The tidal current duration （TCD） and velocity （TCV） and suspended sediment concentration （SSC） were measured in the dry season in December, 2011 and in the flood season in June, 2012 at the upper part of the Nor...The tidal current duration （TCD） and velocity （TCV） and suspended sediment concentration （SSC） were measured in the dry season in December, 2011 and in the flood season in June, 2012 at the upper part of the North Channel of Changjiang Estuary. They were assimilated with the measured data in 2003, 2004, 2006 and 2007, using the tidal range＇s proportion conversion. Variations in TCD and TCV, preferential flow and SSC have been calculated. Influences of typical engineering projects such as Qingcaosha fresh water reservoir, Yangtze River Bridge, and land reclamation on the ebb and flood TCD, TCV and SSC in the North Channel for the last 10 years are discussed. The results show that： （1） currently, in the upper part of North Channel, the ebb tide dominates; after the construction of the typical projects, ebb TCD and TCV tends to be larger and the vertical average ebb and flood SSC decrease during the flood season while SSC increases during the dry season; （2） changes in the vertical average TCV are mainly contributed by seasonal runoff variation during the flood season, which is larger in the flood season than that in the dry season; the controlling parameters of increasing ebb TCD and TCV are those large-scale engineering projects in the North Channel; variation in SSC may result mainly from the reduction of basin annual sediment loads, large-scale nearshore projects and so on.展开更多
An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch （NB） and the South Br...An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch （NB） and the South Branch （SB）. The study assumes that the fiver discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover （WSO and SSO） from the NB into the SB, and tidally averaged （net） water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the fiver discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation.展开更多
Public willingness to pay （WTP） for urban rivers res- toration was investigated in Shanghai, Nanjing and Hangzhou in China with a sample of 1,285. The factors influencing positive WTP against zero WTP are analyzed u...Public willingness to pay （WTP） for urban rivers res- toration was investigated in Shanghai, Nanjing and Hangzhou in China with a sample of 1,285. The factors influencing positive WTP against zero WTP are analyzed using a binary logit model. The results indicate that income, Huff （residential registration） status, household size, home property ownership, riverfront access, and attitudes toward current water quality arc statistically signifi- cant in the likelihood of positive WTR It is also found that respon- dents without local Huff are less willingness to pay positively in pooled sample and Shanghai sample. In the group holding property right of house but without local Huff is less willingness to pay positively in Hangzhou. Respondents in Nanjing are more will- ingness to pay positively than those in Hangzhou. Most common arguments against to pay for the restoration are ＂government＇s duty＂, ＂low income＂, ＂non-local-Huji＂ and ＂lack of trust in the government in how it spends money＂. The results are generally consistent with the hypothesis and specific situations in China. The findings make some contributions to the non-market valua- tion studies as well as provide useful information for public policy making in China.展开更多
A Bayesian multi-model inference framework was used to assess the changes in the occurrence of extreme hydroclimatic events in four major river basins in China （i.e., Liaohe River Basin, Yellow River Basin, Yangtze R...A Bayesian multi-model inference framework was used to assess the changes in the occurrence of extreme hydroclimatic events in four major river basins in China （i.e., Liaohe River Basin, Yellow River Basin, Yangtze River Basin, and Pearl River Basin） under RCP2.6, RCP4.5, and RCP8.5 scenarios using multiple global climate model projections from the IPCC Fifth Assessment Report. The results projected more summer days and fewer frost days in 2006-2099. The ensemble prediction shows the Pearl River Basin is projected to experience more summer days than other basins with the increasing trend of 16.3, 38.0, and 73.0 d per 100 years for RCP2.6, RCP4.5 and RCP8.5, respectively. Liaohe River Basin and Yellow River Basin are forecasted to become wetter and warmer with the co-occurrence of increases in summer days and wet days. Very heavy precipitation days （R20, daily precipitation ≥20 mm） are projected to increase in all basins. The R20 in the Yangtze River Basin are projected to have the highest change rate in 2006-2099 of 1.8, 2.5, and 3.8 d per 100 years for RCP2.6, RCP4.5 and RCP8.5, respectively.展开更多
On the basis of field survey, microscope sighting, TL dating and scanning electron microscope analysis, the characteristics of Quaternary deposits near Songjianghe Town on the west slope of Changbai Mountain are analy...On the basis of field survey, microscope sighting, TL dating and scanning electron microscope analysis, the characteristics of Quaternary deposits near Songjianghe Town on the west slope of Changbai Mountain are analyzed and described. There were two phases of volcanism during Mid-Late Quaternary. One occurred before 15.22×104 aB.P. and the other happened between 14.27×104 aB.P. and 1.41×104 aB.P. Volcanism is a landform-making process which makes the rough relief in the studied area become higher and higher. Flow water is a main erosion agency and it cuts into the basalts making river valleys. The Quaternary fluvial deposits distributed on terraces first come from the weathered debris of basement rocks, then they are transported and deposited by flow water. After 1.41×104 aB.P., the river water quickly cuts into the newly formed basalts making a deep valley. Volcanism in the studied area is a main landform-making event in Mid-Late Quaternary.展开更多
Tidal rivers are intrinsically complex because tidal propagation is influenced by river discharge. This study aims to examine the seasonal variation of tidal prism and energy variance in the tidal river of the Changji...Tidal rivers are intrinsically complex because tidal propagation is influenced by river discharge. This study aims to examine the seasonal variation of tidal prism and energy variance in the tidal river of the Changjiang(Yangtze) River estuary in China. In order to quantify the behaviour of river and tide,we use numerical modelling that has been validated using measured data. We conduct our analysis by quantifying the discharge and energy variance in separate components for both the river and the tide,during wet and dry seasons. We note various definitions of tidal prism and explore the difference between tidal discharge on the flood and ebb and tidal storage volume. The results show that the river discharge attenuates the tidal motion and reduces the tidal flood discharge but the tidal storage volume is approximately constant with different riverine discharge since part of the fresh water discharge is intercepted and captured in the estuary due to the backwater effect. It appears that the tidal discharge adjusts according to the variation of river discharge to keep a constant tidal storage volume. An analysis of the hydraulics shows that the transition from tidal dominance(at the mouth) to river dominance(upstream) depends on the location of tidal current reversal which varies from wet season to dry season. Duringthe wet season,the Changjiang River estuary is totally dominated by energy from fresh water discharge.展开更多
Based on the 1961-1990 observed daily precipitation in the Changjiang-Huaihe River Basin, the NCEP/NCAR reanalysis data, and the HadCM3 model data for IPCC SRES A1B climate projections, the simulation capabilities of ...Based on the 1961-1990 observed daily precipitation in the Changjiang-Huaihe River Basin, the NCEP/NCAR reanalysis data, and the HadCM3 model data for IPCC SRES A1B climate projections, the simulation capabilities of the BP-CCA downscaling approach for extreme precipitation indices of the current climate are assessed by applying canonical correlation analysis (CCA). In addition, future extreme precipitation indices in the middle and late 21st century are projected. The results show that simulation capability of the HadCM3 for regional climate characteristics can be effectively improved by the downscaling approach, with 30%-100% reduction of the relative errors of the climatological mean state of extreme precipitation indices. However, the downscaling results still show wetter winter and dryer summer than the observation. Under the SRES A1B emission scenario, frequency and intensity of extreme precipitation events are projected to increase, and the estimated increasing rate is higher for extreme precipitation indices than for mean precipitation index; and in summer than in winter. Extreme precipitations in the middle and late 21st century are expected to increase by 14% and 25% respectively in winter, and by 24% and 32% respectively in summer.展开更多
Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Liji...Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.展开更多
In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Bas...In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.展开更多
Analysis using historical data on the phosphate sources in Changjiang （Yangtze River） estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the C...Analysis using historical data on the phosphate sources in Changjiang （Yangtze River） estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the Changjiang River, the Taiwan Warm Current （TWC）, a cyclone-type eddy, and the 32°N Upwelling, supplying different phosphates in different times, ways and intensities. The magnitude of their supplying phosphate concentration was related with the size in the order of the Changjiang River 〈 the TWC 〈 the 32°N Upwelling 〈 the cyclone-type eddy, and the duration of the supplying was： the Changjiang River 〉 the TWC 〉 the cyclone-type eddy 〉 the 32°N Upwelling. The four sources supplied a great deal of phosphate so that the phosphate concentration in the estuary was kept above 0.2 pmol/L in previous years, satisfying the phytoplankton growth. The horizontal and vertical distribution of the phosphate concentration showed that near shallow marine areas at 122°E/31°N, the TWC in low nutrient concentration became an upwelling through sea bottom and brought up nutrients from sea bottom to marine surface. In addition, horizontal distribution of phosphate concentration was consistent with that of algae： Rhizosolenia robusta, Rhizosolenia calcaravis and Skeletonema, which showed that no matter during high water or low water of Changjiang River, these species brought by the TWC became predominant species. Therefore, the authors believe that the TWC flowed from south to north along the coast and played a role in deflecting the Changjiang River flow from the southern side.展开更多
On May 12, 2008, an earthquake of 8.0 magnitude on the Richter scale and its numerous aftershocks devastatingly hit Wenchuan County and its nearby region along the Longman Mountains in Sichuan Province, China. The hea...On May 12, 2008, an earthquake of 8.0 magnitude on the Richter scale and its numerous aftershocks devastatingly hit Wenchuan County and its nearby region along the Longman Mountains in Sichuan Province, China. The heavy ruined area was up to 30,000km2 and 13% of its land surface was denuded by the extremely terrible quakes. The mountain collapses, landslides and debris flows induced by the earthquake not only scared the landscape at the immense scale, but also poured L66-billion-m3 sediment combined with offscourings and rubble into the Yangtze River and its breaches. This amount of sediments is 3 times more than the normal amount discharged into the Yangtze River, and will significantly increase sediment transportation of rivers and decrease storage capacities of reservoirs downstream. The dramatic increase in sediment load will imperil the engineering safety and impact the operation of the giant Three-Gorge Hydro-power Station if no proper prevention measures are taken.展开更多
Quantifying the functional relationships relating river discharge and weathering products places key constraints on the negative feedback between the silicate weathering and climate. In this study we analyze the conce...Quantifying the functional relationships relating river discharge and weathering products places key constraints on the negative feedback between the silicate weathering and climate. In this study we analyze the concentration–discharge relationships of weathering products from global rivers using previously compiled time-series datasets for concentrations and discharge from global rivers. To analyze the nature of the covariation between specific discharge and concentrations, we use both a power law equation and a recently developed solute production equation. The solute production equation allows us to quantify weathering efficiency, or the resistance to dilution at high runoff, via the Damkohler coefficient. These results are also compared to those derived using average concentration–discharge pairs.Both the power law exponent and the Damkohler coefficient increase and asymptote as catchments exhibit increasingly chemostatic behavior, resulting in an inverse relationship between the two parameters. We also show that using thedistribution of average concentration–discharge pairs from global rivers, rather than fitting concentration–discharge relationships for each individual river, underestimates global median weathering efficiency by up to a factor of ～10. This study demonstrates the utility of long time-series sampling of global rivers to elucidate controlling processes needed to quantify patterns in global silicate weathering rates.展开更多
The bionomics of Campoletis chlorideae and the regularity of its seasonal fluctuations were studied in Changsha district,Hunan province. Field investigation indicated that there were ten generations of C. chlori...The bionomics of Campoletis chlorideae and the regularity of its seasonal fluctuations were studied in Changsha district,Hunan province. Field investigation indicated that there were ten generations of C. chlorideae a year, of which seven occurred in cotton fields. Three peaks of cotton bollworm parasitization by C. chlorideae were observed, early May to late June, mid August to early September, mid September to mid October respectively. One peak occurred in tomato and tobacco fields, the other two in cotton fields. The parasitization rate ranged from 25.1%- 63.1%. The total development time from egg to adult ranged from 13.0 days at 32℃ to 75.5 days at 11.6℃. Each wasp could parasitize the 5-23 second instar larvae of tobacco caterpillar. C. chlorideae could parasitize the cotton bollworm, beet armyworm and tobacco caterpillar, but preferred the cotton bollworm larvae. C. chlorideae could parasitized 1st-3rd instar larvae of the tobacco caterpillar, but seldom parasitzed 4th-6th instar larvae. Moreover, C. chlorideae preferred second instar larvae. Theoretical models for developmental speed, adult longevity and the influence of temperature were proposed. The overwintering of C. chlorideae Uchida was also discussed. Moreover, methods for utilization of C. chlorideae Uchida in crop protection were presented and the bionomics of Campoletis chlorideae in both the Yangtze River Valley and Yellow River Valley were compared.展开更多
Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside an...Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside and adjacent to the study basins, were analyzed and compared to quantify the hydrological processes involved, and to evaluate the role of human activities in chang- ing river discharges. The Inverse Distance Weighted （IDW） interpolation method was used to obtain climatic data coverage from station observations. According to the runoff coefficient equation, the effect of human activities and climate can be ex- pressed by changes in runoff coefficients and changes in precipitation, respectively. Annual runoff coefficients were calculated for the period 1950-2008, according to the correlation between respective hydrological series and regional precipitation. An- nual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the mid- dle and downstream reaches, with declines of 8.8 and 9.8 ram/10 a, respectively. All annual runoff series for the Yellow River basin showed a significant downward trend. Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 ram/10 a at Lijin. The series results indicated that an abrupt change occurred in the late 1980s to early 1990s. The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations, with rates ranging from 0.013/10 a to 0.019/10 a. For the hydrologic series, all precipitation series showed a downward trend in the Yangtze River basin with de- clines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong. Annual runoff series for the upper reaches of the Yangtze River decreased significantly, at rates ranging from 9.9 to 7.2 mm/10 a. In the middle and lower reaches, the run- off series showed no significant trend, with rates of change ranging from 2.1 to 2.9 ram/10 a. Human activities had the greatest influence on changes in the hydrological series of runoff, regardless of whether the effect was negative or positive. During 1970-2008, human activities contributed to 83% of the reduction in runoff in the Yellow River basin, and to 71% of the in- crease in runoff in the Yangtze River basin. Moreover, the impacts of human activities across the entire basin increased over time. In the 2000s, the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins, respectively. The average annual runoff from 1980 to 2008 fell by about 97%, 83%, 83%, and 91%, compared with 1951-1969, at the Yellow River stations Lanzhou, San- menxia, Huayuankou and Lijin, respectively. Most of the reduction in runoff was caused by human activities. Changes in pre- cipitation also caused reductions in runoff of about 3%, 17%, 17%, and 9% at these four stations, respectively. Falling precipi- tation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan, Yichang, Hankou, and Datong, causing reductions in runoff of 89%, 74%, 43%, and 35%, respectively. Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin. Runoff decreased in arid areas as a result of in- creased water usage, but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.展开更多
In general, China is short of water resources and some regions even experience a shortage of daily water supply. This could threaten the stability and economic development of the nation. A study on the water storage v...In general, China is short of water resources and some regions even experience a shortage of daily water supply. This could threaten the stability and economic development of the nation. A study on the water storage variations is especially important for the water management and storage prediction in three largest river basins of China, namely, Yangtze, Yellow, and Zhujiang, where the most dense population and leading economic regions are located. The satellite gravity mission GRACE （Gravity Recovery and Climate Experiment） provides an opportunity to macroseopically identify water （or mass） variations in the Earth＇s system with a spatial resolution of 300-400 km and a temporal resolution of about one month. We use the first release of the DEOS （Delft Institute of Earth Observation and Space Systems） Mass Transport （DMT-1） model based on GRACE data to analyze water storage changes in the three river basins. The DMT-1 model consists of monthly solutions, which are computed using an innovative methodology. The methodology includes, in particular, the application of a statistically optimal Wiener-type filter based on full varianee-covariance matrices of noise and signal. This results in particularly sharp mass variation maps. Taking one monthly solution as an example, we compare the results derived from the DMT-1 model with ones produced with the standard post-processing scheme based on a combination of the de-striping and Gaussian filtering. The comparison shows that the DMT-1 model outperforms the other models and is suitable for the analysis of the mass changes in river basins. A subset of the DMT-1 solutions in the interval between February 2003 and May 2008 is used to estimate the secular trends and seasonal variations for the three river basins. The estimated trends show that the water storage of the Yellow River basin does not have significant changes, while the Zhujiang and Yangtze river basins have a large and statistically significant water storage increase. The estimation of seasonal variations demonstrates that the water storage variations in Yangtze and Zhujiang river basins are almost in the same phase. The amplitude of variations in the Zhujiang River basin is larger than that in Yangtze. No clear annual variations are observed in the Yellow River basin. The observed water storage variations generally coincide with the observations and conclusions presented in the hydrological reports of the Chinese Ministry of Water Resources展开更多
Here we present the results from the composite analyses of the atmospheric circulations and physical quantity fields associated with rainy-season for the selected floods cases over the Yangtze and Huaihe River basins ...Here we present the results from the composite analyses of the atmospheric circulations and physical quantity fields associated with rainy-season for the selected floods cases over the Yangtze and Huaihe River basins for the 21 years(1990–2010),using the daily rain gauge measurements taken in the 756 stations throughout China and the NCEP/reanalysis data for the rainyseasons(June–July)from 1990 to 2010.The major differences in the atmospheric circulations and physical quantity fields between the Yangtze and Huaihe River basins are as follows:for flooding years of the Yangtze River Basin,the South Asia high center is located further east than normal,the blocking high over the Urals and the Sea of Okhotsk maintains,and the Meiyu front is situated near 30°N whereas for flooding years of the Huaihe River Basin,the South Asia high center is further west than normal,the atmospheric circulations over the mid and high latitudes in the Northern Hemisphere are of meridional distribution,and the Meiyu front is situated near 33°N.In addition,there are distinct differences in water vapor sources and associated transports between the Yangtze and Huaihe River basins.The water vapor is transported by southwesterly flows from the Bay of Bengal and monsoon flows over the South China Sea for flooding years of the Yangtze River Basin whereas by southeast monsoons from the eastern and southern seas off China and monsoon flows over the South China Sea for flooding years of the Huaihe River Basin.展开更多
The observation at the Chongxi gauging station indicated the salinity of saltwater spilling over from the North Branch to the South Branch increased abnormally from November 10 to 12 in 2009 (during neap tide) and fro...The observation at the Chongxi gauging station indicated the salinity of saltwater spilling over from the North Branch to the South Branch increased abnormally from November 10 to 12 in 2009 (during neap tide) and from February 11 to 12 in 2010 (during moderate tide).We found for the first time that the strong northerly wind was responsible for the above abnormal salinity increase.Previous studies indicated that the saltwater intrusion in the Yangtze Estuary is influenced mainly by the river discharge,the tide,and the wind stress,but the impacts of variations of wind speed and direction on it have not been investigated.In this study the impacts of wind stress on the saltwater intrusion were numerically simulated and the associated mechanisms were analyzed.The model results were consistent with the observed data obtained at six gauging stations during February and March in 2007 and four gauging stations in March 2008,and the abnormal salinity risings were well captured.Meanwhile,if the wind speed is reduced by half,the salinity there will be significantly decreased.Driven by the monthly mean river discharge of 11000 m 3 /s and northerly wind of 5 m/s from January to February,the model simulated the temporal and spatial variation of saltwater intrusion.The wind-driven circulation,as well as the net water and salt fluxes from the North Branch into the South Branch,was calculated and analyzed in the cases of different wind speeds and directions.The results indicated that the intensity of the saltwater intrusion in the Yangtze Estuary is significantly influenced by the wind speeds and directions.展开更多
文摘The tidal current duration （TCD） and velocity （TCV） and suspended sediment concentration （SSC） were measured in the dry season in December, 2011 and in the flood season in June, 2012 at the upper part of the North Channel of Changjiang Estuary. They were assimilated with the measured data in 2003, 2004, 2006 and 2007, using the tidal range＇s proportion conversion. Variations in TCD and TCV, preferential flow and SSC have been calculated. Influences of typical engineering projects such as Qingcaosha fresh water reservoir, Yangtze River Bridge, and land reclamation on the ebb and flood TCD, TCV and SSC in the North Channel for the last 10 years are discussed. The results show that： （1） currently, in the upper part of North Channel, the ebb tide dominates; after the construction of the typical projects, ebb TCD and TCV tends to be larger and the vertical average ebb and flood SSC decrease during the flood season while SSC increases during the dry season; （2） changes in the vertical average TCV are mainly contributed by seasonal runoff variation during the flood season, which is larger in the flood season than that in the dry season; the controlling parameters of increasing ebb TCD and TCV are those large-scale engineering projects in the North Channel; variation in SSC may result mainly from the reduction of basin annual sediment loads, large-scale nearshore projects and so on.
基金Supported by the National Basic Science Research Program of Global Change Research(No.2010CB951201)the Funds for Creative Research Groups of China(No.41021064)the Marine Special Program for Scientific Research on Public Causes(No.201005019)
文摘An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch （NB） and the South Branch （SB）. The study assumes that the fiver discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover （WSO and SSO） from the NB into the SB, and tidally averaged （net） water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the fiver discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation.
基金supported by National Natural Science Foundation of China (Grant No.40901291)Innovation Program of Shanghai Municipal Education Commission (Grant No. 13YZ053)National Social Science Key Project Foundation of China (Grant No. 11&ZD003)
文摘Public willingness to pay （WTP） for urban rivers res- toration was investigated in Shanghai, Nanjing and Hangzhou in China with a sample of 1,285. The factors influencing positive WTP against zero WTP are analyzed using a binary logit model. The results indicate that income, Huff （residential registration） status, household size, home property ownership, riverfront access, and attitudes toward current water quality arc statistically signifi- cant in the likelihood of positive WTR It is also found that respon- dents without local Huff are less willingness to pay positively in pooled sample and Shanghai sample. In the group holding property right of house but without local Huff is less willingness to pay positively in Hangzhou. Respondents in Nanjing are more will- ingness to pay positively than those in Hangzhou. Most common arguments against to pay for the restoration are ＂government＇s duty＂, ＂low income＂, ＂non-local-Huji＂ and ＂lack of trust in the government in how it spends money＂. The results are generally consistent with the hypothesis and specific situations in China. The findings make some contributions to the non-market valua- tion studies as well as provide useful information for public policy making in China.
基金Acknowledgments Funding for this research was provided by the National Key Basic Special Foundation Project of China （2010CB428400）, and the National Natural Science Foundation of China （41375139）. We are grateful to the Program for Climate Model Diagnosis and Intercomparison for collecting and archiving the model data.
文摘A Bayesian multi-model inference framework was used to assess the changes in the occurrence of extreme hydroclimatic events in four major river basins in China （i.e., Liaohe River Basin, Yellow River Basin, Yangtze River Basin, and Pearl River Basin） under RCP2.6, RCP4.5, and RCP8.5 scenarios using multiple global climate model projections from the IPCC Fifth Assessment Report. The results projected more summer days and fewer frost days in 2006-2099. The ensemble prediction shows the Pearl River Basin is projected to experience more summer days than other basins with the increasing trend of 16.3, 38.0, and 73.0 d per 100 years for RCP2.6, RCP4.5 and RCP8.5, respectively. Liaohe River Basin and Yellow River Basin are forecasted to become wetter and warmer with the co-occurrence of increases in summer days and wet days. Very heavy precipitation days （R20, daily precipitation ≥20 mm） are projected to increase in all basins. The R20 in the Yangtze River Basin are projected to have the highest change rate in 2006-2099 of 1.8, 2.5, and 3.8 d per 100 years for RCP2.6, RCP4.5 and RCP8.5, respectively.
文摘On the basis of field survey, microscope sighting, TL dating and scanning electron microscope analysis, the characteristics of Quaternary deposits near Songjianghe Town on the west slope of Changbai Mountain are analyzed and described. There were two phases of volcanism during Mid-Late Quaternary. One occurred before 15.22×104 aB.P. and the other happened between 14.27×104 aB.P. and 1.41×104 aB.P. Volcanism is a landform-making process which makes the rough relief in the studied area become higher and higher. Flow water is a main erosion agency and it cuts into the basalts making river valleys. The Quaternary fluvial deposits distributed on terraces first come from the weathered debris of basement rocks, then they are transported and deposited by flow water. After 1.41×104 aB.P., the river water quickly cuts into the newly formed basalts making a deep valley. Volcanism in the studied area is a main landform-making event in Mid-Late Quaternary.
基金Supported by the National Basic Research Program of China(973 Program)(No.2010CB951204)the National Natural Science Foundation of China(No.44107180)the 111 Project(No.B08022)
文摘Tidal rivers are intrinsically complex because tidal propagation is influenced by river discharge. This study aims to examine the seasonal variation of tidal prism and energy variance in the tidal river of the Changjiang(Yangtze) River estuary in China. In order to quantify the behaviour of river and tide,we use numerical modelling that has been validated using measured data. We conduct our analysis by quantifying the discharge and energy variance in separate components for both the river and the tide,during wet and dry seasons. We note various definitions of tidal prism and explore the difference between tidal discharge on the flood and ebb and tidal storage volume. The results show that the river discharge attenuates the tidal motion and reduces the tidal flood discharge but the tidal storage volume is approximately constant with different riverine discharge since part of the fresh water discharge is intercepted and captured in the estuary due to the backwater effect. It appears that the tidal discharge adjusts according to the variation of river discharge to keep a constant tidal storage volume. An analysis of the hydraulics shows that the transition from tidal dominance(at the mouth) to river dominance(upstream) depends on the location of tidal current reversal which varies from wet season to dry season. Duringthe wet season,the Changjiang River estuary is totally dominated by energy from fresh water discharge.
基金supported by the National Natural Science Foundation (No. 40875058)the National Key Basic Research Program (No. 2012CB955200) of Chinafunded by the Priority Academic Program Development (PAPD) of Jiangsu Higher Edusation Institutions
文摘Based on the 1961-1990 observed daily precipitation in the Changjiang-Huaihe River Basin, the NCEP/NCAR reanalysis data, and the HadCM3 model data for IPCC SRES A1B climate projections, the simulation capabilities of the BP-CCA downscaling approach for extreme precipitation indices of the current climate are assessed by applying canonical correlation analysis (CCA). In addition, future extreme precipitation indices in the middle and late 21st century are projected. The results show that simulation capability of the HadCM3 for regional climate characteristics can be effectively improved by the downscaling approach, with 30%-100% reduction of the relative errors of the climatological mean state of extreme precipitation indices. However, the downscaling results still show wetter winter and dryer summer than the observation. Under the SRES A1B emission scenario, frequency and intensity of extreme precipitation events are projected to increase, and the estimated increasing rate is higher for extreme precipitation indices than for mean precipitation index; and in summer than in winter. Extreme precipitations in the middle and late 21st century are expected to increase by 14% and 25% respectively in winter, and by 24% and 32% respectively in summer.
基金Supported by the National Basic Research Program of China(973 Program)(No.2010CB951202)the National Natural Science Foundation of China(Nos.41376055,41030856)
文摘Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.
基金Supported by Pennsylvania Service Corporation at Waynesburg, Pennsylvania, USA the 0utstanding Youth Science Foundation of Henan Province （0612002100）, China.
文摘In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.
基金Supported by Key Laboratory of Marine Spill Oil Identification and Damage Assessment Technology,SOA,the Director's Foundation of the North Sea Monitoring CenterChinese Academy of Sciences (No.KZCX 2-207)the Project of Ecological Environment in Fishery and Technology Controlling Pollution in Zhoushan Fishing Ground (No.2007c23075)
文摘Analysis using historical data on the phosphate sources in Changjiang （Yangtze River） estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the Changjiang River, the Taiwan Warm Current （TWC）, a cyclone-type eddy, and the 32°N Upwelling, supplying different phosphates in different times, ways and intensities. The magnitude of their supplying phosphate concentration was related with the size in the order of the Changjiang River 〈 the TWC 〈 the 32°N Upwelling 〈 the cyclone-type eddy, and the duration of the supplying was： the Changjiang River 〉 the TWC 〉 the cyclone-type eddy 〉 the 32°N Upwelling. The four sources supplied a great deal of phosphate so that the phosphate concentration in the estuary was kept above 0.2 pmol/L in previous years, satisfying the phytoplankton growth. The horizontal and vertical distribution of the phosphate concentration showed that near shallow marine areas at 122°E/31°N, the TWC in low nutrient concentration became an upwelling through sea bottom and brought up nutrients from sea bottom to marine surface. In addition, horizontal distribution of phosphate concentration was consistent with that of algae： Rhizosolenia robusta, Rhizosolenia calcaravis and Skeletonema, which showed that no matter during high water or low water of Changjiang River, these species brought by the TWC became predominant species. Therefore, the authors believe that the TWC flowed from south to north along the coast and played a role in deflecting the Changjiang River flow from the southern side.
基金carried out under the auspices of the public project of the Ministry of Water Conservancy of China (200801073, 2007SHZ0901034)the Knowledge Innovation Project of the Chinese Academy of Science (KZCX1-YW-08)
文摘On May 12, 2008, an earthquake of 8.0 magnitude on the Richter scale and its numerous aftershocks devastatingly hit Wenchuan County and its nearby region along the Longman Mountains in Sichuan Province, China. The heavy ruined area was up to 30,000km2 and 13% of its land surface was denuded by the extremely terrible quakes. The mountain collapses, landslides and debris flows induced by the earthquake not only scared the landscape at the immense scale, but also poured L66-billion-m3 sediment combined with offscourings and rubble into the Yangtze River and its breaches. This amount of sediments is 3 times more than the normal amount discharged into the Yangtze River, and will significantly increase sediment transportation of rivers and decrease storage capacities of reservoirs downstream. The dramatic increase in sediment load will imperil the engineering safety and impact the operation of the giant Three-Gorge Hydro-power Station if no proper prevention measures are taken.
基金supported by a Stanford EDGE-STEM Fellowshipinitiated under NSF EAR-1254156 to Kate Maher and was also supported by the California Alliance Research Exchange NSF HRD-1306595 to C.Page Chamberlain
文摘Quantifying the functional relationships relating river discharge and weathering products places key constraints on the negative feedback between the silicate weathering and climate. In this study we analyze the concentration–discharge relationships of weathering products from global rivers using previously compiled time-series datasets for concentrations and discharge from global rivers. To analyze the nature of the covariation between specific discharge and concentrations, we use both a power law equation and a recently developed solute production equation. The solute production equation allows us to quantify weathering efficiency, or the resistance to dilution at high runoff, via the Damkohler coefficient. These results are also compared to those derived using average concentration–discharge pairs.Both the power law exponent and the Damkohler coefficient increase and asymptote as catchments exhibit increasingly chemostatic behavior, resulting in an inverse relationship between the two parameters. We also show that using thedistribution of average concentration–discharge pairs from global rivers, rather than fitting concentration–discharge relationships for each individual river, underestimates global median weathering efficiency by up to a factor of ～10. This study demonstrates the utility of long time-series sampling of global rivers to elucidate controlling processes needed to quantify patterns in global silicate weathering rates.
文摘The bionomics of Campoletis chlorideae and the regularity of its seasonal fluctuations were studied in Changsha district,Hunan province. Field investigation indicated that there were ten generations of C. chlorideae a year, of which seven occurred in cotton fields. Three peaks of cotton bollworm parasitization by C. chlorideae were observed, early May to late June, mid August to early September, mid September to mid October respectively. One peak occurred in tomato and tobacco fields, the other two in cotton fields. The parasitization rate ranged from 25.1%- 63.1%. The total development time from egg to adult ranged from 13.0 days at 32℃ to 75.5 days at 11.6℃. Each wasp could parasitize the 5-23 second instar larvae of tobacco caterpillar. C. chlorideae could parasitize the cotton bollworm, beet armyworm and tobacco caterpillar, but preferred the cotton bollworm larvae. C. chlorideae could parasitized 1st-3rd instar larvae of the tobacco caterpillar, but seldom parasitzed 4th-6th instar larvae. Moreover, C. chlorideae preferred second instar larvae. Theoretical models for developmental speed, adult longevity and the influence of temperature were proposed. The overwintering of C. chlorideae Uchida was also discussed. Moreover, methods for utilization of C. chlorideae Uchida in crop protection were presented and the bionomics of Campoletis chlorideae in both the Yangtze River Valley and Yellow River Valley were compared.
基金supported by National Basic Research Program of China(Grant No. 2010CB951404)National Natural Science Foundation of China (Grant Nos. 41030527 and 41130368)Hundred Talents Program of Chinese Academy of Sciences
文摘Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside and adjacent to the study basins, were analyzed and compared to quantify the hydrological processes involved, and to evaluate the role of human activities in chang- ing river discharges. The Inverse Distance Weighted （IDW） interpolation method was used to obtain climatic data coverage from station observations. According to the runoff coefficient equation, the effect of human activities and climate can be ex- pressed by changes in runoff coefficients and changes in precipitation, respectively. Annual runoff coefficients were calculated for the period 1950-2008, according to the correlation between respective hydrological series and regional precipitation. An- nual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the mid- dle and downstream reaches, with declines of 8.8 and 9.8 ram/10 a, respectively. All annual runoff series for the Yellow River basin showed a significant downward trend. Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 ram/10 a at Lijin. The series results indicated that an abrupt change occurred in the late 1980s to early 1990s. The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations, with rates ranging from 0.013/10 a to 0.019/10 a. For the hydrologic series, all precipitation series showed a downward trend in the Yangtze River basin with de- clines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong. Annual runoff series for the upper reaches of the Yangtze River decreased significantly, at rates ranging from 9.9 to 7.2 mm/10 a. In the middle and lower reaches, the run- off series showed no significant trend, with rates of change ranging from 2.1 to 2.9 ram/10 a. Human activities had the greatest influence on changes in the hydrological series of runoff, regardless of whether the effect was negative or positive. During 1970-2008, human activities contributed to 83% of the reduction in runoff in the Yellow River basin, and to 71% of the in- crease in runoff in the Yangtze River basin. Moreover, the impacts of human activities across the entire basin increased over time. In the 2000s, the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins, respectively. The average annual runoff from 1980 to 2008 fell by about 97%, 83%, 83%, and 91%, compared with 1951-1969, at the Yellow River stations Lanzhou, San- menxia, Huayuankou and Lijin, respectively. Most of the reduction in runoff was caused by human activities. Changes in pre- cipitation also caused reductions in runoff of about 3%, 17%, 17%, and 9% at these four stations, respectively. Falling precipi- tation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan, Yichang, Hankou, and Datong, causing reductions in runoff of 89%, 74%, 43%, and 35%, respectively. Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin. Runoff decreased in arid areas as a result of in- creased water usage, but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.
基金supported by National Natural Science Foundation of China (Grant No. 40874004)National Basic Research Program of China (Grant No. 2009AA121401)the "111 Project" of China (Grant No. B07037)
文摘In general, China is short of water resources and some regions even experience a shortage of daily water supply. This could threaten the stability and economic development of the nation. A study on the water storage variations is especially important for the water management and storage prediction in three largest river basins of China, namely, Yangtze, Yellow, and Zhujiang, where the most dense population and leading economic regions are located. The satellite gravity mission GRACE （Gravity Recovery and Climate Experiment） provides an opportunity to macroseopically identify water （or mass） variations in the Earth＇s system with a spatial resolution of 300-400 km and a temporal resolution of about one month. We use the first release of the DEOS （Delft Institute of Earth Observation and Space Systems） Mass Transport （DMT-1） model based on GRACE data to analyze water storage changes in the three river basins. The DMT-1 model consists of monthly solutions, which are computed using an innovative methodology. The methodology includes, in particular, the application of a statistically optimal Wiener-type filter based on full varianee-covariance matrices of noise and signal. This results in particularly sharp mass variation maps. Taking one monthly solution as an example, we compare the results derived from the DMT-1 model with ones produced with the standard post-processing scheme based on a combination of the de-striping and Gaussian filtering. The comparison shows that the DMT-1 model outperforms the other models and is suitable for the analysis of the mass changes in river basins. A subset of the DMT-1 solutions in the interval between February 2003 and May 2008 is used to estimate the secular trends and seasonal variations for the three river basins. The estimated trends show that the water storage of the Yellow River basin does not have significant changes, while the Zhujiang and Yangtze river basins have a large and statistically significant water storage increase. The estimation of seasonal variations demonstrates that the water storage variations in Yangtze and Zhujiang river basins are almost in the same phase. The amplitude of variations in the Zhujiang River basin is larger than that in Yangtze. No clear annual variations are observed in the Yellow River basin. The observed water storage variations generally coincide with the observations and conclusions presented in the hydrological reports of the Chinese Ministry of Water Resources
基金supported by the National Basic Research Program of China (Grant No. 2013CB430105)the National Natural Science Foundation of China (Grant Nos. 40775038, 40875031 & 40975036)the Foreign Professors Projects of Chinese Academy of Sciences (Grant No. 2010-c-6)
文摘Here we present the results from the composite analyses of the atmospheric circulations and physical quantity fields associated with rainy-season for the selected floods cases over the Yangtze and Huaihe River basins for the 21 years(1990–2010),using the daily rain gauge measurements taken in the 756 stations throughout China and the NCEP/reanalysis data for the rainyseasons(June–July)from 1990 to 2010.The major differences in the atmospheric circulations and physical quantity fields between the Yangtze and Huaihe River basins are as follows:for flooding years of the Yangtze River Basin,the South Asia high center is located further east than normal,the blocking high over the Urals and the Sea of Okhotsk maintains,and the Meiyu front is situated near 30°N whereas for flooding years of the Huaihe River Basin,the South Asia high center is further west than normal,the atmospheric circulations over the mid and high latitudes in the Northern Hemisphere are of meridional distribution,and the Meiyu front is situated near 33°N.In addition,there are distinct differences in water vapor sources and associated transports between the Yangtze and Huaihe River basins.The water vapor is transported by southwesterly flows from the Bay of Bengal and monsoon flows over the South China Sea for flooding years of the Yangtze River Basin whereas by southeast monsoons from the eastern and southern seas off China and monsoon flows over the South China Sea for flooding years of the Huaihe River Basin.
基金supported by National Natural Science Foundation of China(Grant No. 40976056)National Basic Science Research Program of Global Change Research (Grant No. 2010CB951201)+1 种基金Marine SpecialProgram for Scientific Research on Public Causes (Grant No. 201005019)National Natural Science Foundation of China (Grant No. 40806034)
文摘The observation at the Chongxi gauging station indicated the salinity of saltwater spilling over from the North Branch to the South Branch increased abnormally from November 10 to 12 in 2009 (during neap tide) and from February 11 to 12 in 2010 (during moderate tide).We found for the first time that the strong northerly wind was responsible for the above abnormal salinity increase.Previous studies indicated that the saltwater intrusion in the Yangtze Estuary is influenced mainly by the river discharge,the tide,and the wind stress,but the impacts of variations of wind speed and direction on it have not been investigated.In this study the impacts of wind stress on the saltwater intrusion were numerically simulated and the associated mechanisms were analyzed.The model results were consistent with the observed data obtained at six gauging stations during February and March in 2007 and four gauging stations in March 2008,and the abnormal salinity risings were well captured.Meanwhile,if the wind speed is reduced by half,the salinity there will be significantly decreased.Driven by the monthly mean river discharge of 11000 m 3 /s and northerly wind of 5 m/s from January to February,the model simulated the temporal and spatial variation of saltwater intrusion.The wind-driven circulation,as well as the net water and salt fluxes from the North Branch into the South Branch,was calculated and analyzed in the cases of different wind speeds and directions.The results indicated that the intensity of the saltwater intrusion in the Yangtze Estuary is significantly influenced by the wind speeds and directions.
