The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang Rive...The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang River-valley for providing advices to manage the ecosystem. The results showed that the land use change mainly occurred on forest, farmland and grassland. From 1986 to 1994, the area of farmland increased by 477% （60801 hm^2）, while the area of forest decreased by 4.97% （89012.17 hm^2）. From 1986 to 2000, the eco-service value of forest was degressive but that of farmland increased greatly as the increasing of planting area, while the total eco-service value decreased by 771.11×10^8 yuan RMB due to the rapid increase of population in this region. The driving force of eco-service change was also discussed in the paper. The nation policy of Natural Forest Protection Project has taken effect in preventing the decline of eco-services.展开更多
By using the concept of emergy and method of emergy analysis, this paper has studied two mountain settlement (village) ecosystems in two aspects: input and output of energy in the agro-systems and the use of fuel ener...By using the concept of emergy and method of emergy analysis, this paper has studied two mountain settlement (village) ecosystems in two aspects: input and output of energy in the agro-systems and the use of fuel energy. The result reveals that the settlement agro-system in the valley of Minjiang River is better in both structure and function than that at the so-called half-high mountain. The former one is higher than the latter one regarding such indices as emergy yield ratio, labor productivity of emergy and emergy sustainable index, but lower than the latter one regarding environmental loading ratio. In terms of fuel emergy, the settlement in the valley enjoys more diversified sources and is less depending on bio-energy while the settlement at the half-high mountain has only one source (i. e. fuel wood) , much depending on bio-energy, may exert a greater pressure on environment.展开更多
An increase in extreme precipitation events due to future climate change will have a decisive influence on the formation of debris flows in earthquake-stricken areas. This paper aimed to describe the possible impacts ...An increase in extreme precipitation events due to future climate change will have a decisive influence on the formation of debris flows in earthquake-stricken areas. This paper aimed to describe the possible impacts of future climate change on debris flow hazards in the Upper Minjiang River basin in Northwest Sichuan of China, which was severely affected by the 2008 Wenchuan earthquake. The study area was divided into 1285 catchments, which were used as the basic assessment units for debris flow hazards. Based on the current understanding of the causes of debris flows, a binary logistic regression model was used to screen key factors based on local geologic, geomorphologic, soil,vegetation, and meteorological and climatic conditions. We used the weighted summation method to obtain a composite index for debris flow hazards, based on two weight allocation methods: Relative Degree Analysis and rough set theory. Our results showed that the assessment model using the rough set theory resulted in better accuracy. According to the bias corrected and downscaled daily climate model data, future annual precipitation(2030-2059) in the study area are expected to decrease, with an increasing number of heavy rainfall events. Under future climate change, areas with a high-level of debris flow hazard will be even more dangerous, and 5.9% more of the study area was categorized as having a high-level hazard. Future climate change will cause an increase in debris flow hazard levels for 128 catchments, accounting for 10.5% of the total area. In the coming few decades, attention should be paid not only to traditional areas with high-level of debris flow hazards, but also to those areas with an increased hazard level to improve their resilience to debris flow disasters.展开更多
Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This s...Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This study investigated the possibility of applying boundary-and node-based methods in landscape pattern analysis to the upper reaches of the Minjiang River in the southwestern China.Boundary-based and node-based landscape indices were selected to be used in analyzing changes in landscape patterns,and the results were compared with analysis using traditional pattern indices.We compared the responses of patch-area-based,boundary-length-based and node-number-based indices,and concluded that boundary-based and node-based indices are more sensitive to disturbance than patch-based indices with various patterns,and node-based indices are even more sensitive than boundary-based ones.Thus,the results suggest that boundary-based and node-based pattern analysis methods provide helpful supplementary information to traditional patch-based pattern analysis methods.The results about pattern dynamics of landscapes in the upper reaches of the Minjiang River based on boundaries and nodes showed that with human disturbance,the dominance of forest landscape was weakened by other landscape types;thus the landscape pattern of the study area became more homogeneous and the boundary network became more complex.These changes further augmented disturbance interfaces in the landscape and increased the possibilities of further landscape fragmentation.展开更多
The biogeochemical behavior of DIN (dissolved inorganic nitrogen), phosphate and silicate in the Minjiang River estuary is discussed based on data obtained from May, 1990 to Feb., 1991 oceanographic surveys in the are...The biogeochemical behavior of DIN (dissolved inorganic nitrogen), phosphate and silicate in the Minjiang River estuary is discussed based on data obtained from May, 1990 to Feb., 1991 oceanographic surveys in the area. The annual fluxes of nutrients in the Minjiang River estuary were estimated to be 326.8 ×103 t for silicate, 771.0 t for phosphate, 45.7×103 t for DIN (42.1×103 t for nitrate, 3.0×103 t for ammonia. 600 t for nitrite), respectively.展开更多
As organic pollutants of emerging concern,organophosphate esters(OPEs)have shown toxicity to organisms after entering the water environment.However,research on OPEs in freshwater in Southwest China is very limited.The...As organic pollutants of emerging concern,organophosphate esters(OPEs)have shown toxicity to organisms after entering the water environment.However,research on OPEs in freshwater in Southwest China is very limited.The levels,distribution and partitioning behavior of OPEs in the Minjiang River and their influencing factors is still unknown.In this study,six OPEs,tri-n-butyl phosphate(Tn BP),tri(2-chloroethyl)-phosphate(TCEP),trichloropropyl phosphate(TCPP),triphenyl phosphate(TPh P),tributoxyethyl phosphate(TBEP),and tris(2-ethylhexyl)-phosphate(TEHP),were determined in surface water,suspended particle matter(SPM)and sediments of the Minjiang River.The results showed that the average concentrations of∑_(6)OPEs in surface water,SPM and sediments of the Minjiang River were 199.32±124.95 ng/L,38463.79±45641.89 ng/g dry weight(dw)and 76.45±28.00 ng/g dw,respectively.High concentrations of OPEs were detected in SPM samples,indicating that more attention should be paid to pollution in SPM.It is worth noting that the variation trend of OPEs in SPM was almost opposite to that in water but basically similar to that in sediment.The proportions of alkyl OPEs in∑_(6)OPEs increased from surface water to SPM and sediments.Alkyl OPEs were the main pollutants in SPM(10.44%–80.88%of∑_(6)OPEs,mean of 54.52%)and sediments(59.08%–81.30%of∑_(6)OPEs,mean of 68.91%),whereas chlorinated OPEs were the most abundant components in surface water(43.16%–75.99%ofδ∑_(6)OPEs,mean of 55.50%).The water-sediment partition coefficient(logKOC)of OPEs was 4.97–7.58,while the water-SPM partition coefficient was 6.71–10.00.No significant correlations were found between log KOW and logKOC.KOW was not the main factor affecting the distribution of OPEs in the Minjiang River,China.展开更多
Dual factors of climate and human on the hydrological process are reflected not only in changes in the spatiotemporal distribution of water resource amounts but also in the various characteristics of river flow regime...Dual factors of climate and human on the hydrological process are reflected not only in changes in the spatiotemporal distribution of water resource amounts but also in the various characteristics of river flow regimes. Isolating and quantifying their contributions to these hydrological alterations helps us to comprehensively understand the response mechanism and patterns of hydrological process to the two kinds of factors. Here we develop a general framework using hydrological model and 33 indicators to describe hydrological process and quantify the impact from climate and human. And we select the Upper Minjiang River(UMR) as a case to explore its feasibility. The results indicate that our approach successfully recognizes the characteristics of river flow regimes in different scenarios and quantitatively separates the climate and human contributions to multi-dimensional hydrological alterations. Among these indicators, 26 of 33 indicators decrease over the past half-century(1961–2012) in the UMR, with change rates ranging from 1.3% to 33.2%, and the human impacts are the dominant factor affecting hydrological processes, with an average relative contribution rate of 58.6%. Climate change causes an increase in most indicators, with an average relative contribution rate of 41.4%. Specifically, changes in precipitation and reservoir operation may play a considerable role in inducing these alterations. The findings in this study help us better understand the response mechanism of hydrological process under changing environment and is conducive to climate change adaptation, water resource planning and ecological construction.展开更多
Heavy minerals with a size range of 0.125￣0.250 mm in the surficial sediment of Minjiang Estuary are studied. Thirty-four heavy min- erals have been identified, with an average content of 1.92%. Major minerals includ...Heavy minerals with a size range of 0.125￣0.250 mm in the surficial sediment of Minjiang Estuary are studied. Thirty-four heavy min- erals have been identified, with an average content of 1.92%. Major minerals include magnetite, epidote, hematite, hornblende, il- menite, and zircon mica. These types are the same as those in the 0.063￣0.125 mm range; however, the average content is lower, which reveals that the heavy minerals in Minjiang Estuary are mainly enriched in the very-fine sand fraction. According to the content and distribution characteristics of the major heavy minerals, Minjiang Estuary can be divided into 4 mineral assemblage zones. In each zone the assemblage of heavy minerals is greatly affected by the hydrodynamic condition and the sedimentary environment. Heavy mineral types also show that detrital matters in Minjiang Estuary are originated from the weathering and erosion of the bedrock in the Minjiang River drainage area.展开更多
In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet....In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet. The dammed lake was formed during the Last Glacial Maximum of the Late Pleistocene(~30,000 years ago) and began to empty about 15,000 years ago. The lacustrine sediments(up to 240 m thick) preserve abundant paleoenvironment information. In this paper, a mass of oxygen isotopes and 14 C dating from drilled cores are analyzed and discussed. The δ18 O curve on the paleo climate from this section is comparable with the coeval paleo climatic curves of ice cores and karsts in China and others. Furthermore, the physical model testing has confirmed that the disturbed zones in the core are caused by strong earthquakes occurred at least 10 times, which implies strong crustal deformation, as an important driving force, affecting climate change. This study provides a new window to observe East Asian monsoon formation, paleoenvironmental evolution and the global climate change.展开更多
A bstract With the aim of elucidating the spatial and seasonal behaviors of rare earth elements(REEs), we investigated the dissolved REE concentrations of surface water collected during four seasons from middle, lower...A bstract With the aim of elucidating the spatial and seasonal behaviors of rare earth elements(REEs), we investigated the dissolved REE concentrations of surface water collected during four seasons from middle, lower reaches and estuary of the Minjiang River, southeastern China. The results display that the REE abundances in Minjiang River, ranging from 3.3–785.9 ng/L, were higher than those of many of the major global rivers. The total REE concentrations(∑REE) were seasonally variable, averaging in 5 937.30, 863.79, 825.65 and 1 065.75 ng/L during second highest flow(SHF), normal flow(NF), low flow(LF) and high flow(HF) season, respectively. The R_(( L/M)) and R_((H/M)) ratios reveal the spatial and temporal variations of REE patterns, and particularly vary apparently in the maximum turbidity zone and estuary. REE patterns of dissolved loads are characterized by progressing weaker LREEs-enrichment and stronger HREEsenrichment downstream from middle reaches to estuary during all four seasons. Comparing with NF and LF seasons, in which REE patterns are relatively flat, samples of SHF season have more LREE-enriched and HREE-depleted patterns that close to parent rocks, while samples of HF season are more LREEs-depleted and HREE-enriched. REE fractionations from the middle to lower reaches are stronger in the SHF and HF seasons than those in NF and LF seasons. Generally, spatial and seasonal variations in REE abundance and pattern are presumably due to several factors, such as chemical weathering, mixture with rainfall and groundwater, estuarine mixing, runoff, biological production and mountain river characters, such as strong hydrodynamic forces and steep slopes. The highest Gd/Gd* always occurs at north ports during all four seasons, where most of the large hospitals are located. This suggests Gd anomalies are depended on the density of modern medical facilities. Y/Ho ratios fl uctuate and positively correlate to salinity in estuary, probably because of the geochemical behavior differences between Y and Ho.展开更多
Diexi earthquake(M7.5)in 1933 is a great event that occurred at the east border of Qinghai- Xizang Plateau in the 20th century.There are obviously different opinions about the shape ofisoseismal lines and the genetic ...Diexi earthquake(M7.5)in 1933 is a great event that occurred at the east border of Qinghai- Xizang Plateau in the 20th century.There are obviously different opinions about the shape ofisoseismal lines and the genetic fault of this earthquke.Based on the study of the newlyfound north-south trending active fault and ground fissures of Diexi earthquake,this papertends to hold that,as the southward extension of Miujiang fault,this north-south trendingactive fault might be the genetic fault of this event.展开更多
The distribution of diatoms in surface sediments in the Minjiang Estuary, southeast China, was investigated in2009. Total 56 species and other species belonging to 25 genera were identified, among them 11 species were...The distribution of diatoms in surface sediments in the Minjiang Estuary, southeast China, was investigated in2009. Total 56 species and other species belonging to 25 genera were identified, among them 11 species were dominant over 5%. Dominant species included Actinocyclus ehrenbergii, Coscinodiscus curvatulus, C. divisus, C.jonesianus, C. radiatus, C. rothii, C. subtilis, Cyclotella stylorum, Epithemia hyndmanii, Hydrosera whampoensis,and Trachyneis aspera. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from13 valves/g to 11×104 valves/g, and averaging 2.5×104 valves/g. A canonical correspondence analysis（CCA） was used to explain the relationships between diatom distribution and sediment properties in the Minjiang Estuary.CCA revealed that the major elements（Fe_2O_3, Na_2O, CaO, MgO, TiO_2, SiO_2, Al_2O_3, and K_2O） were closely related to diatom abundance. Four diatom assemblages were distinguished, representing different sediment properties,which may assist late Quaternary palaeoceanographic reconstructions of the Minjiang Estuary.展开更多
In this study,a high-resolution storm surge floodplain numerical model was established based on the ADCIRC ocean numerical model,and was used to simulate the storm surge floodplain of typhoon 9608"HERB",and ...In this study,a high-resolution storm surge floodplain numerical model was established based on the ADCIRC ocean numerical model,and was used to simulate the storm surge floodplain of typhoon 9608"HERB",and the simulation results of tide level and storm water increase are in good agreement with the observation data.On this basis,the influences of runoff,typhoon path,and typhoon intensity on the floodplain submerged area and depth were discussed.Based on the measured runoff data,10 sets of sensitivity experiments with runoff sizes ranging from 0 to 2.5 times were set up.The experimental results show that the increase of runoff mainly increases the submerged area of the coastal area in the upper reaches of the Minjiang River,but has a small effect on the submerged area of the coastal area in the lower reaches of the Minjiang River and the outer sea mouth.Based on the original typhoon path,8 different deflection paths after the typhoon landed were constructed to carry out sensitivity experiments.The results show that the clockwise deflection of typhoon path of 10°-40°to the south will reduce the submerged area,and the counterclockwise deflection of 10°-30°to the north will increase the submerged area,but the counterclockwise deflection of more than 40°to the north will decrease the submerged area.Three weather systems before and after landing of typhoon center pressure of 955 HPA,935 HPA,and 915 HPA was constructed.The results show that the decrease of typhoon center pressure will significantly increase the submerged area of the entire area.Compared with the air pressure of 975 HPA,the submerged area is increased by about 2 times.展开更多
The building of Shuikou Hydropower Station in the Minjiang River is the largest one in the region of east China. Its install capacity is 1.4 million kw., and its generated energy of planning is 4.95 billion kwh each y...The building of Shuikou Hydropower Station in the Minjiang River is the largest one in the region of east China. Its install capacity is 1.4 million kw., and its generated energy of planning is 4.95 billion kwh each year. In accordance with a comprehensive survey of the valley of the middle-lower reaches of the Minjiang River and the characteristic of hydrography and in association with the specific type of the hydrography station, we can be sure that no harm will be done to the ecological environment when a hydropower station is built at Shuikou. Not only the deposition of silt within the reservoir must not be very serious, it is also more favorable than before for the irrigation of farmland on plains in the lower reaches of the Minjiang River and inland navigation.In addition, after the completion of the power station, the ecological environment will be the same as before both at the Minjiang River estuary and beyond it.展开更多
This study on the relationships between dissolved Cd, Cu, Pb and nutrients in the Minjiang River Estuaryduring high and low discharges (in June and Oct., 1990) showed that during both high and lowdischarges Cd, Cu and...This study on the relationships between dissolved Cd, Cu, Pb and nutrients in the Minjiang River Estuaryduring high and low discharges (in June and Oct., 1990) showed that during both high and lowdischarges Cd, Cu and Pb exhibited additive, conservative and removal behaviour, respectively. Cd increaseappeared to be primarily related to Cd regeneration from microplankton and its organic remains. while Pbremoval was dominated by abiotic processes.展开更多
By analyzing the topographic features of past landslides since 1980s and the main land-cover types （including change information） in landslide-prone area, modeled spatial distribution of landslide hazard in upper Mi...By analyzing the topographic features of past landslides since 1980s and the main land-cover types （including change information） in landslide-prone area, modeled spatial distribution of landslide hazard in upper Minjiang River Basin was studied based on spatial analysis of GIS in this paper. Results of GIS analysis showed that landslide occurrence in this region closely related to topographic feature. Most areas with high hazard probability were deep-sheared gorge. Most of them in investigation occurred assembly in areas with elevation lower than 3 000 m, due to fragile topographic conditions and intensive human disturbances. Land-cover type, including its change information, was likely an important environmental factor to trigger landslide. Destroy of vegetation driven by increase of population and its demands augmented the probability of landslide in steep slope.展开更多
The change of coastal wetland vulnerability affects the ecological environment and the economic development of the estuary area.In the past,most of the assessment studies on the vulnerability of coastal ecosystems sta...The change of coastal wetland vulnerability affects the ecological environment and the economic development of the estuary area.In the past,most of the assessment studies on the vulnerability of coastal ecosystems stayed in static qualitative research,lacking predictability,and the qualitative and quantitative relationship was not objective enough.In this study,the“Source-Pathway-Receptor-Consequence”model and the Intergovernmental Panel on Climate Change vulnerability definition were used to analyze the main impact of sea level rise caused by climate change on coastal wetland ecosystem in Minjiang River Estuary.The results show that:(1)With the increase of time and carbon emission,the area of high vulnerability and the higher vulnerability increased continuously,and the area of low vulnerability and the lower vulnerability decreased.(2)The eastern and northeastern part of the Culu Island in the Minjiang River Estuary of Fujian Province and the eastern coastal wetland of Meihua Town in Changle District are areas with high vulnerability risk.The area of high vulnerability area of coastal wetland under high emission scenario is wider than that under low emission scenario.(3)Under different sea level rise scenarios,elevation has the greatest impact on the vulnerability of coastal wetlands,and slope has less impact.The impact of sea level rise caused by climate change on the coastal wetland ecosystem in the Minjiang River Estuary is mainly manifested in the sea level rise,which changes the habitat elevation and daily flooding time of coastal wetlands,and then affects the survival and distribution of coastal wetland ecosystems.展开更多
This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by th...This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by the Water Quality Monitoring Station,Minjiang River Bridge,Leshan City,Sichuan Province.The results of the wavelet analysis indicate that the COD index oscillates alternatively and differently at each time-scale in an oneyear cycle,and the density of COD,subjected to the runoff volume,the effects of Wenchuan Earthquake and agricultural seeding and industrial construction,etc.,is high in winter and spring,mild in summer and autumn.展开更多
The southwest mountainous area is a frequent debris flow disaster area in<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> Chin...The southwest mountainous area is a frequent debris flow disaster area in<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> China, which poses a serious threat to the regional roads and greatly affects the normal traffic operation and the safety of residents’ lives and property. The debris flow risk assessment of highway can quantify the threat degree of debris flow to the roads. In this paper, from the perspective of villages and towns, taking the upper reaches of Minjiang River as the research area, four factors including road network density, highway disaster resistance capacity, population density and highway cost are selected, and the weight is obtained by using entropy weight method, and the debris flow vulnerability evaluation results of highway are obtained by weighted calculation. Four indexes of debris flow density, shape factor, relative height difference and annual rainfall are selected to evaluate the debris flow hazard of highway by using the information method. Based on the vulnerability and hazard evaluation results, the ri</span><span style="font-family:Verdana;">sk of highway debris flow is evaluated, and the results are classified and</span><span style="font-family:Verdana;"> discussed. The results show that: the risk of debris flow on the upper reaches of Minjiang River is relatively low, the overall spatial distribution shows a trend of high in the East and low in the west, and the overall risk of township roads in Wenchuan county is the highest;The risk of debris flow is generally high within </span></span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">-10 to 30</span><span style="font-family:Verdana;"> km from the central fault zone of Longmenshan.</span></span></span></span>展开更多
<span style="font-family:""><span style="font-family:Verdana;">Water resource is an important supporting material for life support system and eco</span><span style="f...<span style="font-family:""><span style="font-family:Verdana;">Water resource is an important supporting material for life support system and eco</span><span style="font-family:Verdana;">nomic development, and the sustainable development and utilization of water resource </span></span><span style="font-family:Verdana;">are</span><span style="font-family:Verdana;"> the guarantee of social sustainable development. The upper Minjiang River is the most important source of water supply for the Chengdu Plain. With the water resources of the upper Minjiang River facing the problems of overall water volume reduction, flood and water pollution, etc.</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> based on the optimal allocation theory, this paper constructs an optimal allocation model of water resourc</span><span style="font-family:Verdana;">es in the upper reaches of the Minjiang River, analyzes its characteristics and proposes some relevant countermeasures and suggestions to solve the existing problems, aiming to provide reference</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> for the sustainable utilization of water resources in the upper reaches of the Minjiang River.展开更多
基金This study was supported and funded by the projects of NKBRSF, P.R. China (No. 2002CB111506)
文摘The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang River-valley for providing advices to manage the ecosystem. The results showed that the land use change mainly occurred on forest, farmland and grassland. From 1986 to 1994, the area of farmland increased by 477% （60801 hm^2）, while the area of forest decreased by 4.97% （89012.17 hm^2）. From 1986 to 2000, the eco-service value of forest was degressive but that of farmland increased greatly as the increasing of planting area, while the total eco-service value decreased by 771.11×10^8 yuan RMB due to the rapid increase of population in this region. The driving force of eco-service change was also discussed in the paper. The nation policy of Natural Forest Protection Project has taken effect in preventing the decline of eco-services.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences(KSCX-07-02)
文摘By using the concept of emergy and method of emergy analysis, this paper has studied two mountain settlement (village) ecosystems in two aspects: input and output of energy in the agro-systems and the use of fuel energy. The result reveals that the settlement agro-system in the valley of Minjiang River is better in both structure and function than that at the so-called half-high mountain. The former one is higher than the latter one regarding such indices as emergy yield ratio, labor productivity of emergy and emergy sustainable index, but lower than the latter one regarding environmental loading ratio. In terms of fuel emergy, the settlement in the valley enjoys more diversified sources and is less depending on bio-energy while the settlement at the half-high mountain has only one source (i. e. fuel wood) , much depending on bio-energy, may exert a greater pressure on environment.
基金jointly funded by the 135 Strategic Program of the Institute of Mountain Hazards and Environment,CAS(Grant No.SDS135-1703)the National Key Basic Research Program of China(973 program)(Grant No.2015CB452702)
文摘An increase in extreme precipitation events due to future climate change will have a decisive influence on the formation of debris flows in earthquake-stricken areas. This paper aimed to describe the possible impacts of future climate change on debris flow hazards in the Upper Minjiang River basin in Northwest Sichuan of China, which was severely affected by the 2008 Wenchuan earthquake. The study area was divided into 1285 catchments, which were used as the basic assessment units for debris flow hazards. Based on the current understanding of the causes of debris flows, a binary logistic regression model was used to screen key factors based on local geologic, geomorphologic, soil,vegetation, and meteorological and climatic conditions. We used the weighted summation method to obtain a composite index for debris flow hazards, based on two weight allocation methods: Relative Degree Analysis and rough set theory. Our results showed that the assessment model using the rough set theory resulted in better accuracy. According to the bias corrected and downscaled daily climate model data, future annual precipitation(2030-2059) in the study area are expected to decrease, with an increasing number of heavy rainfall events. Under future climate change, areas with a high-level of debris flow hazard will be even more dangerous, and 5.9% more of the study area was categorized as having a high-level hazard. Future climate change will cause an increase in debris flow hazard levels for 128 catchments, accounting for 10.5% of the total area. In the coming few decades, attention should be paid not only to traditional areas with high-level of debris flow hazards, but also to those areas with an increased hazard level to improve their resilience to debris flow disasters.
基金Under the auspices of Major State Basic Research Development Program of China(No.2006CB403201)
文摘Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This study investigated the possibility of applying boundary-and node-based methods in landscape pattern analysis to the upper reaches of the Minjiang River in the southwestern China.Boundary-based and node-based landscape indices were selected to be used in analyzing changes in landscape patterns,and the results were compared with analysis using traditional pattern indices.We compared the responses of patch-area-based,boundary-length-based and node-number-based indices,and concluded that boundary-based and node-based indices are more sensitive to disturbance than patch-based indices with various patterns,and node-based indices are even more sensitive than boundary-based ones.Thus,the results suggest that boundary-based and node-based pattern analysis methods provide helpful supplementary information to traditional patch-based pattern analysis methods.The results about pattern dynamics of landscapes in the upper reaches of the Minjiang River based on boundaries and nodes showed that with human disturbance,the dominance of forest landscape was weakened by other landscape types;thus the landscape pattern of the study area became more homogeneous and the boundary network became more complex.These changes further augmented disturbance interfaces in the landscape and increased the possibilities of further landscape fragmentation.
文摘The biogeochemical behavior of DIN (dissolved inorganic nitrogen), phosphate and silicate in the Minjiang River estuary is discussed based on data obtained from May, 1990 to Feb., 1991 oceanographic surveys in the area. The annual fluxes of nutrients in the Minjiang River estuary were estimated to be 326.8 ×103 t for silicate, 771.0 t for phosphate, 45.7×103 t for DIN (42.1×103 t for nitrate, 3.0×103 t for ammonia. 600 t for nitrite), respectively.
基金financial support from the National Natural Science Foundation of China(Nos.41773072,21407014)。
文摘As organic pollutants of emerging concern,organophosphate esters(OPEs)have shown toxicity to organisms after entering the water environment.However,research on OPEs in freshwater in Southwest China is very limited.The levels,distribution and partitioning behavior of OPEs in the Minjiang River and their influencing factors is still unknown.In this study,six OPEs,tri-n-butyl phosphate(Tn BP),tri(2-chloroethyl)-phosphate(TCEP),trichloropropyl phosphate(TCPP),triphenyl phosphate(TPh P),tributoxyethyl phosphate(TBEP),and tris(2-ethylhexyl)-phosphate(TEHP),were determined in surface water,suspended particle matter(SPM)and sediments of the Minjiang River.The results showed that the average concentrations of∑_(6)OPEs in surface water,SPM and sediments of the Minjiang River were 199.32±124.95 ng/L,38463.79±45641.89 ng/g dry weight(dw)and 76.45±28.00 ng/g dw,respectively.High concentrations of OPEs were detected in SPM samples,indicating that more attention should be paid to pollution in SPM.It is worth noting that the variation trend of OPEs in SPM was almost opposite to that in water but basically similar to that in sediment.The proportions of alkyl OPEs in∑_(6)OPEs increased from surface water to SPM and sediments.Alkyl OPEs were the main pollutants in SPM(10.44%–80.88%of∑_(6)OPEs,mean of 54.52%)and sediments(59.08%–81.30%of∑_(6)OPEs,mean of 68.91%),whereas chlorinated OPEs were the most abundant components in surface water(43.16%–75.99%ofδ∑_(6)OPEs,mean of 55.50%).The water-sediment partition coefficient(logKOC)of OPEs was 4.97–7.58,while the water-SPM partition coefficient was 6.71–10.00.No significant correlations were found between log KOW and logKOC.KOW was not the main factor affecting the distribution of OPEs in the Minjiang River,China.
基金Natural Science Foundation of China,No.51879009, No.52079143Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0405+2 种基金National Key Research and Development Program of China,No.2018YFE0196000, No.2017YFC0404405Interdisciplinary Research Foundation of Beijing Normal University for the First-Year Doctoral Students,No.BNUXKJC1905Independent Research Projects of POWERCHINA Chengdu Engineering Corporation Limited,No.P34516。
文摘Dual factors of climate and human on the hydrological process are reflected not only in changes in the spatiotemporal distribution of water resource amounts but also in the various characteristics of river flow regimes. Isolating and quantifying their contributions to these hydrological alterations helps us to comprehensively understand the response mechanism and patterns of hydrological process to the two kinds of factors. Here we develop a general framework using hydrological model and 33 indicators to describe hydrological process and quantify the impact from climate and human. And we select the Upper Minjiang River(UMR) as a case to explore its feasibility. The results indicate that our approach successfully recognizes the characteristics of river flow regimes in different scenarios and quantitatively separates the climate and human contributions to multi-dimensional hydrological alterations. Among these indicators, 26 of 33 indicators decrease over the past half-century(1961–2012) in the UMR, with change rates ranging from 1.3% to 33.2%, and the human impacts are the dominant factor affecting hydrological processes, with an average relative contribution rate of 58.6%. Climate change causes an increase in most indicators, with an average relative contribution rate of 41.4%. Specifically, changes in precipitation and reservoir operation may play a considerable role in inducing these alterations. The findings in this study help us better understand the response mechanism of hydrological process under changing environment and is conducive to climate change adaptation, water resource planning and ecological construction.
基金suported by the natural science of Fujian(No.D94014)
文摘Heavy minerals with a size range of 0.125￣0.250 mm in the surficial sediment of Minjiang Estuary are studied. Thirty-four heavy min- erals have been identified, with an average content of 1.92%. Major minerals include magnetite, epidote, hematite, hornblende, il- menite, and zircon mica. These types are the same as those in the 0.063￣0.125 mm range; however, the average content is lower, which reveals that the heavy minerals in Minjiang Estuary are mainly enriched in the very-fine sand fraction. According to the content and distribution characteristics of the major heavy minerals, Minjiang Estuary can be divided into 4 mineral assemblage zones. In each zone the assemblage of heavy minerals is greatly affected by the hydrodynamic condition and the sedimentary environment. Heavy mineral types also show that detrital matters in Minjiang Estuary are originated from the weathering and erosion of the bedrock in the Minjiang River drainage area.
基金financially supported by the China National Nature Science Foundation(No.41072230,No.41572308,No.41977226)the State Key Laboratory of Geo-hazard Prevention&Geo-environment Protection(No.SKLGP2012Z008,No.SKLGP2016Z015)
文摘In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet. The dammed lake was formed during the Last Glacial Maximum of the Late Pleistocene(~30,000 years ago) and began to empty about 15,000 years ago. The lacustrine sediments(up to 240 m thick) preserve abundant paleoenvironment information. In this paper, a mass of oxygen isotopes and 14 C dating from drilled cores are analyzed and discussed. The δ18 O curve on the paleo climate from this section is comparable with the coeval paleo climatic curves of ice cores and karsts in China and others. Furthermore, the physical model testing has confirmed that the disturbed zones in the core are caused by strong earthquakes occurred at least 10 times, which implies strong crustal deformation, as an important driving force, affecting climate change. This study provides a new window to observe East Asian monsoon formation, paleoenvironmental evolution and the global climate change.
基金Supported by the National Natural Science Foundation of China(No.41376050)
文摘A bstract With the aim of elucidating the spatial and seasonal behaviors of rare earth elements(REEs), we investigated the dissolved REE concentrations of surface water collected during four seasons from middle, lower reaches and estuary of the Minjiang River, southeastern China. The results display that the REE abundances in Minjiang River, ranging from 3.3–785.9 ng/L, were higher than those of many of the major global rivers. The total REE concentrations(∑REE) were seasonally variable, averaging in 5 937.30, 863.79, 825.65 and 1 065.75 ng/L during second highest flow(SHF), normal flow(NF), low flow(LF) and high flow(HF) season, respectively. The R_(( L/M)) and R_((H/M)) ratios reveal the spatial and temporal variations of REE patterns, and particularly vary apparently in the maximum turbidity zone and estuary. REE patterns of dissolved loads are characterized by progressing weaker LREEs-enrichment and stronger HREEsenrichment downstream from middle reaches to estuary during all four seasons. Comparing with NF and LF seasons, in which REE patterns are relatively flat, samples of SHF season have more LREE-enriched and HREE-depleted patterns that close to parent rocks, while samples of HF season are more LREEs-depleted and HREE-enriched. REE fractionations from the middle to lower reaches are stronger in the SHF and HF seasons than those in NF and LF seasons. Generally, spatial and seasonal variations in REE abundance and pattern are presumably due to several factors, such as chemical weathering, mixture with rainfall and groundwater, estuarine mixing, runoff, biological production and mountain river characters, such as strong hydrodynamic forces and steep slopes. The highest Gd/Gd* always occurs at north ports during all four seasons, where most of the large hospitals are located. This suggests Gd anomalies are depended on the density of modern medical facilities. Y/Ho ratios fl uctuate and positively correlate to salinity in estuary, probably because of the geochemical behavior differences between Y and Ho.
文摘Diexi earthquake(M7.5)in 1933 is a great event that occurred at the east border of Qinghai- Xizang Plateau in the 20th century.There are obviously different opinions about the shape ofisoseismal lines and the genetic fault of this earthquke.Based on the study of the newlyfound north-south trending active fault and ground fissures of Diexi earthquake,this papertends to hold that,as the southward extension of Miujiang fault,this north-south trendingactive fault might be the genetic fault of this event.
基金The Special Fund for Basic Scientific Research Foundation of the Third Institute of Oceanography,State Oceanic Administration,China under contract No.2016015the National Natural Science Foundation of China under contract Nos 41306083 and 41376050
文摘The distribution of diatoms in surface sediments in the Minjiang Estuary, southeast China, was investigated in2009. Total 56 species and other species belonging to 25 genera were identified, among them 11 species were dominant over 5%. Dominant species included Actinocyclus ehrenbergii, Coscinodiscus curvatulus, C. divisus, C.jonesianus, C. radiatus, C. rothii, C. subtilis, Cyclotella stylorum, Epithemia hyndmanii, Hydrosera whampoensis,and Trachyneis aspera. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from13 valves/g to 11×104 valves/g, and averaging 2.5×104 valves/g. A canonical correspondence analysis（CCA） was used to explain the relationships between diatom distribution and sediment properties in the Minjiang Estuary.CCA revealed that the major elements（Fe_2O_3, Na_2O, CaO, MgO, TiO_2, SiO_2, Al_2O_3, and K_2O） were closely related to diatom abundance. Four diatom assemblages were distinguished, representing different sediment properties,which may assist late Quaternary palaeoceanographic reconstructions of the Minjiang Estuary.
文摘In this study,a high-resolution storm surge floodplain numerical model was established based on the ADCIRC ocean numerical model,and was used to simulate the storm surge floodplain of typhoon 9608"HERB",and the simulation results of tide level and storm water increase are in good agreement with the observation data.On this basis,the influences of runoff,typhoon path,and typhoon intensity on the floodplain submerged area and depth were discussed.Based on the measured runoff data,10 sets of sensitivity experiments with runoff sizes ranging from 0 to 2.5 times were set up.The experimental results show that the increase of runoff mainly increases the submerged area of the coastal area in the upper reaches of the Minjiang River,but has a small effect on the submerged area of the coastal area in the lower reaches of the Minjiang River and the outer sea mouth.Based on the original typhoon path,8 different deflection paths after the typhoon landed were constructed to carry out sensitivity experiments.The results show that the clockwise deflection of typhoon path of 10°-40°to the south will reduce the submerged area,and the counterclockwise deflection of 10°-30°to the north will increase the submerged area,but the counterclockwise deflection of more than 40°to the north will decrease the submerged area.Three weather systems before and after landing of typhoon center pressure of 955 HPA,935 HPA,and 915 HPA was constructed.The results show that the decrease of typhoon center pressure will significantly increase the submerged area of the entire area.Compared with the air pressure of 975 HPA,the submerged area is increased by about 2 times.
文摘The building of Shuikou Hydropower Station in the Minjiang River is the largest one in the region of east China. Its install capacity is 1.4 million kw., and its generated energy of planning is 4.95 billion kwh each year. In accordance with a comprehensive survey of the valley of the middle-lower reaches of the Minjiang River and the characteristic of hydrography and in association with the specific type of the hydrography station, we can be sure that no harm will be done to the ecological environment when a hydropower station is built at Shuikou. Not only the deposition of silt within the reservoir must not be very serious, it is also more favorable than before for the irrigation of farmland on plains in the lower reaches of the Minjiang River and inland navigation.In addition, after the completion of the power station, the ecological environment will be the same as before both at the Minjiang River estuary and beyond it.
文摘This study on the relationships between dissolved Cd, Cu, Pb and nutrients in the Minjiang River Estuaryduring high and low discharges (in June and Oct., 1990) showed that during both high and lowdischarges Cd, Cu and Pb exhibited additive, conservative and removal behaviour, respectively. Cd increaseappeared to be primarily related to Cd regeneration from microplankton and its organic remains. while Pbremoval was dominated by abiotic processes.
文摘By analyzing the topographic features of past landslides since 1980s and the main land-cover types （including change information） in landslide-prone area, modeled spatial distribution of landslide hazard in upper Minjiang River Basin was studied based on spatial analysis of GIS in this paper. Results of GIS analysis showed that landslide occurrence in this region closely related to topographic feature. Most areas with high hazard probability were deep-sheared gorge. Most of them in investigation occurred assembly in areas with elevation lower than 3 000 m, due to fragile topographic conditions and intensive human disturbances. Land-cover type, including its change information, was likely an important environmental factor to trigger landslide. Destroy of vegetation driven by increase of population and its demands augmented the probability of landslide in steep slope.
基金The National Natural Science Foundation of China under contract No.U22A20585the Education Research Project of Fujian Education Department under contract No.JAT200019.
文摘The change of coastal wetland vulnerability affects the ecological environment and the economic development of the estuary area.In the past,most of the assessment studies on the vulnerability of coastal ecosystems stayed in static qualitative research,lacking predictability,and the qualitative and quantitative relationship was not objective enough.In this study,the“Source-Pathway-Receptor-Consequence”model and the Intergovernmental Panel on Climate Change vulnerability definition were used to analyze the main impact of sea level rise caused by climate change on coastal wetland ecosystem in Minjiang River Estuary.The results show that:(1)With the increase of time and carbon emission,the area of high vulnerability and the higher vulnerability increased continuously,and the area of low vulnerability and the lower vulnerability decreased.(2)The eastern and northeastern part of the Culu Island in the Minjiang River Estuary of Fujian Province and the eastern coastal wetland of Meihua Town in Changle District are areas with high vulnerability risk.The area of high vulnerability area of coastal wetland under high emission scenario is wider than that under low emission scenario.(3)Under different sea level rise scenarios,elevation has the greatest impact on the vulnerability of coastal wetlands,and slope has less impact.The impact of sea level rise caused by climate change on the coastal wetland ecosystem in the Minjiang River Estuary is mainly manifested in the sea level rise,which changes the habitat elevation and daily flooding time of coastal wetlands,and then affects the survival and distribution of coastal wetland ecosystems.
文摘This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by the Water Quality Monitoring Station,Minjiang River Bridge,Leshan City,Sichuan Province.The results of the wavelet analysis indicate that the COD index oscillates alternatively and differently at each time-scale in an oneyear cycle,and the density of COD,subjected to the runoff volume,the effects of Wenchuan Earthquake and agricultural seeding and industrial construction,etc.,is high in winter and spring,mild in summer and autumn.
文摘The southwest mountainous area is a frequent debris flow disaster area in<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> China, which poses a serious threat to the regional roads and greatly affects the normal traffic operation and the safety of residents’ lives and property. The debris flow risk assessment of highway can quantify the threat degree of debris flow to the roads. In this paper, from the perspective of villages and towns, taking the upper reaches of Minjiang River as the research area, four factors including road network density, highway disaster resistance capacity, population density and highway cost are selected, and the weight is obtained by using entropy weight method, and the debris flow vulnerability evaluation results of highway are obtained by weighted calculation. Four indexes of debris flow density, shape factor, relative height difference and annual rainfall are selected to evaluate the debris flow hazard of highway by using the information method. Based on the vulnerability and hazard evaluation results, the ri</span><span style="font-family:Verdana;">sk of highway debris flow is evaluated, and the results are classified and</span><span style="font-family:Verdana;"> discussed. The results show that: the risk of debris flow on the upper reaches of Minjiang River is relatively low, the overall spatial distribution shows a trend of high in the East and low in the west, and the overall risk of township roads in Wenchuan county is the highest;The risk of debris flow is generally high within </span></span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">-10 to 30</span><span style="font-family:Verdana;"> km from the central fault zone of Longmenshan.</span></span></span></span>
文摘<span style="font-family:""><span style="font-family:Verdana;">Water resource is an important supporting material for life support system and eco</span><span style="font-family:Verdana;">nomic development, and the sustainable development and utilization of water resource </span></span><span style="font-family:Verdana;">are</span><span style="font-family:Verdana;"> the guarantee of social sustainable development. The upper Minjiang River is the most important source of water supply for the Chengdu Plain. With the water resources of the upper Minjiang River facing the problems of overall water volume reduction, flood and water pollution, etc.</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> based on the optimal allocation theory, this paper constructs an optimal allocation model of water resourc</span><span style="font-family:Verdana;">es in the upper reaches of the Minjiang River, analyzes its characteristics and proposes some relevant countermeasures and suggestions to solve the existing problems, aiming to provide reference</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> for the sustainable utilization of water resources in the upper reaches of the Minjiang River.
