The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nep...The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.展开更多
The quantitative calculation of the volume of large earthquake-triggered landslides and related dammed lake sediments is of great significance in the study of secondary disasters and focal parameters of strong histori...The quantitative calculation of the volume of large earthquake-triggered landslides and related dammed lake sediments is of great significance in the study of secondary disasters and focal parameters of strong historical earthquakes.In this study,the dammed lake induced by Qishan M7 earthquake(Lingtai County,Gansu Province,Northwest China)is selected as the research object.Based on the information collected from the 4 boreholes in the dammed lake area,we further take advantage of the lowlevel Unmanned Aerial Vehicle(UAV)photogrammetry and the morphology recovery method,to calculate the volume of the dammed lake and landslides,respectively.Finally,major conclusions are obtained as follows:①the AMS-14C age at the bottom of the Qiuzigou Dammed Lake sediments is 2890±30 BP,which coincides with the 780 BC Qishan earthquake;furthermore,the Qiuzigou Landslides seem to have been triggered by the earthquake,forming an enclosed dammed lake deposition environment after the upstream sediments accumulate;②the Qiuzigou landslides are opposite-sliding landslides that have blocked the river valley;in detail,landslide volumes at the right and left banks are 235×104 m3 and 229×104 m3,respectively.The length of the dammed lake is 2.6 km,with a thickness of approximately 43 m near the landslides,and the total sedimentary volume is 573×104 m3;③the erosion rate of Qiuzigou Landslide Dammed Lake is 0.44 mm/a,the accumulation rate is 15.05 mm/a,and the soil erosion modulus is 593 t/(km2/a),characterized as slight erosion.Quantitative research on the formation of landslides and dammed lakes from strong historical earthquakes is vital for increasing our understanding of the vibrational characteristics and surface action processes of these types of earthquakes.展开更多
Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecolo...Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecology,disrupted river continuity,and jeopardized the existence of aquatic creatures in rivers.Studying the impacts of dam construction on rivers can enhance our knowledge of river ecological and environmental concerns and help sustain the health of river ecosystems,thereby realizing the harmony between humans and water in both theoretical and practical aspects.This study used bibliometrics and constructed an author-keyword 2-mode matrix network using Co-Occurrence software to identify the hotspots and research trend in eco-hydrology of dammed rivers.We identified‘FLOW’‘SEDIMENT’‘QUALITY’and‘MODEL’as the research hotspots in the ecological impact of dammed rivers,and combined the related literatures,we highlight the research progress in the four directions.Then the research shortcomings and prospect were discussed,including strengthening the monitoring and analysis of critical ecological variables,enhancing the hydrological monitoring density for small rivers,strengthening the research of relationship between eutrophication and zooplankton,establishing multiscale approaches,and combining multi-sources information technologies to improve parameter accuracy in the model research.展开更多
In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China,10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine sediments.In this pap...In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China,10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine sediments.In this paper,the soft-sediment disturbances caused by earthquakes in the Diexi ancient dammed lake were studied based on field investigations and laboratory core observations.A two-to three-degree-of-freedom spring-type earthquake simulation vibration table was used to carry out disturbance tests on lacustrine sediments under different dynamic conditions.The results support the following conclusions:(1)The disturbance layers in the lacustrine sediments were caused by strong earthquakes in the region.(2)The characteristics of the disturbance layers are related to the seismic parameters and the degree of sediment consolidation.(3)The greater the earthquake intensity is,the greater the disturbance amplitude is;moreover,the lower the consolidation degree is,the greater the disturbance amplitude.(4)The simulation tests verify that the disturbance layers in the sediments of the Diexi ancient dammed lake correspond to strong earthquakes in the region.These results are valuable for ongoing palaeoseismic research in the region.展开更多
The Diexi ancient dammed lake is in the upper reaches of the Minjiang River.Six terraces with lacustrine sediments occur at the base.These terraces are the products of the graded outburst of the Diexi ancient dammed l...The Diexi ancient dammed lake is in the upper reaches of the Minjiang River.Six terraces with lacustrine sediments occur at the base.These terraces are the products of the graded outburst of the Diexi ancient dammed lake.The outburst of the ancient dammed lake would certainly have had an impact on the Chengdu Plain in the lower reaches of the Minjiang River.In this paper,on-site sampling and laboratory analysis were used to analyze the sediments of the Diexi ancient dammed lake and the Jinsha site in Chengdu Plain,and the environmental indicators of each sediment layer were tested.Through a comparative analysis of the environmental indicators in the sediments at the two locations,the following results were obtained:the palaeoclimatic and palaeoenvironmental characteristics at the two locations generally show consistent changes.The most important finding is that the types and content of the major pollen taxa at the two locations are similar.The Pinus content strongly proves that the soil layers at the Jinsha site was sourced from the upper reaches of the Minjiang River.Considering that the demise of the ancient culture at the Jinsha site occurred close in time to the outburst of the ancient dammed lake,this similarity suggests that the cultural change at the Jinsha site may have been related to the outburst of the Diexi ancient dammed lake.展开更多
After the Wenchuan Earthquake, many large-scale debris flows blocked rivers, generated dammed lakes, and produced outburst flood at the seriously hit areas. This paper mainly discussed the formation, outburst, impacts...After the Wenchuan Earthquake, many large-scale debris flows blocked rivers, generated dammed lakes, and produced outburst flood at the seriously hit areas. This paper mainly discussed the formation, outburst, impacts and risks of debris flow dammed lakes. The field investigation showed that the dammed lakes were created by debris flows from gullies and hill-slopes as well as the combination of debris flow and landslides, and also distributed along rivers step-by-step. The height of dams and the length of dammed lakes along river channel varied from 4 m to 18 m and from 400 m to 5000 m, respectively, and the reservoir capacity of dammed lakes were from 1.5 × 105 m3 to 3 × 106 m3. Due to geomorphological impact, dammed lakes commonly partially outburst along their front of debris flow deposition dams (1/4 - /3 outburst) or the suture between debris flow and landslide, and hardly completely outburst. Moreover, the subsequent debris flows continuously increased the magnitude and height of dams, not only increasing the stability of a single dam, but also improving the risks of outburst flood induced by intensive rainstorm. Dammed lakes produced steep rage in the sites of dams with the 4% - 9% of slope and rapidly raised river channel in the upstream due to a mass of alluvial sediment. As a result, the landscapes of step-dams and step-lakes dominate driver channels, significantly increasing the hazards of floods. Then the hazards, impacts and risk of debris flow dammed lakes along Min River from Dujiangyan to Wenchuan were analyzed. In order to mitigate dammed lakes induced by debris flows, the identification model of debris flow blocking rivers, the process of the formation, outburst and evolvement of dammed lakes, and the model of risk assessment for step-dammed lakes were strongly suggested to explore, and be used at the rivers of Min, Yuzi, Caopo, Longxi, Mianyuan, Jian, Shiting, Baishui and Jushui.展开更多
Glacial outburst floods（GLOFs） in alpine regions tend to be relatively complicated, multi-stage catastrophes, capable of causing significant geomorphologic changes in channel surroundings and posing severe threats t...Glacial outburst floods（GLOFs） in alpine regions tend to be relatively complicated, multi-stage catastrophes, capable of causing significant geomorphologic changes in channel surroundings and posing severe threats to infrastructure and the safety and livelihoods of human communities. GLOF disasters have been observed and potential hazards can be foreseen due to the newly formed glacial lakes or the expansion of existing ones in the Poiqu River Basin in Tibet, China. Here we presented a synthesis of GLOF-related studies including triggering mechanism（s）, dam breach modeling, and flood routing simulation that have been employed to reconstruct or forecast GLOF hydrographs. We provided a framework for probability-based GLOFs simulation and hazard mapping in the Poiqu River Basin according to available knowledge. We also discussed the uncertainties and challenges in the model chains, which may form the basis for further research.展开更多
A year from now, dam builders will have blocked the mighty Yangtze River at the Three Gorges, marking the start of the second phase of the gigantic water harnessing and developing scheme.
Alternation of high and low resistance sedimentary beds,active tectonics,large rivers,and slope erosion in valleys consequently resulted in landslide in dammed lakes within the Zagros range.This study presents the res...Alternation of high and low resistance sedimentary beds,active tectonics,large rivers,and slope erosion in valleys consequently resulted in landslide in dammed lakes within the Zagros range.This study presents the results in the analysis of geological and topographic data,satellite imageries,morphotectonics and hydrodynamics of drainage networks about the landslide dammed lakes.There are four landslides in central Zagros(Zagros FoldThrust Belt,ZFTB)which have formed five dammed lakes named,Seymareh,Jaidar,Shur,Shimbar,and Godar.According to the results,damming landslides occurred in the active-tectonic regions on the slopes of anticlines and in valleys with undercutting effects of rivers on their slopes consisting of alternations of loose and resistant beds.The studied landslide dams in narrow valleys are formed as a result of blocking river by sliding debris slopes and rock slides.This study also indicates the formation of Jaidar and Godar in one stage and the presence of Lake Terrace sequence in Seymareh,Shur and Shimbar lakes.The observed sequences of terrace formation in these lakes are caused by four Seymareh Landslides followed by the three-stage excavation of Shur andShimbar lakes.展开更多
Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environment...Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environmental impacts.This study reviews the remarkable benefits of check dams on the land reclamation and environmental improvement on the Loess Plateau,and sediment reduction entering the Yellow River.However,the flood incidents on check dams have been frequently reported for the past decades,which has attracted more attention in the context of climate change and extreme rainfall events recently.Advances in the flood migration techniques achieved by the research group led by the first author have been highlighted to migrate the breach risk of check dams due to floods.The“family tree method”has been proposed to determine the survival status and critical rainfall threshold of each check dam in the complicated dam system.An updated dam breach flood evaluation framework and the corresponding numerical algorithm(i.e.,DB-IWHR)have been developed.Moreover,innovative types of water-release facilities for check dams,including geobag stepped spillway and prestressed concrete cylinder pipe in the underlying conduit,have been proposed and developed.Finally,the perspectives concerning the check dam construction on the Loess Plateau have been put forward.展开更多
The 1320 MW Glen Canyon Dam in northern Arizona in the United States generates power for residents of seven states[1].But in February 2023 the dam’s ability to deliver that electricity was in danger.
Underpinned by the ultrahigh-core rockfill dam at the Nuozhadu Hydropower Station,comprehensive studies and engineering practices have been conducted to address several critical challenges:coordination of seepage defo...Underpinned by the ultrahigh-core rockfill dam at the Nuozhadu Hydropower Station,comprehensive studies and engineering practices have been conducted to address several critical challenges:coordination of seepage deformation in dam materials,prevention and control of high-water-pressure seepage failure,static and dynamic deformation control,and construction quality monitoring.Advanced technologies have been developed for modifying impermeable soil materials and utilizing soft rocks.Constitutive models and high-performance fine computational methods for dam materials have been improved,along with innovative seismic safety measures.Additionally,a“Digital Dam”and an information system for monitoring the construction quality were implemented.These efforts ensured the successful construction of the Nuozhadu Dam,making it the tallest dam in China and the third tallest dam in the world upon completion.This achievement increased the height of core dams in China by 100 m and established a design and safety evaluation framework for ultrahigh-core rockfill dams exceeding 300 m in height.Furthermore,the current safety monitoring results indicate that the Nuozhadu Dam is safe and controllable.展开更多
Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on t...Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on the study and the influence of climate variability on hydroelectric power production at Garafiri dam over 16-year period(2008-2023).The aim of this work is to show the correlation between rainfall anomalies and hydroelectric power production at Garafiri dam.The method used consists of calculating precipitation anomalies at Garafiri site and those for the production of hydroelectric power from Garafiri dam over the study period.This approach led us to calculate the anomalies,leading to the study on climatic variability,in order to establish correlation between rainfall and hydroelectric power dam’s production.The trend with the correlation found made it possible to carry out a significance test between these two variables.These results clearly show that rainfall in Garafiri site increases hydroelectric power production and vice versa,which explains the interdependence between these two parameters,i.e.climatic variability and hydroelectric power production.展开更多
In Niger, irrigated agriculture constitutes the main alternative for meeting family needs. It is within this framework that the state and its partners have adopted strategies to promote irrigated production sites. Thi...In Niger, irrigated agriculture constitutes the main alternative for meeting family needs. It is within this framework that the state and its partners have adopted strategies to promote irrigated production sites. This study was carried out on the Konni irrigated perimeter, the objective of which is to analyze the physical state of hydraulic infrastructures and their operation before the rehabilitation of the said perimeter. The methodology adopted consisted, first of all, of documentary research focused on data relating to this scope and our theme to properly guide the collection of data in the field. The field phase was then followed with an observation of hydraulic infrastructures one by one in order to assess their condition. Thus, the collected data was processed and analyzed. The results of this study show a notable deterioration of hydraulic infrastructure which affected the operating yield of the study area, with the development of barely 700 ha out of 1226 ha planned by the basic study for off-season production (57%). Bathymetric measurements showed that the volume of sediment that accumulated in the Zongo Dam is 1.2 million m3, which reduces its initial capacity from 12 million m3 to 10.8 million m3 after 43 years of service. The expansion joints of the feed canal are all in poor condition. 90% of the total length of the tertiary canals are degraded, 82.32% of the panels of the main canal C are degraded and 17.68% are cracked. All crossing structures are blocked between the RN1 and the Zongo dam. Based on this critical situation, it would be essential to consider rehabilitation work on all infrastructure in order to restore the hydraulic and even agronomic performance of the Konni irrigated area.展开更多
This study addresses the pressing need to evaluate the quality of water resources in the Oued Guir watershed,highlighting the importance of monitoring both surface water and groundwater in the context of environmental...This study addresses the pressing need to evaluate the quality of water resources in the Oued Guir watershed,highlighting the importance of monitoring both surface water and groundwater in the context of environmental and public health.It focuses on the evaluation of physicochemical and bacteriological water quality downstream of the Kaddoussa Dam,as well as the characterization of wastewater from the Boudnib treatment plant discharged into Oued Guir.The goal is to assess the health of aquatic ecosystems and understand the impact of anthropogenic activities on these sensitive environments.A comprehensive analysis was conducted at 15 selected stations during a sampling campaign in November 2023.Groundwater and surface water were assessed using 10 physicochemical parameters,while bacteriological quality was evaluated based on fecal coliforms and Escherichia coli.In addition,38 parameters were studied to characterize the wastewater discharge.All analyses followed standard procedures and the results were compared to Moroccan and World Health Organization(WHO)standards.The study revealed that surface water and groundwater in the study area exhibited strong mineralization,with Electrical Conductivity(EC)exceeding 1400µS/cm at all stations.Nitrogen quality,in terms of Nitrates(NO₃⁻),was moderate across stations,while Ammonium(NH₄⁺)quality was consistently excellent.Physicochemical parameters of surface waters indicated overall excellent quality.Bacteriological analysis showed minimal contamination by fecal coliforms and Escherichia coli,with levels deemed negligible.However,wastewater from the Boudnib treatment plant exceeded Moroccan standards for organic load,presenting a potential environmental risk.展开更多
文摘The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.
基金Received on April 20th,2020revised on July 30th,2020.This project is sponsored by the National Natural Science Foundation of China(42072248)+1 种基金the Seismic Active Fault Exploration Project based on High-Resolution Remote Sensing Interpretation Technology by the Department of Earthquake Damage Defense,CEA(15230003)the Basic Science Research Plan of Institute of Earthquake Forecasting,CEA(2019IEF0201).
文摘The quantitative calculation of the volume of large earthquake-triggered landslides and related dammed lake sediments is of great significance in the study of secondary disasters and focal parameters of strong historical earthquakes.In this study,the dammed lake induced by Qishan M7 earthquake(Lingtai County,Gansu Province,Northwest China)is selected as the research object.Based on the information collected from the 4 boreholes in the dammed lake area,we further take advantage of the lowlevel Unmanned Aerial Vehicle(UAV)photogrammetry and the morphology recovery method,to calculate the volume of the dammed lake and landslides,respectively.Finally,major conclusions are obtained as follows:①the AMS-14C age at the bottom of the Qiuzigou Dammed Lake sediments is 2890±30 BP,which coincides with the 780 BC Qishan earthquake;furthermore,the Qiuzigou Landslides seem to have been triggered by the earthquake,forming an enclosed dammed lake deposition environment after the upstream sediments accumulate;②the Qiuzigou landslides are opposite-sliding landslides that have blocked the river valley;in detail,landslide volumes at the right and left banks are 235×104 m3 and 229×104 m3,respectively.The length of the dammed lake is 2.6 km,with a thickness of approximately 43 m near the landslides,and the total sedimentary volume is 573×104 m3;③the erosion rate of Qiuzigou Landslide Dammed Lake is 0.44 mm/a,the accumulation rate is 15.05 mm/a,and the soil erosion modulus is 593 t/(km2/a),characterized as slight erosion.Quantitative research on the formation of landslides and dammed lakes from strong historical earthquakes is vital for increasing our understanding of the vibrational characteristics and surface action processes of these types of earthquakes.
基金Under the auspices of National Key R&D Program of China(No.2019YFC0409104)。
文摘Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecology,disrupted river continuity,and jeopardized the existence of aquatic creatures in rivers.Studying the impacts of dam construction on rivers can enhance our knowledge of river ecological and environmental concerns and help sustain the health of river ecosystems,thereby realizing the harmony between humans and water in both theoretical and practical aspects.This study used bibliometrics and constructed an author-keyword 2-mode matrix network using Co-Occurrence software to identify the hotspots and research trend in eco-hydrology of dammed rivers.We identified‘FLOW’‘SEDIMENT’‘QUALITY’and‘MODEL’as the research hotspots in the ecological impact of dammed rivers,and combined the related literatures,we highlight the research progress in the four directions.Then the research shortcomings and prospect were discussed,including strengthening the monitoring and analysis of critical ecological variables,enhancing the hydrological monitoring density for small rivers,strengthening the research of relationship between eutrophication and zooplankton,establishing multiscale approaches,and combining multi-sources information technologies to improve parameter accuracy in the model research.
基金funded by the National Natural Science Foundation of China(No.41977226)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(No.SKLGP2016Z015)。
文摘In an earlier study of the Diexi ancient dammed lake along the Minjiang River in Southwest China,10 disturbed layers with envelope and flame structures were found in more than 240 m of lacustrine sediments.In this paper,the soft-sediment disturbances caused by earthquakes in the Diexi ancient dammed lake were studied based on field investigations and laboratory core observations.A two-to three-degree-of-freedom spring-type earthquake simulation vibration table was used to carry out disturbance tests on lacustrine sediments under different dynamic conditions.The results support the following conclusions:(1)The disturbance layers in the lacustrine sediments were caused by strong earthquakes in the region.(2)The characteristics of the disturbance layers are related to the seismic parameters and the degree of sediment consolidation.(3)The greater the earthquake intensity is,the greater the disturbance amplitude is;moreover,the lower the consolidation degree is,the greater the disturbance amplitude.(4)The simulation tests verify that the disturbance layers in the sediments of the Diexi ancient dammed lake correspond to strong earthquakes in the region.These results are valuable for ongoing palaeoseismic research in the region.
基金funded by the National Natural Science Foundation of China(No.41977226)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(No.SKLGP2016Z015)。
文摘The Diexi ancient dammed lake is in the upper reaches of the Minjiang River.Six terraces with lacustrine sediments occur at the base.These terraces are the products of the graded outburst of the Diexi ancient dammed lake.The outburst of the ancient dammed lake would certainly have had an impact on the Chengdu Plain in the lower reaches of the Minjiang River.In this paper,on-site sampling and laboratory analysis were used to analyze the sediments of the Diexi ancient dammed lake and the Jinsha site in Chengdu Plain,and the environmental indicators of each sediment layer were tested.Through a comparative analysis of the environmental indicators in the sediments at the two locations,the following results were obtained:the palaeoclimatic and palaeoenvironmental characteristics at the two locations generally show consistent changes.The most important finding is that the types and content of the major pollen taxa at the two locations are similar.The Pinus content strongly proves that the soil layers at the Jinsha site was sourced from the upper reaches of the Minjiang River.Considering that the demise of the ancient culture at the Jinsha site occurred close in time to the outburst of the ancient dammed lake,this similarity suggests that the cultural change at the Jinsha site may have been related to the outburst of the Diexi ancient dammed lake.
文摘After the Wenchuan Earthquake, many large-scale debris flows blocked rivers, generated dammed lakes, and produced outburst flood at the seriously hit areas. This paper mainly discussed the formation, outburst, impacts and risks of debris flow dammed lakes. The field investigation showed that the dammed lakes were created by debris flows from gullies and hill-slopes as well as the combination of debris flow and landslides, and also distributed along rivers step-by-step. The height of dams and the length of dammed lakes along river channel varied from 4 m to 18 m and from 400 m to 5000 m, respectively, and the reservoir capacity of dammed lakes were from 1.5 × 105 m3 to 3 × 106 m3. Due to geomorphological impact, dammed lakes commonly partially outburst along their front of debris flow deposition dams (1/4 - /3 outburst) or the suture between debris flow and landslide, and hardly completely outburst. Moreover, the subsequent debris flows continuously increased the magnitude and height of dams, not only increasing the stability of a single dam, but also improving the risks of outburst flood induced by intensive rainstorm. Dammed lakes produced steep rage in the sites of dams with the 4% - 9% of slope and rapidly raised river channel in the upstream due to a mass of alluvial sediment. As a result, the landscapes of step-dams and step-lakes dominate driver channels, significantly increasing the hazards of floods. Then the hazards, impacts and risk of debris flow dammed lakes along Min River from Dujiangyan to Wenchuan were analyzed. In order to mitigate dammed lakes induced by debris flows, the identification model of debris flow blocking rivers, the process of the formation, outburst and evolvement of dammed lakes, and the model of risk assessment for step-dammed lakes were strongly suggested to explore, and be used at the rivers of Min, Yuzi, Caopo, Longxi, Mianyuan, Jian, Shiting, Baishui and Jushui.
基金funded by the National Key Technology Research and Development Programthe Key Basic Research Program of the Ministry of Science and Technology of China (2012BAC19B07, 2013FY111400)the National Natural Science Foundation of China (41190084)
文摘Glacial outburst floods（GLOFs） in alpine regions tend to be relatively complicated, multi-stage catastrophes, capable of causing significant geomorphologic changes in channel surroundings and posing severe threats to infrastructure and the safety and livelihoods of human communities. GLOF disasters have been observed and potential hazards can be foreseen due to the newly formed glacial lakes or the expansion of existing ones in the Poiqu River Basin in Tibet, China. Here we presented a synthesis of GLOF-related studies including triggering mechanism（s）, dam breach modeling, and flood routing simulation that have been employed to reconstruct or forecast GLOF hydrographs. We provided a framework for probability-based GLOFs simulation and hazard mapping in the Poiqu River Basin according to available knowledge. We also discussed the uncertainties and challenges in the model chains, which may form the basis for further research.
文摘A year from now, dam builders will have blocked the mighty Yangtze River at the Three Gorges, marking the start of the second phase of the gigantic water harnessing and developing scheme.
文摘Alternation of high and low resistance sedimentary beds,active tectonics,large rivers,and slope erosion in valleys consequently resulted in landslide in dammed lakes within the Zagros range.This study presents the results in the analysis of geological and topographic data,satellite imageries,morphotectonics and hydrodynamics of drainage networks about the landslide dammed lakes.There are four landslides in central Zagros(Zagros FoldThrust Belt,ZFTB)which have formed five dammed lakes named,Seymareh,Jaidar,Shur,Shimbar,and Godar.According to the results,damming landslides occurred in the active-tectonic regions on the slopes of anticlines and in valleys with undercutting effects of rivers on their slopes consisting of alternations of loose and resistant beds.The studied landslide dams in narrow valleys are formed as a result of blocking river by sliding debris slopes and rock slides.This study also indicates the formation of Jaidar and Godar in one stage and the presence of Lake Terrace sequence in Seymareh,Shur and Shimbar lakes.The observed sequences of terrace formation in these lakes are caused by four Seymareh Landslides followed by the three-stage excavation of Shur andShimbar lakes.
基金National Natural Science Foundation of China,Grant/Award Number:42330719National Natural Science Foundation of China,Grant/Award Number:U2443228+1 种基金Power Construction Corporation of China,Grant/Award Number:DJ-ZDXM-2021-51China Institute of Water Resources and Hydropower Research,Grant/Award Number:GE121003A0042022。
文摘Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environmental impacts.This study reviews the remarkable benefits of check dams on the land reclamation and environmental improvement on the Loess Plateau,and sediment reduction entering the Yellow River.However,the flood incidents on check dams have been frequently reported for the past decades,which has attracted more attention in the context of climate change and extreme rainfall events recently.Advances in the flood migration techniques achieved by the research group led by the first author have been highlighted to migrate the breach risk of check dams due to floods.The“family tree method”has been proposed to determine the survival status and critical rainfall threshold of each check dam in the complicated dam system.An updated dam breach flood evaluation framework and the corresponding numerical algorithm(i.e.,DB-IWHR)have been developed.Moreover,innovative types of water-release facilities for check dams,including geobag stepped spillway and prestressed concrete cylinder pipe in the underlying conduit,have been proposed and developed.Finally,the perspectives concerning the check dam construction on the Loess Plateau have been put forward.
文摘The 1320 MW Glen Canyon Dam in northern Arizona in the United States generates power for residents of seven states[1].But in February 2023 the dam’s ability to deliver that electricity was in danger.
基金National Natural Science Foundation of China,Grant/Award Number:52309153Key Science and Technology Projects of China Power Construction Group,Grant/Award Numbers:DJ-ZDXM-2022-01,DJ-ZDXM-12025-45。
文摘Underpinned by the ultrahigh-core rockfill dam at the Nuozhadu Hydropower Station,comprehensive studies and engineering practices have been conducted to address several critical challenges:coordination of seepage deformation in dam materials,prevention and control of high-water-pressure seepage failure,static and dynamic deformation control,and construction quality monitoring.Advanced technologies have been developed for modifying impermeable soil materials and utilizing soft rocks.Constitutive models and high-performance fine computational methods for dam materials have been improved,along with innovative seismic safety measures.Additionally,a“Digital Dam”and an information system for monitoring the construction quality were implemented.These efforts ensured the successful construction of the Nuozhadu Dam,making it the tallest dam in China and the third tallest dam in the world upon completion.This achievement increased the height of core dams in China by 100 m and established a design and safety evaluation framework for ultrahigh-core rockfill dams exceeding 300 m in height.Furthermore,the current safety monitoring results indicate that the Nuozhadu Dam is safe and controllable.
文摘Hydroelectric power production from Garafiri dam and rainfall are essential elements with the observation of hydroelectric power production in West African power system,particularly in Guinea.This article focuses on the study and the influence of climate variability on hydroelectric power production at Garafiri dam over 16-year period(2008-2023).The aim of this work is to show the correlation between rainfall anomalies and hydroelectric power production at Garafiri dam.The method used consists of calculating precipitation anomalies at Garafiri site and those for the production of hydroelectric power from Garafiri dam over the study period.This approach led us to calculate the anomalies,leading to the study on climatic variability,in order to establish correlation between rainfall and hydroelectric power dam’s production.The trend with the correlation found made it possible to carry out a significance test between these two variables.These results clearly show that rainfall in Garafiri site increases hydroelectric power production and vice versa,which explains the interdependence between these two parameters,i.e.climatic variability and hydroelectric power production.
文摘In Niger, irrigated agriculture constitutes the main alternative for meeting family needs. It is within this framework that the state and its partners have adopted strategies to promote irrigated production sites. This study was carried out on the Konni irrigated perimeter, the objective of which is to analyze the physical state of hydraulic infrastructures and their operation before the rehabilitation of the said perimeter. The methodology adopted consisted, first of all, of documentary research focused on data relating to this scope and our theme to properly guide the collection of data in the field. The field phase was then followed with an observation of hydraulic infrastructures one by one in order to assess their condition. Thus, the collected data was processed and analyzed. The results of this study show a notable deterioration of hydraulic infrastructure which affected the operating yield of the study area, with the development of barely 700 ha out of 1226 ha planned by the basic study for off-season production (57%). Bathymetric measurements showed that the volume of sediment that accumulated in the Zongo Dam is 1.2 million m3, which reduces its initial capacity from 12 million m3 to 10.8 million m3 after 43 years of service. The expansion joints of the feed canal are all in poor condition. 90% of the total length of the tertiary canals are degraded, 82.32% of the panels of the main canal C are degraded and 17.68% are cracked. All crossing structures are blocked between the RN1 and the Zongo dam. Based on this critical situation, it would be essential to consider rehabilitation work on all infrastructure in order to restore the hydraulic and even agronomic performance of the Konni irrigated area.
文摘This study addresses the pressing need to evaluate the quality of water resources in the Oued Guir watershed,highlighting the importance of monitoring both surface water and groundwater in the context of environmental and public health.It focuses on the evaluation of physicochemical and bacteriological water quality downstream of the Kaddoussa Dam,as well as the characterization of wastewater from the Boudnib treatment plant discharged into Oued Guir.The goal is to assess the health of aquatic ecosystems and understand the impact of anthropogenic activities on these sensitive environments.A comprehensive analysis was conducted at 15 selected stations during a sampling campaign in November 2023.Groundwater and surface water were assessed using 10 physicochemical parameters,while bacteriological quality was evaluated based on fecal coliforms and Escherichia coli.In addition,38 parameters were studied to characterize the wastewater discharge.All analyses followed standard procedures and the results were compared to Moroccan and World Health Organization(WHO)standards.The study revealed that surface water and groundwater in the study area exhibited strong mineralization,with Electrical Conductivity(EC)exceeding 1400µS/cm at all stations.Nitrogen quality,in terms of Nitrates(NO₃⁻),was moderate across stations,while Ammonium(NH₄⁺)quality was consistently excellent.Physicochemical parameters of surface waters indicated overall excellent quality.Bacteriological analysis showed minimal contamination by fecal coliforms and Escherichia coli,with levels deemed negligible.However,wastewater from the Boudnib treatment plant exceeded Moroccan standards for organic load,presenting a potential environmental risk.
