Abstract: Traditionally,conceptual hydrological models are calibrated by optimizing the model parameters using a single objective function,which makes is difficult to properly consider all behavior of a natural hydrological system.To circumvent this problem,we propose a novel Multi-objective Culture Shuffled Complex Differential Evolution (MOCSCDE) algorithm for model calibration based on multi-objective functions in this paper.The MOCSCDE algorithm takes the Cultural Algorithms (CA) as the evolving framework and adopts the Shuffled Complex Evolution (SCE-UA) in the population space.This evolution strategy can make use of the problem-solving knowledge obtained along with the evolution process to guide the algorithm toward the optimization direction.Meanwhile,as the simplex search operator in the SCE-UA algorithm cannot use the whole information of the individuals,a Differential Evolution (DE) algorithm is employed to serve as a substitute of the simplex search operator.The DE algorithm can more thoroughly utilize the information of the population and enhance the search efficacy of the algorithm.The performance of the MOCSCDE algorithm is tested for parameter estimation of a conceptual hydrological model (Xinanjiang model).The MOCSCDE results are compared to those obtained with the NSGA-II and SPEA2 algorithms.It can be found that the MOCSCDE can get better convergence and spread performance,and can provide more reliable and comprehensive solutions in practical applications.
Abstract: Relief features (e.g.elevation and slope) and hydrological characteristics (e.g.reach length and reach slope) are basic parameters for distributed models of hydrology and water quality.These parameters provide quantified profiles for the natural watershed that is studied with the model.How well the model simulates the processes of water quantity and quality depends directly on the accuracies of those parameters.Currently,Digital Elevation Model (DEM) has been widely used to derive relief and hydrology characteristics in watershed models for hydrology and water quality.Impacts of 10 different resolution DEMs on mean elevation,subbasin area,subbasin slope,reach slope,and longest reach length were evaluated in 4 subbasins with different reliefs.The DEMs,with grid sizes of 1 m,2.5 m,5 m,10 m,20 m,30 m,40 m,80 m,90 m,and 160 m respectively,were resampled with TIN (Triangular Irregular Network) method from digital line graphic data at 1:10 000 scale.Results showed that watershed slope decreased with coarser DEM,and the terrain was smoothed.When DEM was resampled to a coarser one,the rainfall accumulation area and reach length changed along with the boundaries of subbasins and reach network,especially,in hilly areas where the terrains substantially changed within small ranges.No systemic trend was found in reach slope change with DEM resolution.This study reveals the uncertainty in distributed watershed model caused by DEM resolution in parameter level,and provides references for both model developers and users.
Abstract: Using the enhanced vegetation index (IEV) and land surface temperature (TLS) dataset derived from the TERRA/MODIS (Moderate Resolution Imaging Spectroradiometer) synthetic products MOD13 A2 (16-day composite,in DOY (Day of Year) 161-240 between 2001 and 2010,and DOY 145-288 in 2009) and MOD11 A2 (8-day composite,the same items of products with MOD13 A2),the TLS-IEV two-dimensional characteristic space can be constructed.The ITVD (temperature-vegetation drought index) is then extracted to indicate the top-soil moisture of northern Tibet.The intra-annual and inter-annual variations of soil moisture on the northern Tibetan Plateau are respectively analyzed for the 2009 growing season and the summer seasons (2001-2010).The results show that the intra-annual variation of TLS-IEV slope and the slopes of dry-edge and wet-edge will be smaller with the increase of vegetation cover,which indicates the buffering effect of vegetation on in environmental temperature changes.The intra-annual variation of top-soil moisture on the northern Tibetan Plateau appears to be significant.The variation is mainly due to the seasonal changes in temperature,precipitation,vegetation cover and frosting and ice-out of frozen soil.The droughty tendency in study area is detected in the variation of soil moisture in the last decade.However,the tendency appears to be varying in different climatic zones of the study area.The mean summer temperatures at seven weather stations in northern Tibet reveal a significant upward trend.The observed precipitation in the eastern region of northern Tibet suggests a slight downward trend.The inter-annual variations of precipitation can be observed at other stations.Furthermore,the inter-annual variability of soil moisture is in agreement with that of mean summer temperatures.
Abstract: Based on the TRMM (Tropical Rainfall Measuring Mission) 3B43 precipitation data,the Mann-Kendall test was performed and the Hurst index was calculated at the pixel scale to analyze the spatial-temporal dynamics of precipitation in global mid-low latitudes from 1998 to 2010.Furthermore,the "Monthly Calendar" and the seasonal evolvement map were drawn.It shows that,summers and early winters are the rainy period in a year.Significant fluctuations of monthly precipitation in the past 13 years can be observed.Over all,the precipitation shows a decreasing trend from the low latitude to the high latitude.Precipitation in the ocean is more than that on the land and therefore very significant sea-land gradient characteristics can be found.On monthly scale,the changing trends of precipitation in most areas are ‘increasing but not significant' or ‘decreasing but not significant',however,therere very strong self-similarity and long-range dependence for the 12 monthly time sequences of precipitation data.December shows the most prominent spatial differences of precipitation variation while March is the least significant one.On seasonal scale,more than 98% areas have very strong self-similarity and long-range dependence for the 4 seasonal time sequences of precipitation data; the spatial differences of precipitation variation are very significant in the seasonal evolvement map.The results and conclusions in this study are aimed at providing a useful reference on the research of global water cycle,global climate change and so on.
Abstract: The operation of the Three Gorges Reservoir (TGR) could potentially affect the flow regime in the Poyang Lake and its adopted flood control plan.In this paper,the theory of copula function is used to establish the joint probability distribution functions for hydrological variables in the "Yangtze River-Poyang Lake-five rivers" system without considering the TGR operation.These conditional probability distribution functions are then derived.It is assumed that the conditional distribution function remains unchanged in the system after the TGR operation.The new probability distribution functions for hydrological variables can be obtained after the TGR operation through analyzing the probability distribution function of discharges of the Yangtze River after the TGR operation and combining the new discharge probability distribution function with the previously established conditional probability distribution.The difference in the probability distribution functions before and after the TGR operation can be seen as the TGR impact on the flood control in the Poyang Lake.Results show that the pre-releases from the TGR in May and June will increase the water level of the Poyang Lake.The increase in average water level will be greater than that of the maximum water level,and the low water increase will be greater than that of the high water.Under the influence of the TGR operation,the water level is unlikely to exceed the currently adopted design value.Thus,the flood protection standard of the embankments for the Poyang Lake will remain unchanged after the TGR operation.
Abstract: The spatial-temporal variability of streamflow annual distribution during 1956 to 2009 in the Dongjiang River is analyzed.Both monthly observed and naturalized streamflow data and the monthly regional precipitation data are used in the study.The trend and change-point analysis are performed on the data to reveal the characteristics of streamflow.Likely contributions from various factors to the streamflow annual distribution are quantitatively analyzed.These factors include the climate change,the land use and coverage changes,the regulation of water reservoirs and the water consumption.The results show that the significant decreasing trend and change points in 1973 can be identified on the concentration and the nonuniformity in the observed streamflow data.The average change of the concentration degree in the naturalized streamflow data and the regional precipitation change are marginal.However,the nonuniform coefficient during 2000 to 2009 is significantly larger than that during the periods 1980-1989 and 1990-1999.The bigger catchment area is,the greater the concentration and the nonuniformity will be.The decrease of the concentration and nonuniformity is due to the effect of the regulations of water reservoirs and the land use and coverage changes; while,the increase is the result the water consumption and the climate change.The contributions to the spatial-temporal variability of streamflow annual distribution from the regulation of water reservoirs,the land use and coverage changes,the water consumption,and the climate change are respectively -33.5%,-9.0%,4.5% and 1.0%.Among the contribution from the regulation of water reservoirs,the Xinfengjiang,Fengshuba,and Baipenzhu reservoirs contribute -21%,-10%,-2%,respectively.There is an upward tendency in the contribution from the land use and coverage changes and the water consumption in the past 30 years.
Abstract: The aggregate is the fundamental structural unit of a soil.The destruction of a soil aggregate that is transported by overland flow may significantly affect the surface runoff and permeability of soils,sediment content and the general erosion intensity.Experiments were performed in a hydraulic flume with varying slope in flow discharge (0.4-1.2 L/s) and slope gradient (8.8%-46.6%) to investigate the quantitative effects of discharge,slope,flow depth and friction factor on the abrasion extent of red soil aggregates from two parent materials.The results indicated that the effect of discharge and slope on red soil aggregates abrasion extent from two parent materials were both significant,and the effect of slope were greater than discharge.The change regularities of aggregates abrasion extent were not the same at the different combination of discharge and slope.The results of this study suggested that the power function of the discharge and slope was the best equation for predicting the aggregates abrasion extent.The aggregates abrasion extent was decreasing with increasing flow depth and they were increasing with increasing friction factor.
Abstract: Based on the given probability distributions of hydraulic conductivity,porosity,and adsorption coefficient,a sequential Gaussian simulation method is used to generate multiple correlated stochastic parameter fields.The generated parameter values are used in groundwater flow and transport model simulations,and for the subsequent model uncertainty analysis.The results show that the consideration of the spatial variability of multiple correlated parameters in model simulations can result in a contamination plume spreading that is significantly different from that when only the spatial variability of hydraulic conductivity is considered.The contamination plume spreading is reduced when the porosity can be positively correlated to the hydraulic conductivity.On the contrary,the spreading is increased when the porosity can be negatively correlated to the hydraulic conductivity.The similar result is obtained for the adsorption coefficient.When the spatial variability of adsorption coefficient is further considered,the contamination plume spreading shows a long-tailed distribution.When taking into account the spatial variability of hydraulic conductivity,porosity,and adsorption coefficient,the effect of the heterogeneity of porosity on the contamination plume spreading will be greater than that of considering the adsorption coefficient.
Abstract: Climate extremes occur frequently and dam breach occasionally happens at present.It's very significant to present a fast and efficient discriminant method for earth-rock dam's stability under conditions of exceeding standard flood.However,this task is difficult because of the complex structure of dams and too many uncertain factors.In this paper by reference to the analysis methods for nature dam's safety,the discriminant analysis method was applied for earth-rock dam and the results showed it's feasible.The discriminant analysis and Casagli and Ermini's discriminant index IDB are better than the other methods.Both of them have high discriminant accuracy which reach 90 percent based on the samples in this paper.
Abstract: For researching bend flows,as well as expanding the application of the Lattice Boltzmann Method (LBM) in the water conservancy field,a 3D multi-relaxation times LBM model,which includes free surface simulation,curved boundary treatment and turbulence models solving,was established.U-type bend flows under different flow rates were simulated,and the distributions of water level,maximum depth-averaged velocities and turbulent kinetic energy were obtained.Both the theoretical analysis and the simulation result indicate that the model in the paper can adequately simulate 3D bend flows.
Abstract: Groundwater contamination event is hardly observed,and its circumstance has various uncertainties.Risk assessment provides a quantitative approach to evaluate the potential hazard of the contamination.This study develops a new method for risk assessment by using the stochastic collocation method and the polynomial sampling technique.The uncertainties from hydraulic conductivity,porosity and dispersivity are considered simultaneously.The risk distribution is assessed in a complex groundwater system.It is shown that our proposed model avoids the large number of repetitive solutions to the diffusion-dispersion equation.The low-cost stochastic collocation method is able to determine the Lagrange polynomials expression of the concentration field.The concentration samples are thus obtained by zero-cost polynomial sampling technique.Comparing to the traditional analytical methods,the new model does not adopt any assumption to the concentration distribution and the proposed model has superior efficiency and convergence property compared to the Monte Carlo simulation.The distribution type of input variable has significant influence to risk distribution.
Abstract: Through analyzing the characteristics of deuterium and oxygen-18 composition in precipitation,surface water and groundwater,this paper will reveal the isotopic effects of precipitation,the origin and evolution of groundwater,and estimate the mixing processes between various water bodies and groundwater discharge into the Minjiang River estuary.The hydrogen and oxygen isotopic compositions of precipitation are more depleted in heavy isotopes during summer,showing the so-called amount effect.The δ18O versus δD plots for two types of water samples are on the Fuzhou local meteoric water line (LMWL).The two water types are the fissure groundwater and the shallow groundwater respectively collected from a mountainous area in the north bank of the Minjing River estuary and a piedmont plain and hilly land.By contrast,the shallow groundwater samples collected from a piedmont plain and hilly land in the south bank of the Minjiang River estuary mostly fall in the lower right side of LMWL.The intersection points of the two fitted lines on LMWL are so close to the weighted average of isotopic composition of meteoric water during the local agricultural irrigation period from May to September.The result shows that the groundwater in the north bank is mainly recharged from meteoric water,while the groundwater in the south bank is simultaneously recharged from both irrigation water and meteoric water accompanied by a different degree of evaporation during the infiltration process.In addition to the groundwater from both sides of Minjiang River estuary,fracture water from the fracture zone also locally recharge into the estuary.The linear end member mixing model,the digital elevation model and the underground hydrologic analysis are combined to quantitatively study the groundwater contribution to the estuary and the mixing processes among various water sources.The modeling results show that the maximum mixing ratio of groundwater is up to 8.8% in the freshwater zone of the estuary including 0.4% of the fracture water.In the saltwater zone of the estuary,the ratio of freshwater (river water and groundwater) to seawater is 53:47,which includes approximately 1.7% of groundwater.The conservative estimate of groundwater discharge into the Minjiang River estuary is 87.0 m3/s which accounts for 12.8% of the Minjiang River runoff during the dry season.
Abstract: The climate at the Techi Reservoir catchment is suitable for fruit,vegetable,and tea cultivation.So,there are many fruit,vegetable,and tea fields located in the upper stream of the Techi Reservoir catchment.The fertilizers applied are thus washed into the Techi Reservoir during heavy rains.These fertilizers contain vast amounts of nitrogen and phosphorous nutrients,which support the growth of dinoflagellate Peridinium bipes.The dinoflagellate Peridinium bipes cells increase rapidly and as a result Peridinium bipes algal blooms occur.Conventionally,large spatial scale algal bloom studies are conducted using boats and point sampling.This is expensive and time consuming.Remote sensing data can acquire temporal,large spatial,and vast spectrum data and also track the past data.Remote sensing,which quantitatively measures the light reflected from the surface of the earth,is a powerful tool for studying regional-scale aquatic ecosystem dynamics.In this study,Landsat TM data were used to monitor dinoflagellate blooms in the Techi Reservoir with supervised classification in 1995 and the predicted accuracies for algal blooms reached above 87.5%.From the classification results,dinoflagellate blooms were predicted most serious in summer and smallest in winter.The phenomenon was associated with catchment management.The catchments are located in the upper stream of the Techi Reservoir.The results afforded us the entire algal bloom information for the Techi Reservoir instead of the conventional point data.The algal bloom areas and degree of potential seriousness were defined in this study.
Abstract: The analysis of total nitrogen balance in Taihu Lake is conducted using 2007-2010 patrol hydrometric and precipitation data.An investigation is carried out on the existing and planned engineering measures for controlling the total amount of pollutants entering Taihu Lake from multiple sources.Based on both analysis and investigation,a spatial and temporal reduction plan for total nitrogen loading from the Taihu Lake basin is proposed.A mathematical model for simulating lake water environmental problems is developed.The distribution of total nitrogen concentration in the lake is obtained using the model after the implementation of the engineering measures,and a controllable target is thus proposed.The result shows that the total volume of inflow and outflow in Taihu Lake reaches a value of 127.8×108 m3 including 24.9×108 m3 of precipitation that accounts for 19.5% of the total inflow.The annual exchange of total nitrogen loads is 4.47×104 t including 0.07×104 t of wet and dry deposition that can account for 15.5% of the total nitrogen loads.Thus,the nitrogen contribution from wet and dry deposition is significant and non-neglectable.The variation of wet and dry deposition is correlated well with precipitation.Using the simulation result of various water functional areas in the Taihu Lake basin,an average nitrogen value of 2.3 mg/L is proposed as the water quality controllable target for 2015 in the basin.The study provides the technical support and the scientific basis to water pollution control in Taihu Lake.
Abstract: Making use of the hydrological and meteorological data from 1957 to 2009 and remote sensing image data for oasis of the Keriya River basin in 2010,this paper analyzed the oasis stability scales based on the high and low flow variations of water resources by using the methods of Z index and water-heat balance model.The results showed that the runoff of the Keriya River presented obvious high and low flow variations.The water quantity of 1.583×108m3 was utilized to maintain the oasis stability in the downstream of the Keriya River basin.Presently,the artificial oasis of the Keriya River basin was stable during the high flow period.However,both low and medium flow periods were metastable.The stability scales of the regional artificial oasis during the high,medium,and low flow periods were 1 608-2 413 km2,1 157-1 736 km2,and 978-1 467 km2; respectively.However,under the high guarantee degree of water resources,the stability scales of artificial oasis should be controlled within the range of 978-1 736 km2.The research results can provide scientific references in order to realize the reasonable planning of oasis in Keriya River basin.
Abstract: Eco-hydrological impacts caused by urbanization are important issues in protecting and restoring river ecosystem.Given the importance of flow regime in maintaining river ecosystem integrality,an eco-hydrological indicator system including flow duration curve,peak flow frequency exceedance curve and T0.5 (The fraction of the simulation period that the peak flow rate exceeds the peak flow of the predevelopment 0.5-year storm) were developed by analyzing characteristics of current indicators and their feasibility in data-lacking area.Urbanization development degrees and their eco-hydrological impacts were simulated in a hydrological model SWMM (Storm Water Management Model).Results demonstrated that the higher imperviousness,the greater instantaneous flow,peak flow,frequency,duration and smaller T0.5.indicating a negative effect of urbanization on the river in ecology.
Abstract: This paper discusses the unreliability of extreme value statistical inference,its presentation,causes and ways of improving the reliability,practical methods and reliability evaluation.It advances the possibility of applying the phenomenon of super-fitting,sampling error,the domain of convergence criteria,the maximum likelihood estimation of refined estimates and rough estimates,the pan-likelihood estimation,multi-parent phenomenon,Monte Carlo stochastic simulation concepts or methods; and obtained reliable results of the extreme value statistical inference for the multiple meteorological elements of various weather station.The theory of small-sample statistics is initially formed.
Abstract: On the basis of summing up the research process of water-Ecological Shelter Zones (ESZ),the concept of the water-ESZ has been discussed and defined.The advances in the research of the optimal width and function are reviewed based on different types of the water-ESZ,which include river-ESZ,lake-ESZ and reservoir-ESZ.Then the design methods of optimization the width of water-ESZ are discussed based on technical applications of different subject type,which include ecology,hydrology,geography,remote sensing etc.The results indicate that there is no uniform and clear understanding about the standard of optimal width,the design method of the reservoir-ESZ's width in a watershed scale is the difficulty of determining optimal width of the water-ESZ.Eco-hydrological modeling based on the multi-subjects and multi-technology could be an effective approach in determining the water-ESZ's width,especially the reservoir-ESZ's width.
Abstract: The initial basin water rights assignment is not only the important premise that realize the reasonable water rights circulation and play a fundamental role in market allocation water resources,it is also the important content under the China socialist market economy condition to realize the basin water resources integrated dispatch and to alleviate water resources supply and demand contradiction.To provide technical support for promoting the construction process of China's water rights system and implementing the most stringent water resources management system,based on existing research results of two-dimensional water rights concept and connotation,and considering the research progress of the initial water rights allocation at home and abroad,the theoretical framework is put forward including the initial two dimensional water rights allocation(simplified initial allocation),the basin water resources optimal regulation based on the initial two-dimensional water rights(simplified as optimal regulation) and three-part real-time control,and further elaborated on the modeling process and support technology and its work relation of the above three elements.