Every river basin is characterised by an evolutionary history,which may be analysed at different time scales.This study provides a geological and geomorphic history of different river basins of India at different time...Every river basin is characterised by an evolutionary history,which may be analysed at different time scales.This study provides a geological and geomorphic history of different river basins of India at different time scales ranging from millions of years to millennial time scales.The river basins in India are divided into six different groups on the basis of different tectono-climatic settings and geomorphic characteristics.The evolutionary trajectories in the past strongly govern the modern day geomorphic characteristics and processes in a river basin.The basin scale data compiled in this paper highlights the role of geological inheritance and‘landscape memory’in the evolution of river systems of India.展开更多
In order to reduce the environmental and ecological problems induced by water resources development and utilization, this paper proposes a concept of environmental and ecological water requirement. It is defined as th...In order to reduce the environmental and ecological problems induced by water resources development and utilization, this paper proposes a concept of environmental and ecological water requirement. It is defined as the minimum water amount to be consumed by the natural water bodies to conserve its environmental and ecological functions. Based on the definition, the methods on calculating the amount of environmental and ecological water requirement are determined. In the case study on Haihe-Luanhe river system, the water requirement is divided into three parts, i.e., the basic in-stream flow, water requirement for sediment transfer and water consumption by evaporation of the lakes or everglades. The results of the calculation show that the environmental and ecological water requirement in the river system is about 124×108 m3, including 57×108 m3 for basic in-stream flow, 63×108 m3 for sediment transfer and 4×108 m3 for net evaporation loss of lakes. The total amount of environmental and ecological water requirement accounts for 54% of the amount of runoff (228×108 m3). However, it should be realized that the amount of environmental and ecological water requirement must be more than that we have calculated. According to this result, we consider that the rational utilization rate of the runoff in the river systems must not be more than 40%. Since the current utilization rate of the river system, which is over 80%, has been far beyond the limitation, the problems of environment and ecology are quite serious. It is imperative to control and adjust water development and utilization to eliminate the existing problems and to avoid the potential ecological or environmental crisis.展开更多
An estimated 0.048-13 million tons are discharged annually into marine systems through rivers and other pathways[1],resulting in about 75-199 million tons of plastic waste,which constitutes 85%of the total weight of m...An estimated 0.048-13 million tons are discharged annually into marine systems through rivers and other pathways[1],resulting in about 75-199 million tons of plastic waste,which constitutes 85%of the total weight of marine debris[2].These plastics decompose into microplastics(MPs)with a diameter of less than 5 mm,contributing to long-term and increasingly severe environmental and health issues.Considering the high carbon content of MPs(38%-92%)[3].展开更多
Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that help...Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that helps registering climate and tectonic signals into its geomorphology and sedimentary history.The paper discusses the late Quaternary landscape evolution of the mountain and its foreland and reviews the published literature in the context.展开更多
Anthropogenic activity is an important driver of changes in the chemistry of nutrients(N,P,and Si)over watersheds at the sub-continental scale(e.g.,106km^(2))and can markedly modify their seaward fluxes to the global ...Anthropogenic activity is an important driver of changes in the chemistry of nutrients(N,P,and Si)over watersheds at the sub-continental scale(e.g.,106km^(2))and can markedly modify their seaward fluxes to the global ocean.In the present study,we reviewed the current status of nutrient chemistry in Changjiang(Yangtze River)based on data collected through 11 expeditions along a river course spanning 4,500 km and 15–20 major tributaries during 1997–2016 as well as monthly monitoring at the river mouth since 1980.The data were analyzed together with published results in the literature to synthesize the recent developments and current state of nutrients in the Changjiang.Previously published results from the Qinghai-Tibetan Plateau head waters were included to realize the systematics of nutrients for the whole drainage basin.Here,we showed that tributaries of the upper reaches of watersheds collectively determine the regime with high concentration and skewed species ratio of nutrients in the Changjiang mainstream,producing profound effects over a water course of 2,000–2,500 km further downstream and until the river mouth.Moreover,using data across the Three Gorges Reservoir(TGR)during 2003–2016,we evaluated the trapping and/or amplifying effects of the Three Gorges Dam(TGD)on nutrient chemistry.Tide-influenced river delta contributed an additional 20%dissolved inorganic phosphorus and 5–10%dissolved inorganic nitrogen and dissolved silicates to the seaward flux,dramatically affecting the stoichiometry of nutrients at the river mouth.Next,based on compiled data on supply and export,legacy nutrients were evaluated.Both nitrogen and phosphorus are in the accumulation phase over the watersheds,and the legacy nutrient fluxes are much higher than the annual riverine seaward fluxes.Finally,we demonstrated that the seaward fluxes of anthropogenic nutrients from the Changjiang exceed those from other top 10 largest rivers on this planet,which can be attributed to land use changes in the China over the last three to four decades.展开更多
基金supported by COFUND fellowship at Durham University,UKSonam was supported by PhD fellowship provided by CSIR-UGC,India(Fellowship No.061320507-23/06/2013(i)EU-V).
文摘Every river basin is characterised by an evolutionary history,which may be analysed at different time scales.This study provides a geological and geomorphic history of different river basins of India at different time scales ranging from millions of years to millennial time scales.The river basins in India are divided into six different groups on the basis of different tectono-climatic settings and geomorphic characteristics.The evolutionary trajectories in the past strongly govern the modern day geomorphic characteristics and processes in a river basin.The basin scale data compiled in this paper highlights the role of geological inheritance and‘landscape memory’in the evolution of river systems of India.
基金Key Project of Chinese Academy of Sciences, KZ951-A1-203 Knowledge Innovation Project of Institute of Geographic Sciences and N
文摘In order to reduce the environmental and ecological problems induced by water resources development and utilization, this paper proposes a concept of environmental and ecological water requirement. It is defined as the minimum water amount to be consumed by the natural water bodies to conserve its environmental and ecological functions. Based on the definition, the methods on calculating the amount of environmental and ecological water requirement are determined. In the case study on Haihe-Luanhe river system, the water requirement is divided into three parts, i.e., the basic in-stream flow, water requirement for sediment transfer and water consumption by evaporation of the lakes or everglades. The results of the calculation show that the environmental and ecological water requirement in the river system is about 124×108 m3, including 57×108 m3 for basic in-stream flow, 63×108 m3 for sediment transfer and 4×108 m3 for net evaporation loss of lakes. The total amount of environmental and ecological water requirement accounts for 54% of the amount of runoff (228×108 m3). However, it should be realized that the amount of environmental and ecological water requirement must be more than that we have calculated. According to this result, we consider that the rational utilization rate of the runoff in the river systems must not be more than 40%. Since the current utilization rate of the river system, which is over 80%, has been far beyond the limitation, the problems of environment and ecology are quite serious. It is imperative to control and adjust water development and utilization to eliminate the existing problems and to avoid the potential ecological or environmental crisis.
基金supported by the Yellow River Scientific Expedition Special Project of the State Key Laboratory of Loess Science(E352010000)the National Natural Science Foundation of China(41991252,12405336,42330114,42472253,and 22406145)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0298).
文摘An estimated 0.048-13 million tons are discharged annually into marine systems through rivers and other pathways[1],resulting in about 75-199 million tons of plastic waste,which constitutes 85%of the total weight of marine debris[2].These plastics decompose into microplastics(MPs)with a diameter of less than 5 mm,contributing to long-term and increasingly severe environmental and health issues.Considering the high carbon content of MPs(38%-92%)[3].
文摘Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that helps registering climate and tectonic signals into its geomorphology and sedimentary history.The paper discusses the late Quaternary landscape evolution of the mountain and its foreland and reviews the published literature in the context.
基金funded by the National Natural Science Foundation of China through the“Creative Research Team”on“Land-Sea Interactions in Highly Turbid Estuaries and Adjacent Coastal Environments”(Grant Nos.40721004 and 41021064)。
文摘Anthropogenic activity is an important driver of changes in the chemistry of nutrients(N,P,and Si)over watersheds at the sub-continental scale(e.g.,106km^(2))and can markedly modify their seaward fluxes to the global ocean.In the present study,we reviewed the current status of nutrient chemistry in Changjiang(Yangtze River)based on data collected through 11 expeditions along a river course spanning 4,500 km and 15–20 major tributaries during 1997–2016 as well as monthly monitoring at the river mouth since 1980.The data were analyzed together with published results in the literature to synthesize the recent developments and current state of nutrients in the Changjiang.Previously published results from the Qinghai-Tibetan Plateau head waters were included to realize the systematics of nutrients for the whole drainage basin.Here,we showed that tributaries of the upper reaches of watersheds collectively determine the regime with high concentration and skewed species ratio of nutrients in the Changjiang mainstream,producing profound effects over a water course of 2,000–2,500 km further downstream and until the river mouth.Moreover,using data across the Three Gorges Reservoir(TGR)during 2003–2016,we evaluated the trapping and/or amplifying effects of the Three Gorges Dam(TGD)on nutrient chemistry.Tide-influenced river delta contributed an additional 20%dissolved inorganic phosphorus and 5–10%dissolved inorganic nitrogen and dissolved silicates to the seaward flux,dramatically affecting the stoichiometry of nutrients at the river mouth.Next,based on compiled data on supply and export,legacy nutrients were evaluated.Both nitrogen and phosphorus are in the accumulation phase over the watersheds,and the legacy nutrient fluxes are much higher than the annual riverine seaward fluxes.Finally,we demonstrated that the seaward fluxes of anthropogenic nutrients from the Changjiang exceed those from other top 10 largest rivers on this planet,which can be attributed to land use changes in the China over the last three to four decades.
