The Palmer drought severity index(PDSI) is physically based with multivariate concepts, but requires complicated calibration and cannot easily be used for multiscale comparison. Standardized drought indices(SDIs), suc...The Palmer drought severity index(PDSI) is physically based with multivariate concepts, but requires complicated calibration and cannot easily be used for multiscale comparison. Standardized drought indices(SDIs), such as the standardized precipitation index(SPI) and standardized precipitation evapotranspiration index(SPEI), are multiscalar and convenient for spatiotemporal comparison, but they are still challenged by their lack of physical basis. In this study, a hybrid multiscalar indicator, the standardized Palmer drought index(SPDI), was used to examine drought properties of two meteorological stations(the Beijing and Guangzhou stations) in China, which have completely different drought climatologies. The results of our case study show that the SPDI is correlated with the well-established drought indices(SPI, SPEI, and PDSI) and presents generally consistent drought/wetness conditions against multiple indicators and literature records. Relative to the PDSI, the SPDI demonstrates invariable statistical characteristics and better comparable drought/wetness frequencies over time and space. Moreover,characteristics of major drought events(drought class, and onset and end times) indicated by the SPDI are generally comparable to those detected by the PDSI. As a physically-based standardized multiscalar drought indicator, the SPDI can be regarded as an effective development of the Palmer drought indices, providing additional choices and tools for practical drought monitoring and assessment.展开更多
Nowadays, isotope environmental technique tends to be used as a reconnaissance tool , both qualitative and quantitative, to calculate the aquifer parameters particularly in carbonate rock aquifers. But, the hetero...Nowadays, isotope environmental technique tends to be used as a reconnaissance tool , both qualitative and quantitative, to calculate the aquifer parameters particularly in carbonate rock aquifers. But, the heterogeneous flow is still problematic when Lumped parameter Models are usually used to calculate the residence times and hydraulic parameters. However, Discrete State Compartment Model can provide a powerful model to heterogeneous medium. One such study was carried on in Dazha valley, where the environmental tritium was used as a tracer for determining hydrogeological parameters based on a discrete state compartment model展开更多
Zhoushan City in Zhejiang Province is the focus of China's reclamation area, and it also has a great influence on the groundwater quality. Based on the observed data of groundwater level and chloride ion concentra...Zhoushan City in Zhejiang Province is the focus of China's reclamation area, and it also has a great influence on the groundwater quality. Based on the observed data of groundwater level and chloride ion concentration, groundwater quality in the next 6 years in Zhoushan area is predicted and analyzed by using groundwater numerical simulation software GMS. According to the comparison of observed groundwater level and simulated groundwater level at the end time, it is found that the whole water level in the filling area has the small fluctuation, which is within the range of 1 m. And the highest concentration of chloride ion is in the eastern coastal area. The prediction results indicate that there is no obvious trend of sea water with high chloride ion concentration to land. Under the condition of the current groundwater utilization, the groundwater level in Donggang sea area of Zhoushan is stable, and the chloride ion concentration has a slight decrease trend.展开更多
Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences o...Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection. However, little concern focuses on this in China. The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches. This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China. The empirical bay equation can morphologically estimate beach stabilization state, but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades. By using Digital Shoreline Analysis System suggested by USGS, the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000. The conclusions of this paper include that （a） most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000; （b） two bays, Haimen Bay and Hailingshan Bay, originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation, have been unstable by the influence of coastal engineering; and （c） these 31 bays have different recession and accretion characters occuning in some bays and some segments. On the one hand, some bays totally exhibit accretion, but some bays show erosion on the whole. Shanwei Bay, Houmen Bay, Pinghai Bay and Yazhou Bay have the similar planforms, characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments. On the other hand, different segments of some bays have two dissimilar evolvement characters. Dacheng Bay, Shenquan Bay, Hudong Bay, Wukan Bay, Fengjia Bay, Wuchang Bay, Lingshui Bay and Tufu Bay produce accretion on the tangential segment, erosion on the transitional segment and accretion on the sheltering segment. However, Guang＇ao Bay, Haimen Bay, Jinghai Bay, Sanya Bay（a）, Dajiao Bay, Hailingshan Bay, Hebei Bay, Fuhu Bay, Shuidong Bay, Wangcun Bay and Bomao Bay generate erosion on the tangential part, accretion on the transitional part and accretion on the sheltering part. It seems to imply some relations between headland-bay beach evolvement and controls on headland-bay beaches, which may possibly to classify headland-bay beach types and should be further studied.展开更多
Regional evaluation of drought characteristics provides critical information for water resource management. In this case, this study attempts to analyze the probability behaviors of drought events of a given severity ...Regional evaluation of drought characteristics provides critical information for water resource management. In this case, this study attempts to analyze the probability behaviors of drought events of a given severity in the Pearl River Basin and to construct severity-area-frequency curves of drought events. Due to possible impacts of complicated topographical properties and diverse climate types within the Pearl River Basin, the entire Pearl River Basin is subdivided into different homogeneous regions. In general, the Pearl River Basin can be categorized into four homogeneous regions, and the severity-area-frequency analysis results for the short-, medium- and long-term drought episodes within each homogeneous regions indicate stressful challenge for the water resource management in the Pearl River Basin due to the fact that severe droughts usually occur over the entire Pearl River Basin. Meanwhile, the Pearl River Delta will face a higher risk of drought when compared to other regions of the Pearl River Basin in terms of the medium-term drought. The Pearl River Basin is highly economically development and is heavily populated, thus impacts of droughts and related resilience resolutions or policies should be taken into account in the formulation of regional sustainable development of water resources and socio-economy within the Pearl River Basin, China.展开更多
It is accepted that climate change has a great impact on water cycle and regional water balance,and thus it would change the formation and evolution conditions of drought in some degree. By using data at 42 meteorolog...It is accepted that climate change has a great impact on water cycle and regional water balance,and thus it would change the formation and evolution conditions of drought in some degree. By using data at 42 meteorological stations of the Pearl River Basin,the Standardized Precipitation Evapotranspiration Index（ SPEI） at different time scales was calculated. Based on the SPEIs of 1- 12 months,a newly proposed index for drought--Joint Drought Index（ JDI） was established under the multi-scale perspective through the copula function. Since short-term SPEIs are essential for the identification of emerging droughts and long-term SPEIs are useful for prolonged droughts,the JDI,which integrates all the usefull informations of drought and can thus form an overall judgement,is superior than the single SPEI in drought monitoring. By the forcast evaluation system and comparison to the actual drought,the accuracy and effectiveness of JDI in drought monitoring were verified. In general,JDI can be used as a new ideal index for future drought monitoring and assessment. Additionly,we analyzed the spatio-temperal characteristics of drought across the Pearl River Basin using the JDI. The results indicate that mild drought was the most frequent drought occurred in the Pearl River Basin over the past half century,and moderate drought followed. Severe drought and extreme drought would appear occasionally while exceptional drought could hardly be found. A dry-wet-dry interdecadal variation pattern had been found from the 1960 s to the 2000 s. Since the 21 stcentury,an obvious trend toward drought can be observed in the whole basin,especially in the Xijiang subbasin,which,consequently,poses an increasing challenge for the water resource planning and management.展开更多
The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configurati...The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configuration of Olympus and Fthia＇s mounts and the hydraulic singularities of drained lakes Askouris in Olympus, favour the installation of series of sustainable small hydroelectric plants. The present action consists of a serious effort towards the systematic sustainable small hydropower exploitation of Fthia＇s and Olympus hydraulic potential, including the Archimedean hydropower perspectives of Sperchios River.展开更多
The Dongjiang River, one of the tributaries of the Pearl River, serves as the critical water source for Guangdong Province and the District of Hong Kong in China. In this study, the change trend and change points of f...The Dongjiang River, one of the tributaries of the Pearl River, serves as the critical water source for Guangdong Province and the District of Hong Kong in China. In this study, the change trend and change points of flow at three main gaging stations in the Dongjiang River were analyzed using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. Flow regime changes in the Dongjiang River were quantified by using both the Indicators of Hydrologic Alteration （IHA） parameters and eco-statistics, such as ecosurplus and eeodeficit. It was found that the change trend for annual median flow in the Dongjiang River increased over the past 60years, with the major change occurring sometime between 1970 and 1974. IHA analyses showed that the magnitude of monthly flow decreased during the flood period, but increased greatly during the dry period. The median date of the one-day minimum flow moved ahead, and the duration of low pulse for the Dongjiang River was reduced significantly because of reservoir construction and operations. The IHA-based Dundee Hydrological Regime Alteration Method analysis indicated that all three stations have experienced a moderate risk of impact since 1974. The eco-statistical analyses showed that the majority of the flows appeared to be ecosurplus at all three locations after 1974, while flows with less than 30%, or higher exceedance probability, had ecodeficit in the summer flood period due to heavy reservoir operations.展开更多
The morphology of sediment particles plays an important role in interfacial interactions.The difficulties in complex morphological description significantly limit the research on interfacial interactions.In this study...The morphology of sediment particles plays an important role in interfacial interactions.The difficulties in complex morphological description significantly limit the research on interfacial interactions.In this study,images of a single sediment particle extracted from electron microscope photos were used to analyze the gray values and present the probability of shape of the sediment particles.Moreover,the morphological features of the sediment particles were qualitatively described using the fractal method(surface area-volume method).The fractal dimension D of a single sediment particle was calculated to analyze the features and quantitative complexity of the sediment particle morphology.Results indicate that the probability of shape can provide intuitive morphological structure and fully describe the complex morphological characteristics of sediment particle surfaces.The fractal dimension abstractly described the complexity of the morphology of a sediment particle surface and matched well with the experimental results.The methods discussed in this study are suitable for describing the complex morphology of the sediment particle surface and lay the scientific foundation for further research on the interfacial interaction between the sediment particle and the pollutant.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41701022)the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2017491011)the Scientific and Technical Innovation Team Foundation for Universities of Henan Province(Grant No.18IRTSTHN009)
文摘The Palmer drought severity index(PDSI) is physically based with multivariate concepts, but requires complicated calibration and cannot easily be used for multiscale comparison. Standardized drought indices(SDIs), such as the standardized precipitation index(SPI) and standardized precipitation evapotranspiration index(SPEI), are multiscalar and convenient for spatiotemporal comparison, but they are still challenged by their lack of physical basis. In this study, a hybrid multiscalar indicator, the standardized Palmer drought index(SPDI), was used to examine drought properties of two meteorological stations(the Beijing and Guangzhou stations) in China, which have completely different drought climatologies. The results of our case study show that the SPDI is correlated with the well-established drought indices(SPI, SPEI, and PDSI) and presents generally consistent drought/wetness conditions against multiple indicators and literature records. Relative to the PDSI, the SPDI demonstrates invariable statistical characteristics and better comparable drought/wetness frequencies over time and space. Moreover,characteristics of major drought events(drought class, and onset and end times) indicated by the SPDI are generally comparable to those detected by the PDSI. As a physically-based standardized multiscalar drought indicator, the SPDI can be regarded as an effective development of the Palmer drought indices, providing additional choices and tools for practical drought monitoring and assessment.
文摘Nowadays, isotope environmental technique tends to be used as a reconnaissance tool , both qualitative and quantitative, to calculate the aquifer parameters particularly in carbonate rock aquifers. But, the heterogeneous flow is still problematic when Lumped parameter Models are usually used to calculate the residence times and hydraulic parameters. However, Discrete State Compartment Model can provide a powerful model to heterogeneous medium. One such study was carried on in Dazha valley, where the environmental tritium was used as a tracer for determining hydrogeological parameters based on a discrete state compartment model
基金supported by monitoring and evaluation of groundwater environment in Donggang reclamation area,Zhoushan(42932016001)
文摘Zhoushan City in Zhejiang Province is the focus of China's reclamation area, and it also has a great influence on the groundwater quality. Based on the observed data of groundwater level and chloride ion concentration, groundwater quality in the next 6 years in Zhoushan area is predicted and analyzed by using groundwater numerical simulation software GMS. According to the comparison of observed groundwater level and simulated groundwater level at the end time, it is found that the whole water level in the filling area has the small fluctuation, which is within the range of 1 m. And the highest concentration of chloride ion is in the eastern coastal area. The prediction results indicate that there is no obvious trend of sea water with high chloride ion concentration to land. Under the condition of the current groundwater utilization, the groundwater level in Donggang sea area of Zhoushan is stable, and the chloride ion concentration has a slight decrease trend.
基金supported by the National Nature Science Foundation of China(Grant No. 40576041)
文摘Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection. However, little concern focuses on this in China. The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches. This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China. The empirical bay equation can morphologically estimate beach stabilization state, but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades. By using Digital Shoreline Analysis System suggested by USGS, the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000. The conclusions of this paper include that （a） most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000; （b） two bays, Haimen Bay and Hailingshan Bay, originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation, have been unstable by the influence of coastal engineering; and （c） these 31 bays have different recession and accretion characters occuning in some bays and some segments. On the one hand, some bays totally exhibit accretion, but some bays show erosion on the whole. Shanwei Bay, Houmen Bay, Pinghai Bay and Yazhou Bay have the similar planforms, characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments. On the other hand, different segments of some bays have two dissimilar evolvement characters. Dacheng Bay, Shenquan Bay, Hudong Bay, Wukan Bay, Fengjia Bay, Wuchang Bay, Lingshui Bay and Tufu Bay produce accretion on the tangential segment, erosion on the transitional segment and accretion on the sheltering segment. However, Guang＇ao Bay, Haimen Bay, Jinghai Bay, Sanya Bay（a）, Dajiao Bay, Hailingshan Bay, Hebei Bay, Fuhu Bay, Shuidong Bay, Wangcun Bay and Bomao Bay generate erosion on the tangential part, accretion on the transitional part and accretion on the sheltering part. It seems to imply some relations between headland-bay beach evolvement and controls on headland-bay beaches, which may possibly to classify headland-bay beach types and should be further studied.
文摘Regional evaluation of drought characteristics provides critical information for water resource management. In this case, this study attempts to analyze the probability behaviors of drought events of a given severity in the Pearl River Basin and to construct severity-area-frequency curves of drought events. Due to possible impacts of complicated topographical properties and diverse climate types within the Pearl River Basin, the entire Pearl River Basin is subdivided into different homogeneous regions. In general, the Pearl River Basin can be categorized into four homogeneous regions, and the severity-area-frequency analysis results for the short-, medium- and long-term drought episodes within each homogeneous regions indicate stressful challenge for the water resource management in the Pearl River Basin due to the fact that severe droughts usually occur over the entire Pearl River Basin. Meanwhile, the Pearl River Delta will face a higher risk of drought when compared to other regions of the Pearl River Basin in terms of the medium-term drought. The Pearl River Basin is highly economically development and is heavily populated, thus impacts of droughts and related resilience resolutions or policies should be taken into account in the formulation of regional sustainable development of water resources and socio-economy within the Pearl River Basin, China.
基金Supported by National Natural Science Foundation,China(41371498)Comprehensive Process Observation and Test Platform Construction of Natural Geography in Marina Small Watershed,Sun Yat-sen University,China
文摘It is accepted that climate change has a great impact on water cycle and regional water balance,and thus it would change the formation and evolution conditions of drought in some degree. By using data at 42 meteorological stations of the Pearl River Basin,the Standardized Precipitation Evapotranspiration Index（ SPEI） at different time scales was calculated. Based on the SPEIs of 1- 12 months,a newly proposed index for drought--Joint Drought Index（ JDI） was established under the multi-scale perspective through the copula function. Since short-term SPEIs are essential for the identification of emerging droughts and long-term SPEIs are useful for prolonged droughts,the JDI,which integrates all the usefull informations of drought and can thus form an overall judgement,is superior than the single SPEI in drought monitoring. By the forcast evaluation system and comparison to the actual drought,the accuracy and effectiveness of JDI in drought monitoring were verified. In general,JDI can be used as a new ideal index for future drought monitoring and assessment. Additionly,we analyzed the spatio-temperal characteristics of drought across the Pearl River Basin using the JDI. The results indicate that mild drought was the most frequent drought occurred in the Pearl River Basin over the past half century,and moderate drought followed. Severe drought and extreme drought would appear occasionally while exceptional drought could hardly be found. A dry-wet-dry interdecadal variation pattern had been found from the 1960 s to the 2000 s. Since the 21 stcentury,an obvious trend toward drought can be observed in the whole basin,especially in the Xijiang subbasin,which,consequently,poses an increasing challenge for the water resource planning and management.
文摘The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configuration of Olympus and Fthia＇s mounts and the hydraulic singularities of drained lakes Askouris in Olympus, favour the installation of series of sustainable small hydroelectric plants. The present action consists of a serious effort towards the systematic sustainable small hydropower exploitation of Fthia＇s and Olympus hydraulic potential, including the Archimedean hydropower perspectives of Sperchios River.
基金Acknowledgements The authors would like to express their sincere gratitude to two anonymous referees for their constructive comments and useful suggestions that helped us improve our paper. We also want to thank Lisa Shepherd from University of Illinois at Urbana-Champaign for editing. This study was financially supported by the National Natural Science Foundation of China （Grant Nos. 51379223 and 51210013）, the Pearl-River- New-Star of Science and Technology supported by Guangzhou City （2011J2200051）, and the Natural Science Foundation of Guangdong Province （$2011010001549）.
文摘The Dongjiang River, one of the tributaries of the Pearl River, serves as the critical water source for Guangdong Province and the District of Hong Kong in China. In this study, the change trend and change points of flow at three main gaging stations in the Dongjiang River were analyzed using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. Flow regime changes in the Dongjiang River were quantified by using both the Indicators of Hydrologic Alteration （IHA） parameters and eco-statistics, such as ecosurplus and eeodeficit. It was found that the change trend for annual median flow in the Dongjiang River increased over the past 60years, with the major change occurring sometime between 1970 and 1974. IHA analyses showed that the magnitude of monthly flow decreased during the flood period, but increased greatly during the dry period. The median date of the one-day minimum flow moved ahead, and the duration of low pulse for the Dongjiang River was reduced significantly because of reservoir construction and operations. The IHA-based Dundee Hydrological Regime Alteration Method analysis indicated that all three stations have experienced a moderate risk of impact since 1974. The eco-statistical analyses showed that the majority of the flows appeared to be ecosurplus at all three locations after 1974, while flows with less than 30%, or higher exceedance probability, had ecodeficit in the summer flood period due to heavy reservoir operations.
基金supported by the National Natural Science Foundation of China (Grant No. 50909107)the China Post-doctoral Science Special Foundation (Grant No. 201003385)Young Teachers Cultivation Project from Sun Yat-sen University (Grant No. 37000-3161402)
文摘The morphology of sediment particles plays an important role in interfacial interactions.The difficulties in complex morphological description significantly limit the research on interfacial interactions.In this study,images of a single sediment particle extracted from electron microscope photos were used to analyze the gray values and present the probability of shape of the sediment particles.Moreover,the morphological features of the sediment particles were qualitatively described using the fractal method(surface area-volume method).The fractal dimension D of a single sediment particle was calculated to analyze the features and quantitative complexity of the sediment particle morphology.Results indicate that the probability of shape can provide intuitive morphological structure and fully describe the complex morphological characteristics of sediment particle surfaces.The fractal dimension abstractly described the complexity of the morphology of a sediment particle surface and matched well with the experimental results.The methods discussed in this study are suitable for describing the complex morphology of the sediment particle surface and lay the scientific foundation for further research on the interfacial interaction between the sediment particle and the pollutant.
