An Integrated Modelling Approach for Flood Simulation in the Urbanized Qinhuai River Basin,China

Water Resources Management - The accurate simulation and prediction of flood response in urbanized basins remains a great challenge due to the spatial and temporal heterogeneities in land surface...     

经营成本变化对大庄电站经济效益的影响

我国水电蕴藏量居世界首位。近年来水电事业发展迅速,中小型水电项目的经济效益是投资者最为关注的内容,是影响投资者决策的首要因素。本文根据大庄水电站实际年运行费与设计阶段的经营成本对比,分析了经营成本变化的原因以及对项目经济效益的影响。分析结果显示,项目FIRR低于原设计标准,但高于新的财务基准收益率,项目连续亏损尚有其他原因,应做进一步分析。同时提出对经营成本与营业成本两个概念进行理论研究的建议。     

Global sensitivity analysis of outputs over rice-growth process in ORYZA model

Dynamic crop models usually have a complex structure and a large number of parameters. Those parameter values usually cannot be directly measured, and they vary with crop cultivars, environmental conditions and managements. Thus, parameter estimation and model calibration are always difficult issues for crop models. Therefore, the quantification of parameter sensitivity and the identification of influential parameters are very important and useful. In this work, late-season rice was simulated with meteorological data in Nanchang, China. Furthermore, we conducted a sensitivity analysis of 20 selected parameters in ORYZA_V3 using the Extended FAST method. We presented the sensitivity results for four model outputs (LAI, WAGT, WST and WSO) at four development stages and the results for yield. Meanwhile, we compared the differences among the sensitivity results for the model outputs simulated in cold, normal and hot years. The uncertainty of output variables derived from parameter variation and weather conditions were also quantified. We found that the development rates, RGRLMN and FLV0.5 had strong effects on all model outputs in all conditions, and parameters WGRMX and SPGF had relative high effects on yield in cold year. Only LAI was sensitive to ASLA. Those influential parameters had unequal effects on different outputs, and they had different effects at four development stages. With the interaction effects of parameter variation and different weather conditions, the uncertainty of model outputs varied significantly. However, the weather conditions had negligible effects on the identification of influential parameters, although they had slight effects on the ranks of the parameters' sensitivity for outputs in the panicle-formation phase and the grain-filling phase, including yield at maturity. The results suggested that the influential parameters should be recalibrated in priority and fine-tuned with higher accuracy during model calibration.     

An innovative method for determining hydrological calibration parameters for the WRF-Hydro model in arid regions

The techniques presented herein allow to directly determine certain crucial calibration parameters for the WRF-Hydro flood forecasting model. Typically, calibrations are chosen by an iterative, empirical, trial and error procedure. We suggest a more systematic methodology to arrive at a usable calibration. Our method is based on physical soil properties and does not depend on observed runoff from certain basins during specific storm events. Three specific calibration variables that most strongly affect the runoff predictions are addressed: topographic slope, saturated hydraulic conductivity, and infiltration. We outline a procedure for creating spatially distributed values for each of the three variables. Simulation runs are performed covering several storm events with calculated calibrations, with default values, and with an expert calibration. We show that our calibration, derived solely from soil physical properties, achieves forecast skill better than the default calibration and at least as good as an expert based calibration.     

隧道通风过程中空气湿热状态变化研究

隧道及巷道等地下工程在施工及运营阶段需要以自然或机械通风设施等方式进行通风,以保持充足的新鲜空气量,并维持其内人员的舒适感。当前大多研究集中在隧道通风过程中的空气质量以及烟雾透过率,而较少关注通风过程中空气的湿热状态的变化。以热力学及流体力学的基本理论为基础,研究地下隧道长距离、大规模地下输送新鲜空气过程中,隧道内空气湿热状态的变化。通过论证,在经过隧道长距离输送后,空气湿热状态参数发生较大变化。这说明,空气在地下输送过程中,尽管有风机做功以及摩擦生热过程,但在恒温层的保温作用下,温度只会略有上升;而湿度则会升至饱和状态。这将对地下储库、地下采矿等地下工程的空气调节系统设计研究工作有一定指导意义。     

An analytical procedure for multi-site,multi-season streamflow generation using maximum entropy bootstrapping

Stochastic time series models are very useful in many environmental domains. In this paper, an analytical procedure for multi-site, multi-season streamflow generation using maximum entropy bootstrap stochastic model (M3EB) is developed that can implicitly preserve both the spatial and temporal dependence structure, in addition to the other statistical characteristics present in the historical time series. The proposed model is computationally less demanding and simple in terms of modeling complexity. The maximum entropy bootstrap (MEB) generates random samples from the empirical cumulative distribution function (ECDF) and rearranges the random series based on the rank ordering of the historical time series. The modeling structure of MEB implicitly satisfies the ergodic theorem (preservation of summary statistics) and guarantees the reproduction of the time dependent structure of an underlying process. The orthogonal transformation is used with M3EB to capture the spatial dependence present in the multi-site collinear data. The performance of M3EB is verified by comparing the statistical characteristics between the observed and synthetically generated streamflows. Three case studies from Colorado River Basin, USA; Red River Basin, USA and Canada; and Cauvery River Basin, India; are used to demonstrate the advantages of M3EB. The statistical measures adopted for evaluation of M3EB performance include monthly statistics (mean, standard deviation and skewness), temporal and spatial correlation, smoothing (flows other than present in historical data) and extrapolation (flows outside the range of historical data). The M3EB model shows (i) a high level of accuracy in preserving the statistics; and (ii) a high computational efficiency. Since M3EB can be used for multiple variable problems, the model can be easily extended to other environmental or hydroclimatic time series data.     

An improved form of smoothed particle hydrodynamics method for crack propagation simulation applied in rock mechanics

The simulation of crack propagation processes in rock engineering has been not only a research hot spot among scholars but also a challenge. Based on this background, a new numerical method named improved kernel of smoothed particle hydrodynamics(IKSPH) has been put forward. By improving the kernel function in the traditional smoothed particle hydrodynamics(SPH) method, the brittle fracture characteristics of the base particles are realized. The particle domain searching method(PDSM) has also been put forward to generate the arbitrary complex fissure networks. Three numerical examples are analyzed to validate the efficiency of IKSPH and PDSM, which can correctly reveal the morphology of wing crack and the laws of crack coalescence compared with previous experimental and numerical studies.Finally, a rock slope model with complex joints is numerically simulated and the progressive failure processes are exhibited, which indicates that the IKSPH method can be well applied to rock mechanics engineering. The research results showed that IKSPH method reduces the programming difficulties and avoids the traditional grid distortion, which can provide some references for the application of IKSPH to rock mechanics engineering and the understanding of rock fracture mechanisms.     

Application of a dynamic numerical solution to high speed fracture experiments—I. analysis of experimental geometries

The application of a dynamic, generation mode, finite element program to the analysis of experimental geometries is reported. Particular attention is given to the DCB specimen, which is widely used in high speed fracture studies despite strong inertia effects, which are described. Finite strip and infinite plate results are also considered. Here, idealised cases are discussed, while in Part II the application of the analysis to experimental measurements, to derive propagating crack fracture resistance data, is reported.     

Impact of blasting parameters on vibration signal spectrum: Determination and statistical evidence

Research on the impact of blasting parameters on vibration signals is of significant value for guiding blast-resistant design. Previous research was primarily aimed at the impact on vibration amplitude in the time domain but rarely focused on energy distribution in the frequency domain (i.e., spectrum). Based on large amounts of blast signals from a series of events, in this study, the primary parameters that affect the vibration spectrum were determined. First, the K-means method was used to cluster all of the signals into six distinct spectrum clusters. The T test was then utilized among different clusters, to detect discrepancies in continuous parameters, including total charge, maximum charge, concrete age and distance between the explosion source and measuring point. Meanwhile, a random clustering simulation was conducted to determine whether the other two discrete parameters, i.e., the number of detonator relays and the explosion source location, influence the spectrums of vibration signals. The results show that three of the six parameters studied have a close link to the vibration spectrum, whereas the other three do not. This study also discusses how the parameters impact the occurrence and evolution of vibration signals.     

An Impact Assessment Method of Dam/Sluice on Instream Ecosystem and its Application to the Bengbu Sluice of China

A method is presented for impact evaluation of dams/sluices on their downstream aquatic ecosystems in the absence of detailed long-sequence ecology ecosystem data. It is based on the analysis of relations between indices of water quality and aquatic organisms. It can be applied to a river section absent of long-sequence ecology ecosystem data. For this study it was used to evaluate the effects of the Bengbu Sluice (BS), a typical sluice in the Huai River in China. Results indicate that in April and May the impact of BS on different downstream aquatic organisms varied. The most significant impact was on phytoplankton, with 91.7% of phytoplankton indices showing a 100% increase in quantity and biomass. The second most significant was on zooplankton, with 60.0% of zooplankton showing greater increase in quantity and biomass. The least significant impact was on zoobenthos, with only 33.3% showing greater increase in quantity and biomass. Most of these organisms have higher pollution-resistibility. These findings suggest that the present operation scheme will gradually lead to biodiversity decrease in the downstream aquatic ecology system, which will harm the instream aquatic ecology. Overall, BS has a negative impact on the downstream aquatic ecology system. It is argued that, in order to reduce the negative impact on the downstream aquatic ecology system, the operation of BS needs to be improved so that the discharge into the downstream river course is increased. Data comparison of the aquatic ecosystem condition between 1982 and 2006 also demonstrates the decreasing aquatic ecosystem quality downstream of BS.