Abstract: With regard to the characteristics of waves,tidal currents,sediment and seabed evolution in Caofeidian sea area in Bohai Bay,a 2D sediment mathematical model under the coaction of waves and tidal currents is employed to study the development schemes.The verification of spring and neap tidal currents and sediment in winter of 2006 shows that the calculated values of tidal stages as well as flow velocities,flow directions and sediment concentration of 15 synchronous vertical lines are in good agreement with the measured ones.The deposition and erosion of the sea area in front of Caofeidian ore dock induced by suspended load under the co-action of tidal currents and waves are verified,and the calculated depths of deposition and erosion as well as their distribution are approximate to the measured ones.On such a basis,the effect of Caofeidian harbor reclamation scheme,that is,island in the front and land in the back,on hydrodynamic and sediment environment is studied,including change of flow velocities of the deep channel at the south side of Caofeidian foreland,Laolonggou and various harbor basins as well as the change of the deposition and erosion of the bed induced by the project.
Abstract: Vortex ripple is widely formed in the coastal region,and the dynamics of vortex is responsible for the sediment transport.The evolution of the initially flat sandy bed is studied in a laboratory wave tank under cnoidal wave conditions.The Acoustic Doppler Velocimeter(ADV)was used to acquire detailed velocity measurements at different positions.The nonlinear wave flow induces asymmetric rippled bed.CCD images were analyzed and the data on topography changes were obtained.The flow structure in the asymmetric rippled bed under the action of the cnoidal wave,and the complete process of the vortex formation,evolvement and disappearance were observed.The formation and the evolution of ripple were analyzed.A separation of the near-bed velocity field of the cnoidal waves over the asymmetric ripples indicates that the near-bed flow field is dominated by the turbulent motion,and the level of turbulence decreases with the increase of the distance away from the bed.The turbulence is anisotropic.The experiment result shows that the mechanism by which sand ripples maintain their shape is in the form of the dynamic equilibrium.Sediment may be lifted from the ripple face,picked up in suspension by the local velocity,and deposited over the crest and in the lee of the ripples.
Abstract: The potentiometric titration and dry-bulk density experiment was done using the sediment of different Ca2+ concentration in the Yellow River and the Yangtze River and some conclusions are given as following: ①The surface negative charge of sediment firstly unceasingly reduces and then tends stable with the increasing of the Ca2+ concentration;②The influence of the Ca2+ concentration on the dry-bulk density can be divided into three phases with the increasing of Ca2+ concentration:the first phase is that the dry-bulk density reduces,the second one is that the dry-bulk density increases and gets the maximal value,and the third one is that the dry-bulk density reduces and finally doesn't change;③When the Ca2+ concentration is equal,the influence of sediment concentration on the dry-bulk density has different change with the increasing of the Ca2+ concentration;④As the Ca2+ concentration and the sediment concentration are the same,the dry-bulk density will get bigger when the sediment median size increases,and the sand whose median size is big needs liter Ca2+ when its dry-bulk density gets the maximal value;And ⑤ the sediment electrostatic repulsion is different because of the dif erent surface negative charges in the different Ca2+ concentration,and the water film force is different,too.Both of two reasons show that the dry-bulk density reflects the above mentioned changes.
Abstract: The systems of soil plant environment can be controlled in greenhouse with the water heating migration mode, which is different from open field. In the paper,the crop canopy degrees are introduced and the air dynamics value is modified in Penman Monteith(P-M)equation. As a result,a modified P-M equation that can simplify the calculation of the reference crop evapotranspiration in greenhouse is obtained.The equation is analyzed theoretically and verified by the meteorological data.The results show that the daily evapotranspiration varies with the same trend as the climate factors,but the difference is not negligible. Its precision is higher and the result of the experiment is in accordance with the calculation value through the modified P-M equation.The results show a higher precision and with a daily relative deviation of the prediction 9.1% on average.
Abstract: The framework of optimization,fitting,re-optimization and simulation approach for deriving the optimal operating rules for cascade reservoirs is proposed and developed in this paper. Fmstly,the optimal data set is obtained by using the deterministic dynamic programming method to solve the optimization rmdel. Secondly,the operating rules are established by using the statistical analysis of the optimal data set. Thirdly,the operating rules are refined by using the simulation based optimization method. Finally,the operating rules are verified by using the synthetic inflow generated based on the stochastic hydrology. The Qingjiang cascade hydropower plants are selected as the case study.It is shown that the proposed method works well and can improve the hydropower generation greatly.
Abstract: The vertical velocity distributions in the vegetated channel and the relationship between resistance coefficient and flow depth were measured in laboratory experiments.Based on the assumption that the velocity in the region with vegetation keeps constant,the velocity distributions above the top of vegetation may be well predicted which closely fit the results of the experiment.And then the relationship between the resistane coefficient and flow depth for the vegetations under the unsubmerged and submerged conditions is deduced theoretically.Finally an example is given that the relationship between n and h for reeds is extended successfully from unsubmerged to submerged condition,and some experimental results approve such a conversion.
Abstract: The adjoint equations of the nonlinear shallow water conservative equations are set up,and the formulas for adjusting the open boundary conditions of unstructured triangular meshes are presented,based on the idea of the Godunov scheme and the Roe's scheme.The adjoint model used to invert the open boundary is founded based on the unstructured triangular meshes and finite volume method.The adjoint model is used to inverse the open boundary conditions of the generalized tidal bore estuary and the Qiantangjiang tidal bore estuary through some iterations.The average errors of amplitude along the open boundary are 0.000 6 m and 0.053 3 m respectively.The results indicate that the adjoint model is viable and adaptable to the discontinuous solutions.
Abstract: In this paper,forty nine lakes along the middle and lower reaches of Yangtze River are chosen. Based on the analysis of the seasonal changes of environmental parameters,including dissolved inorganic nitrogen(DIN),total nitrogen(TN), total phosphorus(TP),dissolved inorganic phosphorus(DIP)and chlorophyⅡ a(Chla),etc,the characteristics of water environmental change and the mechanisms of biological response in lakes of different nutrient levels are studied.The results show that the impacts of geochemical processes are reflected by the variational laws of lakes in dif erent nutrient levels.The seasonal variations of Chla,ammonia nitrogen(NH4-N),DIP,TP,and TN,especialy NH4-N are closely related to nutrient levels. When TP<0.05 mg/L,because NH4-N increases more quickly in winter than other seasons with TP increasing and TN/TP is closely related to nitrate-nitrogen(NO3-N)and TN,the composition of nutrient sources and ammonification might be the main determinant. When 0.5 mg/L < TP<0.10 mg/L,NH4-N increases equally in each season with TP increasing and TN/TP is closely related to NO3-N,nitrite-nitrogen(NO2-N)and TN,which suggests that the composition of nutrient sources,ammonification and denitrification might be the main determinant. When TP>0.1 mg/L,NH4-N increases more quickly in winter than other seasons with TP increasing and TN/TP are closely related to TN and NO3-N in spring and winter,but to TP in summer and autumn.The main reasons are that the effects of hydrophyte and denitrification and the internal release of phosphorus from sediment increase significantly.
Abstract: The model investigations of the vertical vortex at a horizontal intake are performed by a self made model.The particle movement at the surface of the vertical vortex is traced by a color pigment,which shows the moving trace is a multi-circle helical flow. According to the characteristics,the average tangential and axial velocities are obtained by the photography method and the image processing technique By comparison with the theoretical results,the simple and economic means is proved to be feasible.The influence on the vertical vortex formation of different approaching directions is also analyzed,and the result shows the oversize angle between the intake axis and the approaching direction is a factor of the vertical vortex generation.The formulas of the critical depth of submergence of different approaching directions are obtained by the measured data, and the formula is extended for the reference of the design.
Abstract: A major factor in deviation from optimal performance of the activated sludge secondary clarifier is the presence of density currents,resulting from the density difference and temperature difference. In this study,the density flow caused by the activated sludge and surface heat loss in radial clarifier is modeled with the Boussinesq approximation,the multiphase Eulerian model and the standard k-ε turbulent model on a two-dimensional grid. The water surface heat loss is estimated with the experiential equations.The calculations are reported to estimate the flow pattern,and the temperature and sludge distribution for activated sludge secondary clarifier and the results are compared with the experimental data.It is suggested that Frp2Gr/Re2 can be used for analyzing the major cause of the density currents,buoyancy force resulting from the temperature difference,or the gravitational force from the density difference.
Abstract: To investigate the characteristics of throughfall in citrus orchard in this study. Results show that:throughfal percentage of gross rainfall accounts for 68.3% during the whole measurement period.The maximal volume of throughfall(245.1 mm)occurred in May and the maximal throughfall percentage(73.3%)occurres in August. There is significantly positive correlation between throughfall and rainfall depth(p<0.01),as wel as the correlation between throughfall percentage and rain fall depth or rainfall intensity(p<0.05).The significant spatial variation in throughfall is observed below the canopy of citrus orchard. Moreover,the spatial heterogeneity of throughfal among different sampling sites varies significantly(p<0.05)and the CV of throughfal percentage decreases with the increase of rainfall depth or rainfall intensity. The cluster analysis shows throughfal percentage amongal sampling sites differs significantly(p<0.05),and the throughfall below the canopy has the evident rainfall concentration in citrus orchard.
Abstract: The current interest in ponds stems mainly from their utilization for irrigation,domestic use,livestock watering, fishing and so on.The ponds,whose distribution results from geomorphological erosion and development as well as human activities,are important components for hydrologicl cycle in irrigation system. Here we report the analyses of the ponds distribution from Zhanghe irrigation system to determine their frcatal structure based on the geographic information system(GIS).The ponds areas,both in the whole region and the sub regions,are close to the hyperbolic distribution and exhibit power law properties of the fractal structure for the scale invariance in probability spaces.The covering cell method is used to obtain the box dimension and information dimension of ponds distribution in the whole region and 14 sub-regions,and the results show that the ponds are fratal structures lying on the two dimensional space Lastly,the linear relations between the two-fratal dimentions and the topographic factors are analyzed.
Abstract: Heihe river basin,as one of the greatest inland rivers in China,is confronted with water resources scarceness due to the unreasonable development or utilization.To utilize the limited water resource effectively,the isotope techniques are widely used to study hydrological cycle.The variations of δ18O in different water are analyzed during the period of sampling using the data of precipitation,surface water and groundwater in Heihe river basin.It is found that δ18O is affected by rainfall, altitude,season and temperature.As is also shown through the multivariate linear regression equation,the most important factor affecting the δ18O is the temperature.The maximum,minimum and mean of δ18O in river water are lower at mountain outlets than those in mountain areas or in river basin.The change of δ18O with time in river water in mountain areas accords with that in precipitation,however at mountain outlets it is contrary to that in precipitation.The δ18O in river water increases progressively from the upper to the lower reaches of Heihe river.The δ18O fluctuates in a wide range in groundwater at Zhangye, in a more narrow range at Linze,and is divided into two parts at Gaotai.The δ18O in groundwater sampled in September is higher than those in J une at Linze.Conversely it is lower than that in June against the high δ18O part at Gaotai.Furthermore, the impact of different factors on the variations of δ18O in the process of water cycle and their interaction are evaluated in the study.Therefore,the isotopic technique can be widely applied to thorough study on the water cycle in Heihe river basin.
Abstract: Based on the Saint-Venant equations,the advection-diffusion equation and the uncertain mathematics theory,both a one-dimensional hydrodynamic model and a uncertain water quality mathematical model are established.The Preissmann implicit four-point scheme is used to solve the Saint-Venant equations,and the explicit scheme is used to solve the advection-equation.Two reasonable computational codings of hydrodynamic and water quality for the river network are conducted.The model considers the controlling projects of pump and brake,rainfall-runoff.The Computer program of the unsteady flow is compiled by using the three-level solution method for river network to solve the water level and the discharge at different cross sections.The data connection of the two sub-model is realized.The differential water quality model is computed based on the uncertain mathematics theory,including two unascertained parameters at the first time.According to the model proposed,both the interval values of pollutant concentration and the respective corresponding veliability can be obtained directly.The case shows that the hydrodynamic model and the uncertain water quality model for looping river network are reliable and can be applied to water quality regulation project and the water environmental assessment.
Abstract: Theory analysis is made about the feasibility of using system dynamics method for water resources carrying capacity evaluating in the paper first.Then the concept of deficiency coefficient of water supply and water demand is put forward for water resource carrying capacity evaluation.Based on the water resource characteristic of Jiangsu province,water resources carrying capacity is studied with the method of system dynamics.Eight typical models of Jiangsu water resources carrying capacity are formulated by calculating the economic growth rate,the water supply planning and the different guarantee rate,which are helpful for Jiangsu water resources carrying capacity building.
Abstract: Based on the aerial photos of sea ice floes in the marginal ice zone(MIZ)of Prydz bay near 69°00'S、76°24'E taken during the 21st Chinese. Antarctic Research Expedition(CHINARE2004),the image processing techniques are employed to extract many geometric parameters of ice floes in the MIZ.The variations of floe size parameters,such as area and mean caliper diameter(MCD)with increasing distance to open water are obtained. And according to the variation trend,the whole MIZ is divided into three zones made up of floes of quite different characterist ics:edge zone,transition zone and internal zone Such division is closely associated with the wave attenuation in the MIZ.The variation of floe roundness reveals that the floes in the transition zone receive most sufficient abrasion because of significant collisions in there Moreover,an improved power law function and a Weibull function fit the cumulative distribution of floe size,and the calculated parameters contained in the two functions give nice descriptions of the evolution of floe size distribution in the MIZ.The parameter Lr increases with the distance to open water,revealing the increase of max floe size with wave attenuation Scale parameter L0 increases with the distance to open water,showing the increase of average floe size and the proportion of large floes.The distribution dimension D decreases with the distance to open water,displaying the weakening of confinement degree as ice breakup Shape parameter decreases with the distance to open water,disclosing the widening range of floe size distribution.
Abstract: The characteristic values of drift ice,the freeze up and breakup dates in the Ningxia Inner Mongolia reach of Yellow River from 1950 to 2004 are analyzed,and their distributions are also showed.The maximum channel-storage increment are summarized.The result shows that the break-up from upstream to downstream in the Ningxia Inner Mongolia reach of Yellow River,the channel-storage capacity are constantly set free and added along the river,and the flood peak of ice flow is added along the river during the break-up period.The formation,development and dissolution course of ice regime are mainly decided by the river pattern,the hydrometeorological regime and human activity.The reservoir operation is an important influence on the evolution of ice regime.
Abstract: According to the workflow and role-based access control models,a model for flood control task integration management is presented to support the portal integration of the Flood Control Decision Support System(FCDSS).And the related integration management database is designed and applied to the flood task integration management system.It makes the system prossesses some important features,such as flexibility,integration,reusage and extensibility.Through the above models and techniques,the workflow-based flood task integration management system in the Heilongjiang province is developed,which has four main functions:the flood control task workflow management,the flood control organization management,the module man-agement of FCDSS and access control.And its effect is illustrated,too.
Abstract: In this paper,the advances in physical model distortion ratio study are introduced in three aspects of theoretical analysis,model experiments and numerical model.The recent experiments and numercal model for the distorted ratio study under the actions of tidal currents and waves are summarized.And the limitations of distortion ratio for flow,tidal currents,suspended and bed loads are given.
Abstract: The effective hydraulic properties of unsaturated soil are the key parameters in the quantitative modeling of water flow and solute transport in the vadose zone,which can be predicted by the pore network model.The major advantages of the pore network model are the direct and exact representation of the pore space topology and the pore-scale modeling of transport phenomena in soil.In recent years,the considerable progresses have been made in the image acquisition and processing,the pore network generation and the numerical solution techniques of the pore-scale models.The recent advances in pore network modeling in the vadose hydrology are reviewed,and the problems and the future development of this technique are also discussed.
Abstract: This paper briefly describes the history of the ecological economics and its basic viewpoints.The basic viewpoints are applied to the research of sustainable utilization of water resources.The issues such as the threshold of sustainable utilization of water resources,the second law of thermodynamics and interdependence of ecosystems are discussed.