Abstract: This paper describes a flood routing method applied in an ungauged basin, utilizing the Muskingum model with variable parameters of wave travel time K and weight coefficient of discharge x based on the physical characteristics of the river reach and flood, including the reach slope, length, width, and flood discharge. Three formulas for estimating parameters of wide rectangular, triangular, and parabolic cross sections are proposed. The influence of the flood on channel flow routing parameters is taken into account. The HEC-HMS hydrological model and the geospatial hydrologic analysis module HEC-GeoHMS were used to extract channel or watershed characteristics and to divide sub-basins. In addition, the initial and constant-rate method, user synthetic unit hydrograph method, and exponential recession method were used to estimate runoff volumes, the direct runoff hydrograph, and the baseflow hydrograph, respectively. The Muskingum model with variable parameters was then applied in the Louzigou Basin in Henan Province of China, and of the results, the percentages of flood events with a relative error of peak discharge less than 20% and runoff volume less than 10% are both 100%. They also show that the percentages of flood events with coefficients of determination greater than 0.8 are 83.33%, 91.67%, and 87.5%, respectively, for rectangular, triangular, and parabolic cross sections in 24 flood events. Therefore, this method is applicable to ungauged basins.
Abstract: A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning’s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning’s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning’s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.
Abstract: The SEBAL (surface energy balance algorithm for land) model provides an efficient tool for estimating the spatial distribution of evapotranspiration, and performs a simple adjustment procedure to calculate sensible heat flux using the wind speed data set from only one weather station. This paper proposes a simplified method to modify the traditional SEBAL model for calculating the 24-hour evapotranspiration ( ) in the Haihe Basin with data from 34 weather stations. We interpolated the wind speeds using the inverse distance weighting method to establish a wind field and then used it to calculate the friction velocity directly. This process also simplifies the iterative computation process of sensible heat flux. To validate the feasibility of this simplified method, we compared the results with those obtained with an appropriate but more complex method proposed by Tasumi, which separates a vast area into several sub-areas based on the weather conditions, and runs the SEBAL model separately in each sub-area. The results show good agreement between the evapotranspiration generated by the two methods, with a coefficient of determination (r2) of 0.966, which indicates the feasibility of estimating evapotranspiration over a large region with the simplified method.
Abstract: In this study, the 54-year (1950 to 2003) monthly runoff series from February, April, August, and November, as well as the annual runoff series, measured at both Huayuankou and Lijin hydrological stations were chosen as representative data, and the continuous wavelet transform (CWT) was applied to analyze the impacts of human activities on the runoff regime of the middle and lower Yellow River. A point of change in 1970 was first determined, and the observed series before 1970 were considered natural runoff while those after 1970 were restored according to linear trends. Then, the CWT was applied to both the observed and restored runoff series to reveal their variations at multi-temporal scales, including the five temporal ranges of 1-4, 6-8, 9-12, 16-22, and 22-30 years, and the trend at the temporal scale of 54 years. These analysis results are compared and discussed in detail. In conclusion, because of the impacts of human activities, there have been significant changes in the runoff regime in the middle and lower Yellow River since 1970. The decaying tendency of annual runoff has become more pronounced, and the inner-annual distribution of runoff has changed, but human activities have had little impact on the periodic characteristics of runoff.
Abstract: The finite difference method and the VOF method have been used to develop a three dimensional numerical model to study wave interaction with a perforated caisson. And the partial cell method is also adopted to this type of problems for the first time. The validity of the present model, with and without the presence of structures, is examined by comparing the model results with experimental data. Then, the numerical model is used to investigate the effects of various wave and structure parameters on the wave forces and the wave runup of the perforated quasi-ellipse caisson. Compared with the solid quasi-ellipse caisson, the wave force of the perforated quasi-ellipse caisson is significantly reduced with the increasing of porosity on the perforated quasi-ellipse caisson. Furthermore, the perforated quasi-ellipse caisson can reduce the wave runup compared with the solid quasi-ellipse caisson. This reduction tends to increase as the porosity of the perforated quasi-ellipse caisson and relative wave height increase.
Abstract: In this paper, a hybrid improved particle swarm optimization (IPSO) algorithm is proposed for the optimization of hydroelectric power scheduling in multi-reservoir systems. The conventional particle swarm optimization (PSO) algorithm is improved in two ways: (1) The linearly decreasing inertia weight coefficient (LDIWC) is replaced by a self-adaptive exponential inertia weight coefficient (SEIWC), which could make the PSO algorithm more balanceable and more effective in both global and local searches. (2) The crossover and mutation idea inspired by the genetic algorithm (GA) is imported into the particle updating method to enhance the diversity of populations. The potential ability of IPSO in nonlinear numerical function optimization was first tested with three classical benchmark functions. Then, a long-term multi-reservoir system operation model based on IPSO was designed and a case study was carried out in the Minjiang Basin in China, where there is a power system consisting of 26 hydroelectric power plants. The scheduling results of the IPSO algorithm were found to outperform PSO and to be comparable with the results of the dynamic programming successive approximation (DPSA) algorithm.
Abstract: The process of decomposing p-nitrophenol (PNP) with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but not ultrasonic frequency, were controlled strictly at constant levels. The absorbency and the COD concentrations of the samples were measured in order to show the variation of the sample concentration. The results show significant differences in the trend of the solution degradation rate as acoustic power increases after the PNP solution (with a concentration of 114 mg/L and a pH value of 5.4) is irradiated for 60 min with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz. The degradation rate of the solution increases with time and acoustic power (acoustic intensity). On the other hand, the degradation rate of the solution is distinctly dependent on frequency when the acoustic power and intensity are strictly controlled and maintained at constant levels. The degradation rate of the PNP solution declines with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz; the COD concentration, on the contrary, increase.
Abstract: The land area in river network is divided into some foursquare cells with certain scale for the demand of precision, proceeding from the physical mechanism of the rainfall-runoff and runoff pollution, the non-point source pollution from cells are estimated using the export coefficient of different land use types. According to the terrain of plain river network area and the positions of land cells and river network’s reaches, a principle is advanced which indicates that the non-point source pollution from a land cell should all get into its closest reach. A corresponding relationship between a single land cell and its pollution receiving reach can be obtained under the principle. In view of the above, a spatial distribution model of the rainfall-runoff and non-point source pollution in reaches of plain river network area is established. The method can provide a technological support for the further research on the dynamic effect on water quality which is caused by non-point source pollution.
With the rapid development of aquaculture in lakes and reservoirs, its negative effects on water quality and aquatic organisms are clearly emerging. Toward a better understanding of these effects, chemical and biological monitoring was conducted in the Fangbian Reservoir to study the relationship between aquaculture and eutrophication. As a domestic water supply source, this reservoir has reached the mesotrophic level. The concentrations of total nitrogen (TN) and total phosphorus (TP) in the Fangbian Reservoir have frequently exceeded the prescriptive level according to the Environmental Quality Standards for Surface Water (GB3838-2002). Pond and fence aquaculture feeding is the main cause of high levels of nitrogen and phosphorus, accounting for nearly half of the total pollution, and causing the reservoir environmental capacity to be exceeded. The amounts of nitrogen and phosphorus that went directly to the reservoir through the residual bait and fish droppings in fence aquaculture were 42 768 kg per year and 10 856 kg per year respectively, from 2007 to 2009. About 2 913 kg of nitrogen and 450 kg of phosphorus were imported to the reservoir through the exchange of water from the culturing ponds at the same time. Therefore, controlling the aquaculture scale and promoting eco-aquaculture are key measures for lessening the eutrophication degree and improving the water quality. .
Abstract: Based on the sliding plane hypothesis of Coulumb earth pressure theory, a new method for calculation of the passive earth pressure of cohesive soil was constructed with Culmann’s graphical construction. The influences of the cohesive force, adhesive force, and the fill surface form were considered in this method. In order to obtain the passive earth pressure and sliding plane angle, a program based on the sliding surface assumption was developed with the VB.NET programming language. The calculated results from this method were basically the same as those from the Rankine theory and Coulumb theory formulas. This method is conceptually clear, and the corresponding formulas given in this paper are simple and convenient for application when the fill surface form is complex.
Abstract: This paper introduces the method of data envelopment analysis (DEA) for evaluation of the degree of harmony between water resources and economic development of the water conservancy area of China’s South-to-North Water Diversion Project (SNWDP). For this evaluation, a super-efficiency DEA (SEDEA) model was developed based on the super-efficiency method. To verify the applicability of the SEDEA model, both the SEDEA model and a normal-efficiency DEA (NEDEA) model were used to evaluate the degree of harmony between water resources and economic development of typical cities in the SNWDP water conservancy area. The results show that the SEDEA model ranks the degree of harmony of typical cities more efficiently than the NEDEA model, and thus can better evaluate the degree of harmony between water resources and economic development of different cities than the NEDEA model. Furthermore, the SEDEA model can be applied as an operational research tool in regional water resources management.
