Abstract: The Yellow River is shortage in water resources,and it's of significance to analyze variation of hydrological variables for sustainable development of water resources.According to the characters of geomorphology and distribution of key hydrometric stations,the middle reaches of the Yellow River is divided into three regions,which are the region from Hekouzhen to Longmen,the region from Longmen to Sanmenxia,and the region from Sanmenxia to Huayuankou.Historical variation trends of runoff in each region are tested with the Mann-Kendall method and the linear regression method.Based on the hypothetical climate scenario and the natural discharge simulation for each region,the responses of runoff to climate change are studied.And results indicate that there are a significant decline trends in the recorded runoff at each key hydrometric stations and the regional runoff.Annual runoff would decrease 3.7%~6.6% if air temperature rise 1℃,while runoff would decrease 17%~22% if precipitation increase by 10%.Thereby,runoff is rmre sensitive to change in precipitation than that to temperature change.
Abstract: Based on the daily data from 20 meteorological stations from 1960 to 2006 and the combination of the Penman-Monteith model,the change trend in potential evaporation (PE) over Qilian mountains and Hexi corridor is analyzed in this study.With the method of Spline under ArcGIS, the spatial distribution of PE is drawn in order to research the regional difference.And the multiple regression method is used to discuss the dominant factor affecting the PE.The results indicate that the annual PE is higher before 1980s than after,and experiences the process from the decrease before 1967 to the increase since then, and to decrease after 1974 to the increase after 1993.There is a decreasing trend in general because the change rate of the annual PE varies at-1.67 mm.The potential evaporation increases in autumn,however,decreases in other seasons,especially in spring.The wind speed is a dominant factor influencing PE.When autumn comes,the temperature becomes the key factor influencing PE.
Abstract: The rmnthly precipitation data from 97 stations over Qinghai-Tibet Plateau from 1961 to 2000 are analyzed by using the Mann-Kendall test and the principal component analysis methods.The spatial-temporal variability characteristics of precipitation during last four decades are briefly described,and the abrupt of the further factors of the distribution in spatial and the variation trends of abrupt changes are discussed.The results indicate that the precipitation of rmst stations over Qinghai-Tibet Plateau shows an increasing trend,while the decreasing trend appears in some stations in southeast of qnghai and the stations scattered in Tibet.There is an opposite-phase spatial relation between the variation trend of precipitation in the middle and east of Plateau and that in the south and north.At the same time there is an obviously increasing trend in of precipitation in the cool sewn.According to the spatial distribution of the third loading eigenvectors (TLE) of precipitation in cool and warm seasons,the regions classified (RC) are reflected in spatiality between the interdecadal and interannual variations.Cbrresponding to the RC the variation trends in precipitation in warm season have an obvious relationship with the TLE in temporal variation, with their abrupt changes detected in 1989,without the detection of the abrupt changes in the same situation in cool season.
Abstract: In view of interlaced tributaries,and the abundant of reserwir,dams and water gates in the Huaihe river,a coupled numerical model for 1D and 2D water quantity and quality is developed to meet the requirement of flood regulation and the water pollutants' contml.The established model is calibrated and tested by the real time data of Huaihe river in 1999 and 2004,respectively.The results suggest that this model can provide precise description of the movement trend in the flood and the pollutants,and can be used for the prediction and assessment of the effects of each regulation scheme on the water quality improvement.
Abstract: Based on the analysis of control pattern of water diversion on the Yangtze River-Taihu lake water transfer prototype test, a model coupling water quantity and quality simulation and schedule is established to study the main water problem of Taihu basin.In view of the complexity of the model optimization, some rational and feasible solutions are put forward in the key links, including mainly the algorithm of the water quantity and quality numerical simulation model, the objective function and the constraint condition of the optimal operation model, and the coordination and connection between the simulation model and the optimization model.Aiming at the irrational distribution of the water diversion in the Yangtze River-Taihu lake water transfer prototype test, the rational scheduling mode of the water diversion from Wangyu river in special time period is studied, and the effect of the water diversion on the ecological environment of Taihu lake under different working conditions is emphatically analyzed.Results of the case study show very good feasibility of the methods above, and also provide theoretical reference for the quantitative study of the cross-regional integrated regulation of water quantity and quality.
Abstract: Water consumption (WC) law of winter wheat and summer maize rotation system in the Northwestern Shandong plain is investigated on the base of 20 years' data from the weighing lysimeter in Yucheng comprehensive experimental station of the Chinese Academy of Sciences.The results indicate that the average WC of them are 457.6 and 411.7mm,respectively.For the winter wheat,the average daily WC and the maximum are 1.97 and 6mm/d,respectively.For the summer maize,the values are 3.18 and 4.8~6.0mm,respectively.The climate changes might contribute to the reduction of the WC by summer maize.Compared to the 2 years' synchronization data,the results determined by the ed by covariance(EC) technique can commendably reveal the WC law.However,the EC technique can bring about 20% decrease systemally,and the observation technique and unusual data processing methods are expected to produce preferable results after a further improvement.
Abstract: Aiming at the optimal operation of the cascade hydropower plants with the characteristics of highly nonlinear and complicated constrain conditions,this paper presents the nested searching algorithm with the fractal division interpolation and chaos optimization.This algorithm uses the nested structure to unite determinate and stochastic searches,and can find out the global optimum according to its own regularity.The results of a practical example prove the nested algorithm's validity and practicability,and show it not only has many advantages such as strong ergodicity,simplified parameter configuration,high stability,global optimization,and easy programming,but also can get consistent convergence accurately and use less computing time compared with POA algorithm.Furthermore,the results also suggest the nested searching algorithm can solve the nonlinear optimal problems in the complicated constraint conditions and lay a foundation in the future study.
Abstract: The relationship between deuterium and oxygen 18 in atmospheric precipitation shows the certain law.This paper analyaes the impact factors for fractionation coefficient in Rayleigh fractionation,gives the differential equation models of stable isotope composition in precipitation in the open system and closed system,and discloses the variation law of deuterium and oxygen 18 in precipitation.And the relationship between deuterium and oxygen 18 in precipitation and clouds vapor is deducted.The result shows that it is not simply linear relation between the deuterium and oxygenl8 in precipitation.
Abstract: Using the methods of the field data analyses, the relationship between the bank-full discharge in the tail channel and the flow-sediment is studied.The research results show that the bank full discharge has decreased from 6 000 m3/s at the beginning of the formation of the flow river to 3 000 m3/s in the early of 21th century.The bank-full discharge has double memory effect, that is, the strongest memory lasts nearly two years with the short-term effect, and the deeper memory lasts nearly six years with the long-rang effect.The incoming flow is much bigger and the incoming sediment coefficient is more smaller, so the bank-full discharge become much bigger, and contrarily, the bank-full discharge become much smaller.If the bank-full discharge maintains 4000m3/s, the annual incoming flow must be bigger than 23.3 billion m3, the incoming flow in annual flood season is bigger than 14.1 billion m3, and incoming sediment coefficient in the flood season is about 0.03.The regulation of the flow and sediment of Xiaolangdi reservoir should be made continuously for more than 5-6 years, and will bring good effect During uniform controlling water, daily the minimum discharge in the flood season should be confirmed at Lijin station, it will maintain definite bank full discharge in the tail channel.
Abstract: Based on the vertical 2-D hydrodynamic model and the sediment model,this paper presents a 2-D sediment model.The main characteristics of this model are follows:the hydrodynamic model is an oblique press model so that it can reflect the influence of water temperature on hydrodynamics and suspending sediment.The numerical solution to the sediment equation uses a fractional step procedure so that it can simplify the elution process.The cohesive sediment and the non-cohesive sediment are simulated by the different methods.Mme empirical formulas are used to calculate the model parameters under the condition that little field data would be available.Rnally,the application of this model is studied according to the field data, and the results indicate that the relative errors of the simulating value and the field value of suspending sediment are small and their space-time distribution characteristic are similar to each other.At the same time,this rmdel can simulate the distribution characteristics of the temperature and the sediment which are accurately controlled by the outflow and inflow in the head and trail of a reservoir.
Abstract: According to the periodicity and self-similarity,a new method for predicting the change characteristics of the coastal water quality is proposed through the study of the fractional theory based on the environmental monitoring data completely.Taking the coastal marine of Tianjin as an example,firstly,according to the fractional collage theory,the fractal interpolation based on affine transform is used to find the iterated function systems of the historical water quality.Secondly,the weighted summation method is adopted to find the iterated function system of the predicting period according to the above iter ated function systems based on the periodicity.Then the fractal predicting rmdel is established according to the iterated function system of predicting period.Finally,the random iterated algorithm is used to find the attractor of each prediction periods which can provide the prediction data according to the time values.The predicted results show that the average prediction error of the dry,rainy and mean water period are 29.6%,27.5% and 16.1%,respectively,and the average prediction error of the three periods is 24.4%.Through application it can be found that the fractional prediction method has high prediction preciseon.It is practicable and can povide the decision-making for the environment management of the coastal marine.
Abstract: The partial pressure of CO2(pCO2) in the water of the Yellow River was directly measured in November 2006,and the distribution and dynamics of pCO2 are discovered in the combination of the related parameters.The results indicate that the pCO2 in the surface water ranges between 80 and 166 Pa,with an average value of 110 Pa,and is lower than that in other important rivers in the world.Furthermore,the significant variations in the spatial pCO2 distribution,i.e,the pCO2 value in the middle part of the river is higher than upstream and downstream.Photosynthesis of phytoplankton has a slight effect on pCO2, even though Chla reaches the maximum 3.58 μg/L at Baotou station where the pCO2 value is still 91 Pa.Since the organic matter level in the Yellow River water is low and hard to degrade,the EpCO2/AOU value just varies from 0.14 to 0.20 in the mainstream and reserwir,lower than the theoretical value of 0.62,which suggests that the biological aerobic respiration effect has little contribution to pCO2.The content of TSS and DIC in the Yellow River water varies from 3.77 to 1308.33 mg/L and from 3.03 to 4.14 mmol/L,respectively,both of which are generally higher than other rivers in the world,and the maximum appears at Tongguan.Meanwhile the pCO2 has a positive relationships with TSS,PIC and DIC.So the main control factors of pCO2 are attributed to the carbonate system with high carbonate content induced by the strong mechanical erosion and chemical weathering in the Yellow River drainage area.Based on the model of wanninkhof and the wind speed,the released CO2 from the Yellow River to atmosphere is estimated about 14.5×108 mol in autumn at the rate of 0.229 μmol/(m2·s),which is equal to the CO2 absorption of 8 250 km2 grass or 112 kmz forest.CO2 outgassing flux from the Yellow River is close to that of the Ottawa River and less than the Amawn River.
Abstract: Flow pattern and hydraulic parameter characteristics are quantified under the rainfall intensities of 60,90,and 130 mm/h using the hillslope-gullyslope system including different slope gradients with the simulated rainfall experiment.The resups show that the hillslope runoff discharging into gullyslope or the increase of the rainfall intensity will result in the increase of the Reynolds number and Froude number and the shift of flow pattern from the stratum flow into torrent flow.The hillslope runoff discharging into hillslope-gullyslope system causes the decrease of the Darcy-Weisbach coefficient and the increase of the sediment delivery at the same time.
Abstract: To reduce uncertainty in the forecast or analysis of unsteady flows,the ensemble Kalman filter technique(EnKF) is introduced based on the stochastic unsteady flow system with a stochastic state space model.The multivariate analysis scheme is proposedfor updating flow states when the water stage and the discharge measurements are both assimilated.Taking a single-wave flood event in open channel as an example,the performance of EnKF is investigated with the experiments of 13 groups.The investigation mainly focuses on the comparisons of the effects of water stage or discharge measurements with different order of the available accuracy on the EnKF analysis.Main results show that one can identify flow states well by assimilating the water stage measurements with less than Scm standard deviation alone.And the results using discharge measurement with 5%relative standard deviation are close to those using water stage with lOcm standard deviation.Further,when both kinds of measurements are assimilated,the appropriate variable transformation is required to remedy the truncation errors of the numerical computation.
Abstract: The Navier-Stokes (N-S) equation with stream function formulation is used as the governing equation.It has no pressure terms or velocity terms compared with the N-S equations,and no vorticity terms or velocity terms compared with the wrticity-stream function equations,awiding the problems of wrticity boundary conditions.The variable is only the stream function term.Considering the upwindfeature of convective term,the upwind scheme is adopted to simulate the 2-D sudden expansion laminar.The results are basically consistent with the experiment results of the Durst and Hybrid Fnnite Analytic Method.On the basic of series of calculations,it establishes the relation between the characteristic value and the Reynolds number, when the main flow deflects after sudden expansion section.This complements the researches on sudden expansion flow.
Abstract: In this article, three turbulent models, namely the standard κ-ε model, the renormalization κ-ε model, and the v-f model, are adopted to calculate the turbulent separated flow passing on sill, based on the co-located grid system and the volume method.The results show that the three models can simulate the characteristics of the turbulent separated flow passing on sill, such as the front vortex and back vortex, the pattern of back flow, etc, but there are different in the profiles of velocity, the location of the vortex behind the sill, the length of back flow and the head loss among the models.Compared with the experimental data, the results of LES indicate that the results simulated by the v-f (κ-ε-ν2) model behave best among the three models.Therefore, the v-f (κ-ε-ν2) model has the predominance in the simulation in the turbulent separated flows.
Abstract: The quantified relationship between relative permeability and saturation is the key dynamic parameter relationship of multiphase flow system in porous media.Under the dynamic condition,the designed apparatus and method are employed to measure the relative permeability and saturation in wateroil twa-phase system.The experiment was conducted in a one dimension sand column and the results were analyzed.It indicates that the results measured by the apparatus are in acrd with those in practical condition.The fine sand is hydrophilic,which remarkably affects the relative permeability and saturation of water oil and causes the displacement mechanism difference of different fluids in different firstly wetting conditions.The oil-water phase saturation is the main influential factor of phase relative permeability,and the viscous difference of different fluids affects the relative permeability.And the relative permeability should be determined by the liquids distribution in porous media and the saturation history of fluids.The experimental data are very well fitted in with the VGM model (or the Parker-Lenhard model).At the same time the parameter in fitting capillary pressure-saturation data using the van formula is transferred in predicting relative permeability-saturation curve with VGM model in the water firstly wetting condition.And the result is compared with that of direct fitting of the relative permeability-saturation data by the VGM model,which suggests the latter model shows a better performance.
Abstract: Qiantangjiang estuary and Hangzhou bay are famous for their macro tide ranges in China.During typhoon period,if high tide levels formed by the spring tides piled up with the peal}value of storm surge higher than the dike elevation,the sea water overflow will happen,and the people and estate in the protected area behind the dikes will be endangered.A storm tide overflow model for Qiantangjiang estuary and Hangahou bay is set up to enhance the technique for storm tide forecasting in the case of overflow.A computed method for the overflow is presented to simulate the processing of the storm surge flowing over the dike.The inundation risk of the area behind the dikes is studied when the storm surge overflow is happened.And the response of storm tidal water levels induced by the overflow is discussed.
Abstract: The finite element method,which suits complex domain shapes well andfits the irregular boundary conveniently,is used to salve the elliptic mild slope equation in the model of this paper.And the modified conjugate-gradient method,which solves the linear system of equations efficiently and requires less memory,is used to solve the linear system of the mild slope equation.This model is tested with the laboratory measurements of Rizhao Port waters.The results show that the model could be used in relative large region and get ideal results.
Abstract: Combined with the nonlinear Stokes wave and the parallel flow instability theory,the high-order inviscid Orr-mmerfeld equations,the formulas of pressure over wave surface and the energy transfer are derived.Furthermore,for the secondorder model,the quasi-nonlinear energy transfer coefficient,a new parameter,is introduced to take nonlinear energy into consideration,and the uniform expression of total energy is established.The energy transfer coefficients considering water depth are obtained from the numerical solutions to the first-order Orr-Somerfeld equation with a singular point.The findings are that,through coordinate transformations,the high-order inviscid Orr-mmerfeld equations can be solved simultaneously.For small values of dimensionless wave speed c/U1,the energy transfer coefficients considering the influence of water depth are less than those with infinite water depth.
Abstract: Ice thickness is the most fundamentally integrative and crucial parameter for the investigation involving ice science and ice engineering.It is necessary to develop the new technologies for the fixed site monitoring ice thickness according to the multi-applied motive.This objective has now been achieved with the development of three new technologies.Based on the principle of these new technologies and their applications in field or in the laboratory,their applicability and advantage are discussed.The precision of the apparatus based on the magnetostrictive delay line technique reaches to ±2mm,which solves the crucial problem imvlved in developing and modifying the ice mass equilibrium rmdel.The technology based on resistance is more effective than the method based on temperature profile measurement for ice thickness detecting;and it has the potential for measuring mass equilibrium on the surface of ice glacier and monitoring water level under river ice,lake ice and resemvir ice associated with ice thickness.It is expedient and cost-efficient for the manufacture,and disposed in field of the hot-wire ice thickness gauge,thus it can be popularized in the small hydrological observation stations in the north of China.
Abstract: Ice discharge under ice jam or ice cover is the result from the combined effects of the thermal, hydraulic and boundary conditions.Based on the analysis of the experimental data, the formula for calculating ice discharge is proposed.Meanwhile, compared with the data of stability freezing period from Hequ region in the Yellow River, the result shows that the proposed form of formula is rational and can offer reference to the calculation of ice discharge in the during freeze-up.
Abstract: First, from the view of the erosion mechanism, the main achievements in the furrow irrigation erosion (FIE) affected by the characteristics of irrigation water and the mode of irrigation action are analyzed.The primary differences between the furrow erosion from irrigation and the erosion from rainfall in the farmland are explained.Next, the prediction model for the furrow irrigation erosion is introduced, and the primal problems of the prediction model is brief described.Then, the prevention and the cure technique for the FIE are presented.Finally, the tentative plan on the research of FIE in China is proposed.
Abstract: A detailed review of experimental study on dam-break is made in this paper.The key results of the experimental study on dam-break such as dam-break flood and dam-break mechanism at home and abroad are summarized,and its existing level and trend of development in the future are also analyzed from the angles of study contents,the similarity theory,the mode1 scale,the test techniques and、on.It indicates that the experimental study should be greatly developed in the future and mainly focuses on the mechanism of danrbreak,and keeps improving the study level in order to provide protection for the dam safety of China.