Abstract: The percentage of flow discharge is an important concept and tool proposed by the author to study non-equilibrium transportation of nonuniform sediment.In this paper the definition and expression for the percentog of flow discharge are presented.And then the three characteristics are revealed: the carrying capacity of the nonuniform sediment being able to expressed as the summation of uniform sediment using the percentage, the percentage of flow discharge equaling to size distribution of the bed material, and the percentage being the same as the percentage of energy.Based on the concept of this percentage it is proved that the bed material load, the wash load and the total load follow the same rule of the carrying capacity, and the composition of the carrying capacity and the expressions of size distribut ion of the carrying capacity and the effective bed material all can be derived.
Abstract: The main difference between resistances of subaqueous debris flows and the subaerial debris flows are the intermingling and shearing resistances acted on the surface of debris flows.By a series of experiments on the subaqueous debris flows and subaerial debris flows, we can get the velocity ratio of subaqueous debris flows and subaerial debris flows at the same condit ions.The characteristics of debris flow, such as the yield stress, are strongly affecting the velocity relationship of subaqueous debris flows and subaerial debris flows.An equation on the velocity relationship of subaqueous debris flows and subaerial debris flows is given based on the dimensionless yield stress and density of debris flows by non hydroplaning subaqueous debris flows experiments.With the subaerial debris flows calculating, this equat ion is good at calculating the velocity of non-hydroplaning subaqueous debris flows.
Abstract: The man-induced water diversion and consumption constitute a sub-system of the drainage basin water cycle system, namely, sub-system of side-branch water cycle.In this context, the main-stem water cycle is referred to as the water cycling processes including the runoff generation and movement from hill slopes and the diverse channels to the sea.Based on the data from the Yellow River, the man-induced side-branch water cycle and the main-stem water cycle are studied.The results show that since the late 1960s, the intensity of the side-branch water cycle and the ratio of the side-branch to the main-stem water cycles increase markedly, and the intensity of the main-stem water cycle decreases.Using the annual data, a number of multiple regression equations are established to express the relationship between the side-branch and main-stem water cycles and the influencing factors.The equations indicate that the contribution of variations in the irrigated land area, the annual precipitation and the annual temperature to the variation in the relative intensity of the side-branch water cycle are 86155%, 2118%, 11125%, respectively, and that the contribution of variations in the irrigated land area, the annual precipitation and the annual temperature and the area of soil-water conservation to the variation in the relative intensity of the main-stem water cycle are 57161%, 20178%, 11103%, 10157%, respectively.
Abstract: Based on the data of the number of flood hazard counties during 1644-1839 and 1840-1949 and the area of flooded cropland during 1950-2004,the periodic features of flood disaster over China since 1644 are analyzed in this paper.A uniform flood disaster series is established by the rermving trend from the on ginal data and standardizing the data then in each interval in order to make the data from different sources comparable and remove the effect of human factors.The methods of the classical spectrum analysis and Butteiworth filter are used to analyze the standard series.It is found that(1) changes of flood disaster over China during 1644-2004 is an integration of the different time-scale periodic oscillations dominated by the scales of 80 year,50-year,30-year and 20-year,and (2) the dominant periods are different in different times,which are the centennial scale oscillation during 1644-1833,and the 20-year scale periodic oscillation is sensitive in addition to the centennial scale oscillation during 1833-1920,while the interdecadal periodic oscillation is dominant after 1921 within which a change from 20-year to 30-year scale occurred in 1947.
Abstract: In this study, the heterogeneous flow transport patterns are investigated in various soil stmctures to address the flow heterogeneity issue.The objectives are to investigate heterogeneity of soil water flow and solute transport, to characterize the heterogeneity information included in different water and the concentration distribution patterns, and to exam the dye tracer method to visualize flow paths.The experunents were carried out in four different soils.The dyed preferential pathways were observed in all the experiments.The lognmmal distribution was used to descxlbe the heterogeneity of water flow patterns.Compared with water flow, the concentration distributions show higher heterogeneity and uncertainty.
Abstract: In order to know about concentration change of different fomn phosphorus and find out the contributed faotoxs during a whole wind wave process (including the periods of disturbance and calm wind), a simulated disturbance experiment was done.The results show that at the beginning of disturbance, suspended solid(SS)、total phosphorus(TP)、particle phosphorus (PP) and dissolved total phosphorus(DTP) in water increase remarkably; SS, TP and PP will reach their maximum value when the disturbance lasts half a day; SS, TP and PP need at least 10 days to drop to undisturbed level.During the disturbance period, DTP kept high value, but it drops immediately when the disturbance stops, while SRP had no big change during the whole process.Phosphorus combined with Fe (Fe-P) and Mn (Mn-P) in anaerobic sediment will be releases easily at the beginning of disturbance, then they sink to the bottom of water During the period of disturbance and a day after calm wind, the middle size particle of SS decreases constantly, which means SS is able to adsorb more and more phosphorus.Long time after calm wind, particle size become bigger and bigger for flocculation and SS brought by disturbance settled almost completely.The study states that the crease of oxygen in water, the percent growth of organic matter in SS and the decrease of particle size with the disturbance lasting can enhance SS's ability to absorb phosphorus, though the wind wave disturbance can bring much PP and DTP into water, which can be used directly or indirectly by algae.Activated phosphorus concentration in water has no big change as a result of the two processes interaction.
Abstract: The dissolved and particulate organic carbon (POC) at Yellow River estuary are studied by 4 cruises of April and September 2004, Septenber 2005 and April 2006, and simultaneously and consecutively measured in August 2003.The result indicates that POC in the total suspended sediment (TSS) is about 0.51% without variations from dry weather to wet one.With this uniformity, POC values are correlated well with the concentrations of the total suspended matter.Due to the terrestrial TSS dilution, the contribution of autochthonous POC to total POC appears when TSS < 200 mg/L,Φ<16μm portion of TSS increases in the composite particles, which causes the decrease of median size-particles after precipitation of particles, and the percentage of POC increases with the decrease of the particles size.More than 80% POC concentrates on particles with Φ<16μm, and POC in particles with Φ<32μm account for 95% flux from the Yellow River estuary to Bohai sea.65% of the total POC will be settled with the precipitation of particles in the maximum turbidity zone (MTz).When TSS=455 mg/L, the ratio of DOC/POC is 1.A linear distribution of DOC versus salinity are observed when S > 10 both in dry and wet weather, but the input of DOC in the sediments desorption process, when S < 10 range, will make DOC's effective concentration 10% and 20% higher respectively than in situ freshwater in dry and wet weather.
Abstract: The soil-water balance is very important in the ecosystem restoration in the typical water-wind erosion crisscross region on the Loess Plateau.An effective way to study the water balance is modeling.In this paper, a numerical model, soil-water-atmosphereplant model (SWAP), is used to simulate the water balances and evapotranspiration in different land use patterns based on field observations.The results of SWAP model simulating soil-water balance are consistent with the observed values in different land use patterns.The model can simulate soil-water dynamics of the loess slope land after some parameters are adjusted according to the measured values.The outputs of SWAP model can be used to analysis water balance daily, and the daily evapotranspirations of millet and alfalfa are 1.2-2.6 and 1.2-2.5, respectively.
Abstract: The parameters of alkalization including SAR,SDR,SSP,RSC,pH and total alkalinity of groundwater are calculated in order to accelerate deteriorated grassland improvement and sustainable utilization of groundwater.The equations of linear regression in these parameters of alkalization are analysed.The results show that:(1)sodium adsorption ratio(SAR) is linearly related to SSP,SDR and total alkalinity,the regression equations between SAR and SSP,SDR and total alkalinity are significant(p<0.0001),(2) shallow groundwater takes on a obvious characteristics of alkalization,and the harm of alkalization is from rmderate to very high,deep groundwater has a slight characteristics of alkalization,and extent of harm is very small,and (3) based on the irrigation water quality evaluation criterions by FAO(1994),the soil permeability could be deteriorated when the groundwater is usedfor irrigation,and the degree of deterioation on irrigated use is from slight to moderate.
Abstract: The drainage system is self formed by flow on certain geology, terrain and climate conditions, with obvious characteristic of self organization.In this paper a cellular model is developed to simulate the form and the development of the drainage system.By changing geology, terrain, and climate conditions, many drainage systems are acquired which coincide with the natural river system.The river system forming process is simulated by combined with the union water trough reality.A similar drainage system is also got on the basis of the flume experiments.A simplified model is formed, too, to simulate the development process of the Alake area, east Kunlun mountain, the headwaters of the Yellow River, and the result proves to be effective.
Abstract: In this aztide, the characteristic values of cross-section mean vozticity is chosen as the useful physical variable to evaluate the hydraulic conditions in the Chinese sturgeon habitat.The computing methods for the cross-section mean vozticity are developed.The distribution of mean vozticity is computed along Chinese sturgeon spawn field based on the field measured data.The range of vozticity strength is about 0.27/s to 0.85/s, but Chinese sturgeon spawns are distributed mainly over the area where the vozticity strength is larger than 0.4/s.It means that the Chinese sturgeon prefers in the water area with larger vozticity strength of cross-section in order to increase their fertilization rate.
Abstract: An empirical formula for the turbulence intensity in subemerged river flows with plant is deduced,considering tur bulence intensity as a function of velocity and its gradient.The existence of the turbulence intensity maximum is validated mathematically according to this formula.According to the laboratory experiments,the magnitude and location of the turbulence intensity maximum is influenced by both the submerged canopy and the river flow.The foliage-spacing influences the magnitude of the maximum turbulence intensity by increasing the resistance of river flow.The swing of the frond foliage contributes to the initial disturber of turbulence,therefore the location of this maximum is controlled by the canopy/water-depth ratio.The cross-sectional averaged velocity influences the stability of water flow and the height of bend canopy,therefore modifying the magnitude and location of this maximum.
Abstract: In order to study local scouring field near the pier with sediment control dam,the 3-D velocity field of the pier in monomer model is subtly measured by ADV velocimeter of Sontek.This paper analyses the velocity distribution in the scouring pool of pier and takes turbulent strength distribution in different direction.Three new characters for the local scours of piers with the sediment control dam are analyaed and the dam's applicability is brought forward.The flow field near the pier is simulated by the 3-D mathematical model with FCVM,and the computing resuts have finer coherence compared with the measured value of ADV.The characteristic of the 3-D velocity distribution in front of piers and its influence on the local scour of the pier are studied in detail with the data from the measurement and simulation.It is very useful to analyae thoroughly the flow field structure of piers with the complex boundary and the local scouring theory.
Abstract: A 3-D flow and matter transport numerical model is budded in the improved σ-coordinate system in this paper.A vertical transform coefficient is used in this work.The govern equations,the boundary conditions and the initialization condidons are obtained through the strict calculation.The rmdel is dispersed by finite difference method (FDM).The computation program is expressed wrath Fortran.The model and its program are confirmed by the test computation of the flow and the salinity process in part sea area of the Oujiang estuary.
Abstract: The tidal bore is getting weak greatly at the Qinlonggang position of the Yangtze River estuary since 2003.The reason is that the reclamation projects make the up and middle river segment to form a bend channel with the small change rate of the river width along the channel.At the same time,the condition of the river depth is meliorated.The occurrence of tidal bore is bated.On the other hand,the reasonable relation between local terrain and the average tide fluctuation rate at Qinlonggang is set up by introducing local terrain index.The research shows that the annual variatiion in the average tide fluctuation rate at Qinlonggang correspond to the course of human activity (e.g.the reclamation projects) and the variation in the local terrain.It also indicates that using whole section index for the tidal bore can not reflect the effect from the local terrain very well.Owing to the variation in the tidal bore at the north bayou of the Yangtze River estuary in recent years affecting the river bed evolution at the bifurcation area of the north and south branches,this research has realistic meaningfor the repairing of the water course and the utilization of the river banks.
Abstract: In this paper,the concept of generalized water environment carrying capacity (WECC) and its corresponding assessment index are put forward based on the analysis of generalized water environment system.The set pair analysis(SPA) method for regional WECC assessment is improved through introducing the entropy weight method.Taking Guangdong province as a case,the assessment indicator system is estabished according to the practical situation of water environment in Guangdong Province.The regional WECC in Guangdong province and its three sub-systems are comprehensively appraised by adopting the improved SPA method.Rnally,the improved measures of regional WECC are presented.
Abstract: The comprehensive assessment of water environment for urban stream(WEUS) aims at providing the essential information for its restoration.Starting with the idea of environment, this paper analyzes the concept of water environment of urban stream and its connotation.To fit for the objective of stream restoration, the index system, including morphology, hydrodynamics, water quality, zoology and landscape, is established, and the fitting assessment model is put forward.Furthermore, the above theory and method are applied to the case study of 6 representative reaches of the Ancient Canal in Zhenjiang city, and some suggestions are provided for the next restoration based on the result of evaluation.
Abstract: From the perspective of the characteristics of river ecosystem, this paper put forward to some new approaches to calculate the appropriate ecological flow with fish habitat and fish biomass.The method utilizes the long-term hydrological data to set up the relationship by traditional hydrological method; while the fish habitat method, according to the theory of stream rehabilitation ecology, namely calculating the appropriate ecological flow through the analysis of the relation between fish biomass and annual flow.Because of the shortage of the fish biomass data, the fishery quantities are replaced in this paper, and then with the relation between fishery quantities and flow, we can calculate the appropriate ecological flow.With the fish habitat method and the fish biomass method, the appropriate ecological flow of Songhuajiang river basin is studied.It shows that the results of the two methods are almost consistent.Commonly, the two methods can be considered as the validation for each other, the account error of the two methods is below 3%.Without the influence of backwater, the fish habitat method is adaptive to the rivers of various scales.Though the fish biomass method is usually adaptive to large floodplain river, it should be used with cautions for the small stream in mountains.
Abstract: Chlorosity, water level and river runoff from each saltwater intrusion observation station are collected in recent years (2004-2006) in Modaomen watercourse of Pear River Estary, south China, when the saltwater intrusion occurs.The daily and monthly change of chlorosity and water level at the observation stations are analyzed The correlations among salinity, runoff, estuarine chlorosity and the geometry of estuary are analyzed synthetically, and the model formula between salinity and other hydrological factors (runoff, geometry of estuary and Kx) are deduced.Then, the simulation model for saltwater intrusion length from river mouth in Modaomen watercourse is established Finally, the simulation values of the saltwater intrusion of Modaomen watercourse on January 12, 2006 are calculated based on the model and are very close to the observed values of field.Thus, the maximum length (chlorine: 250 mg/L, upper limit of drinking water) of the saltwater intrusion is calculated based on the modified model parameters of salinity So, in the dry season (usually last December to next March), the model can provide decision making for quick reaction to saltwater intrusion event, and the corresponding measures can be early adopted and the disaster of saltwater intrusion is able to be expected and reduced to the minimization.
Abstract: In this paper, the passive and active L/S band sensor (PALS) data obtained during SMEX02, which consists of airborne L-and S-band radar and radiometer data, are used for the estimat ion of soil moisture.First ly, the multiple regression analysis is performed by combining the two channels, the most active and passive channel to retrieve soil moisture, but no effective improvement is achieved, which suggests that the multiple regression combining active and passive channels is not useful for the retrieval of soil moisture, a new method for soil moisture retrieval from large-scale C-band spaceborne radiometer is modified only to perform more efficiently, and the PALS data are used to prove the applicability of the method to high-resolution airborne radiometer and other band of the electromagnetic wave spectrum In addit ion, the evaluation of the method is conducted quant itatively.
Abstract: The specular reflected light above water surface,including sun-glint and skyglint,is one of the key factors that affect remote sensing of water color.This paper aims to correct the sun-glint and sky-glint effects in measurements of upward radunce from water surface based on the polarized principle and the multi-angle polarized remote sensing.A polarization filter was placed in front of the sensor of ASD field spectrometer to obtain the polarized characteristics of water surface spectrum in various conditions.By contrast with the spectral obtained under different incident geometry and polarized conditions,the experimental results show that the reflected light can be corrected completely with an incident zenith angle of 53 degree (Brewster's angle) and zero polarized angle.And most of the reflected light can be corrected with a random incident angle and zero polarized angle.In conclusion,the reflected light can be reduced obviously or even removed completely based on the polarized principle,which provide important value to improve the accuracy of water color remote sensing.
Abstract: The new advances in hydrology stochastic simulation are introduced.Those advances are as following: the modification and presentation of stochastic models, and new advances in the application of hydrology stochastic simulat ion and knowledge of hydrology stochastic simulation.Finally the further study directions are prospected: (1) the physical and statistical characteristics of hydrology time series, (2) the nonparametric stochastic model and the nonlinear stochastic model, (3) the stochastic model based on basin system, (4) the approaches of application of more hydrological information during construct ing the stochastic model, and (5) the test and validation of stochastic hydrological model.
Abstract: The catchment can be viewed as complex open system.The nonlinear effect in hydrology is closely related to spatial and temporal scale.This paper reviews the research of hydrologic nonlinear effect in hydrology.The nonlinear mechanisms are summarized as follows: (1) the catchment organization patterns; (2) the interaction between water flow and the different subsystem in catchment; (3) the interaction between catchment system and environment; and (4) in different space-time scale level, the dominated factor and process changes.The future simulation development needs to pay attention to the myriad and complexity of catchments again and seek common threads in hydrologic processes.The nonlinear effect and scale effect in hydrology need to be explored further.The hydrology research methods are facing great challenge today.
Abstract: River management covers a wide range including irrigation, flood control, river ecology and environment etc., aiming at protecting and recovering the ecological function of river ecosystem.The vegetation is an important feature of ecological river.It provides the habitat for animals and is a key factor to maintain the healthy development of river.The vegetation changes flow characteristic and sediment and contaminant transport, and thus the flows with vegetation have been wide interested in rivermanagement and become a new important topic in river dynamics.This paper reviews the main research achievements of the flow with vegetation, including four main aspects: flows resistance, turbulence structure, sediment transport and passive scalar dispersion and transport.The main methods, conclusions and measurement techniques are introduced in detail and some limitation of recent research and the research tendencies are also discussed.