Abstract: A coupled model integrating MODFLOW and TOPNET with the models interacting through the exchange of recharge and baseflow and river-aquifer interactions was developed and applied to the Big Darby Watershed in Ohio, USA. Calibration and validation results show that there is generally good agreement between measured streamflow and simulated results from the coupled model. At two gauging stations, average goodness of fit ( ), percent bias ( ), and Nash Sutcliffe efficiency ( ) values of 0.83, 11.15%, and 0.83, respectively, were obtained for simulation of streamflow during calibration, and values of 0.84, 8.75%, and 0.85, respectively, were obtained for validation. The simulated water table depths yielded average values of 0.77 and 0.76 for calibration and validation, respectively. The good match between measured and simulated streamflows and water table depths demonstrates that the model is capable of adequately simulating streamflows and water table depths in the watershed and also capturing the influence of spatial and temporal variation in recharge.
Abstract: Flood is essential for the regeneration and growth of floodplain forests in arid and semiarid regions. However, river flow, especially the flood, had changed greatly with the increase of water diversion from rivers and/or reservoir regulation, which may result in severer deterioration of the floodplain ecosystems. The estimation of appropriate flood stage to inundate the floodplain forests is necessary for their restoration or protection in flow regulation. To balance the economical water use and flood for the floodplain forest, we proposed the inundated forest width method to estimate minimum flood stage for floodplain forests from the inundated forest width – stage curve. The minimum flood stage was defined as the breakpoint of the inundated forest width – stage curve, and could be determined directly from the curve or analytically. For the latter case, the problem under consideration was described by a multi-objective optimization model, which can be solved by the ideal point method. In order to protect the forest in a river floodplain in semiarid area in Xinjiang that subjected to reservoir regulation in the upstream, the proposed method was used to determine the minimum flood stage and flow for the forest. Field survey on hydrology, topography and forest distribution was carried out at representative cross sections in the floodplain. Based on the surveying results, minimum flood flows for six representative cross sections were estimated to be 306 m3/s to 393 m3/s. Their maximum, 393 m3/s, was taken as the minimum flood flow for the studying river reach. It provides an appropriate flood flow for the protection of floodplain forest and can be used in the regulation of the upstream reservoir.
Abstract: This paper presented the application of autoregressive integrated moving average (ARIMA), seasonal ARIMA (SARIMA) and Jordan-Elman artificial neural networks (ANN) models in forecasting monthly streamflow in the Kizil River, Xinjiang, China. Two different types of monthly streamflow data (original and deseasonalized data) were used to develop time series and Jordan-Elman neural networks forecasting models using previous flow conditions as predictors. The one-month-ahead forecasting performance of all models for testing period (1998-2005) were compared using average monthly flow of Kalabeili Gaging Station on Kizil River, Xinjiang, China. The Jordan-Elman ANN models using previous flow conditions as inputs resulted no significant improvement in one-month-ahead forecasts over time series models. The results of this study suggested that simple time series models (ARIMA and SARIMA) models could be used in one-month-ahead streamflow forecasting at the study site with a simple, explicit model structure and similar model performance as the Jordan-Elman neural networks models.
Abstract: The purpose of the paper is to study the evolution mechanism of hydrochemical field and to promote unpredictable benefits to the living standards of local people and to the local economy in the southern plain area of Pengyang County, Ningxia, China. Based on the understanding of the hydrogeological conditions in Pengyang County, the chemical evolution characters of groundwater in the plain area were analyzed. PHREEQC geochemical modeling software was used to perform a hydrochemical modeling for water-rock interaction and to analyze quantitatively the evolution processes and the forming mechanism of the local groundwater. Geochemical modeling results showed that along path ①, Na+ adsorption played the leading role in the precipitation process and its amount was the largest, up to 6.08 mmol/L, cation exchange was obvious on path ①, while on simulated path ② albite took up the largest amount of dissolution, reaching 9.06 mmol/L, the cation exchange was not obvious along path ②. Some conclusions were summarized according to the modeling results that along the groundwater flow path, calcite and dolomite in the whole simulation showed oversaturated status with a precipitation trend, while the fluorite and gypsum throughout the simulated path were not saturated and showed a dissolution trend. Total dissolved solids (TDS) increased and water quality become worse along the flow path. Dissolution reactions of albite, CO2 and halite, exchange adsorption reaction of Na+ as well as precipitation action of sodium montmorillonite and calcite are the primary hydrogeochemical reactions which resulted in changes of hydrochemical ingredients.
Abstract: An analytical solution of drawdown caused by pumping is developed in an aquifer hydraulically connected to a finite-width stream on the condition of two streams. The proposed analytical solution modified Hunt’s analytical solution and not only considers the effect of stream width on drawdown, but also takes the distribution of drawdown on the interaction of two streams into account. Advantages of the solution include its simple structure, consisting of the Theis well function, parameters of aquifer and streambed semipervious material. The calculated results show that the proposed analytical solution agrees well with the previous solution and the errors between the two solutions are equal to zero on the condition of a stream without considering the effect of stream width. Also, deviations between the two analytical solutions increase with the increase of stream width. Furthermore, four cases are studied to discuss the effect of two streams on drawdown. It assumes that some parameters are changeable, and other parameters are constant, such as stream width, the distance between stream and pumping well, stream recharge rate, and the leakance coefficient of streambed semipervious material, etc. The analytical solution may provide estimates for parameters of aquifer and streambed semipervious material using the Type Curve Method through the data of field test
Abstract: The prediction of solitary wave run-ups has important practical significance in coastal and ocean engineering. But the precision of calculating is limited from the existing models. Artificial neural network technology has rapidly developed and been widely used in many fields. In this paper, a solitary wave run-up calculation model is established based on artificial neural networks. A BP network with one hidden layer is modified by an additional momentum method and an auto-adjusting learning rate. The correlation coefficients between the model results and the experimental values are 0.9635 and 0.9965, respectively. It is concluded that the neural network model is an appropriate methodology to be applied to solitary wave run-up scenario calculation and analysis.
Abstract: The finite element method (FEM) was used to simulate sediment hydrodynamics at the Beidaihe International Yacht Club, and a two-dimensional model was established. The sediment movement and deposition were analyzed under many tidal conditions in conjunction with the hydrological regime of the Daihe River. The peak value of the sediment deposition thickness appears in the main channel and around the estuary. The sediment deposition thickness is essentially constant and relatively small in the project area. The sediment deposition thickness in the main channel, in the yachting area, and around the hotel is greater than the other areas in the project. Regular excavation and dredging of the channel is the best measure for mitigating the sedimentation.
Abstract: The orifice plate energy dissipater is an economic and highly efficient dissipater. However, there is a risk of cavitaion around the orifice plate flow. In order to provide references for engineering practice, we examined the cavitation mechanism around the orifice plate and its influencing factors by utilizing mathematical analysis methods to analyze the flow conditions around the orifice plate in view of gas bubble dynamics. Through the research presented in this paper, the following can be observed: The critical radius and the critical pressure of the gas nucleus in orifice plate flow increase with its initial state parameter ; the development speed of bubbles stabilizes at a certain value after experiencing a peak value and a small valley value; and the orifice plate cavitation is closely related to the distribution of the gas nucleus in flow. For computing the orifice plate cavitation number, we ought to take into account the effects of pressure fluctuation. The development time of the gas nucleus from the initial radius to the critical radius is about 10-7-10-5 s; therefore, the gas nucleus has sufficient time to develop into bubbles in the negative half-cycle of flow fluctuation. The orifice critical cavitation number is closely related to the orifice plate size, and especially closely related with the ratio of the orifice plate radius to the tunnel radius. The approximate formula for the critical cavitation number of the square orifice plate that only considers the main influencing factor was obtained by model experiments.
Abstract: This paper presents important fundaments associated to the water/energy consumption and enhances the importance of renewable energy sources. A model of multi-criterion optimization for energy efficiency based on water and environment management policy, the preservation of the water resources, the control of water pressure and energy consumption, through a hybrid energy solution is developed and applied to a water supply system. The methodology developed includes three solutions: (i) water turbine installation in pipes where there is a need to control the pressure by pressure reducing valves, (ii) the optimization of pumping operations according to the electricity tariff and the water demand and (iii) the addition of a renewable energy source, a wind turbine, to supply energy to the pump-station and to sell the remaining to the national grid. The use of an integrated solution (water/energy) shows to be a valuable input to benefit from available hydro energy in WSS to produce clean power and the use of wind source allows reducing the energy consumption in pump-stations, which is still mostly based on fossil fuels with high levels of CO2 emissions.
Abstract: The flow field around spur dike is with three-dimension characteristic. To analysis the influences of the flow field on pollutant transport, based on compressive VOF scheme, the 3D transient compressive pollutant transport model CPTM and CE bounded differencing scheme were developed. For the calibration and validation of CPTM, laboratory experiments were carried out in a flume with a non-submerged spur dike. The spur dike was angled at 60, 90, and 120ο to the upstream. The simulations agreed with the experiments very well. The simulations and experiments showed that the distribution of pollutant concentration is decided by circumfluence and main flow. Concentration decay in circumfluence zone is slower than that in main flow. Behind of the spur dike,the concentration fluctuation increases with the increasing of spur dike angle.
Abstract: The West Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries-the Dadu River and Yalong River- to the upper Yellow River. The project may ease the water shortage in the Yellow River Basin. However, the project may have some effects on the ecosystem in the upper Yangtze River Basin. The benthic invertebrates play an important role in the river ecosystem and act on the circulation of materials and nutrition. The benthic invertebrates are widely applied to quickly assess the river ecosystem for their rapid response to the change of the water environment. The diversity of the benthic invertebrates is closely associated with the aquatic habitat area. This paper works on the coupling interaction between them by sampling in the benthic invertebrates in an area of expanding. The conclusions are drawn that the diversity of the benthic invertebrates will begin to decrease when the habitat area is reduced to 45% of the original area, and decrease greatly when the habitat area is reduce to 10%. The aquatic habitat area shall be kept more than 45% of the original area in order to maintain the high diversity of the benthic invertebrates. Keywords: West Route Project; River ecosystem; Benthic invertebrates; Biodiversity; Aquatic habitat area
