Traditional source-to-sink analyses cannot effectively characterize deep-time sedimentary processes involving multiple sediment sources and the spatiotemporal evolution of sediment contributions from different sources...Traditional source-to-sink analyses cannot effectively characterize deep-time sedimentary processes involving multiple sediment sources and the spatiotemporal evolution of sediment contributions from different sources.In this study,a dynamic,quantitative source-to-sink analysis approach using stratigraphic forward modeling(SFM)is proposed,and it is applied to the Paleogene Enping Formation in the Baiyun Sag,Pearl River Mouth Basin.The built-in spatiotemporal provenance tagging of the model assigns a unique time-source label to sediments from each provenance,making each source's contribution identifiably“labeled”in the simulated formation,and thus enabling a direct precise tracking and high spatiotemporal resolution quantification of such contributions.Five pseudo-wells(from proximal to distal locations)in the Baiyun Sag were analyzed.The simulation results quantitatively represent the varied proportion of contribution of each source at different locations and in different periods and verify the proposed approach's operability and accuracy of the proposed approach.The simulated 3D deposit distribution shows a high agreement with the measured stratigraphic data,validating the model's reliability.Results reveal significant spatiotemporal changes in the Enping sedimentary system.In the late stage of Enping Formation deposition,a distal source supply from the northern part of the sag became dominant,the depocenter migrated northward to the deepwater area,and large-scale deltaic sand bodies extensively progradating into the sag were formed.The modeled 3D deposit distribution indicates that extensive high-quality reservoir sandstones are likely present across the deepwater area of the Baiyun Sag,which are identified as key exploration targets.Compared to traditional static approaches,the SFM-based dynamic simulation markedly enhances the spatiotemporal resolution of source-to-sink analysis and quantitatively captures the sedimentary system's responses to tectonic activity,base-level fluctuations and other external drivers.The proposed approach provides a novel quantitative framework for investigating complex,deep-time,multi-source systems,and offers an effective tool for reservoir prediction and hydrocarbon exploration planning in underexplored deepwater areas.展开更多
Glacial meltwater constitutes a vital component of the water supply in arid and semi-arid areas.However,the influence of glacial melting on runoff and evapotranspiration under global warming remains insufficiently und...Glacial meltwater constitutes a vital component of the water supply in arid and semi-arid areas.However,the influence of glacial melting on runoff and evapotranspiration under global warming remains insufficiently understood.Previous studies coupling the Soil and Water Assessment Tool(SWAT)model with glacier modules often failed to consider the spatial heterogeneity of temperature during glacial melting,potentially leading to biased estimates of meltwater volume.In this study,we developed a glacier-coupled SWAT(SWAT-glacier)model considering the digital elevation model(DEM)based temperature-driven glacial melt processes to elucidate the impact of glacial melting on hydrological processes across four river basins(Dongda,Xiying,Jinta,and Zamu)of the upper Shiyang River Basin(SYRB)in northwestern China from 1986 to 2021.Compared with the standard SWAT model,the proposed SWAT-glacier model significantly improved the simulation accuracy for both runoff and evapotranspiration.Specifically,in comparison with the standard SWAT model,the Nash-Sutcliffe efficiency of the SWAT-glacier model showed a relative improvement of approximately 0.42%–9.16%and 1.50%–10.15%for runoff and evapotranspiration,respectively,in the four river basins during the validation period.Annual glacial runoff occurred predominantly from May to October,whereas glacial melt-induced evapotranspiration peaked between June and August.From 1986 to 2021,the average contributions of glacial melt to runoff were 6.97%for Dongda,3.06%for Xiying,2.70%for Jinta,and 0.67%for Zamu,whereas its contributions to evapotranspiration were 9.06%,5.14%,3.21%,and 1.59%,respectively.This study presents a SWAT-glacier modeling framework that enhances the simulation of hydrological processes in cold regions.The proposed methodology can be extended to other glacierized basins to provide valuable insights into water resource management under climate change.展开更多
Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow ...Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.展开更多
As one of China's most important ecological conservation regions,the source region of the Yellow River(SRYR)has a fragile ecological environment.Investigating land use transformations and their ecological conseque...As one of China's most important ecological conservation regions,the source region of the Yellow River(SRYR)has a fragile ecological environment.Investigating land use transformations and their ecological consequences in this region is of great significance for optimizing territorial spatial structure and promoting regional sustainable development.Based on the dominant functions of production-living-ecological space(PLES),we employed the land use transfer matrix and the standard deviational ellipse method to elucidate the spatiotemporal evolution characteristics of PLES in the SRYR from 2000 to 2020.Furthermore,the mechanism underlying the differentiation of eco-environmental effects in this region was explored using the optimal parameter-based geographical detector(OPGD)model.Results indicated that ecological space predominated within the PLES of the SRYR,accounting for approximately 98.74%of the total area.Living space was sparsely distributed in township areas with a proportion below 1.00%.Production space was mainly distributed in Guinan County and Gonghe County,accounting for about 1.16%of the area.In terms of the temporal scale,during 2000–2020,the overall eco-environmental quality of the SRYR exhibited an improving trend,primarily driven by the conversion of other ecological spaces into grassland ecological space.Interaction detection results revealed that the interaction between normalized difference vegetation index and gross domestic product was the strongest.In addition,the interaction between precipitation and temperature showed a significant bilinear enhancement effect.This finding suggests that the variations in eco-environmental quality in the SRYR during 2000–2020 have been jointly influenced by natural,climatic,and human factors.This study helps to provide a scientific basis for the rational layout of PLES and guiding ecological restoration efforts in the SRYR.展开更多
With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir trib...With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir tributary, a one-dimensional eutrophication model was developed for the Xiangxi River tributary of the Three Gorges Reservoir, and the influence of hydrodynamic conditions on the primary growth rate of algae was investigated. Furthermore, numerical predictions of hydraulic variables and eutrophication factors, such as the concentration distribution of TP, TN, and Chl-a in the spatial and temporal domains, were carried out. Comparison of computation results of TP, TN, and Chl-a concentrations along the river in the spring of 2005 with experimental data demonstrates the validity of the model. The agreement between the computation results and the experimental data of TP and TN concentrations is better than the agreement between those of Chl-a concentration. The simulated results also show that the Chl-a concentration downstream is much higher than that in the upstream tributary, which potentially indicates the outbreak of algae in this area. Therefore, this study provides a feasible method of accurately predicting the state of eutrophication in river-type reservoirs and their tributaries.展开更多
The Xiangxi River is one of the main tributaries in the Three Gorges reservoir, with the shortest distance to the Three Gorges Project Dam. Severe and frequent algal bloom events have occurred frequently in the Xiangx...The Xiangxi River is one of the main tributaries in the Three Gorges reservoir, with the shortest distance to the Three Gorges Project Dam. Severe and frequent algal bloom events have occurred frequently in the Xiangxi River in recent years. Therefore, the current study develops a three-dimensional unstructured-mesh model to investigate the dynamic process of algal bloom. The developed model comprises three modules, namely, hydrodynamics, nutrient cycles, and phytoplankton ecological dynamics. A number of factors, including hydrodynamic condition, nutrient concentration, temperature, and light illumination, that would affect the evolution of phytoplankton were considered. Moreover, the wave equation was used to solve the free surface fluctuations and vertical Z-coordinates with adjustable layered thicknesses. These values, in turn, are suitable for solving the algal bloom problems that occurred in the fiver style reservoir that has a complex boundary and dramatically changing hydrodynamic conditions. The comparisons between the modeling results and field data of years 2007 and 2008 indicate that the developed model is capable of simulating the algal bloom process in the Xiangxi River with reasonable accuracy. However, hydrodynamic force and external pollution loads affect the concentrations of nutrients, which, along with the underwater light intensity, could consequently affect phytoplankton evolution. Thus, flow velocity cannot be ignored in the analysis of fiver algal bloom. Based on the modeling results, building an impounding reservoir and increasing the releasing discharge at appropriate times are effective ways for controlling algal bloom.展开更多
A three-dimensional wave-current-sediment coupled numerical model is developed to understand the sediment transport dynamics in the Zhujiang(Pearl)River Estuary(ZRE),China.The model results are in good agreement with ...A three-dimensional wave-current-sediment coupled numerical model is developed to understand the sediment transport dynamics in the Zhujiang(Pearl)River Estuary(ZRE),China.The model results are in good agreement with observed data,and statistics show good model skill scores.Numerical studies are conducted to assess the scenarios of suspended sediment in the ZRE under the effects of different forcing(river discharges,waves,and winds).The model results indicate that the estuarine gravitational circulation plays an important role in the development of estuarine turbidity maximum in the ZRE,particularly during neap tides.The increased river discharge can result in a seaward sediment transport.The suspended sediment concentration(SSC)in the bottom increases with both wave bottom orbital velocity and wave height.Because of the shallow water depth,the effect of waves on sediment in the west shoal is greater than that in the east channel.The southwesterly wind-induced wave affects the SSC more than those resulting from the northeasterly wind,while the northeasterly wind-driven circulation has a slightly greater influence on the SSC than that of the southwesterly wind.However,a steady southwesterly wind condition favors the increase of the SSC in the Lingding Bay more so than a steady northeasterly wind condition.If the other forcings are same,the averaged SSC under a steady southwesterly wind condition is about 1.1 times that resulting from a steady northeasterly wind.展开更多
Goksu Delta is an important wetland where the Goksu River reaches to sea in the eastern of the town Tasucu-lcel. The delta is classified as a Wetland of International Importance according to the Ramsar Convention on W...Goksu Delta is an important wetland where the Goksu River reaches to sea in the eastern of the town Tasucu-lcel. The delta is classified as a Wetland of International Importance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N- and P compounds but also some heavy metals. The contents of all pollutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System （GIS） has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concen- tration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agricultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH3 and NO3 followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of Goksu River is modeled and determined that the waste water discharge of 10,700 m3/day from Silifke city does not create a serious problem because of the high amount of flow rate of Goksu River.展开更多
Hydraulic models for the generation of flood inundation maps are not commonly applied in mountain river basins because of the difficulty in modeling the hydraulic behavior and the complex topography. This paper presen...Hydraulic models for the generation of flood inundation maps are not commonly applied in mountain river basins because of the difficulty in modeling the hydraulic behavior and the complex topography. This paper presents a comparative analysis of the performance of four twodimensional hydraulic models (HEC-RAS 2D, Iber 2D, Flood Modeller 2D, and PCSWMM 2D) with respect to the generation of flood inundation maps. The study area covers a 5-km reach of the Santa B-arbara River located in the Ecuadorian Andes, at 2330 masl, in Gualaceo. The model's performance was evaluated based on the water surface elevation and flood extent, in terms of the mean absolute difference and measure of fit. The analysis revealed that, for a given case, Iber 2D has the best performance in simulating the water level and inundation for flood events with 20- and 50-year return periods, respectively, followed by Flood Modeller 2D, HEC-RAS 2D, and PCSWMM 2D in terms of their performance. Grid resolution, the way in which hydraulic structures are mimicked, the model code, and the default value of the parameters are considered the main sources of prediction uncertainty.展开更多
This paper firstly investigated the land-use and land-cover change （LUCC） in the Hun-Taizi River water- shed, Northeast China from 1988 to 2004 based on remotely sensed images and geographic information systems （GI...This paper firstly investigated the land-use and land-cover change （LUCC） in the Hun-Taizi River water- shed, Northeast China from 1988 to 2004 based on remotely sensed images and geographic information systems （GIS） technology. Then, using the famous land-use change model of Conversion of Land Use and its Effects at Small re- gional extent （CLUE-S）, this paper simulated the land use changes under historical trend （HT）, urban planning （UP） and ecological protection （EP） scenarios considering urban planning and ecological protection over the next 20 years. The simulated results under UP scenario in 2020 were compared with the planning map to assess the feasibility of us- ing land-use change model to guide regional planning. Results show that forest land, dry farmland, paddy, and shrub land were the main land-use categories. Paddy and dry farmland being converted to urban area and rural settlement characterized the land-use change from 1988 to 2004. The main land-use categories changed over time. Landscape-pattem fragmentation will be worse under HT and UP scenarios, but better in EP scenario. The comparing results of simulated map with planning map in 2020 show that land-use change model is powerful tool to guide regional planning. Land-use scenarios can support regional planning and policy-making through analyzing future consequences scientifically.展开更多
Building the Yangtze River Economic Belt(YREB)is one of China’s three national development policies in the new era.The ecological environment of the Yangtze River Economic Belt must be protected not only for regional...Building the Yangtze River Economic Belt(YREB)is one of China’s three national development policies in the new era.The ecological environment of the Yangtze River Economic Belt must be protected not only for regional economic development but also for regional ecological security and ecological progress in this region.This paper takes the ecological space of the Yangtze River Economic Belt as the research object,based on land use data in 2010 and 2015,and uses the FLUS model to simulate and predict the ecological space of the research area in 2035.The variation of the research area’s ecological space area and its four sub-zones has remarkable stability under diverse situations.Both the production space priority scenarios(S1)and living space priority scenarios(S2)saw a fall in ecological space area,with the former experiencing the highest reduction(a total reduction of 25,212 km^(2)).Under the ecological space priority scenarios(S3)and comprehensive space optimization scenario(S4),the ecological space area increased,and the ecological space area expanded even more under the former scenario(a total growth of 23,648 km^(2)).In Yunnan-Guizhou,the ecological space is relatively stable,with minimal signs of change.In Sichuan-Chongqing,the Sichuan Basin,Zoige Grassland,and Longmen Mountains were significant regions of area changes in ecological space.In the middle reaches of the Yangtze River,the ecological space changes mainly occur in the Wuyi Mountains,Mufu Mountains,and Dabie Mountains,as well as the surrounding waters of Dongting Lake.The Yangtze River Delta’s changes were mainly observed in the eastern Dabie Mountains and Jianghuai Hills.展开更多
In this study, a 47-day regional climate simulation of the heavy rainfall in the Yangtze-Huai River Basin during the summer of 2003 was conducted using the Weather Research and Forecast （WRY） model. The simulation r...In this study, a 47-day regional climate simulation of the heavy rainfall in the Yangtze-Huai River Basin during the summer of 2003 was conducted using the Weather Research and Forecast （WRY） model. The simulation reproduces reasonably well the evolution of the rainfall during the study period＇s three successive rainy phases, especially the frequent heavy rainfall events occurring in the Huai River Basin. The model captures the major rainfall peak observed by the monitoring stations in the morning. Another peak appears later than that shown by the observations. In addition, the simulation realistically captures not only the evolution of the low-level winds but also the characteristics of their diurnal variation. The strong southwesterly （low-level jet, LLJ） wind speed increases beginning in the early evening and reaches a peak in the morning; it then gradually decreases until the afternoon. The intense LLJ forms a strong convergent circulation pattern in the early morning along the Yangtze-Huai River Basin. This pattern partly explains the rainfall peak observed at this time. This study furnishes a basis for the further analysis of the mechanisms of evolution of the LLJ and for the further study of the interactions between the LLJ and rainfall.展开更多
River ice is a natural phenomenon in cold regions, influenced by meteorology, geomorphology, and hydraulic conditions. River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal pro...River ice is a natural phenomenon in cold regions, influenced by meteorology, geomorphology, and hydraulic conditions. River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal processes, and they are also influenced by weather and hydrologic conditions. Because natural rivers are serpentine, with bends, narrows, and straight reaches, the commonly-used one-dimensional river ice models and two-dimensional models based on the rectangular Cartesian coordinates are incapable of simulating the physical phenomena accurately. In order to accurately simulate the complicated river geometry and overcome the difficulties of numerical simulation resulting from both complex boundaries and differences between length and width scales, a two-dimensional river ice numerical model based on a boundary-fitted coordinate transformation method was developed. The presented model considers the influence of the frazil ice accumulation under ice cover and the shape of the leading edge of ice cover during the freezing process. The model is capable of determining the velocity field, the distribution of water temperature, the concentration distribution of frazil ice, the transport of floating ice, the progression, stability, and thawing of ice cover, and the transport, accumulation, and erosion of ice under ice cover. A MacCormack scheme was used to solve the equations numerically. The model was validated with field observations from the Hequ Reach of the Yellow River. Comparison of simulation results with field data indicates that the model is capable of simulating the river ice process with high accuracy.展开更多
Predicting the responses of an alluvial channel to changes in flow and sediment supply is essential for engineering design. Many methods have been developed in the last few decades to describe sectional bankfull chara...Predicting the responses of an alluvial channel to changes in flow and sediment supply is essential for engineering design. Many methods have been developed in the last few decades to describe sectional bankfull characteristics(elevation and discharge); however, studies on long-term reach-scale bankfull discharge are still limited. In this study, a hydraulic model is built to calculate the reach-scale bankfull discharge, and the effects of reservoir building on downstream bankfull discharges are discussed. The studied river reach is located at the lower Wei River(WR), where the planned Dongzhuang Reservoir would be built on its largest tributary, the Jing River. A quasi-two-dimensional numerical model coupled with a bankfull discharge estimating method is put forward to calculate the reach-scale bankfull discharge. The soundness of the model is verified. Results show that the temporal variation of reach-scale bankfull discharge of the lower reach of the WR would be highly influenced by the planned reservoir, especially during the first 20 years of operation. The effect of the planned reservoir on bankfull discharge may reach its maximum when the total trapped sediment load reaches approximately 75% of the reservoir capacity. Our results show that after the first 17 years of operation,the effect of the planned reservoir on bankfull discharge of the river reach may decrease gradually.The soundness and predictive capability of the coupled model have also been calibrated by comparing with existing reservoirs. All analyses indicate that the numerical model can be used to predict the changed reach-scale bankfull discharge of the lower WR.展开更多
The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by a...The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by approximately 6.7 million people.The basin has limited hydraulic conservancy infrastructure and insufficient ability to cope with climate change risks.Studying the hydrological characteristics and changes in the basin provides the scientific basis for rational protection and development of the basin.However,owing to the limitation of observation data,previous studies have focused on the local area and neglected the study of the lower reaches,which is not enough to reflect the spatial characteristics of the entire basin.In this study,the ECMWF 5th generation reanalysis data(ERA5)and Multi-Source Weighted-Ensemble Precipitation(MSWEP)were applied to develop a geomorphology-based hydrological model(GBHM)for reconstructing hydrological datasets(i.e.GBHM-ERA5 and GBHM-MSWEP).The reconstructed datasets covering the complete basin were verified against the gauge observation and compared with other commonly used streamflow products,including Global Flood Awareness System v2.1,GloFAS-Reanalysis dataset v3.0,and linear optimal runoff aggregate(LORA).The comparison results revealed that GBHM-ERA5 is significantly better than the other four datasets and provides a good reproduction of the hydrological characteristics and trends of the NSR.Detailed analysis of GBHM-ERA5 revealed that:(1)A multi-year mean surface runoff represented 39%of precipitation over the basin during 1980–2018,which had low surface runoff in the upstream,while areas around the Three Parallel Rivers Area and the estuary had abundant surface runoff.(2)The surface runoff and discharge coefficient of variations in spring were larger than those in other seasons,and the inter-annual variation in the downstream was smaller than that in the upstream and midstream regions.(3)More than 70%of the basin areas showed a decreasing trend in the surface runoff,except for parts of Nagqu,south of Shan State in Myanmar,and Thailand,where surface runoff has an increasing trend.(4)The downstream discharge has dropped significantly at a rate of approximately 680 million cubic metresper year,and the decline rate is greater than that of upstream and midstream,especially in summer.This study provides a data basis for subsequent studies in the NSR basin and further elucidates the impact of climate change on the basin,which is beneficial to river planning and promotes international cooperation on the water-and eco-security of the basin.展开更多
基金Supported by the National Natural Science Foundation of China(92055204)Strategic Priority Research Program of the Chinese Academy of Sciences(Class A)(XDA14010401)China National Offshore Oil Corporation(CNOOC)(CCL2021SKPS0118)。
文摘Traditional source-to-sink analyses cannot effectively characterize deep-time sedimentary processes involving multiple sediment sources and the spatiotemporal evolution of sediment contributions from different sources.In this study,a dynamic,quantitative source-to-sink analysis approach using stratigraphic forward modeling(SFM)is proposed,and it is applied to the Paleogene Enping Formation in the Baiyun Sag,Pearl River Mouth Basin.The built-in spatiotemporal provenance tagging of the model assigns a unique time-source label to sediments from each provenance,making each source's contribution identifiably“labeled”in the simulated formation,and thus enabling a direct precise tracking and high spatiotemporal resolution quantification of such contributions.Five pseudo-wells(from proximal to distal locations)in the Baiyun Sag were analyzed.The simulation results quantitatively represent the varied proportion of contribution of each source at different locations and in different periods and verify the proposed approach's operability and accuracy of the proposed approach.The simulated 3D deposit distribution shows a high agreement with the measured stratigraphic data,validating the model's reliability.Results reveal significant spatiotemporal changes in the Enping sedimentary system.In the late stage of Enping Formation deposition,a distal source supply from the northern part of the sag became dominant,the depocenter migrated northward to the deepwater area,and large-scale deltaic sand bodies extensively progradating into the sag were formed.The modeled 3D deposit distribution indicates that extensive high-quality reservoir sandstones are likely present across the deepwater area of the Baiyun Sag,which are identified as key exploration targets.Compared to traditional static approaches,the SFM-based dynamic simulation markedly enhances the spatiotemporal resolution of source-to-sink analysis and quantitatively captures the sedimentary system's responses to tectonic activity,base-level fluctuations and other external drivers.The proposed approach provides a novel quantitative framework for investigating complex,deep-time,multi-source systems,and offers an effective tool for reservoir prediction and hydrocarbon exploration planning in underexplored deepwater areas.
基金supported by the National Key Research and Development Program of China(2022YFD1900501)the Gansu Provincial Water Conservancy Scientific Experimental Research and Technology Extension Project(25GSLK044,26GSLK093).
文摘Glacial meltwater constitutes a vital component of the water supply in arid and semi-arid areas.However,the influence of glacial melting on runoff and evapotranspiration under global warming remains insufficiently understood.Previous studies coupling the Soil and Water Assessment Tool(SWAT)model with glacier modules often failed to consider the spatial heterogeneity of temperature during glacial melting,potentially leading to biased estimates of meltwater volume.In this study,we developed a glacier-coupled SWAT(SWAT-glacier)model considering the digital elevation model(DEM)based temperature-driven glacial melt processes to elucidate the impact of glacial melting on hydrological processes across four river basins(Dongda,Xiying,Jinta,and Zamu)of the upper Shiyang River Basin(SYRB)in northwestern China from 1986 to 2021.Compared with the standard SWAT model,the proposed SWAT-glacier model significantly improved the simulation accuracy for both runoff and evapotranspiration.Specifically,in comparison with the standard SWAT model,the Nash-Sutcliffe efficiency of the SWAT-glacier model showed a relative improvement of approximately 0.42%–9.16%and 1.50%–10.15%for runoff and evapotranspiration,respectively,in the four river basins during the validation period.Annual glacial runoff occurred predominantly from May to October,whereas glacial melt-induced evapotranspiration peaked between June and August.From 1986 to 2021,the average contributions of glacial melt to runoff were 6.97%for Dongda,3.06%for Xiying,2.70%for Jinta,and 0.67%for Zamu,whereas its contributions to evapotranspiration were 9.06%,5.14%,3.21%,and 1.59%,respectively.This study presents a SWAT-glacier modeling framework that enhances the simulation of hydrological processes in cold regions.The proposed methodology can be extended to other glacierized basins to provide valuable insights into water resource management under climate change.
基金supported by Special major projects for research and development of Henan Provincial(Science and Technology Research Project)(No.252102321104)Humanities and Social Sciences Youth Foundation,Ministry of Education(24YJCZH410)。
文摘Effective management of mining areas in the Luo River Basin,located in the eastern Qinling Mountains,is vital for the integrated protection and restoration needed to support the high-quality development of the Yellow River Basin.Using the‘cupball'model,this study analyzes the limiting factors and restoration characteristics across four mining areas and proposes a conceptual model for selecting appropriate restoration approaches.A second conceptual model is then introduced to address regional development needs,incorporating ecological conservation,safety protection,and people's wellbeing.The applicability of the integrated model selection framework is demonstrated through a case study on the south bank of the Qinglongjian River.The results indicate that:(1)The key limiting factors are similar across cases,but the degree of ecological degradation varies.(2)Mildly degraded areas are represented by a shallower and narrower‘cup',where natural recovery is the preferred approach,whereas moderately and severely degraded systems call for assisted regeneration and ecological reconstruction,respectively.(3)When the restoration models determined based on limiting factors and development needs are consistent,the model is directly applicable;if they differ,the option involving less artificial intervention is preferred;(4)Monitoring of the restored mining area on the Qinglongjian River's south bank confirms significant improvements in soil erosion control and vegetation coverage.This study provides a transferable methodology for balancing resource extraction with ecosystem conservation,offering practical insights for other ecologically vulnerable mining regions.
基金financially supported by the Qinghai Provincial Applied Basic Research Program,China(2024-ZJ-953)。
文摘As one of China's most important ecological conservation regions,the source region of the Yellow River(SRYR)has a fragile ecological environment.Investigating land use transformations and their ecological consequences in this region is of great significance for optimizing territorial spatial structure and promoting regional sustainable development.Based on the dominant functions of production-living-ecological space(PLES),we employed the land use transfer matrix and the standard deviational ellipse method to elucidate the spatiotemporal evolution characteristics of PLES in the SRYR from 2000 to 2020.Furthermore,the mechanism underlying the differentiation of eco-environmental effects in this region was explored using the optimal parameter-based geographical detector(OPGD)model.Results indicated that ecological space predominated within the PLES of the SRYR,accounting for approximately 98.74%of the total area.Living space was sparsely distributed in township areas with a proportion below 1.00%.Production space was mainly distributed in Guinan County and Gonghe County,accounting for about 1.16%of the area.In terms of the temporal scale,during 2000–2020,the overall eco-environmental quality of the SRYR exhibited an improving trend,primarily driven by the conversion of other ecological spaces into grassland ecological space.Interaction detection results revealed that the interaction between normalized difference vegetation index and gross domestic product was the strongest.In addition,the interaction between precipitation and temperature showed a significant bilinear enhancement effect.This finding suggests that the variations in eco-environmental quality in the SRYR during 2000–2020 have been jointly influenced by natural,climatic,and human factors.This study helps to provide a scientific basis for the rational layout of PLES and guiding ecological restoration efforts in the SRYR.
基金supported by the National Natural Science Foundation of China (Grant No. 50779028)the National Science and Technology Supporting Plan (Grant No. 2008BAB29B09)
文摘With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir tributary, a one-dimensional eutrophication model was developed for the Xiangxi River tributary of the Three Gorges Reservoir, and the influence of hydrodynamic conditions on the primary growth rate of algae was investigated. Furthermore, numerical predictions of hydraulic variables and eutrophication factors, such as the concentration distribution of TP, TN, and Chl-a in the spatial and temporal domains, were carried out. Comparison of computation results of TP, TN, and Chl-a concentrations along the river in the spring of 2005 with experimental data demonstrates the validity of the model. The agreement between the computation results and the experimental data of TP and TN concentrations is better than the agreement between those of Chl-a concentration. The simulated results also show that the Chl-a concentration downstream is much higher than that in the upstream tributary, which potentially indicates the outbreak of algae in this area. Therefore, this study provides a feasible method of accurately predicting the state of eutrophication in river-type reservoirs and their tributaries.
基金supported by the National Natural Science Foundation of China (No. 50823005)
文摘The Xiangxi River is one of the main tributaries in the Three Gorges reservoir, with the shortest distance to the Three Gorges Project Dam. Severe and frequent algal bloom events have occurred frequently in the Xiangxi River in recent years. Therefore, the current study develops a three-dimensional unstructured-mesh model to investigate the dynamic process of algal bloom. The developed model comprises three modules, namely, hydrodynamics, nutrient cycles, and phytoplankton ecological dynamics. A number of factors, including hydrodynamic condition, nutrient concentration, temperature, and light illumination, that would affect the evolution of phytoplankton were considered. Moreover, the wave equation was used to solve the free surface fluctuations and vertical Z-coordinates with adjustable layered thicknesses. These values, in turn, are suitable for solving the algal bloom problems that occurred in the fiver style reservoir that has a complex boundary and dramatically changing hydrodynamic conditions. The comparisons between the modeling results and field data of years 2007 and 2008 indicate that the developed model is capable of simulating the algal bloom process in the Xiangxi River with reasonable accuracy. However, hydrodynamic force and external pollution loads affect the concentrations of nutrients, which, along with the underwater light intensity, could consequently affect phytoplankton evolution. Thus, flow velocity cannot be ignored in the analysis of fiver algal bloom. Based on the modeling results, building an impounding reservoir and increasing the releasing discharge at appropriate times are effective ways for controlling algal bloom.
基金The National Natural Science Foundation of China under contract Nos 41890851 and 41521005the Key Research Program of Frontier Sciences,Chinese Academy of Sciences under contract No.QYZDJ-SSW-DQC034the Foundation of Institution of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences under contract No.ISEE2018PY05
文摘A three-dimensional wave-current-sediment coupled numerical model is developed to understand the sediment transport dynamics in the Zhujiang(Pearl)River Estuary(ZRE),China.The model results are in good agreement with observed data,and statistics show good model skill scores.Numerical studies are conducted to assess the scenarios of suspended sediment in the ZRE under the effects of different forcing(river discharges,waves,and winds).The model results indicate that the estuarine gravitational circulation plays an important role in the development of estuarine turbidity maximum in the ZRE,particularly during neap tides.The increased river discharge can result in a seaward sediment transport.The suspended sediment concentration(SSC)in the bottom increases with both wave bottom orbital velocity and wave height.Because of the shallow water depth,the effect of waves on sediment in the west shoal is greater than that in the east channel.The southwesterly wind-induced wave affects the SSC more than those resulting from the northeasterly wind,while the northeasterly wind-driven circulation has a slightly greater influence on the SSC than that of the southwesterly wind.However,a steady southwesterly wind condition favors the increase of the SSC in the Lingding Bay more so than a steady northeasterly wind condition.If the other forcings are same,the averaged SSC under a steady southwesterly wind condition is about 1.1 times that resulting from a steady northeasterly wind.
基金Scientific and Technological Research Council of Turkey,(TUBITAK),No.105Y285
文摘Goksu Delta is an important wetland where the Goksu River reaches to sea in the eastern of the town Tasucu-lcel. The delta is classified as a Wetland of International Importance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N- and P compounds but also some heavy metals. The contents of all pollutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System （GIS） has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concen- tration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agricultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH3 and NO3 followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of Goksu River is modeled and determined that the waste water discharge of 10,700 m3/day from Silifke city does not create a serious problem because of the high amount of flow rate of Goksu River.
基金supported by the Research Directorate of the University of Cuenca(DIUC)
文摘Hydraulic models for the generation of flood inundation maps are not commonly applied in mountain river basins because of the difficulty in modeling the hydraulic behavior and the complex topography. This paper presents a comparative analysis of the performance of four twodimensional hydraulic models (HEC-RAS 2D, Iber 2D, Flood Modeller 2D, and PCSWMM 2D) with respect to the generation of flood inundation maps. The study area covers a 5-km reach of the Santa B-arbara River located in the Ecuadorian Andes, at 2330 masl, in Gualaceo. The model's performance was evaluated based on the water surface elevation and flood extent, in terms of the mean absolute difference and measure of fit. The analysis revealed that, for a given case, Iber 2D has the best performance in simulating the water level and inundation for flood events with 20- and 50-year return periods, respectively, followed by Flood Modeller 2D, HEC-RAS 2D, and PCSWMM 2D in terms of their performance. Grid resolution, the way in which hydraulic structures are mimicked, the model code, and the default value of the parameters are considered the main sources of prediction uncertainty.
基金Under the auspices of National Natural Science Foundation of China(No.40801069)Special Research Program for Public-welfare Forestry of China(No.200804001)
文摘This paper firstly investigated the land-use and land-cover change （LUCC） in the Hun-Taizi River water- shed, Northeast China from 1988 to 2004 based on remotely sensed images and geographic information systems （GIS） technology. Then, using the famous land-use change model of Conversion of Land Use and its Effects at Small re- gional extent （CLUE-S）, this paper simulated the land use changes under historical trend （HT）, urban planning （UP） and ecological protection （EP） scenarios considering urban planning and ecological protection over the next 20 years. The simulated results under UP scenario in 2020 were compared with the planning map to assess the feasibility of us- ing land-use change model to guide regional planning. Results show that forest land, dry farmland, paddy, and shrub land were the main land-use categories. Paddy and dry farmland being converted to urban area and rural settlement characterized the land-use change from 1988 to 2004. The main land-use categories changed over time. Landscape-pattem fragmentation will be worse under HT and UP scenarios, but better in EP scenario. The comparing results of simulated map with planning map in 2020 show that land-use change model is powerful tool to guide regional planning. Land-use scenarios can support regional planning and policy-making through analyzing future consequences scientifically.
基金The Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan),No.CUG2018123。
文摘Building the Yangtze River Economic Belt(YREB)is one of China’s three national development policies in the new era.The ecological environment of the Yangtze River Economic Belt must be protected not only for regional economic development but also for regional ecological security and ecological progress in this region.This paper takes the ecological space of the Yangtze River Economic Belt as the research object,based on land use data in 2010 and 2015,and uses the FLUS model to simulate and predict the ecological space of the research area in 2035.The variation of the research area’s ecological space area and its four sub-zones has remarkable stability under diverse situations.Both the production space priority scenarios(S1)and living space priority scenarios(S2)saw a fall in ecological space area,with the former experiencing the highest reduction(a total reduction of 25,212 km^(2)).Under the ecological space priority scenarios(S3)and comprehensive space optimization scenario(S4),the ecological space area increased,and the ecological space area expanded even more under the former scenario(a total growth of 23,648 km^(2)).In Yunnan-Guizhou,the ecological space is relatively stable,with minimal signs of change.In Sichuan-Chongqing,the Sichuan Basin,Zoige Grassland,and Longmen Mountains were significant regions of area changes in ecological space.In the middle reaches of the Yangtze River,the ecological space changes mainly occur in the Wuyi Mountains,Mufu Mountains,and Dabie Mountains,as well as the surrounding waters of Dongting Lake.The Yangtze River Delta’s changes were mainly observed in the eastern Dabie Mountains and Jianghuai Hills.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-Q11-04)the National High Technology Research and Development Program of China (863 Program, Grant No. 2010AA012304)+2 种基金the National Natural Science Foundation of China (Grant No. 40905049)the LASG State Key Laboratory special fundthe LASG free exploration fund
文摘In this study, a 47-day regional climate simulation of the heavy rainfall in the Yangtze-Huai River Basin during the summer of 2003 was conducted using the Weather Research and Forecast （WRY） model. The simulation reproduces reasonably well the evolution of the rainfall during the study period＇s three successive rainy phases, especially the frequent heavy rainfall events occurring in the Huai River Basin. The model captures the major rainfall peak observed by the monitoring stations in the morning. Another peak appears later than that shown by the observations. In addition, the simulation realistically captures not only the evolution of the low-level winds but also the characteristics of their diurnal variation. The strong southwesterly （low-level jet, LLJ） wind speed increases beginning in the early evening and reaches a peak in the morning; it then gradually decreases until the afternoon. The intense LLJ forms a strong convergent circulation pattern in the early morning along the Yangtze-Huai River Basin. This pattern partly explains the rainfall peak observed at this time. This study furnishes a basis for the further analysis of the mechanisms of evolution of the LLJ and for the further study of the interactions between the LLJ and rainfall.
基金supported by the National Natural Science Foundation of China(Grant No.50579030)
文摘River ice is a natural phenomenon in cold regions, influenced by meteorology, geomorphology, and hydraulic conditions. River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal processes, and they are also influenced by weather and hydrologic conditions. Because natural rivers are serpentine, with bends, narrows, and straight reaches, the commonly-used one-dimensional river ice models and two-dimensional models based on the rectangular Cartesian coordinates are incapable of simulating the physical phenomena accurately. In order to accurately simulate the complicated river geometry and overcome the difficulties of numerical simulation resulting from both complex boundaries and differences between length and width scales, a two-dimensional river ice numerical model based on a boundary-fitted coordinate transformation method was developed. The presented model considers the influence of the frazil ice accumulation under ice cover and the shape of the leading edge of ice cover during the freezing process. The model is capable of determining the velocity field, the distribution of water temperature, the concentration distribution of frazil ice, the transport of floating ice, the progression, stability, and thawing of ice cover, and the transport, accumulation, and erosion of ice under ice cover. A MacCormack scheme was used to solve the equations numerically. The model was validated with field observations from the Hequ Reach of the Yellow River. Comparison of simulation results with field data indicates that the model is capable of simulating the river ice process with high accuracy.
基金funded by the National Natural Science Foundation of China(Grants No.2011CB403305,51579230,51109198,41571005,and 51479179)
文摘Predicting the responses of an alluvial channel to changes in flow and sediment supply is essential for engineering design. Many methods have been developed in the last few decades to describe sectional bankfull characteristics(elevation and discharge); however, studies on long-term reach-scale bankfull discharge are still limited. In this study, a hydraulic model is built to calculate the reach-scale bankfull discharge, and the effects of reservoir building on downstream bankfull discharges are discussed. The studied river reach is located at the lower Wei River(WR), where the planned Dongzhuang Reservoir would be built on its largest tributary, the Jing River. A quasi-two-dimensional numerical model coupled with a bankfull discharge estimating method is put forward to calculate the reach-scale bankfull discharge. The soundness of the model is verified. Results show that the temporal variation of reach-scale bankfull discharge of the lower reach of the WR would be highly influenced by the planned reservoir, especially during the first 20 years of operation. The effect of the planned reservoir on bankfull discharge may reach its maximum when the total trapped sediment load reaches approximately 75% of the reservoir capacity. Our results show that after the first 17 years of operation,the effect of the planned reservoir on bankfull discharge of the river reach may decrease gradually.The soundness and predictive capability of the coupled model have also been calibrated by comparing with existing reservoirs. All analyses indicate that the numerical model can be used to predict the changed reach-scale bankfull discharge of the lower WR.
基金This work is jointly supported by the National Key Research and Development Program of China(2016YFA0601603)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0206)+1 种基金the National Natural Science Foundation of China(91747101&41801260)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100103).
文摘The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by approximately 6.7 million people.The basin has limited hydraulic conservancy infrastructure and insufficient ability to cope with climate change risks.Studying the hydrological characteristics and changes in the basin provides the scientific basis for rational protection and development of the basin.However,owing to the limitation of observation data,previous studies have focused on the local area and neglected the study of the lower reaches,which is not enough to reflect the spatial characteristics of the entire basin.In this study,the ECMWF 5th generation reanalysis data(ERA5)and Multi-Source Weighted-Ensemble Precipitation(MSWEP)were applied to develop a geomorphology-based hydrological model(GBHM)for reconstructing hydrological datasets(i.e.GBHM-ERA5 and GBHM-MSWEP).The reconstructed datasets covering the complete basin were verified against the gauge observation and compared with other commonly used streamflow products,including Global Flood Awareness System v2.1,GloFAS-Reanalysis dataset v3.0,and linear optimal runoff aggregate(LORA).The comparison results revealed that GBHM-ERA5 is significantly better than the other four datasets and provides a good reproduction of the hydrological characteristics and trends of the NSR.Detailed analysis of GBHM-ERA5 revealed that:(1)A multi-year mean surface runoff represented 39%of precipitation over the basin during 1980–2018,which had low surface runoff in the upstream,while areas around the Three Parallel Rivers Area and the estuary had abundant surface runoff.(2)The surface runoff and discharge coefficient of variations in spring were larger than those in other seasons,and the inter-annual variation in the downstream was smaller than that in the upstream and midstream regions.(3)More than 70%of the basin areas showed a decreasing trend in the surface runoff,except for parts of Nagqu,south of Shan State in Myanmar,and Thailand,where surface runoff has an increasing trend.(4)The downstream discharge has dropped significantly at a rate of approximately 680 million cubic metresper year,and the decline rate is greater than that of upstream and midstream,especially in summer.This study provides a data basis for subsequent studies in the NSR basin and further elucidates the impact of climate change on the basin,which is beneficial to river planning and promotes international cooperation on the water-and eco-security of the basin.
