基于分形插值的城市降雨时间序列精细化估算

基于分形原理对济宁市降雨时间序列进行精细化插值,对降雨数据的分形特征进行分析,通过MATLAB软件计算降雨分形插值,最终将分形插值与传统插值进行对比;所得结果可满足当前中小型城市的城市雨洪建模的降雨数据需求.     

降雨空间尺度对径流模拟的影响研究

通过分析不同分辨率的雷达降雨数据所产生的降雨空间分布的变化对径流模拟的影响发现:本文所用的基于DEM的蓄满产流分布式水文模型对降雨时间和空间的变化是比较敏感的;由于降雨空间分辨率的变化计算的径流总量、洪峰都有不同程度的变化,但是这种变化的大小又与降雨场的特征、流域面积的大小以及土壤含水量的变化有很大的关系:随着面平均降雨量(P BAS)的增减,洪量也随着增减,P BAS与洪量有很好的相关性;降雨CV值的增加导致洪峰和洪量都相应的增加;流域的面积越小洪峰和洪量对降雨空间变化就越敏感;在前期干旱的条件下降雨空间变化导致的洪峰和洪量的变化要比在湿润的条件下产生的洪峰和洪量的变化大。     

考虑降雨空间变化的流域产流模型

本文从确定性与随机性相结合的途径出发，将超渗产流模型与降雨空间变化的频率特性有机结合，引入流域降雨产流计算中，经在黄土地区四个流域的初步应用，表明模型具有模型具有物理概念明确，弹性大的特点，对不同面积大小的流域均具有良好的适用性。     

Symbiotic algal bacterial wastewater treatment: effect of food to microorganism ratio and hydraulic retention time on the process performance.

Algal incorporation into the biomass is important in an innovative wastewater treatment that exploits the symbiosis between bacterial activated sludge and microalgae (Chlorella vulgaris sp. Hamburg). It allows a good and easy algae separation by means of clarification. The effect of process parameters food to microorganisms ratio (F/M) and hydraulic retention time (HRT) on the process performance, evaluated by settleability, microalgae incorporation to biomass and nutrient removal, was studied. HRT hinted at a significant influence in the growth rate of algae, while F/M turned out to be important for stability when algae are incorporated into the biomass. This parameter also affects the total nitrogen removal of the treatment. Stable flocs with incorporated algae and supernatants with low free swimming algae concentrations were obtained at high HRT and low F/M values.     

Identification of sewer pipes to be cleaned for reduction of CSO pollutant load.

To reduce the CSO (Combined Sewer Overflow) pollutant discharge, one of the effective options is cleaning of sewer pipes before rainfall events. To maximize the efficiency, identification of pipes to be cleaned is necessary. In this study, we discussed the location of pipe deposit in dry weather in a combined sewer system using a distributed model and investigated the effect of pipe cleaning to reduce the pollutant load from the CSO. First we simulated the dry weather flow in a combined sewer system. The pipe deposit distribution in the network was estimated after 3 days of dry weather period. Several specific pipes with structural defect and upper end pipes tend to have an accumulation of deposit. Wet weather simulations were conducted with and without pipe cleaning in rainfall events with different patterns. The SS loads in CSO with and without the pipe cleaning were compared. The difference in the estimated loads was interpreted as the contribution of wash-off in the cleaned pipe. The effect of pipe cleaning on reduction of the CSO pollutant load was quantitatively evaluated (e.g. the cleaning of one specific pipe could reduce 22% of total CSO load). The CSO simulations containing pipe cleaning options revealed that identification of pipes with accumulated deposit using the distributed model is very useful and informative to evaluate the applicability of pipe cleaning option for CSO pollutant reduction.     

太湖流域降雨时空分布规律分析

以太湖流域140个雨量站1951-2001年的实测资料为基础,对影响流域降雨的因素进行了较为详尽的分析,比较清楚地揭示了太湖流域降雨的时空分布规律。     

On the issue of trend and noise in the estimation of extreme rainfall properties.

Up until today extreme rainfall properties are frequently applied in sewer design guidelines. Uncertainty in the estimation of such properties will hence directly influence the dimensions of sewers, structures and pumps. In this paper the issue of potential trend and noise in the estimation is investigated for 6 rain series ranging from 19 to 55 years in duration. Different to recent research that predicts a climate induced-increase in heavy precipitation no clear indication for such trend was found in the investigated historical rain series. Another important aspect is the length of the rain series that is required for the estimation of extreme rainfall properties and the associated uncertainty. The analysis indicates that at least a period of 10 years should be used for the estimation. But even so the possible deviation expressed in terms of the 90 percentile is in the order of 5 to 10% of the 'true value', defined as the value derived when the whole given series is used for the estimation.     

The effect of rainfall measurement uncertainties on rainfall-runoff processes modelling.

Rainfall data are a crucial input for various tasks concerning the wet weather period. Nevertheless, their measurement is affected by random and systematic errors that cause an underestimation of the rainfall volume. Therefore, the general objective of the presented work was to assess the credibility of measured rainfall data and to evaluate the effect of measurement errors on urban drainage modelling tasks. Within the project, the methodology of the tipping bucket rain gauge (TBR) was defined and assessed in terms of uncertainty analysis. A set of 18 TBRs was calibrated and the results were compared to the previous calibration. This enables us to evaluate the ageing of TBRs. A propagation of calibration and other systematic errors through the rainfall-runoff model was performed on experimental catchment. It was found that the TBR calibration is important mainly for tasks connected with the assessment of peak values and high flow durations. The omission of calibration leads to up to 30% underestimation and the effect of other systematic errors can add a further 15%. The TBR calibration should be done every two years in order to catch up the ageing of TBR mechanics. Further, the authors recommend to adjust the dynamic test duration proportionally to generated rainfall intensity.     

蒲河流域降雨侵蚀力时空分布规律研究

降雨侵蚀力时空分布规律是研究土壤侵蚀预报的基础,是反映流域降雨对土壤侵蚀程度的重要指标.根据蒲河流域9个水文气象站的日降雨量资料,分析蒲河流域的降雨侵蚀力时空分布规律.研究可知:蒲河流域在37年的长系列中,年降雨量与年降雨侵蚀力的变化趋势都呈逐步上升趋势,其变化趋势并不明显.全年降雨侵蚀力主要集中在6—9月,年内降雨侵...     

小区雨水利用工程的运行效果分析

结合北京某居住小区雨水利用工程的运行情况,阐述了该工程的雨水收集、利用情况,探讨了其在延迟径流流量峰值出现、涵养地下水源等方面的效果,结果表明居住小区开展雨水利用效果明显。     

灰色时序模型在变形监测中的应用

随着基坑工程的规模向更大、更深的方向发展,基坑变形规律的监测和研究具有重要的工程应用价值.笔者从灰色系统、时间序列及其组合模型三个方面对工程实例进行模拟,并将拟合结果与监测数据进行对比,分析了各模型的精度.     

灰色时序模型在变形监测中的应用

随着基坑工程的规模向更大、更深的方向发展,基坑变形规律的监测和研究具有重要的工程应用价值.笔者从灰色系统、时间序列及其组合模型三个方面对工程实例进行模拟,并将拟合结果与监测数据进行对比,分析了各模型的精度.     

观音寺闸裂缝处理及效果评价

1988年在观音寺水闸众多的裂缝中,对最严重的闸底板中部垂直于水流方向贯穿性裂缝进行了化学灌浆处理。1991年对水闸进行全面检测,统计裂缝127条,其中贯穿性裂缝24条。经计算分析认为对底板贯穿性裂缝灌浆材料的选择要求具有一定强度,抗渗性好,对混凝土结构变形有良好的适应性。经过比选,决定采用聚氨酯灌浆材料,底板贯穿性裂缝共分3层进行灌浆。对其它危害较大的裂缝灌改性环氧树脂浆液;危害较小的裂缝以及表面裂缝结合混凝土防碳化,使用丙乳砂浆进行表面粉刷封闭,整旧如新。通过观测测试,证明裂缝处理效果好,加固完成的第2年就经受了长江历史高水位的工时间考验,至今运行正常。     

Constructed wetlands for CSO treatment: an overview of practice and research in Germany.

Vertical flow treatment wetlands have been developed as very useful tools for treatment of combined sewage overflow. Several systems have been in operation for over 15 years. Based on recent research work, new technical guidelines now recommend systems with a drained filter of sand 0/2 mm and a throttled outflow. COD, NH4-N and SS removal rates of 85-99% can be expected from this type of filter. SS loadings that are too high and very long or frequent inundation affect the performance adversely. Information for successful long-term operation were derived from various existing plants.     

Quantification of infiltration into sewers based on time series of pollutant loads.

We introduce the concepts of a novel approach that allows for the quantification of infiltrating non-polluted waters by a combined analysis of time series of pollutant concentrations and discharged wastewater volume. The methodology is based on the use of automated sensors for the recording of the pollutant concentrations. This provides time series in a high temporal resolution that are suitable for a detailed data analysis and discussion on the underlying assumptions. The procedure is demonstrated on two examples from recent measurement campaigns in Switzerland.     

Multicriteria decision-aid method to evaluate the performance of stormwater infiltration systems over the time

Nowadays, stormwater infiltration systems are frequently used because of their ability to reduce flows and volumes in downstream sewers, decrease overflows in surface waters and make it possible to recharge groundwater. Moreover, they come in various forms with different uses. Despite these advantages the long term sustainability of these systems is questionable and their real performances have to be assessed taking into account various and sometimes conflicting aspects. To address this problem a decision support system is proposed. It is based on a multicriteria method built to help managers to evaluate the performance of an existing infiltration system at different stages of its lifespan and identify whether it performs correctly or not, according to environmental, socio-economic, technical and sanitary aspects. The paper presents successively: the performance indicators and the way they were built, the multicriteria method to identify if the system works properly and a case study.     

Interaction of oxygen concentration and retention of pollutants in vertical flow constructed wetlands for CSO treatment.

The EU Water Framework Directive (WFD) calls for a good quality of all water bodies. Retention soil filters (RSF) have been developed to treat discharges from combined sewers systems. RSF have proved over the past 15 years to be the most effective measure to meet the EU WFD standards, especially for small or particularly sensitive receiving waters, which require an enhanced reduction of emissions from combined sewer overflows (CSOs). The paper presents results from laboratory-scale experiments, in which the oxygen measurement in the filter plays a main role. The results show remarkable differences in oxygen concentrations in different filter depths. The highest oxygen consumption takes place in the upper part of the filter. In the lower part the re-aeration of sewage from the soil air dominates. This indicates that the biological activity is limited to the upper part of the filter. The availability of oxygen in the filter is a sign for degradation of wastewater compounds (ammonium, COD) under certain conditions and already takes place during the filter operation. The removal of ammonium especially cannot be strictly divided into phases of sorption during the loading and oxidation during the dry period any more.     

Use of ensemble simulations to evaluate the urban effect on a localized heavy rainfall event in Tokyo,Japan

Recently, localized heavy rainfall over highly urbanized areas has caused severe damage in Japan. Although studies have indicated that the presence of urban areas can intensify rainfall, the chaotic noise caused by differences in initial conditions can change the urban effect. Therefore, the usability of ensemble simulation methods for urban effects on a single localized heavy rainfall event must be clarified to synthesize state-of-the-art observations and numerical model studies. This study examined the difference in a localized heavy rainfall event under different initial conditions. We demonstrated the advantage of ensemble experiments using a cloud-resolving model to evaluate the urban effect. In this study, we focused on a localized heavy rainfall event that occurred over Tokyo on 5 August 2008 and killed five people working in a drainpipe. Two ensemble experiments were performed according to the lagged average forecasting (LAF) method. Each experiment had six members, with initial conditions spanning 6 h from 02 to 07 Local Standard Time (LST) on 5 August 2008. The model was integrated continuously through 18 LST for each run. The model had a horizontal grid resolution of 2 km. The first experiment (CTRL) used the actual land cover, anthropogenic heat, and geometric structures. The second experiment (PDDY) used an imaginary land cover in which the urban area was changed to paddy fields. Comparison of the ensemble means showed that the peak value of the maximum hourly rainfall decreased and the peak time was delayed in PDDY compared with CTRL. The smaller peak value and delayed peak time of rainfall in PDDY seemed to be caused by the weaker updraft associated with near-surface convergence, which was caused by weaker surface heating. Regardless of the difference caused by the initial conditions, the decrease in the peak value and the delay in the peak time were significant according to the t-test. Although the area was limited compared with near-surface temperature and horizontal wind convergence, a significant reduction in rainfall was also seen over the heavily urbanized area of Tokyo in the horizontal distribution of the difference in accumulated rainfall. These results indicate that although differences in the initial condition can change the modeled urban effect on rainfall, ensemble simulation methods can be used to examine the significance of the urban effect on a single localized heavy rainfall event.     

Extension of the IWA/COST simulation benchmark to include expert reasoning for system performance evaluation.

In this paper the development of an extension module to the IWA/COST simulation benchmark to include expert reasoning is presented. This module enables the detection of suitable conditions for the development of settling problems of biological origin (filamentous bulking, foaming and rising sludge) when applying activated sludge control strategies to the simulation benchmark. Firstly, a flow diagram is proposed for each settling problem, and secondly, the outcome of its application is shown. Results of the benchmark for two evaluated control strategies illustrate that, once applied to the simulation outputs, this module provides supplementary criteria for plant performance assessment. Therefore, simulated control strategies can be evaluated in a more realistic framework, and results can be recognised as more realistic and satisfactory from the point of view of operators and real facilities.     

坡面植被分布对降雨侵蚀的影响研究

在黄土高原约15°的自然荒草坡面上,对两个坡面小区进行野外模拟降雨实验,其中一个从坡顶向坡底逐渐破坏地表植被和结皮,另一个从坡底向坡顶逐渐破坏地表植被和结皮,分别对破坏过程中各种植被面积下的降雨产流产沙量进行比较,结果认为:在相同面积条件下,位于坡底的植被比位于坡顶的植被保水作用高2.4倍,保土作用高2.8倍;随着植被面积的减少,坡面产流量和产沙量呈不均匀的增加趋势,在不同的植被面积变化范围,坡面产流量和产沙量的增幅不同。