the three-river headwater region(TRHR),which is an important part of“Chinese Water Tower”due to climate warming.However,these effects remain unclear owing to the sparse and uneven distribution of monitoring sites and limited field investigations.Quantifying the contribution of cryospheric meltwater to outlet runoff is a key scientific question that needs to be addressed.In this study,we analyzed 907 precipitation,river water,ground ice,supra-permafrost water,and glacier snow meltwater samples collected from October 2019 to September 2020 in the TRHR.The following results were obtained:(1)There was significant spatio-temporal variation in stable isotopes in different waters;(2)The seasonal trends of stable isotopes for different waters,the relationship between each water body and the local meteoric water line(LWML)confirmed that river water was mainly recharged by precipitation,supra-permafrost water,and glacier snow meltwater;(3)Precipitation,supra-permafrost water,and glacier snow meltwater accounted for 52%,39%,and 9%of river water,respectively,during the ablation period according to the end-member mixing analysis(EMMA);(4)In terms of future runoff components,there will be many challenges due to increasing precipitation and evaporation,decreasing snow cover,glacier retreat,and permafrost degradation.Therefore,it is crucial to establish the“star-machine-ground”observation networks,forecast extreme precipitation and hydrological events,build the“TRHE on the Cloud”platform,and implement systematic hydraulic engineering projects to support the management and utilization of water resources in the TRHR.The findings of environmental isotope analysis provide insights into water resources as well as scientific basis for rational use of water resources in the TRHR.展开更多
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2010CB429004)the National Natural Science Foundation of China(Grant Nos.50879086,50639070)the Chutian Scholarship(Grant No.KJ2010B002)
文摘Hydropower development changes the river hydrological regime,thereby altering river ecosystem significantly.One important measure for reducing degradation of ecosystem is to determine ecological flow and implement it by reservoir operation.This paper described a method to calculate river ecological flow based on fish habitat conservation and applied it to Jinping River Bend of Yalong River.Schizothorax chongi was selected as target species,and the fish habitat model coupling with water environmental model was developed according to the relationship between fish and water environment factors.Moreover,improved hydraulic habitat suitability index(IHHS) and habitat fragment index(HFI) varying with discharge were discussed in this paper.Habitat area representing average annual flow was taken as a reference,and then ecological hydrographs under different habitat conservation levels were calculated considering season variation and life stages of fish.Compared to the natural condition,the model results indicated that the reservoir operation clearly influenced the habitat of the target fish.It was proposed to ensure flow releases to maintain 70%-90% habitat in section after joint while about 60% before joint.
文摘Bamako’s geographic and demographic expansion is sure to increase the need for water, and the slow development of the water supply network seems unable to meet this need. The knowledge of the approximate quantity of water reaching the groundwater is crucial, given the high dependence of this city and its surrounding area on groundwater. The aim of this study is to estimate the average groundwater recharge on a monthly scale, based on measurements taken over a 24-month period by using Water Table Fluctuation (WTF). The monthly recharge values obtained from the 15 piezometers in the study area by using WTF method vary from 1.04 to 38.81 mm with an average value of 9.74 mm. As part of the precipitations, these values represent respectively 1.29%, 48.52% and 12.17% of monthly average precipitation. It appears in this study that despite the piezometers belonging to the same climatic zone, the recharge rate can be different because of many factors such as the thickness of the aquifers, the soil and geology type, the local land cover and land use activities.
基金supported by the National Basic Research Program of China (973 Program) (Grant No.2006CB403402)
文摘The deficiencies of basic particle swarm optimization （bPSO） are its ubiquitous prematurity and its inability to seek the global optimal solution when optimizing complex high-dimensional functions. To overcome such deficiencies, the chaos-PSO （COSPSO） algorithm was established by introducing the chaos optimization mechanism and a global particle stagnation-disturbance strategy into bPSO. In the improved algorithm, chaotic movement was adopted for the particles＇ initial movement trajectories to replace the former stochastic movement, and the chaos factor was used to guide the particles＇ path. When the global particles were stagnant, the disturbance strategy was used to keep the particles in motion. Five benchmark optimizations were introduced to test COSPSO, and they proved that COSPSO can remarkably improve efficiency in optimizing complex functions. Finally, a case study of COSPSO in calculating design flood hydrographs demonstrated the applicability of the improved algorithm.
文摘This paper firstly described the dam break in the aspects of theories and models. Break parameters prediction, the understanding of dam break mechanics, peak outflow prediction were shown as the essential for the dam break analysis, and eventually determined the loss of the damages. Secondly, as an application example, Foster Joseph Sayers Dam break was further modeled and analyzed using USACE Hydrologic Engineering Center’s River Analysis System (HEC-RAS) model based on available geometry data. The results show that dam break is a complicated and comprehensive process involving lots of principles. Combination of mechanics and case studies, reflection of predominant mechanisms of headcut erosion, more specific categorization of dam, prudent investigation and inference of dam break process are needed in developing a satisfactory dam break simulation model. Foster Joseph Sayers Dam break due to piping elongates the time period of high water surface level, which increases the duration of risk. However, the dam break does not increase the downstream maximum water surface elevation (Max. W.S. Elev) significantly at previous design Probable Maximum Flood (PMF). Dam break has a greater impact on the downstream location where is closer to the dam in accordance with the comparison of the hydrographs at different downstream locations. Sensitivity analysis demonstrates that the changes of dam break parameters had no much influence on the downstream Max. W.S. Elev.
基金supported by the key project of the National Natural Science Foundation of China (NSFC No. 50739002)the National Science Council of Taibei of China (NSC 97-2625-M-019-001)+1 种基金the Open Research Fund Program of State key Laboratory of Hydraulics and River Engineering,Sichuan University,China (No. 1001)Financial supports from the above organizations are fully acknowledged
文摘Floods are one of the most common natural hazards occurring all around the world.However,the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet.This lack of understanding is particularly acute in mountainous regions with large degrees in Sichuan Province,China,where runoff is seldom measured.The nature of streamflow in a region is related to the time and spatial distribution of rainfall quantity and watershed geomorphology.The geomorphologic characteristics are the channel network and surrounding landscape which transform the rainfall input into an output hydrograph at the outlet of the watershed.With the given geomorphologic properties of the watershed,theoretically the hydrological response function can be determined hydraulically without using any recorded data of past rainfall or runoff events.In this study,a kinematic-wave-based geomorphologic instantaneous unit hydrograph (KW-GIUH) model was adopted and verified to estimate runoff in ungauged areas.Two mountain watersheds,the Yingjing River watershed and Tianquan River watershed in Sichuan were selected as study sites.The geomorphologic factors of the two watersheds were obtained by using a digital elevation model (DEM) based on the topographic database obtained from the Shuttle Radar Topography Mission of US's NASA.The tests of the model on the two watersheds were performed both at gauged and ungauged sites.Comparison between the simulated and observed hydrographs for a number of rainstorms at the gauged sites indicated the potential of the KW-GIUH model as a useful tool for runoff analysis in these regions.Moreover,to simulate possible concentrated rainstorms that could result in serious flooding in these areas,synthetic rainfall hyetographs were adopted as input to the KW-GIUH model to obtain the flow hydrographs at two ungauged sites for different return period conditions.Hydroeconomic analysis can be performed in the future to select the optimum design return period for determining the flood control work
基金supported by funding from the USDA Forest Service Northern Research Station iTree Spatial Simulation (No. PL-5937)the National Urban and Community Forest Advisory Council iT ree Tool (No. 11-DG-11132544340)The SUNY ESF Department of Environmental Resources Engineering provided computing facilities and logistical support
文摘Flood wave propagation modeling is of critical importance to advancing water resources management and protecting human life and property. In this study, we investigated how the advection-diffusion routing model performed in flood wave propagation on a 16 km long downstream section of the Big Piney River, MO. Model performance was based on gaging station data at the upstream and downstream cross sections. We demonstrated with advection-diffusion theory that for small differences in watershed drainage area between the two river cross sections, inflow along the reach mainly contributes to the downstream hydrograph＇s rising limb and not to the falling limb. The downstream hydrograph＇s falling limb is primarily determined by the propagated flood wave originating at the upstream cross section. This research suggests the parameter for the advectiondiffusion routing model can be calibrated by fitting the hydrograph falling limb. Application of the advection diffusion model to the flood wave of January 29, 2013 supports our theoretical finding that the propagated flood wave determines the downstream cross section falling limb, and the model has good performance in our test examples.
基金supported by the Key Project in the National Science and Technology Pillar Program during the Twelfth Five-Year Plan Period(Grant No.2012BAK10B04)the Specific Research Fund of the China Institute of Water Resources and Hydropower Research(Grant No.JZ0145B032014)
文摘Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of flash flood hazard mapping. In this study, the headwater catchment of the Xiapu River Basin in central China was selected as a pilot study area for flash flood hazard mapping. A conceptual distributed hydrological model was developed for flood calculation based on the framework of the Xinanjiang model, which is widely used in humid and semi-humid regions in China. The developed model employs the geomorphological unit hydrograph method, which is extremely valuable when simulating the overland flow process in ungauged catchments, as compared with the original Xinanjiang model. The model was tested in the pilot study area, and the results agree with the measured data on the whole. After calibration and validation, the model is shown to be a useful tool for flash flood calculation. A practicable method for flash flood hazard mapping using the calculated peak discharge and digital elevation model data was presented, and three levels of flood hazards were classified. The resulting flash flood hazard maps indicate that the method successfully predicts the spatial distribution of flash flood hazards, and it can meet the current requirements in China.
文摘Channel roughness is a sensitive parameter in development of hydraulic model for flood forecasting and flood inundation mapping. The requirement of multiple channel roughness coefficient Mannnig’s ‘n’ values along the river has been spelled out through simulation of floods, using HEC-RAS, for years 1998 and 2003, supported with the photographs of river reaches collected during the field visit of the lower Tapi River. The calibrated model, in terms of channel roughness, has been used to simulate the flood for year 2006 in the river. The performance of the calibrated HEC-RAS based model has been accessed by capturing the flood peaks of observed and simulated floods;and computation of root mean squared error (RMSE) for the intermediated gauging stations on the lower Tapi River.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0405)National Nature Science Foundation of China(42077187)+2 种基金Chinese Academy of Sciences Young Crossover Team Project(JCTD-2022-18)the National Key Research and Development Program of China(2020YFA0607702)the"Western Light"-Key Laboratory Cooperative Research Cross-Team Project of Chinese Academy of Sciences,Innovative Groups in Gansu Province(20JR10RA038).
文摘Cryospheric meltwater is an important runoff component and it profoundly influences changes in water resources in the Tibetan Plateau.Significant changes in runoff components occur in the three-river headwater region(TRHR),which is an important part of“Chinese Water Tower”due to climate warming.However,these effects remain unclear owing to the sparse and uneven distribution of monitoring sites and limited field investigations.Quantifying the contribution of cryospheric meltwater to outlet runoff is a key scientific question that needs to be addressed.In this study,we analyzed 907 precipitation,river water,ground ice,supra-permafrost water,and glacier snow meltwater samples collected from October 2019 to September 2020 in the TRHR.The following results were obtained:(1)There was significant spatio-temporal variation in stable isotopes in different waters;(2)The seasonal trends of stable isotopes for different waters,the relationship between each water body and the local meteoric water line(LWML)confirmed that river water was mainly recharged by precipitation,supra-permafrost water,and glacier snow meltwater;(3)Precipitation,supra-permafrost water,and glacier snow meltwater accounted for 52%,39%,and 9%of river water,respectively,during the ablation period according to the end-member mixing analysis(EMMA);(4)In terms of future runoff components,there will be many challenges due to increasing precipitation and evaporation,decreasing snow cover,glacier retreat,and permafrost degradation.Therefore,it is crucial to establish the“star-machine-ground”observation networks,forecast extreme precipitation and hydrological events,build the“TRHE on the Cloud”platform,and implement systematic hydraulic engineering projects to support the management and utilization of water resources in the TRHR.The findings of environmental isotope analysis provide insights into water resources as well as scientific basis for rational use of water resources in the TRHR.
